Star Raiders source code by Lorenz Wiest#

Lorenz Wiest did a tremendous must see job with a complete commented Star Raiders source code at the highest level possible! Highly recommended!!!
Every assembly source code should look like this. The reader can take his work as a template on how to do it the right way!

Source Code in TXT-Format#

Read Me from Lorenz Wiest#

Fully documented, reverse-engineered STAR RAIDERS source code

During the last years, as a hobby afterhours project, I reverse-engineered a complete, extensively documented assembly language source code of STAR RAIDERS for the Atari 8-bit Home Computer System. I created it directly from the binary file of the ROM cartridge, finishing it in September 2015.

You may find it useful if you are curious about the internals of STAR RAIDERS or if you are planning to make your own, modified version.

After very positive reader feedback on the initial release of my reverse-engineered source code I reviewed it again, resulting in a minor update.

Enjoy -- Lorenz

PS: I was absolutely thrilled to learn that in October 2015 scans of the original STAR RAIDERS source code re-surfaced.

To my delight, inspection of the original source code confirmed the findings of my reverse-engineered version and caused only a few trivial corrections.

Even more, the documentation of my reverse-engineered version adds a substantial amount of information - from overall theory of operation down to some tricky details - to the understanding of the often sparsely commented original (quite expected for source code never meant for publication). So, if you are interested in learing how STAR RAIDERS works, my reverse-engineered source code could be of help to you.

References#

Source Code Listing#

              00001 ;*******************************************************************************
              00002 ;*                                                                             *
              00003 ;*                           S T A R   R A I D E R S                           *
              00004 ;*                                                                             *
              00005 ;*                  for the Atari 8-bit Home Computer System                   *
              00006 ;*                                                                             *
              00007 ;*       Reverse-engineered and documented assembly language source code       *
              00008 ;*                                                                             *
              00009 ;*                                     by                                      *
              00010 ;*                                                                             *
              00011 ;*                                Lorenz Wiest                                 *
              00012 ;*                                                                             *
              00013 ;*                            (lo.wiest(at)web.de)                             *
              00014 ;*                                                                             *
              00015 ;*                                First Release                                *
              00016 ;*                                 22-SEP-2015                                 *
              00017 ;*                                                                             *
              00018 ;*                                 Last Update                                 *
              00019 ;*                                 15-MAR-2016                                 *
              00020 ;*                                                                             *
              00021 ;*                STAR RAIDERS was created by Douglas Neubauer                 *
              00022 ;*                  STAR RAIDERS was published by Atari Inc.                   *
              00023 ;*                                                                             *
              00024 ;*******************************************************************************
              00025
              00026 ; I wrote this document out of my own curiosity. When STAR RAIDERS was released
              00027 ; in 1979 it became the killer app for the Atari 8-bit Home Computer System.
              00028 ; Since then I have always been wondering what made it tick and how its (at that
              00029 ; time) spectacular 3D graphics worked, especially the rotating star field.
              00030 ; Impressed by "The Atari BASIC Source Book" I decided to reverse-engineer the
              00031 ; STAR RAIDERS 8KB ROM cartridge to recreate a fully documented assembly
              00032 ; language source code file. I had no access to the original source code, so the
              00033 ; only way to succeed was a combination of educated guesses, trial-and-error,
              00034 ; and patience. Eventually, I made it.
              00035 ;
              00036 ; Essential in preparing this document were three programs I wrote:
              00037 ;
              00038 ; (1) A 6502-cross-assembler based on the syntax of the MAC/65 assembler for the
              00039 ;     Atari 8-bit Home Computer System to create the binary file that I verified
              00040 ;     against the binary of the original ROM cartridge.
              00041 ;
              00042 ; (2) A text formatter to layout the source code file with its copious comment
              00043 ;     sections. This was a big time saver, because as the documentation grew the
              00044 ;     source code had to be reformatted over and over again.
              00045 ;
              00046 ; (3) A symbol checker to verify that the ubiquitous symbol-value pairs in the
              00047 ;     documentation match the corresponding symbol values produced by the
              00048 ;     assembler.
              00049 ;
              00050 ; This assembly language source code file is compatible with the MAC/65
              00051 ; assembler for the Atari 8-bit Home Computer System. I was able to assemble it
              00052 ; on an emulated Atari running MAC/65, producing the identical binary of the ROM
              00053 ; cartridge.
              00054 ;
              00055 ; Your feedback is welcome! Send feedback to lo.wiest(at)web.de.
              00056 ;
              00057 ; Enjoy! -- Lorenz
              00058
              00059 ;*******************************************************************************
              00060 ;*                                                                             *
              00061 ;*                               N O T A T I O N                               *
              00062 ;*                                                                             *
              00063 ;*******************************************************************************
              00064
              00065 ; BITS AND BYTES
              00066 ;
              00067 ; o   A "byte" consists of 8 bits. They are numbered B7..0. Bit B0 is the least
              00068 ;     significant bit.
              00069 ;
              00070 ; o   A "word" consists of 16 bits. They are numbered B15..B0. Bit B0 is the
              00071 ;     least significant bit. A word is stored in low-order then high-order byte
              00072 ;     order.
              00073 ;
              00074 ; o   The high-order byte ("high byte") of a word consists of bits B15..8 of the
              00075 ;     word.
              00076 ;
              00077 ; o   The low-order byte ("low byte") of a word consists of bits B7..0 of the
              00078 ;     word.
              00079 ;
              00080 ; NUMBERS
              00081 ;
              00082 ; o   The dollar sign ($) prefixes hexadecimal numbers.
              00083 ;     Example: $101 is the decimal number 257.
              00084 ;
              00085 ; o   The percent sign (%) prefixes binary numbers.
              00086 ;     Example: %101 is the decimal number 5.
              00087 ;
              00088 ; o   The asterisk (*) is a wildcard character for a single hexadecimal or
              00089 ;     binary digit.
              00090 ;     Example: $0*00 is a placeholder for the numbers $0000, $0100, ..., $0F00.
              00091 ;
              00092 ; o   The lowercase R (r) is a wildcard character for a single random
              00093 ;     hexadecimal or binary digit. The random digit r is chosen by a random
              00094 ;     number generator.
              00095 ;     Example: %00r0 is a placeholder for the numbers %0000 or %0010.
              00096 ;
              00097 ; OPERATORS
              00098 ;
              00099 ; o   The exclamation mark (!) is the binary OR operator.
              00100 ;     Example: $01!$02 is $03.
              00101 ;
              00102 ; o   The less-than sign (<) indicates bits B7..0 of a word.
              00103 ;     Example: <$1234 is $34.
              00104 ;
              00105 ; o   The greater-than sign (>) indicates bits B15..8 of a word.
              00106 ;     Example: >$1234 is $12.
              00107 ;
              00108 ; o   A pair of brackets ([]) groups mathematical expressions.
              00109 ;     Example: [3-1]*4 is 8.
              00110 ;
              00111 ; ASSEMBLY LANGUAGE
              00112 ;
              00113 ; o   The uppercase A (A) indicates the accumulator register of the 6502 CPU.
              00114 ;
              00115 ; o   The uppercase X (X) indicates the X register of the 6502 CPU.
              00116 ;
              00117 ; o   The uppercase Y (Y) indicates the Y register of the 6502 CPU.
              00118 ;
              00119 ; o   The prefix uppercase L and dot (L.) indicates a local variable, a memory
              00120 ;     location used temporarily in a subroutine.
              00121 ;
              00122 ; PSEUDO-FUNCTIONS
              00123 ;
              00124 ; o   The function ABS(<num>) returns the absolute value of <num>.
              00125 ;     Example: ABS(3) returns 3.
              00126 ;     Example: ABS(-3) returns 3.
              00127 ;
              00128 ; o   The function RND(<num1>..<num2>) returns a random integer in
              00129 ;     <num1>..<num2>.
              00130 ;     Example: RND(3..5) returns a random number out of 3, 4, or 5.
              00131 ;
              00132 ; o   The function MAX(<num1>,<num2>) returns the larger number of <num1> and
              00133 ;     <num2>.
              00134 ;     Example: MAX(2,4) returns 4.
              00135 ;
              00136 ; VECTORS
              00137 ;
              00138 ; o   The lowercase X (x) indicates the x-axis of the 3D coordinate system.
              00139 ;
              00140 ; o   The lowercase Y (y) indicates the y-axis of the 3D coordinate system.
              00141 ;
              00142 ; o   The lowercase Z (z) indicates the z-axis of the 3D coordinate system.
              00143 ;
              00144 ; o   Components of a position vector (called "coordinates") have the arbitrary
              00145 ;     unit <KM> ("kilometers").
              00146 ;
              00147 ; o   Components of a velocity vector have the arbitrary unit <KM/H>
              00148 ;     ("kilometers per hour").
              00149 ;
              00150 ; o   A positive component of a position vector (coordinate) in hexadecimal
              00151 ;     notation is written in the form +$<hexNum> <KM>. <hexNum> is an unsigned
              00152 ;     integer value.
              00153 ;     Example: The starbase is +$1000 (or 4096) <KM> ahead of our starship.
              00154 ;
              00155 ; o   A negative component of a position vector (coordinate) in hexadecimal
              00156 ;     notation is written in the form -($<hexNum>) <KM>. <hexNum> is an unsigned
              00157 ;     integer value. To calculate the actual bit pattern of this coordinate
              00158 ;     value compute the two's-complement of <hexNum>. See also "ON POSITION
              00159 ;     VECTORS".
              00160 ;     Example: The starbase is -($1000) (or -4096) <KM> behind our starship.
              00161 ;
              00162 ; o   An absolute component of a position vector (coordinate) in hexadecimal
              00163 ;     notation is written in the form $<hexNum> <KM>. <hexNum> is an unsigned
              00164 ;     integer value.
              00165 ;     Example: The Zylon fighter fires when it is closer than $1000 (or 4096)
              00166 ;              <KM>.
              00167 ;
              00168 ; DISPLAY LIST
              00169 ;
              00170 ; o   The following notation is used for Display List instructions:
              00171 ;
              00172 ;     BLK<n>           = Display <n> blank video lines (<n> in 1..8)
              00173 ;     GR1              = Display one GRAPHICS 1 row of 20 text characters
              00174 ;     GR2              = Display one GRAPHICS 2 row of 20 text characters
              00175 ;     GR7              = Display one GRAPHICS 7 row of 160 pixels
              00176 ;     DLI              = Trigger a Display List Interrupt
              00177 ;     ... @ <addr>     = Point to screen memory at address <addr>
              00178 ;     JMP @ <addr>     = Jump to next Display List instruction at address <addr>
              00179 ;     WAITJMP @ <addr> = Wait for vertical blank phase, then jump to next
              00180 ;                        Display List instruction at address <addr>
              00181 ;
              00182 ; MISCELLANEOUS
              00183 ;
              00184 ; o   Probabilities are written in the form <percentage>% (<number of values out
              00185 ;     of the possible values>:<number of possible values>).
              00186 ;     Example: The probability to throw the number 3 with a die is 16% (1:6).
              00187 ;
              00188 ; o   A "game loop iteration" (or "game loop") is a single execution of the game
              00189 ;     loop, the main program of the game.
              00190 ;
              00191 ; o   A "TICK" is the time span it takes to update the TV screen (1/60 s on an
              00192 ;     NTSC TV system, 1/50 s on a PAL TV system).
              00193 ;
              00194 ; o   A pair of braces ({}) encloses color names.
              00195 ;     Example: {BLACK}
              00196 ;
              00197 ; o   A pair of parentheses enclosing a question mark ((?)) indicates code that
              00198 ;     is not well understood.
              00199 ;
              00200 ; o   A pair of parentheses enclosing an exclamation mark ((!)) indicates a
              00201 ;     potential bug.
              00202
              00203 ;*******************************************************************************
              00204 ;*                                                                             *
              00205 ;*                               O V E R V I E W                               *
              00206 ;*                                                                             *
              00207 ;*******************************************************************************
              00208
              00209 ; ON POSITION VECTORS
              00210 ;
              00211 ; The program uses a 3D coordinate system with the position of our starship at
              00212 ; its center and the following coordinate axes:
              00213 ;
              00214 ; o   The x-axis points to the right.
              00215 ; o   The y-axis points up.
              00216 ; o   The z-axis points in flight direction.
              00217 ;
              00218 ; By the way, this is called a "left-handed" coordinate system.
              00219 ;
              00220 ; The locations of all space objects (Zylon ships, meteors, photon torpedoes,
              00221 ; starbase, transfer vessel, Hyperwarp Target Marker, stars, and explosion
              00222 ; fragments) are described by a "position vector".
              00223 ;
              00224 ; A "position vector" is composed of an x, y, and z component. The values of the
              00225 ; position vector components are called the x, y, and z "coordinates". They have
              00226 ; the arbitrary unit <KM>.
              00227 ;
              00228 ; Each coordinate is a signed 17-bit integer number, which fits into 3 bytes:
              00229 ;
              00230 ;     Sign     Mantissa
              00231 ;          B16 B15...B8 B7....B0
              00232 ;            | |      | |      |
              00233 ;     0000000* ******** ********
              00234 ;
              00235 ; o   B16 contains the sign bit. Used values are:
              00236 ;       1 -> Positive sign
              00237 ;       0 -> Negative sign
              00238 ; o   B15..0 contain the coordinate value (or "mantissa") as a two's-complement
              00239 ;     integer number.
              00240 ;
              00241 ; The range of a position vector component is -65536..+65535 <KM>.
              00242 ;
              00243 ; Examples:
              00244 ;
              00245 ;     00000001 11111111 11111111 = +65535 <KM>
              00246 ;     00000001 00010000 00000000 =  +4096 <KM>
              00247 ;     00000001 00001111 11111111 =  +4095 <KM>
              00248 ;     00000001 00000001 00000000 =   +256 <KM>
              00249 ;     00000001 00000000 11111111 =   +255 <KM>
              00250 ;     00000001 00000000 00010000 =    +16 <KM>
              00251 ;     00000001 00000000 00001111 =    +15 <KM>
              00252 ;     00000001 00000000 00000001 =     +1 <KM>
              00253 ;     00000001 00000000 00000000 =     +0 <KM>
              00254 ;
              00255 ;     00000000 11111111 11111111 =     -1 <KM>
              00256 ;     00000000 11111111 11111110 =     -2 <KM>
              00257 ;     00000000 11111111 11110001 =    -15 <KM>
              00258 ;     00000000 11111111 11110000 =    -16 <KM>
              00259 ;     00000000 11111111 00000001 =   -255 <KM>
              00260 ;     00000000 11111111 00000000 =   -256 <KM>
              00261 ;     00000000 11110000 00000001 =  -4095 <KM>
              00262 ;     00000000 11110000 00000000 =  -4096 <KM>
              00263 ;     00000000 00000000 00000000 = -65536 <KM>
              00264 ;
              00265 ; The position vector for each space object is stored in 9 tables:
              00266 ;
              00267 ; o   XPOSSIGN ($09DE..$0A0E), XPOSHI ($0A71..$0AA1), and XPOSLO ($0B04..$0B34)
              00268 ; o   YPOSSIGN ($0A0F..$0A3F), YPOSHI ($0AA2..$0AD2), and YPOSLO ($0B35..$0B65)
              00269 ; o   ZPOSSIGN ($09AD..$09DD), ZPOSHI ($0A40..$0A70), and ZPOSLO ($0AD3..$0B03)
              00270 ;
              00271 ; There are up to 49 space objects used in the program simultaneously, thus each
              00272 ; table is 49 bytes long.
              00273 ;
              00274 ; o   Position vectors 0..4 belong to space objects represented by PLAYERs
              00275 ;     (Zylon ships, meteors, photon torpedoes, starbase, transfer vessel, and
              00276 ;     Hyperwarp Target Marker).
              00277 ; o   Position vectors 5..48 belong to space objects represented by PLAYFIELD
              00278 ;     pixels. Position vectors 5..16 (stars, explosion fragments) are used for
              00279 ;     stars, position vectors 17..48 are used for explosion fragments and star
              00280 ;     trails.
              00281 ;
              00282 ; INFO: The x and y coordinates of space objects are converted and displayed by
              00283 ; the THETA and PHI readouts of the Control Panel Display in "gradons". The
              00284 ; z-coordinate is converted and displayed by the RANGE readout in "centrons".
              00285 ; The conversion takes place in subroutine SHOWDIGITS ($B8CD) where the high
              00286 ; byte of a coordinate (with values $00..$FF) is transformed with lookup table
              00287 ; MAPTOBCD99 ($0EE9) into a BCD value of 00..99 in "gradons" or "centrons".
              00288 ;
              00289 ;
              00290 ; ON VELOCITY VECTORS
              00291 ;
              00292 ; The velocities of all space objects are described by a "velocity vector". The
              00293 ; velocity vector is relative to our starship.
              00294 ;
              00295 ; A "velocity vector" is composed of an x, y, and z component. The values of the
              00296 ; velocity vector components are called the x, y, and z "velocities". They have
              00297 ; the arbitrary unit <KM/H>.
              00298 ;
              00299 ; Each velocity vector component is an 8-bit integer number, which fits into 1
              00300 ; byte:
              00301 ;
              00302 ;     B7 Sign
              00303 ;     |
              00304 ;     |B6...B0 Mantissa
              00305 ;     ||     |
              00306 ;     ********
              00307 ;
              00308 ; o   B7 contains the sign bit. Used values are:
              00309 ;     0 -> Positive sign, movement along the positive coordinate axis
              00310 ;          (x-velocity: right, y-velocity: up, z-velocity: in flight direction)
              00311 ;     1 -> Negative sign, movement along the negative coordinate axis
              00312 ;          (x-velocity: left, y-velocity: down, z-velocity: in reverse flight
              00313 ;          direction)
              00314 ; o   B6..B0 contain the velocity value (or "mantissa"). It is an unsigned
              00315 ;     number.
              00316 ;
              00317 ; The range of a velocity vector component is -127..+127 <KM/H>.
              00318 ;
              00319 ; Examples:
              00320 ;
              00321 ;     01111111 = +127 <KM/H>
              00322 ;     00010000 =  +16 <KM/H>
              00323 ;     00001111 =  +15 <KM/H>
              00324 ;     00000001 =   +1 <KM/H>
              00325 ;     00000000 =   +0 <KM/H>
              00326 ;
              00327 ;     10000000 =   -0 <KM/H>
              00328 ;     10000001 =   -1 <KM/H>
              00329 ;     10001111 =  +15 <KM/H>
              00330 ;     10010000 =  +16 <KM/H>
              00331 ;     11111111 = -127 <KM/H>
              00332 ;
              00333 ; The velocity vector for each space object stored in 3 tables:
              00334 ;
              00335 ; o   XVEL ($0B97..$0BC7)
              00336 ; o   YVEL ($0BC8..$0BF8)
              00337 ; o   ZVEL ($0B66..$0B96)
              00338 ;
              00339 ; There are up to 49 space objects used in the program simultaneously, thus each
              00340 ; table is 49 bytes long.
              00341 ;
              00342 ; o   Velocity vectors 0..4 belong to space objects represented by PLAYERs
              00343 ;     (Zylon ships, meteors, photon torpedoes, starbase, transfer vessel, and
              00344 ;     Hyperwarp Target Marker).
              00345 ; o   Velocity vectors 5..48 belong to space objects represented by PLAYFIELD
              00346 ;     pixels. Velocity vectors 5..16 are used for stars, velocity vectors 17..48
              00347 ;     are used for explosion fragments and star trails.
              00348 ;
              00349 ; INFO: The velocity of our starship is converted and displayed by the VELOCITY
              00350 ; readout of the Control Panel Display in "metrons per second" units. The
              00351 ; conversion takes place in subroutine SHOWDIGITS ($B8CD) where our starship's
              00352 ; velocity VELOCITYL ($70) (with values $00..$FF) is transformed with lookup
              00353 ; table MAPTOBCD99 ($0EE9) into a BCD value of 00..99 in "metrons per second".
              00354
              00355 ;*******************************************************************************
              00356 ;*                                                                             *
              00357 ;*                             M E M O R Y   M A P                             *
              00358 ;*                                                                             *
              00359 ;*******************************************************************************
              00360 ;
              00361 ; The following variables are not changed by a SYSTEM RESET:
              00362 ;
              00363 ; $62      MISSIONLEVEL
              00364 ;
              00365 ;          Mission level. Used values are:
              00366 ;            $00 -> NOVICE mission
              00367 ;            $01 -> PILOT mission
              00368 ;            $02 -> WARRIOR mission
              00369 ;            $03 -> COMMANDER mission
              00370 ;
              00371 ; $63      FKEYCODE
              00372 ;
              00373 ;          Function key code. Used values are:
              00374 ;            $00 -> No function key pressed
              00375 ;            $01 -> START function key pressed
              00376 ;            $02 -> SELECT function key pressed
              00377 ;
              00378 ; $64      ISDEMOMODE
              00379 ;
              00380 ;          Indicates whether the program is in game or demo mode. Used values
              00381 ;          are:
              00382 ;            $00 -> Game mode
              00383 ;            $FF -> Demo mode
              00384 ;
              00385 ; $65      NEWTITLEPHR
              00386 ;
              00387 ;          New title phrase offset for the text in the title line. The new title
              00388 ;          phrase is not immediately displayed in the title line but only after
              00389 ;          the display time of the currently displayed title phrase has expired.
              00390 ;          Thus, setting a value to NEWTITLEPHR ($65) "enqueues" the display of
              00391 ;          new title phrase. Used values are:
              00392 ;            $00..$7B -> Title phrase offset into PHRASETAB ($BBAA)
              00393 ;            $FF      -> Hide title line
              00394 ;
              00395 ;          See also TITLEPHR ($D1).
              00396 ;
              00397 ; $66      IDLECNTHI
              00398 ;
              00399 ;          Idle counter (high byte). Forms a 16-bit counter together with
              00400 ;          IDLECNTLO ($77), which is incremented during the execution of the
              00401 ;          Vertical Blank Interrupt handler VBIHNDLR ($A6D1). IDLECNTHI ($66) is
              00402 ;          reset to 0 when the joystick trigger or a keyboard key has been
              00403 ;          pressed, or to 1..3 when a function key has been pressed. When
              00404 ;          IDLECNTHI ($66) reaches a value of 128 (after about 10 min idle time)
              00405 ;          the program enters demo mode.
              00406 ;
              00407 ; The following variables are set to 0 after a SYSTEM RESET:
              00408 ;
              00409 ; $67      ISVBISYNC
              00410 ;
              00411 ;          Indicates whether the Vertical Blank Interrupt handler VBIHNDLR
              00412 ;          ($A6D1) is executed. Used to synchronize the execution of a new game
              00413 ;          loop iteration in GAMELOOP ($A1F3) with the vertical blank phase.
              00414 ;          Used values are:
              00415 ;            $00 -> Halt execution at start of game loop and wait for VBI
              00416 ;            $FF -> Continue execution of game loop
              00417 ;
              00418 ; $68..$69 MEMPTR
              00419 ;
              00420 ;          A 16-bit memory pointer.
              00421 ;
              00422 ;          Also used as a local variable.
              00423 ;
              00424 ; $6A..$6B DIVIDEND
              00425 ;
              00426 ;          A 16-bit dividend value passed in GAMELOOP ($A1F3) to subroutine
              00427 ;          PROJECTION ($AA21) to calculate a division.
              00428 ;
              00429 ;          Also used as a local variable.
              00430 ;
              00431 ; $6C      Used as a local variable.
              00432 ;
              00433 ; $6D      JOYSTICKDELTA
              00434 ;
              00435 ;          Used to pass joystick directions from GAMELOOP ($A1F3) to subroutine
              00436 ;          ROTATE ($B69B). Used values are:
              00437 ;            $01 -> Joystick pressed right or up
              00438 ;            $00 -> Joystick centered
              00439 ;            $FF -> Joystick pressed left or down
              00440 ;
              00441 ;          Also used as a local variable.
              00442 ;
              00443 ; $6E      Used as a local variable.
              00444 ;
              00445 ; $70      VELOCITYLO
              00446 ;
              00447 ;          Our starship's current velocity (low byte) in <KM/H>. Forms a 16-bit
              00448 ;          value together with VELOCITYHI ($C1). In subroutine UPDPANEL ($B804),
              00449 ;          VELOCITYLO ($70) is mapped to a BCD-value in 00..99 and displayed by
              00450 ;          the VELOCITY readout of the Control Panel Display. See also
              00451 ;          NEWVELOCITY ($71).
              00452 ;
              00453 ; $71      NEWVELOCITY
              00454 ;
              00455 ;          Our starship's new velocity (low byte) in <KM/H>. It is set by
              00456 ;          pressing one of the speed keys '0'..'9'. A pressed speed key is
              00457 ;          mapped to the new velocity value with VELOCITYTAB ($BAB4).
              00458 ;
              00459 ; $72      COUNT8
              00460 ;
              00461 ;          Wrap-around counter. Counts from 0..7, then starts over at 0. It is
              00462 ;          incremented every game loop iteration. It is used to change the
              00463 ;          brightness of stars and explosion fragments more randomly in GAMELOOP
              00464 ;          ($A1F3) and to slow down the movement of the hyperwarp markers of the
              00465 ;          Galactic Chart in subroutine SELECTWARP ($B162).
              00466 ;
              00467 ; $73      EXPLLIFE
              00468 ;
              00469 ;          Explosion lifetime. It is decremented every game loop iteration. Used
              00470 ;          values are:
              00471 ;              $00 -> Explosion is over
              00472 ;            < $18 -> Number of explosion fragment space objects is decremented
              00473 ;            < $70 -> HITBADNESS ($8A) is reset
              00474 ;              $80 -> Initial value at start of explosion
              00475 ;
              00476 ; $74      CLOCKTIM
              00477 ;
              00478 ;          Star date clock delay timer. Counts down from 40 to 0. It is
              00479 ;          decremented every game loop iteration. When the timer falls below 0
              00480 ;          the last digit of the star date of the Galactic Chart Panel Display
              00481 ;          is increased and the timer is reset to a value of 40.
              00482 ;
              00483 ; $75      DOCKSTATE
              00484 ;
              00485 ;          State of docking operation. Used values are:
              00486 ;            $00 -> NOT DOCKED
              00487 ;            $01 -> TRANSFER COMPLETE
              00488 ;            $81 -> RETURN TRANSFER VESSEL
              00489 ;            $FF -> ORBIT ESTABLISHED
              00490 ;
              00491 ; $76      COUNT256
              00492 ;
              00493 ;          Wrap-around counter. Counts from 0..255, then starts over at 0. It is
              00494 ;          incremented every game loop iteration. It is used to make the
              00495 ;          starbase pulsate in brightness in GAMELOOP ($A1F3) and to decide on
              00496 ;          the creation of a meteor in subroutine MANEUVER ($AA79).
              00497 ;
              00498 ; $77      IDLECNTLO
              00499 ;
              00500 ;          Idle counter (low byte). Forms a 16-bit counter together with
              00501 ;          IDLECNTHI ($66), which is incremented during the execution of the
              00502 ;          Vertical Blank Interrupt handler VBIHNDLR ($A6D1).
              00503 ;
              00504 ;          NOTE: This variable is never properly initialized except at initial
              00505 ;          cartridge startup (cold start).
              00506 ;
              00507 ; $78      ZYLONUNITTIM
              00508 ;
              00509 ;          Zylon unit movement timer. This delay timer triggers movement of
              00510 ;          Zylon units on the Galactic Chart. At the start of the game, the
              00511 ;          timer is initialized to a value of 100. It is decremented every 40
              00512 ;          game loop iterations. When the timer falls below 0 the Zylon units
              00513 ;          move on the Galactic Chart and the timer value is reset to 49. If a
              00514 ;          starbase is surrounded the timer is reset to 99 to buy you some extra
              00515 ;          time to destroy one of the surrounding Zylon units.
              00516 ;
              00517 ; $79      MAXSPCOBJIND
              00518 ;
              00519 ;          Maximum index of used space objects in the current game loop
              00520 ;          iteration. Frequently used values are:
              00521 ;            $10 -> During regular cruise (5 PLAYER space objects + 12 PLAYFIELD
              00522 ;                   space objects (stars))
              00523 ;            $30 -> During explosion or hyperwarp (5 PLAYER space objects + 12
              00524 ;                   PLAYFIELD space objects (stars) + 32 PLAYFIELD space objects
              00525 ;                   (explosion fragments or stars of star trails))
              00526 ;
              00527 ; $7A      OLDMAXSPCOBJIND
              00528 ;
              00529 ;          Maximum index of used space objects in the previous game loop
              00530 ;          iteration. Frequently used values are:
              00531 ;            $10 -> During regular cruise (5 PLAYER space objects + 12 PLAYFIELD
              00532 ;                   space objects (stars))
              00533 ;            $30 -> During explosion or hyperwarp (5 PLAYER space objects + 12
              00534 ;                   PLAYFIELD space objects (stars) + 32 PLAYFIELD space objects
              00535 ;                   (explosion fragments or stars of star trails))
              00536 ;
              00537 ; $7B      ISSTARBASESECT
              00538 ;
              00539 ;          Indicates whether a starbase is in this sector. Used values are:
              00540 ;            $00 -> Sector contains no starbase
              00541 ;            $FF -> Sector contains starbase
              00542 ;
              00543 ; $7C      ISTRACKCOMPON
              00544 ;
              00545 ;          Indicates whether the Tracking Computer is on or off. Used values
              00546 ;          are:
              00547 ;            $00 -> Tracking Computer is off
              00548 ;            $FF -> Tracking Computer is on
              00549 ;
              00550 ; $7D      DRAINSHIELDS
              00551 ;
              00552 ;          Energy drain rate of the Shields per game loop iteration in energy
              00553 ;          subunits. See also subroutine UPDPANEL ($B804). Used values are:
              00554 ;            $00 -> Shields are off
              00555 ;            $08 -> Shields are on
              00556 ;
              00557 ; $7E      DRAINATTCOMP
              00558 ;
              00559 ;          Energy drain rate of the Attack Computer per game loop iteration in
              00560 ;          energy subunits. See also subroutine UPDPANEL ($B804). Used values
              00561 ;          are:
              00562 ;            $00 -> Attack Computer off
              00563 ;            $02 -> Attack Computer on
              00564 ;
              00565 ; $7F      ENERGYCNT
              00566 ;
              00567 ;          Running counter of consumed energy subunits (256 energy subunits = 1
              00568 ;          energy unit displayed by the 4-digit ENERGY readout of the Control
              00569 ;          Panel Display). Forms an invisible fractional or "decimals" part of
              00570 ;          the 4-digit ENERGY readout of the Control Panel Display. See also
              00571 ;          subroutine UPDPANEL ($B804).
              00572 ;
              00573 ; $80      DRAINENGINES
              00574 ;
              00575 ;          Energy drain rate of our starship's Engines per game loop iteration
              00576 ;          in energy subunits (256 energy subunits = 1 energy unit displayed by
              00577 ;          the 4-digit ENERGY readout of the Control Panel Display). Values are
              00578 ;          picked from table DRAINRATETAB ($BAD3). See also subroutine UPDPANEL
              00579 ;          ($B804).
              00580 ;
              00581 ; $81      SHIELDSCOLOR
              00582 ;
              00583 ;          Shields color. Used values are:
              00584 ;            $00 -> {BLACK} (Shields are off)
              00585 ;            $A0 -> {DARK GREEN} (Shields are on)
              00586 ;
              00587 ; $82      PL3HIT
              00588 ;
              00589 ;          Collision register of PLAYER3 (usually our starship's photon torpedo
              00590 ;          0) with other PLAYERs. Used values are:
              00591 ;              $00 -> No collision
              00592 ;            > $00 -> PLAYER3 has collided with another PLAYER space object. See
              00593 ;                     subroutine COLLISION ($AF3D) for details which PLAYER has
              00594 ;                     been hit by PLAYER3.
              00595 ;
              00596 ; $83      PL4HIT
              00597 ;
              00598 ;          Collision register of PLAYER4 (usually our starship's photon torpedo
              00599 ;          1) with other PLAYERs. Used values are:
              00600 ;              $00 -> No collision
              00601 ;            > $00 -> PLAYER4 has collided with another PLAYER space object. See
              00602 ;                     subroutine COLLISION ($AF3D) for details which PLAYER has
              00603 ;                     been hit by PLAYER4.
              00604 ;
              00605 ; $84      OLDTRIG0
              00606 ;
              00607 ;          Joystick trigger state. Used values are:
              00608 ;            $00 -> Joystick trigger was pressed
              00609 ;            $01 -> Joystick trigger was not pressed
              00610 ;            $AA -> Joystick trigger was "virtually" pressed (will launch
              00611 ;                   another of our starship's photon torpedoes, see subroutine
              00612 ;                   TRIGGER ($AE29).
              00613 ;
              00614 ; $86      ISTRACKING
              00615 ;
              00616 ;          Indicates whether one of our starship's photon torpedoes is currently
              00617 ;          tracking (homing in on) the target space object. Used values are:
              00618 ;              $00 -> No target space object tracked. Our starship's photon
              00619 ;                     torpedoes will fly just straight ahead.
              00620 ;            > $00 -> Tracking a target space object. Our starship's photon
              00621 ;                     torpedoes will home in on the tracked space object.
              00622 ;
              00623 ; $87      BARRELNR
              00624 ;
              00625 ;          Barrel from which our starship's next photon torpedo will be
              00626 ;          launched. Used values are:
              00627 ;            $00 -> Left barrel
              00628 ;            $01 -> Right barrel
              00629 ;
              00630 ; $88      LOCKONLIFE
              00631 ;
              00632 ;          Lifetime of target lock-on. A target remains in lock-on while
              00633 ;          LOCKONLIFE ($88) counts down from 12 to 0. It is decremented every
              00634 ;          game loop iteration.
              00635 ;
              00636 ; $89      PLTRACKED
              00637 ;
              00638 ;          Index of currently tracked PLAYER. It is copied in subroutine TRIGGER
              00639 ;          ($AE29) from TRACKDIGIT ($095C). Used values are:
              00640 ;            $00 -> Track Zylon ship 0
              00641 ;            $01 -> Track Zylon ship 1
              00642 ;            $02 -> Track starbase during docking operations
              00643 ;            $03 -> Track Hyperwarp Target Marker during hyperwarp
              00644 ;
              00645 ; $8A      HITBADNESS
              00646 ;
              00647 ;          Severeness of a Zylon photon torpedo hit. Used values are:
              00648 ;            $00 -> NO HIT
              00649 ;            $7F -> SHIELDS HIT
              00650 ;            $FF -> STARSHIP DESTROYED
              00651 ;
              00652 ; $8B      REDALERTLIFE
              00653 ;
              00654 ;          Lifetime of red alert. It decreases from 255 to 0. It is decremented
              00655 ;          every game loop iteration.
              00656 ;
              00657 ; $8C      WARPDEPRROW
              00658 ;
              00659 ;          Departure hyperwarp marker row number on the Galactic Chart. It is
              00660 ;          given in Player/Missile pixels relative to the top Galactic Chart
              00661 ;          border. It is initialized to a value of $47 (vertical center of
              00662 ;          Galactic Chart). Divide this value by 16 to get the departure sector
              00663 ;          row number. Used values are: $00..$7F.
              00664 ;
              00665 ; $8D      WARPDEPRCOLUMN
              00666 ;
              00667 ;          Departure hyperwarp marker column number on the Galactic Chart. It is
              00668 ;          given in Player/Missile pixels relative to the left Galactic Chart
              00669 ;          border and initialized to a value of $43 (horizontal center of
              00670 ;          Galactic Chart). Divide this value by 8 to get the departure sector
              00671 ;          column number. Used values are: $00..$7F.
              00672 ;
              00673 ; $8E      WARPARRVROW
              00674 ;
              00675 ;          Arrival hyperwarp marker row number on the Galactic Chart in
              00676 ;          Player/Missile pixels relative to top Galactic Chart border. It is
              00677 ;          initialized to a value of $47 (vertical center of Galactic Chart).
              00678 ;          Divide this value by 16 to get the arrival sector row number. Used
              00679 ;          values are: $00..$7F.
              00680 ;
              00681 ; $8F      WARPARRVCOLUMN
              00682 ;
              00683 ;          Arrival hyperwarp marker column number on the Galactic Chart in
              00684 ;          Player/Missile pixels relative to left Galactic Chart border. It is
              00685 ;          initialized to a value of $43 (horizontal center of Galactic Chart).
              00686 ;          Divide this value by 8 to get the arrival sector column number. Used
              00687 ;          values are: $00..$7F.
              00688 ;
              00689 ; $90      CURRSECTOR
              00690 ;
              00691 ;          Galactic Chart sector of the current location of our starship. At the
              00692 ;          start of the game it is initialized to a value of $48. Used values
              00693 ;          are: $00..$7F with, for example,
              00694 ;            $00 -> NORTHWEST corner sector
              00695 ;            $0F -> NORTHEAST corner sector
              00696 ;            $70 -> SOUTHWEST corner sector
              00697 ;            $7F -> SOUTHWEST corner sector
              00698 ;
              00699 ;          See also ARRVSECTOR ($92).
              00700 ;
              00701 ; $91      WARPENERGY
              00702 ;
              00703 ;          Energy required to hyperwarp between the departure and arrival
              00704 ;          hyperwarp marker locations on the Galactic Chart divided by 10.
              00705 ;          Values are picked from table WARPENERGYTAB ($BADD). Multiply this
              00706 ;          value by 10 to get the actual value in energy units displayed by the
              00707 ;          Galactic Chart Panel Display.
              00708 ;
              00709 ; $92      ARRVSECTOR
              00710 ;
              00711 ;          Galactic Chart arrival sector of our starship after hyperwarp. Used
              00712 ;          values are: $00..$7F with, for example,
              00713 ;            $00 -> NORTHWEST corner sector
              00714 ;            $0F -> NORTHEAST corner sector
              00715 ;            $70 -> SOUTHWEST corner sector
              00716 ;            $7F -> SOUTHWEST corner sector
              00717 ;
              00718 ;          See also CURRSECTOR ($90).
              00719 ;
              00720 ; $93      HUNTSECTOR
              00721 ;
              00722 ;          Galactic Chart sector of the starbase toward which the Zylon units
              00723 ;          are currently moving. Used values are: $00..$7F with, for example,
              00724 ;            $00 -> NORTHWEST corner sector
              00725 ;            $0F -> NORTHEAST corner sector
              00726 ;            $70 -> SOUTHWEST corner sector
              00727 ;            $7F -> SOUTHWEST corner sector
              00728 ;
              00729 ; $94      HUNTSECTCOLUMN
              00730 ;
              00731 ;          Galactic Chart sector column number of the starbase toward which the
              00732 ;          Zylon units are currently moving. Used values are: 0..15.
              00733 ;
              00734 ; $95      HUNTSECTROW
              00735 ;
              00736 ;          Galactic Chart sector row number of the starbase toward which the
              00737 ;          Zylon units are currently moving. Used values are: 0..7.
              00738 ;
              00739 ; $96..$9E NEWZYLONDIST
              00740 ;
              00741 ;          Table of distances between a Zylon unit and the hunted starbase when
              00742 ;          the Zylon unit is tentatively moved in one of the 9 possible
              00743 ;          directions NORTH, NORTHWEST, WEST, SOUTHWEST, SOUTH, SOUTHEAST, EAST,
              00744 ;          NORTHEAST, CENTER. Used to decide into which sector the Zylon unit
              00745 ;          should move.
              00746 ;
              00747 ; $9E      OLDZYLONDIST
              00748 ;
              00749 ;          Current distance between the Zylon unit and the hunted starbase.
              00750 ;
              00751 ; $9F      HUNTTIM
              00752 ;
              00753 ;          Delay timer for Zylon units to decide on which starbase to hunt. It
              00754 ;          counts down from 7. It is decremented every game loop iteration. When
              00755 ;          the timer falls below 0 the Zylon units re-decide toward which
              00756 ;          starbase to move.
              00757 ;
              00758 ; $A0      BLIPCOLUMN
              00759 ;
              00760 ;          Top-left screen pixel column number of blip shape displayed in the
              00761 ;          Attack Computer Display. Used in subroutine UPDATTCOMP ($A7BF). Used
              00762 ;          values are: 120..142.
              00763 ;
              00764 ; $A1      BLIPROW
              00765 ;
              00766 ;          Top-left screen pixel row number of blip shape displayed in the
              00767 ;          Attack Computer Display. Used in subroutine UPDATTCOMP ($A7BF). Used
              00768 ;          values are: 71..81.
              00769 ;
              00770 ; $A2      BLIPCYCLECNT
              00771 ;
              00772 ;          Blip cycle counter. It controls drawing the blip shape in the Attack
              00773 ;          Computer Display. Its value is incremented every game loop iteration.
              00774 ;          Used in subroutine UPDATTCOMP ($A7BF). Used values are:
              00775 ;            $00..$04 -> Draw 0..4th row of blip shape
              00776 ;            $05..$09 -> Do not draw blip shape (delay)
              00777 ;            $0A      -> Recalculate blip shape position, erase Attack Computer
              00778 ;                        Display
              00779 ;
              00780 ; $A3      ISINLOCKON
              00781 ;
              00782 ;          Indicates whether the tracked space object is currently in full
              00783 ;          lock-on (horizontally and vertically centered as well as in range) in
              00784 ;          the Attack Computer Display. If so, all lock-on markers show up on
              00785 ;          the Attack Computer Display and our starship's launched photon
              00786 ;          torpedoes will home in on the tracked space object. Used values are:
              00787 ;            $00 -> Not in lock-on
              00788 ;            $A0 -> In lock-on
              00789 ;
              00790 ; $A4      DIRLEN
              00791 ;
              00792 ;          Used to pass the direction and length of a single line to be drawn in
              00793 ;          the PLAYFIELD. Used in subroutines DRAWLINES ($A76F), DRAWLINE
              00794 ;          ($A782), and UPDATTCOMP ($A7BF). Used values are:
              00795 ;            Bit B7 = 0 -> Draw right
              00796 ;            Bit B7 = 1 -> Draw down
              00797 ;            Bits B6..0 -> Length of line in pixels.
              00798 ;
              00799 ;          See also PENROW ($A5) and PENCOLUMN ($A6).
              00800 ;
              00801 ; $A5      PENROW
              00802 ;
              00803 ;          Used to pass the start screen pixel row number of the line to be
              00804 ;          drawn in the PLAYFIELD. Used in subroutines DRAWLINES ($A76F),
              00805 ;          DRAWLINE ($A782), and UPDATTCOMP ($A7BF).
              00806 ;
              00807 ; $A6      PENCOLUMN
              00808 ;
              00809 ;          Used to pass the start screen pixel column number of the line to be
              00810 ;          drawn in the PLAYFIELD. Used in subroutines DRAWLINES ($A76F),
              00811 ;          DRAWLINE ($A782), and UPDATTCOMP ($A7BF).
              00812 ;
              00813 ; $A7      CTRLDZYLON
              00814 ;
              00815 ;          Index of Zylon ship currently controlled by the program. Used in
              00816 ;          subroutine MANEUVER ($AA79). The value is toggled every other game
              00817 ;          loop iteration. Used values are:
              00818 ;            $00 -> Control Zylon ship 0.
              00819 ;            $01 -> Control Zylon ship 1.
              00820 ;
              00821 ; $A8      ZYLONFLPAT0
              00822 ;
              00823 ;          Flight pattern of Zylon ship 0. Used in subroutine MANEUVER ($AA79).
              00824 ;          Used values are:
              00825 ;            $00 -> Attack flight pattern "0"
              00826 ;            $01 -> Flight pattern "1"
              00827 ;            $04 -> Flight pattern "4"
              00828 ;
              00829 ; $A9      ZYLONFLPAT1
              00830 ;
              00831 ;          Flight pattern of Zylon ship 1. Compare ZYLONFLPAT0 ($A8).
              00832 ;
              00833 ; $AA      MILESTTIM0
              00834 ;
              00835 ;          Delay timer of the milestone velocity indices of Zylon ship 0. Used
              00836 ;          in subroutine MANEUVER ($AA79).
              00837 ;
              00838 ;          When Zylon ship 0 is active, this value is decremented every game
              00839 ;          loop iteration. If it falls below 0 then the milestone velocity
              00840 ;          indices of Zylon ship 0 are recalculated. When Zylon ship 0 is
              00841 ;          controlled by the computer for the first time, the timer is set to an
              00842 ;          initial value of 1, later to an initial value of 120.
              00843 ;
              00844 ; $AB      MILESTTIM1
              00845 ;
              00846 ;          Delay timer of the milestone velocity index vector of Zylon ship 1.
              00847 ;          Compare MILESTTIM0 ($AA).
              00848 ;
              00849 ; $AC      MILESTVELINDZ0
              00850 ;
              00851 ;          Milestone z-velocity index of Zylon ship 0. Used in subroutine
              00852 ;          MANEUVER ($AA79). The current z-velocity index of Zylon ship 0
              00853 ;          ZYLONVELINDZ0 ($B2) is compared with this index and gradually
              00854 ;          adjusted to it. Used values are: 0..15.
              00855 ;
              00856 ; $AD      MILESTVELINDZ1
              00857 ;
              00858 ;          Milestone z-velocity index of Zylon ship 1. Compare MILESTVELINDZ0
              00859 ;          ($AC).
              00860 ;
              00861 ; $AE      MILESTVELINDX0
              00862 ;
              00863 ;          Milestone x-velocity index of Zylon ship 0. Used in subroutine
              00864 ;          MANEUVER ($AA79). The current x-velocity index of Zylon ship 0
              00865 ;          ZYLONVELINDX0 ($B4) is compared with this index and gradually
              00866 ;          adjusted to it. Used values are: 0..15.
              00867 ;
              00868 ; $AF      MILESTVELINDX1
              00869 ;
              00870 ;          Milestone x-velocity index of Zylon ship 1. Compare MILESTVELINDX0
              00871 ;          ($AE).
              00872 ;
              00873 ; $B0      MILESTVELINDY0
              00874 ;
              00875 ;          Milestone y-velocity index of Zylon ship 0. Used in subroutine
              00876 ;          MANEUVER ($AA79). The current y-velocity index of Zylon ship 0
              00877 ;          ZYLONVELINDY0 ($B6) is compared with this index and gradually
              00878 ;          adjusted to it. Used values are: 0..15.
              00879 ;
              00880 ; $B1      MILESTVELINDY1
              00881 ;
              00882 ;          Milestone y-velocity index of Zylon ship 1. Compare MILESTVELINDY0
              00883 ;          ($B0).
              00884 ;
              00885 ; $B2      ZYLONVELINDZ0
              00886 ;
              00887 ;          Current z-velocity index of Zylon ship 0. Used in subroutine MANEUVER
              00888 ;          ($AA79). It indexes velocity values in ZYLONVELTAB ($BF99). Used
              00889 ;          values are: 0..15.
              00890 ;
              00891 ; $B3      ZYLONVELINDZ1
              00892 ;
              00893 ;          Current z-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00894 ;          ($B2).
              00895 ;
              00896 ; $B4      ZYLONVELINDX0
              00897 ;
              00898 ;          Current x-velocity index of Zylon ship 0. Compare ZYLONVELINDZ0
              00899 ;          ($B2).
              00900 ;
              00901 ; $B5      ZYLONVELINDX1
              00902 ;
              00903 ;          Current x-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00904 ;          ($B2).
              00905 ;
              00906 ; $B6      ZYLONVELINDY0
              00907 ;
              00908 ;          Current y-velocity index of Zylon ship 0. Compare ZYLONVELINDZ0
              00909 ;          ($B2).
              00910 ;
              00911 ; $B7      ZYLONVELINDY1
              00912 ;
              00913 ;          Current y-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00914 ;          ($B2).
              00915 ;
              00916 ; $B8      ISBACKATTACK0
              00917 ;
              00918 ;          Indicates whether Zylon ship 0 will attack our starship from the
              00919 ;          back. Used in subroutine MANEUVER ($AA79). Used values are:
              00920 ;            $00 -> Zylon ship 0 attacks from the front of our starship
              00921 ;            $01 -> Zylon ship 0 attacks from the front and back of our starship
              00922 ;
              00923 ; $B9      ISBACKATTACK1
              00924 ;
              00925 ;          Indicates whether Zylon ship 1 will attack our starship from the
              00926 ;          back. Compare ISBACKATTACK0 ($B8).
              00927 ;
              00928 ; $BA      ZYLONTIMX0
              00929 ;
              00930 ;          Delay timer of the x-velocity index of Zylon ship 0. Used in
              00931 ;          subroutine MANEUVER ($AA79). It is decremented every game loop
              00932 ;          iteration. When the timer value falls below 0 the current velocity
              00933 ;          index ZYLONVELINDX0 ($B4) is adjusted depending on the current
              00934 ;          joystick position. The new timer value is set depending on the
              00935 ;          resulting new x-velocity index. Used values are: 0, 2, 4, ..., 14.
              00936 ;
              00937 ; $BB      ZYLONTIMX1
              00938 ;
              00939 ;          Delay timer of x-velocity index of Zylon ship 1. Compare ZYLONTIMX0
              00940 ;          ($BA).
              00941 ;
              00942 ; $BC      ZYLONTIMY0
              00943 ;
              00944 ;          Delay timer of y-velocity index of Zylon ship 0. Compare ZYLONTIMX0
              00945 ;          ($BA).
              00946 ;
              00947 ; $BD      ZYLONTIMY1
              00948 ;
              00949 ;          Delay timer of y-velocity index of Zylon ship 1. Compare ZYLONTIMX0
              00950 ;          ($BA).
              00951 ;
              00952 ; $BE      TORPEDODELAY
              00953 ;
              00954 ;          After a Zylon photon torpedo has hit our starship this delay timer is
              00955 ;          initialized to a value of 2. It is decremented every game loop
              00956 ;          iteration and so delays the launch of the next Zylon photon torpedo
              00957 ;          for 2 game loop iterations.
              00958 ;
              00959 ; $BF      ZYLONATTACKER
              00960 ;
              00961 ;          Index of the Zylon ship that launched the Zylon photon torpedo. It is
              00962 ;          used in GAMELOOP ($A1F3) to override the current tracking computer
              00963 ;          settings in order to track this Zylon ship first. Used values are:
              00964 ;            $00 -> Zylon photon torpedo was launched by Zylon ship 0
              00965 ;            $01 -> Zylon photon torpedo was launched by Zylon ship 1
              00966 ;
              00967 ; $C0      WARPSTATE
              00968 ;
              00969 ;          Hyperwarp state. Used values are:
              00970 ;            $00 -> Hyperwarp not engaged
              00971 ;            $7F -> Hyperwarp engaged
              00972 ;            $FF -> In hyperspace
              00973 ;
              00974 ; $C1      VELOCITYHI
              00975 ;
              00976 ;          Our starship's velocity (high byte) in <KM/H>. Used values are:
              00977 ;            $00 -> Not in hyperspace (regular cruise or accelerating to
              00978 ;                   hyperspace velocity)
              00979 ;            $01 -> Hyperspace velocity
              00980 ;
              00981 ;          See also VELOCITYLO ($70).
              00982 ;
              00983 ; $C2      TRAILDELAY
              00984 ;
              00985 ;          Delay timer to create the next star trail. Its value is decremented
              00986 ;          from 3 to 0 every game loop iteration during the hyperwarp STAR TRAIL
              00987 ;          PHASE in subroutine INITTRAIL ($A9B4).
              00988 ;
              00989 ; $C3      TRAILIND
              00990 ;
              00991 ;          Position vector index of the star trail's first star. Used in
              00992 ;          subroutine INITTRAIL ($A9B4) to initialize a star trail, which is
              00993 ;          then displayed during the hyperwarp STAR TRAIL PHASE. Used values
              00994 ;          are: 17..48 in wrap-around fashion.
              00995 ;
              00996 ; $C4      WARPTEMPCOLUMN
              00997 ;
              00998 ;          Temporary arrival column number of our starship on the Galactic Chart
              00999 ;          at the begin of hyperspace. It is given in Player/Missile pixels
              01000 ;          relative to the left Galactic Chart border. Divide this value by 8 to
              01001 ;          get the sector column number. Used values are: $00..$7F. See also
              01002 ;          WARPARRVCOLUMN ($8F).
              01003 ;
              01004 ; $C5      WARPTEMPROW
              01005 ;
              01006 ;          Temporary arrival row number of our starship on the Galactic Chart at
              01007 ;          the begin of hyperspace. It is given in Player/Missile pixels
              01008 ;          relative to top Galactic Chart border. Divide this value by 16 to get
              01009 ;          the sector row number.  Used values are: $00..$7F. See also
              01010 ;          WARPARRVROW ($8E).
              01011 ;
              01012 ; $C6      VEERMASK
              01013 ;
              01014 ;          Limits the veer-off velocity of the Hyperwarp Target Marker during
              01015 ;          the hyperwarp ACCELERATION PHASE in subroutine HYPERWARP ($A89B).
              01016 ;          Values are picked from table VEERMASKTAB ($BED7).
              01017 ;
              01018 ;          Also used as a local variable.
              01019 ;
              01020 ; $C7      VICINITYMASK
              01021 ;
              01022 ;          Mask to confine space objects' position vector components
              01023 ;          (coordinates) in a sector into a certain interval around our starship
              01024 ;          after its arrival from hyperspace. Values are picked from table
              01025 ;          VICINITYMASKTAB ($BFB3).
              01026 ;
              01027 ; $C8      JOYSTICKX
              01028 ;
              01029 ;          Horizontal joystick direction. Values are picked from table
              01030 ;          STICKINCTAB ($BAF5). Used values are:
              01031 ;            $01 -> Right
              01032 ;            $00 -> Centered
              01033 ;            $FF -> Left
              01034 ;
              01035 ; $C9      JOYSTICKY
              01036 ;
              01037 ;          Vertical joystick direction. Values are picked from table STICKINCTAB
              01038 ;          ($BAF5). Used values are:
              01039 ;            $01 -> Up
              01040 ;            $00 -> Centered
              01041 ;            $FF -> Down
              01042 ;
              01043 ; $CA      KEYCODE
              01044 ;
              01045 ;          Hardware keyboard code of the pressed key on the keyboard. Shift and
              01046 ;          Control key bits B7..6 are always set.
              01047 ;
              01048 ; $CB..$CC SCORE
              01049 ;
              01050 ;          Internal 16-bit score of the game in low byte-high byte order
              01051 ;
              01052 ; $CD      SCOREDRANKIND
              01053 ;
              01054 ;          Scored Rank Index. It is translated with table RANKTAB ($BEE9) to a
              01055 ;          title phrase offset pointing to the rank string. Used values are:
              01056 ;            $00 -> GALACTIC COOK
              01057 ;            $01 -> GARBAGE SCOW CAPTAIN
              01058 ;            $02 -> GARBAGE SCOW CAPTAIN
              01059 ;            $03 -> ROOKIE
              01060 ;            $04 -> ROOKIE
              01061 ;            $05 -> NOVICE
              01062 ;            $06 -> NOVICE
              01063 ;            $07 -> ENSIGN
              01064 ;            $08 -> ENSIGN
              01065 ;            $09 -> PILOT
              01066 ;            $0A -> PILOT
              01067 ;            $0B -> ACE
              01068 ;            $0C -> LIEUTENANT
              01069 ;            $0D -> WARRIOR
              01070 ;            $0E -> CAPTAIN
              01071 ;            $0F -> COMMANDER
              01072 ;            $10 -> COMMANDER
              01073 ;            $11 -> STAR COMMANDER
              01074 ;            $12 -> STAR COMMANDER
              01075 ;
              01076 ; $CE      SCOREDCLASSIND
              01077 ;
              01078 ;          Scored Class Index. It is translated into a class number with table
              01079 ;          CLASSTAB ($BEFC). Used values are:
              01080 ;            $00 -> Class 5
              01081 ;            $01 -> Class 5
              01082 ;            $02 -> Class 5
              01083 ;            $03 -> Class 4
              01084 ;            $04 -> Class 4
              01085 ;            $05 -> Class 4
              01086 ;            $06 -> Class 4
              01087 ;            $07 -> Class 3
              01088 ;            $08 -> Class 3
              01089 ;            $09 -> Class 3
              01090 ;            $0A -> Class 2
              01091 ;            $0B -> Class 2
              01092 ;            $0C -> Class 2
              01093 ;            $0D -> Class 1
              01094 ;            $0E -> Class 1
              01095 ;            $0F -> Class 1
              01096 ;
              01097 ; $CF      TITLELIFE
              01098 ;
              01099 ;          Lifetime of title line. It is decremented every game loop iteration.
              01100 ;          Used initial values are:
              01101 ;            $3C -> When displaying regular title phrases
              01102 ;            $FE -> When displaying "STARBASE SURROUNDED", "STARBASE DESTOYED",
              01103 ;                   and "RED ALERT" messages
              01104 ;            $FF -> Hide title line
              01105 ;
              01106 ; $D0      SHIPVIEW
              01107 ;
              01108 ;          Current view of our starship. Values are picked from table
              01109 ;          VIEWMODETAB ($BE22). Used values are:
              01110 ;            $00 -> Front view
              01111 ;            $01 -> Aft view
              01112 ;            $40 -> Long-Range Scan view
              01113 ;            $80 -> Galactic Chart view
              01114 ;
              01115 ; $D1      TITLEPHR
              01116 ;
              01117 ;          Title phrase offset for text phrase in title line. Used values are:
              01118 ;            $00..$7B -> Title phrase offset into PHRASETAB ($BBAA)
              01119 ;            $FF      -> Hide title line
              01120 ;
              01121 ;          See also NEWTITLEPHR ($65).
              01122 ;
              01123 ; $D2      BEEPFRQIND
              01124 ;
              01125 ;          Beeper sound pattern: Running index into frequency table BEEPFRQTAB
              01126 ;          ($BF5C). See also BEEPFRQSTART ($D7). See also subroutines BEEP
              01127 ;          ($B3A6) and SOUND ($B2AB).
              01128 ;
              01129 ; $D3      BEEPREPEAT
              01130 ;
              01131 ;          Beeper sound pattern: Number of times the beeper sound pattern is
              01132 ;          repeated - 1. See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01133 ;
              01134 ; $D4      BEEPTONELIFE
              01135 ;
              01136 ;          Beeper sound pattern: Lifetime of tone in TICKs - 1. See also
              01137 ;          subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01138 ;
              01139 ; $D5      BEEPPAUSELIFE
              01140 ;
              01141 ;          Beeper sound pattern: Lifetime of pause in TICKs - 1. Used values
              01142 ;          are:
              01143 ;            < $FF -> Number of TICKs - 1 to play
              01144 ;              $FF -> Skip playing pause
              01145 ;
              01146 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01147 ;
              01148 ; $D6      BEEPPRIORITY
              01149 ;
              01150 ;          Beeper sound pattern: Pattern priority. Each beeper sound pattern has
              01151 ;          a priority. When a pattern of higher priority is about to be played
              01152 ;          the pattern that is currently playing is stopped. Used values are:
              01153 ;              $00 -> No pattern playing at the moment
              01154 ;            > $00 -> Pattern priority
              01155 ;
              01156 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01157 ;
              01158 ; $D7      BEEPFRQSTART
              01159 ;
              01160 ;          Beeper sound pattern: Index to first byte of the pattern frequency in
              01161 ;          table BEEPFRQTAB ($BF5C). See also BEEPFRQIND ($D2). See also
              01162 ;          subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01163 ;
              01164 ; $D8      BEEPLIFE
              01165 ;
              01166 ;          Beeper sound pattern: Lifetime of the current tone or pause in TICKs.
              01167 ;          It is decremented every TICK. See also subroutines BEEP ($B3A6) and
              01168 ;          SOUND ($B2AB).
              01169 ;
              01170 ; $D9      BEEPTOGGLE
              01171 ;
              01172 ;          Beeper sound pattern: Indicates that either a tone or a pause is
              01173 ;          currently played. Used values are:
              01174 ;            $00 -> Tone
              01175 ;            $01 -> Pause
              01176 ;
              01177 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01178 ;
              01179 ; $DA      NOISETORPTIM
              01180 ;
              01181 ;          Noise sound pattern: Delay timer for PHOTON TORPEDO LAUNCHED noise
              01182 ;          sound pattern. It is decremented every TICK. See also subroutines
              01183 ;          NOISE ($AEA8) and SOUND ($B2AB).
              01184 ;
              01185 ; $DB      NOISEEXPLTIM
              01186 ;
              01187 ;          Noise sound pattern: Delay timer for SHIELD EXPLOSION and ZYLON
              01188 ;          EXPLOSION noise sound pattern. It is decremented every TICK. See also
              01189 ;          subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01190 ;
              01191 ; $DC      NOISEAUDC2
              01192 ;
              01193 ;          Noise sound pattern: Audio channel 1/2 control shadow register. See
              01194 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01195 ;
              01196 ; $DD      NOISEAUDC3
              01197 ;
              01198 ;          Noise sound pattern: Audio channel 3 control shadow register. See
              01199 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01200 ;
              01201 ; $DE      NOISEAUDF1
              01202 ;
              01203 ;          Noise sound pattern: Audio channel 1 frequency shadow register. See
              01204 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01205 ;
              01206 ; $DF      NOISEAUDF2
              01207 ;
              01208 ;          Noise sound pattern: Audio channel 2 frequency shadow register. See
              01209 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01210 ;
              01211 ; $E0      NOISEFRQINC
              01212 ;
              01213 ;          Noise sound pattern: Audio channel 1/2 frequency increment. See also
              01214 ;          subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01215 ;
              01216 ; $E1      NOISELIFE
              01217 ;
              01218 ;          Noise sound pattern: Noise sound pattern lifetime. It is decremented
              01219 ;          every TICK. See also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01220 ;
              01221 ; $E2      NOISEZYLONTIM
              01222 ;
              01223 ;          Delay timer to trigger the ZYLON EXPLOSION noise sound pattern. It is
              01224 ;          set in subroutine COLLISION ($AF3D) when an impact of one of our
              01225 ;          starship's photon torpedoes into a target is imminent. The timer is
              01226 ;          decremented every TICK during the execution of the Vertical Blank
              01227 ;          Interrupt handler VBIHNDLR ($A6D1). When the timer value reaches 0
              01228 ;          the ZYLON EXPLOSION noise sound pattern is played in subroutine SOUND
              01229 ;          ($B2AB).
              01230 ;
              01231 ; $E3      NOISEHITLIFE
              01232 ;
              01233 ;          Lifetime of STARSHIP EXPLOSION noise when our starship was destroyed
              01234 ;          by a Zylon photon torpedo. It is set in routine GAMELOOP ($A1F3) to a
              01235 ;          value of 64 TICKs. It is decremented every TICK during the execution
              01236 ;          of the Vertical Blank Interrupt handler VBIHNDLR ($A6D1).
              01237 ;
              01238 ; $E4      PL0SHAPOFF
              01239 ;
              01240 ;          PLAYER0 offset into shape table PLSHAP2TAB ($B9B1)
              01241 ;
              01242 ; $E5      PL1SHAPOFF
              01243 ;
              01244 ;          PLAYER1 offset into shape table PLSHAP2TAB ($B9B1)
              01245 ;
              01246 ; $E6      PL2SHAPOFF
              01247 ;
              01248 ;          PLAYER2 offset into shape table PLSHAP1TAB ($B8E4)
              01249 ;
              01250 ; $E7      PL3SHAPOFF
              01251 ;
              01252 ;          PLAYER3 offset into shape table PLSHAP1TAB ($B8E4)
              01253 ;
              01254 ; $E8      PL4SHAPOFF
              01255 ;
              01256 ;          PLAYER4 offset into shape table PLSHAP1TAB ($B8E4)
              01257 ;
              01258 ; $E9      PL0LIFE
              01259 ;
              01260 ;          Lifetime of the space object represented by PLAYER0 (usually Zylon
              01261 ;          ship 0). Any value other than $FF is decremented with every game loop
              01262 ;          iteration. Used values are:
              01263 ;            $00      -> Space object not alive (= not in use)
              01264 ;            $01..$FE -> Values during lifetime countdown
              01265 ;            $FF      -> Infinite lifetime (not counted down)
              01266 ;
              01267 ; $EA      PL1LIFE
              01268 ;
              01269 ;          Lifetime of a space object represented by PLAYER1 (usually Zylon ship
              01270 ;          1). Compare PL0LIFE ($E9).
              01271 ;
              01272 ; $EB      PL2LIFE
              01273 ;
              01274 ;          Lifetime of a space object represented by PLAYER2 (usually the Zylon
              01275 ;          photon torpedo). Compare PL0LIFE ($E9).
              01276 ;
              01277 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01278 ;          decremented from an initial value of $FF.
              01279 ;
              01280 ; $EC      PL3LIFE
              01281 ;
              01282 ;          Lifetime of a space object represented by PLAYER3 (usually our
              01283 ;          starship's photon torpedo 0). Compare PL2LIFE ($EB).
              01284 ;
              01285 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01286 ;          decremented from an initial value of $FF.
              01287 ;
              01288 ; $ED      PL4LIFE
              01289 ;
              01290 ;          Lifetime of a space object represented by PLAYER4 (usually our
              01291 ;          starship's photon torpedo 1). Compare PL2LIFE ($EB).
              01292 ;
              01293 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01294 ;          decremented from an initial value of $FF.
              01295 ;
              01296 ; $EE      PL0COLOR
              01297 ;
              01298 ;          Color of PLAYER0
              01299 ;
              01300 ; $EF      PL1COLOR
              01301 ;
              01302 ;          Color of PLAYER1
              01303 ;
              01304 ; $F0      PL2COLOR
              01305 ;
              01306 ;          Color of PLAYER2
              01307 ;
              01308 ; $F1      PL3COLOR
              01309 ;
              01310 ;          Color of PLAYER3
              01311 ;
              01312 ; $F2      PF0COLOR
              01313 ;
              01314 ;          Color of PLAYFIELD0
              01315 ;
              01316 ; $F3      PF1COLOR
              01317 ;
              01318 ;          Color of PLAYFIELD1
              01319 ;
              01320 ; $F4      PF2COLOR
              01321 ;
              01322 ;          Color of PLAYFIELD2
              01323 ;
              01324 ; $F5      PF3COLOR
              01325 ;
              01326 ;          Color of PLAYFIELD3
              01327 ;
              01328 ; $F6      BGRCOLOR
              01329 ;
              01330 ;          Color of BACKGROUND
              01331 ;
              01332 ; $F7      PF0COLORDLI
              01333 ;
              01334 ;          Color of PLAYFIELD0 after DLI
              01335 ;
              01336 ; $F8      PF1COLORDLI
              01337 ;
              01338 ;          Color of PLAYFIELD1 after DLI
              01339 ;
              01340 ; $F9      PF2COLORDLI
              01341 ;
              01342 ;          Color of PLAYFIELD2 after DLI
              01343 ;
              01344 ; $FA      PF3COLORDLI
              01345 ;
              01346 ;          Color of PLAYFIELD3 after DLI
              01347 ;
              01348 ; $FB      BGRCOLORDLI
              01349 ;
              01350 ;          Color of BACKGROUND after DLI
              01351 ;
              01352 ; $0280..$02E9 DSPLST
              01353 ;
              01354 ;              Display List
              01355 ;
              01356 ; $0300..$03FF PL4DATA
              01357 ;
              01358 ;              PLAYER4 data area
              01359 ;
              01360 ; $0400..$04FF PL0DATA
              01361 ;
              01362 ;              PLAYER0 data area
              01363 ;
              01364 ; $0500..$05FF PL1DATA
              01365 ;
              01366 ;              PLAYER1 data area
              01367 ;
              01368 ; $0600..$06FF PL2DATA
              01369 ;
              01370 ;              PLAYER2 data area
              01371 ;
              01372 ; $0700..$07FF PL3DATA
              01373 ;
              01374 ;              PLAYER3 data area
              01375 ;
              01376 ; $0800..$0863 PFMEMROWLO
              01377 ;
              01378 ;              Lookup table of start addresses (low byte) for each row of
              01379 ;              PLAYFIELD memory, which is located at PFMEM ($1000). The table
              01380 ;              contains 100 bytes for 100 rows (of which only 99 are shown by
              01381 ;              the Display List, the PLAYFIELD is 160 x 99 pixels). The
              01382 ;              addresses grow in increments of 40 (40 bytes = 160 pixels in
              01383 ;              GRAPHICS7 mode = 1 PLAYFIELD row of pixels). See also PFMEMROWHI
              01384 ;              ($0864).
              01385 ;
              01386 ; $0864..$08C7 PFMEMROWHI
              01387 ;
              01388 ;              Lookup table of start addresses (high byte) of each row of
              01389 ;              PLAYFIELD memory. See also PFMEMROWLO ($0800).
              01390 ;
              01391 ; $08C9..$0948 GCMEMMAP
              01392 ;
              01393 ;              Galactic Chart memory map (16 columns x 8 rows = 128 bytes)
              01394 ;
              01395 ; $0949..$0970 PANELTXT
              01396 ;
              01397 ;              Memory of Control Panel Display (bottom text window) in Front
              01398 ;              view, Aft view, and Long-Range Scan view (20 characters x 2 rows
              01399 ;              = 40 bytes).
              01400 ;
              01401 ; $094A        VELOCD1
              01402 ;
              01403 ;              First digit (of 2) of the VELOCITY readout in Control Panel
              01404 ;              Display memory.
              01405 ;
              01406 ; $0950        KILLCNTD1
              01407 ;
              01408 ;              First digit (of 2) of the KILL COUNTER readout in Control Panel
              01409 ;              Display memory.
              01410 ;
              01411 ; $0955        ENERGYD1
              01412 ;
              01413 ;              First digit (of 4) of the ENERGY readout in Control Panel Display
              01414 ;              memory.
              01415 ;
              01416 ; $095A        TRACKC1
              01417 ;
              01418 ;              Character of the TRACKING readout 'T' or 'C' in Control Panel
              01419 ;              Display memory.
              01420 ;
              01421 ; $095C        TRACKDIGIT
              01422 ;
              01423 ;              Digit of the TRACKING readout in Control Panel Display memory. It
              01424 ;              is used to store the index of the currently tracked space object.
              01425 ;              Used values are:
              01426 ;                $00 -> Track Zylon ship 0
              01427 ;                $01 -> Track Zylon ship 1
              01428 ;                $02 -> Track starbase
              01429 ;                $03 -> Track Hyperwarp Target Marker
              01430 ;
              01431 ; $0960        THETAC1
              01432 ;
              01433 ;              First character of the THETA readout in Control Panel Display
              01434 ;              memory.
              01435 ;
              01436 ; $0966        PHIC1
              01437 ;
              01438 ;              First character of the PHI readout in Control Panel Display
              01439 ;              memory.
              01440 ;
              01441 ; $096C        RANGEC1
              01442 ;
              01443 ;              First character of the RANGE readout in Control Panel Display
              01444 ;              memory.
              01445 ;
              01446 ; $0971..$09AC GCTXT
              01447 ;
              01448 ;              Memory of Galactic Chart Panel Display (bottom text window) of
              01449 ;              Galactic Chart view (20 characters x 3 rows = 60 bytes).
              01450 ;
              01451 ; $097D        GCWARPD1
              01452 ;
              01453 ;              First digit (of 4) of the HYPERWARP ENERGY readout in Galactic
              01454 ;              Chart Panel Display memory.
              01455 ;
              01456 ; $098D        GCTRGCNT
              01457 ;
              01458 ;              First target counter digit (of 2) in Galactic Chart Panel Display
              01459 ;              memory.
              01460 ;
              01461 ; $0992        GCSTATPHO
              01462 ;
              01463 ;              Photon Torpedo status letter in Galactic Chart Panel Display
              01464 ;              memory. Used values are:
              01465 ;                %00****** -> OK
              01466 ;                %10****** -> Destroyed
              01467 ;                %11****** -> Damaged
              01468 ;
              01469 ; $0993        GCSTATENG
              01470 ;
              01471 ;              Engines status letter in Galactic Chart Panel Display memory.
              01472 ;              Used values are:
              01473 ;                %00****** -> OK
              01474 ;                %10****** -> Destroyed
              01475 ;                %11****** -> Damaged
              01476 ;
              01477 ; $0994        GCSTATSHL
              01478 ;
              01479 ;              Shields status letter in Galactic Chart Panel Display memory.
              01480 ;              Used values are:
              01481 ;                %00****** -> OK
              01482 ;                %10****** -> Destroyed
              01483 ;                %11****** -> Damaged
              01484 ;
              01485 ; $0995        GCSTATCOM
              01486 ;
              01487 ;              Attack Computer status letter in Galactic Chart Panel Display
              01488 ;              memory. Used values are:
              01489 ;                %00****** -> OK
              01490 ;                %10****** -> Destroyed
              01491 ;                %11****** -> Damaged
              01492 ;
              01493 ; $0996        GCSTATLRS
              01494 ;
              01495 ;              Long-Range Scan status letter in Galactic Chart Panel Display
              01496 ;              memory. Used values are:
              01497 ;                %00****** -> OK
              01498 ;                %10****** -> Destroyed
              01499 ;                %11****** -> Damaged
              01500 ;
              01501 ; $0997        GCSTATRAD
              01502 ;
              01503 ;              Subspace Radio status letter in Galactic Chart Panel Display
              01504 ;              memory. Used values are:
              01505 ;                %00****** -> OK
              01506 ;                %10****** -> Destroyed
              01507 ;                %11****** -> Damaged
              01508 ;
              01509 ; $09A3        GCSTARDAT
              01510 ;
              01511 ;              First (of 5) digits of the star date clock in the Galactic Chart
              01512 ;              Panel Display memory.
              01513 ;
              01514 ; $09AD..$09DD ZPOSSIGN
              01515 ;
              01516 ;              Table containing the sign bit (B16) of position vector
              01517 ;              z-components (z-coordinate) (49 bytes). Bytes 0..4 belong to
              01518 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01519 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01520 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01521 ;              are:
              01522 ;                $00 -> Negative sign (behind our starship)
              01523 ;                $01 -> Positive sign (in front of our starship)
              01524 ;
              01525 ;              See also "ON POSITION VECTORS".
              01526 ;
              01527 ; $09AD        PL0ZPOSSIGN
              01528 ;
              01529 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01530 ;              PLAYER0. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01531 ;              VECTORS".
              01532 ;
              01533 ; $09AE        PL1ZPOSSIGN
              01534 ;
              01535 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01536 ;              PLAYER1. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01537 ;              VECTORS".
              01538 ;
              01539 ; $09AF        PL2ZPOSSIGN
              01540 ;
              01541 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01542 ;              PLAYER2. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01543 ;              VECTORS".
              01544 ;
              01545 ; $09B0        PL3ZPOSSIGN
              01546 ;
              01547 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01548 ;              PLAYER3. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01549 ;              VECTORS".
              01550 ;
              01551 ; $09B1        PL4ZPOSSIGN
              01552 ;
              01553 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01554 ;              PLAYER4. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01555 ;              VECTORS".
              01556 ;
              01557 ; $09DE..$0A0E XPOSSIGN
              01558 ;
              01559 ;              Table containing the sign bit (B16) of position vector
              01560 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01561 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01562 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01563 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01564 ;              are:
              01565 ;                $00 -> Negative sign (left)
              01566 ;                $01 -> Positive sign (right)
              01567 ;
              01568 ;              See also "ON POSITION VECTORS".
              01569 ;
              01570 ; $09DE        PL0XPOSSIGN
              01571 ;
              01572 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01573 ;              PLAYER0. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01574 ;              VECTORS".
              01575 ;
              01576 ; $09DF        PL1XPOSSIGN
              01577 ;
              01578 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01579 ;              PLAYER1. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01580 ;              VECTORS".
              01581 ;
              01582 ; $09E0        PL2XPOSSIGN
              01583 ;
              01584 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01585 ;              PLAYER2. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01586 ;              VECTORS".
              01587 ;
              01588 ; $09E1        PL3XPOSSIGN
              01589 ;
              01590 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01591 ;              PLAYER3. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01592 ;              VECTORS".
              01593 ;
              01594 ; $09E2        PL4XPOSSIGN
              01595 ;
              01596 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01597 ;              PLAYER4. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01598 ;              VECTORS".
              01599 ;
              01600 ; $0A0F..$0A3F YPOSSIGN
              01601 ;
              01602 ;              Table containing the sign bit (B16) of position vector
              01603 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01604 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01605 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01606 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01607 ;              are:
              01608 ;                $00 -> Negative sign (down)
              01609 ;                $01 -> Positive sign (up)
              01610 ;
              01611 ;              See also "ON POSITION VECTORS".
              01612 ;
              01613 ; $0A0F        PL0YPOSSIGN
              01614 ;
              01615 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01616 ;              PLAYER0. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01617 ;              VECTORS".
              01618 ;
              01619 ; $0A10        PL1YPOSSIGN
              01620 ;
              01621 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01622 ;              PLAYER1. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01623 ;              VECTORS".
              01624 ;
              01625 ; $0A11        PL2YPOSSIGN
              01626 ;
              01627 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01628 ;              PLAYER2. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01629 ;              VECTORS".
              01630 ;
              01631 ; $0A12        PL3YPOSSIGN
              01632 ;
              01633 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01634 ;              PLAYER3. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01635 ;              VECTORS".
              01636 ;
              01637 ; $0A13        PL4YPOSSIGN
              01638 ;
              01639 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01640 ;              PLAYER4. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01641 ;              VECTORS".
              01642 ;
              01643 ; $0A40..$0A70 ZPOSHI
              01644 ;
              01645 ;              Table containing the high byte (B15..8) of position vector
              01646 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01647 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01648 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01649 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01650 ;              "ON POSITION VECTORS".
              01651 ;
              01652 ; $0A40        PL0ZPOSHI
              01653 ;
              01654 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01655 ;              of PLAYER0. Compare ZPOSHI ($0A40). See also "ON POSITION
              01656 ;              VECTORS".
              01657 ;
              01658 ; $0A41        PL1ZPOSHI
              01659 ;
              01660 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01661 ;              of PLAYER1. Compare ZPOSHI ($0A40). See also "ON POSITION
              01662 ;              VECTORS".
              01663 ;
              01664 ; $0A42        PL2ZPOSHI
              01665 ;
              01666 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01667 ;              of PLAYER2. Compare ZPOSHI ($0A40). See also "ON POSITION
              01668 ;              VECTORS".
              01669 ;
              01670 ; $0A43        PL3ZPOSHI
              01671 ;
              01672 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01673 ;              of PLAYER3. Compare ZPOSHI ($0A40). See also "ON POSITION
              01674 ;              VECTORS".
              01675 ;
              01676 ; $0A44        PL4ZPOSHI
              01677 ;
              01678 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01679 ;              of PLAYER4. Compare ZPOSHI ($0A40). See also "ON POSITION
              01680 ;              VECTORS".
              01681 ;
              01682 ; $0A71..$0AA1 XPOSHI
              01683 ;
              01684 ;              Table containing the high byte (B15..8) of position vector
              01685 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01686 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01687 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01688 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01689 ;              "ON POSITION VECTORS".
              01690 ;
              01691 ; $0A71        PL0XPOSHI
              01692 ;
              01693 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01694 ;              of PLAYER0. Compare XPOSHI ($0A71). See also "ON POSITION
              01695 ;              VECTORS".
              01696 ;
              01697 ; $0A72        PL1XPOSHI
              01698 ;
              01699 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01700 ;              of PLAYER1. Compare XPOSHI ($0A71). See also "ON POSITION
              01701 ;              VECTORS".
              01702 ;
              01703 ; $0A73        PL2XPOSHI
              01704 ;
              01705 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01706 ;              of PLAYER2. Compare XPOSHI ($0A71). See also "ON POSITION
              01707 ;              VECTORS".
              01708 ;
              01709 ; $0A74        PL3XPOSHI
              01710 ;
              01711 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01712 ;              of PLAYER3. Compare XPOSHI ($0A71). See also "ON POSITION
              01713 ;              VECTORS".
              01714 ;
              01715 ; $0A75        PL4XPOSHI
              01716 ;
              01717 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01718 ;              of PLAYER4. Compare XPOSHI ($0A71). See also "ON POSITION
              01719 ;              VECTORS".
              01720 ;
              01721 ; $0AA2..$0AD2 YPOSHI
              01722 ;
              01723 ;              Table containing the high byte (B15..8) of position vector
              01724 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01725 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01726 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01727 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01728 ;              "ON POSITION VECTORS".
              01729 ;
              01730 ; $0AA2        PL0YPOSHI
              01731 ;
              01732 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01733 ;              of PLAYER0. Compare YPOSHI ($0AA2). See also "ON POSITION
              01734 ;              VECTORS".
              01735 ;
              01736 ; $0AA3        PL1YPOSHI
              01737 ;
              01738 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01739 ;              of PLAYER1. Compare YPOSHI ($0AA2). See also "ON POSITION
              01740 ;              VECTORS".
              01741 ;
              01742 ; $0AA4        PL2YPOSHI
              01743 ;
              01744 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01745 ;              of PLAYER2. Compare YPOSHI ($0AA2). See also "ON POSITION
              01746 ;              VECTORS".
              01747 ;
              01748 ; $0AA5        PL3YPOSHI
              01749 ;
              01750 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01751 ;              of PLAYER3. Compare YPOSHI ($0AA2). See also "ON POSITION
              01752 ;              VECTORS".
              01753 ;
              01754 ; $0AA6        PL4YPOSHI
              01755 ;
              01756 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01757 ;              of PLAYER4. Compare YPOSHI ($0AA2). See also "ON POSITION
              01758 ;              VECTORS".
              01759 ;
              01760 ; $0AD3..$0B03 ZPOSLO
              01761 ;
              01762 ;              Table containing the low byte (B7..0) of position vector
              01763 ;              z-components (z-coordinate) (49 bytes). Bytes 0..4 belong to
              01764 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01765 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01766 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01767 ;              "ON POSITION VECTORS".
              01768 ;
              01769 ; $0AD3        PL0ZPOSLO
              01770 ;
              01771 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01772 ;              PLAYER0. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01773 ;
              01774 ; $0AD4        PL1ZPOSLO
              01775 ;
              01776 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01777 ;              PLAYER1. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01778 ;
              01779 ; $0AD5        PL2ZPOSLO
              01780 ;
              01781 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01782 ;              PLAYER2. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01783 ;
              01784 ; $0AD6        PL3ZPOSLO
              01785 ;
              01786 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01787 ;              PLAYER3. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01788 ;
              01789 ; $0AD7        PL4ZPOSLO
              01790 ;
              01791 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01792 ;              PLAYER4. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01793 ;
              01794 ; $0B04..$0B34 XPOSLO
              01795 ;
              01796 ;              Table containing the low byte (B7..0) of position vector
              01797 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01798 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01799 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01800 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01801 ;              "ON POSITION VECTORS".
              01802 ;
              01803 ; $0B04        PL0XPOSLO
              01804 ;
              01805 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01806 ;              PLAYER0. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01807 ;
              01808 ; $0B05        PL1XPOSLO
              01809 ;
              01810 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01811 ;              PLAYER1. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01812 ;
              01813 ; $0B06        PL2XPOSLO
              01814 ;
              01815 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01816 ;              PLAYER2. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01817 ;
              01818 ; $0B07        PL3XPOSLO
              01819 ;
              01820 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01821 ;              PLAYER3. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01822 ;
              01823 ; $0B08        PL4XPOSLO
              01824 ;
              01825 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01826 ;              PLAYER4. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01827 ;
              01828 ; $0B35..$0B65 YPOSLO
              01829 ;
              01830 ;              Table containing the low byte (B7..0) of position vector
              01831 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01832 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01833 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01834 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01835 ;              "ON POSITION VECTORS".
              01836 ;
              01837 ; $0B35        PL0YPOSLO
              01838 ;
              01839 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01840 ;              PLAYER0. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01841 ;
              01842 ; $0B36        PL1YPOSLO
              01843 ;
              01844 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01845 ;              PLAYER1. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01846 ;
              01847 ; $0B37        PL2YPOSLO
              01848 ;
              01849 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01850 ;              PLAYER2. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01851 ;
              01852 ; $0B38        PL3YPOSLO
              01853 ;
              01854 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01855 ;              PLAYER3. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01856 ;
              01857 ; $0B39        PL4YPOSLO
              01858 ;
              01859 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01860 ;              PLAYER4. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01861 ;
              01862 ; $0B66..$0B96 ZVEL
              01863 ;
              01864 ;              Table containing velocity vector z-components (z-velocities) (49
              01865 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01866 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01867 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01868 ;              fragments). Each z-velocity is stored in the binary format
              01869 ;              %sxxxxxxx where
              01870 ;                %s = 0   -> Positive sign (moving in flight direction)
              01871 ;                %s = 1   -> Negative sign (moving in reverse flight direction)
              01872 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01873 ;
              01874 ;              See also "ON VELOCITY VECTORS".
              01875 ;
              01876 ; $0B66        PL0ZVEL
              01877 ;
              01878 ;              Velocity vector z-component (z-velocity) of PLAYER0. Compare ZVEL
              01879 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01880 ;
              01881 ; $0B67        PL1ZVEL
              01882 ;
              01883 ;              Velocity vector z-component (z-velocity) of PLAYER1. Compare ZVEL
              01884 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01885 ;
              01886 ; $0B68        PL2ZVEL
              01887 ;
              01888 ;              Velocity vector z-component (z-velocity) of PLAYER2. Compare ZVEL
              01889 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01890 ;
              01891 ; $0B69        PL3ZVEL
              01892 ;
              01893 ;              Velocity vector z-component (z-velocity) of PLAYER3. Compare ZVEL
              01894 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01895 ;
              01896 ; $0B6A        PL4ZVEL
              01897 ;
              01898 ;              Velocity vector z-component (z-velocity) of PLAYER4. Compare ZVEL
              01899 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01900 ;
              01901 ; $0B97..$0BC7 XVEL
              01902 ;
              01903 ;              Table containing velocity vector x-components (x-velocities) (49
              01904 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01905 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01906 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01907 ;              fragments). Each x-velocity is stored in the binary format
              01908 ;              %sxxxxxxx where
              01909 ;                %s = 0   -> Positive sign (moving to the right)
              01910 ;                %s = 1   -> Negative sign (moving to the left)
              01911 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01912 ;
              01913 ;              See also "ON VELOCITY VECTORS".
              01914 ;
              01915 ; $0B97        PL0XVEL
              01916 ;
              01917 ;              Velocity vector x-component (x-velocity) of PLAYER0. Compare XVEL
              01918 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01919 ;
              01920 ; $0B98        PL1XVEL
              01921 ;
              01922 ;              Velocity vector x-component (x-velocity) of PLAYER1. Compare XVEL
              01923 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01924 ;
              01925 ; $0B99        PL2XVEL
              01926 ;
              01927 ;              Velocity vector x-component (x-velocity) of PLAYER2. Compare XVEL
              01928 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01929 ;
              01930 ; $0B9A        PL3XVEL
              01931 ;
              01932 ;              Velocity vector x-component (x-velocity) of PLAYER3. Compare XVEL
              01933 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01934 ;
              01935 ; $0B9B        PL4XVEL
              01936 ;
              01937 ;              Velocity vector x-component (x-velocity) of PLAYER4. Compare XVEL
              01938 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01939 ;
              01940 ; $0BC8..$0BF8 YVEL
              01941 ;
              01942 ;              Table containing velocity vector y-components (y-velocities) (49
              01943 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01944 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01945 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01946 ;              fragments). Each y-velocity is stored in the binary format
              01947 ;              %sxxxxxxx where
              01948 ;                %s = 0   -> Positive sign (moving up)
              01949 ;                %s = 1   -> Negative sign (moving down)
              01950 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01951 ;
              01952 ;              See also "ON VELOCITY VECTORS".
              01953 ;
              01954 ; $0BC8        PL0YVEL
              01955 ;
              01956 ;              Velocity vector y-component (y-velocity) of PLAYER0. Compare YVEL
              01957 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01958 ;
              01959 ; $0BC9        PL1YVEL
              01960 ;
              01961 ;              Velocity vector y-component (y-velocity) of PLAYER1. Compare YVEL
              01962 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01963 ;
              01964 ; $0BCA        PL2YVEL
              01965 ;
              01966 ;              Velocity vector y-component (y-velocity) of PLAYER2. Compare YVEL
              01967 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01968 ;
              01969 ; $0BCB        PL3YVEL
              01970 ;
              01971 ;              Velocity vector y-component (y-velocity) of PLAYER3. Compare YVEL
              01972 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01973 ;
              01974 ; $0BCC        PL4YVEL
              01975 ;
              01976 ;              Velocity vector y-component (y-velocity) of PLAYER4. Compare YVEL
              01977 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01978 ;
              01979 ; $0BF9..$0C29 PIXELROWNEW
              01980 ;
              01981 ;              Table containing the new pixel row number of space objects (49
              01982 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              01983 ;              Player/Missile (PM) pixel row numbers. They are counted from
              01984 ;              vertical PM position 0, which is offscreen. Bytes 5..48 belong to
              01985 ;              PLAYFIELD space objects (stars, explosion fragments) and contain
              01986 ;              PLAYFIELD pixel row numbers. They are counted from the top border
              01987 ;              of the PLAYFIELD and have values of 0..99. See also PIXELROW
              01988 ;              ($0C5B).
              01989 ;
              01990 ; $0BF9        PL0ROWNEW
              01991 ;
              01992 ;              New pixel row number of PLAYER0 in Player/Missile pixels. See
              01993 ;              also PIXELROWNEW ($0BF9).
              01994 ;
              01995 ; $0BFA        PL1ROWNEW
              01996 ;
              01997 ;              New pixel row number of PLAYER1 in Player/Missile pixels. See
              01998 ;              also PIXELROWNEW ($0BF9).
              01999 ;
              02000 ; $0BFB        PL2ROWNEW
              02001 ;
              02002 ;              New pixel row number of PLAYER2 in Player/Missile pixels. See
              02003 ;              also PIXELROWNEW ($0BF9).
              02004 ;
              02005 ; $0BFC        PL3ROWNEW
              02006 ;
              02007 ;              New pixel row number of PLAYER3 in Player/Missile pixels. See
              02008 ;              also PIXELROWNEW ($0BF9).
              02009 ;
              02010 ; $0BFD        PL4ROWNEW
              02011 ;
              02012 ;              New pixel row number of PLAYER4 in Player/Missile pixels. See
              02013 ;              also PIXELROWNEW ($0BF9).
              02014 ;
              02015 ; $0C2A..$0C5A PIXELCOLUMN
              02016 ;
              02017 ;              Table containing the pixel column number of space objects (49
              02018 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              02019 ;              Player/Missile (PM) pixel column numbers. They are counted from
              02020 ;              horizontal PM position 0, which is offscreen. Bytes 5..48 belong
              02021 ;              to PLAYFIELD space objects (stars, explosion fragments) and
              02022 ;              contain PLAYFIELD pixel column numbers. They are counted from the
              02023 ;              left border of the PLAYFIELD and have values of 0..159.
              02024 ;
              02025 ; $0C2A        PL0COLUMN
              02026 ;
              02027 ;              Pixel column number of PLAYER0 in Player/Missile pixels. See also
              02028 ;              PIXELCOLUMN ($0C2A).
              02029 ;
              02030 ; $0C2B        PL1COLUMN
              02031 ;
              02032 ;              Pixel column number of PLAYER1 in Player/Missile pixels. See also
              02033 ;              PIXELCOLUMN ($0C2A).
              02034 ;
              02035 ; $0C2C        PL2COLUMN
              02036 ;
              02037 ;              Pixel column number of PLAYER2 in Player/Missile pixels. See also
              02038 ;              PIXELCOLUMN ($0C2A).
              02039 ;
              02040 ; $0C2D        PL3COLUMN
              02041 ;
              02042 ;              Pixel column number of PLAYER3 in Player/Missile pixels. See also
              02043 ;              PIXELCOLUMN ($0C2A).
              02044 ;
              02045 ; $0C2E        PL4COLUMN
              02046 ;
              02047 ;              Pixel column number of PLAYER4 in Player/Missile pixels. See also
              02048 ;              PIXELCOLUMN ($0C2A).
              02049 ;
              02050 ; $0C5B..$0C8B PIXELROW
              02051 ;
              02052 ;              Table containing the pixel row number of space objects (49
              02053 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              02054 ;              Player/Missile (PM) pixel row numbers. They are counted from
              02055 ;              vertical PM position 0, which is offscreen. Bytes 5..48 belong to
              02056 ;              PLAYFIELD space objects (stars, explosion fragments) and contain
              02057 ;              PLAYFIELD pixel row numbers. They are counted from the top border
              02058 ;              of the PLAYFIELD and have values of 0..99. See also PIXELROWNEW
              02059 ;              ($0BF9).
              02060 ;
              02061 ; $0C5B        PL0ROW
              02062 ;
              02063 ;              Pixel row number of PLAYER0 in Player/Missile pixels. See also
              02064 ;              PIXELROW ($0C5B).
              02065 ;
              02066 ; $0C5C        PL1ROW
              02067 ;
              02068 ;              Pixel row number of PLAYER1 in Player/Missile pixels. See also
              02069 ;              PIXELROW ($0C5B).
              02070 ;
              02071 ; $0C5D        PL2ROW
              02072 ;
              02073 ;              Pixel row number of PLAYER2 in Player/Missile pixels. See also
              02074 ;              PIXELROW ($0C5B).
              02075 ;
              02076 ; $0C5E        PL3ROW
              02077 ;
              02078 ;              Pixel row number of PLAYER3 in Player/Missile pixels. See also
              02079 ;              PIXELROW ($0C5B).
              02080 ;
              02081 ; $0C5F        PL4ROW
              02082 ;
              02083 ;              Pixel row number of PLAYER4 in Player/Missile pixels. See also
              02084 ;              PIXELROW ($0C5B).
              02085 ;
              02086 ; $0C8C..$0CBC PIXELBYTEOFF
              02087 ;
              02088 ;              Table containing a byte offset into PLAYFIELD memory for each
              02089 ;              PLAYFIELD space object (stars, explosion fragments) (49 bytes):
              02090 ;              the number of bytes from the start of the PLAYFIELD row to the
              02091 ;              byte containing the space object pixel in the same PLAYFIELD row.
              02092 ;              In other words, the pixel column modulo 4 (1 byte = 4 GRAPHICS7
              02093 ;              pixels).
              02094 ;
              02095 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02096 ;              this way. Bytes 0..4 are used differently. See PL0SHAPTYPE
              02097 ;              ($0C8C)..PL4SHAPTYPE ($0C90).
              02098 ;
              02099 ; $0C8C        PL0SHAPTYPE
              02100 ;
              02101 ;              Shape type of PLAYER0. Used to index the PLAYER's set of shape
              02102 ;              cells in tables PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB ($BE7F).
              02103 ;              Used values are:
              02104 ;                $00 -> PHOTON TORPEDO
              02105 ;                $10 -> ZYLON FIGHTER
              02106 ;                $20 -> STARBASE RIGHT
              02107 ;                $30 -> STARBASE CENTER
              02108 ;                $40 -> STARBASE LEFT
              02109 ;                $50 -> TRANSFER VESSEL
              02110 ;                $60 -> METEOR
              02111 ;                $70 -> ZYLON CRUISER
              02112 ;                $80 -> ZYLON BASESTAR
              02113 ;                $90 -> HYPERWARP TARGET MARKER
              02114 ;
              02115 ; $0C8D        PL1SHAPTYPE
              02116 ;
              02117 ;              Shape type of PLAYER1. Compare PL0SHAPTYPE ($0C8C).
              02118 ;
              02119 ; $0C8E        PL2SHAPTYPE
              02120 ;
              02121 ;              Shape type of PLAYER2. Compare PL0SHAPTYPE ($0C8C).
              02122 ;
              02123 ; $0C8F        PL3SHAPTYPE
              02124 ;
              02125 ;              Shape type of PLAYER3. Compare PL0SHAPTYPE ($0C8C).
              02126 ;
              02127 ; $0C90        PL4SHAPTYPE
              02128 ;
              02129 ;              Shape type of PLAYER4. Compare PL0SHAPTYPE ($0C8C).
              02130 ;
              02131 ; $0CBD..$0CED PIXELSAVE
              02132 ;
              02133 ;              Table containing the byte of PLAYFIELD memory before drawing the
              02134 ;              PLAYFIELD space object pixel into it (star, explosion fragments),
              02135 ;              for each PLAYFIELD space object (49 bytes).
              02136 ;
              02137 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02138 ;              this way. Bytes 0..4 are used differently. See PL0HEIGHT
              02139 ;              ($0CBD)..PL4HEIGHT ($0CC1).
              02140 ;
              02141 ; $0CBD        PL0HEIGHT
              02142 ;
              02143 ;              Shape height of PLAYER0
              02144 ;
              02145 ; $0CBE        PL1HEIGHT
              02146 ;
              02147 ;              Shape height of PLAYER1
              02148 ;
              02149 ; $0CBF        PL2HEIGHT
              02150 ;
              02151 ;              Shape height of PLAYER2
              02152 ;
              02153 ; $0CC0        PL3HEIGHT
              02154 ;
              02155 ;              Shape height of PLAYER3
              02156 ;
              02157 ; $0CC1        PL4HEIGHT
              02158 ;
              02159 ;              Shape height of PLAYER4
              02160 ;
              02161 ; $0CEE..$0D1E PIXELBYTE
              02162 ;
              02163 ;              Table containing a 1-byte bit pattern for 4 pixels in the color
              02164 ;              of the space object's pixel, for each PLAYFIELD space object (49
              02165 ;              bytes).
              02166 ;
              02167 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02168 ;              this way. Bytes 0..4 are used differently. See PL0HEIGHTNEW
              02169 ;              ($0CEE)..PL4HEIGHTNEW ($0CF2).
              02170 ;
              02171 ; $0CEE        PL0HEIGHTNEW
              02172 ;
              02173 ;              New shape height of PLAYER0
              02174 ;
              02175 ; $0CEF        PL1HEIGHTNEW
              02176 ;
              02177 ;              New shape height of PLAYER1
              02178 ;
              02179 ; $0CF0        PL2HEIGHTNEW
              02180 ;
              02181 ;              New shape height of PLAYER2
              02182 ;
              02183 ; $0CF1        PL3HEIGHTNEW
              02184 ;
              02185 ;              New shape height of PLAYER3
              02186 ;
              02187 ; $0CF2        PL4HEIGHTNEW
              02188 ;
              02189 ;              New shape height of PLAYER4
              02190 ;
              02191 ; $0D1F..$0D32 TITLETXT
              02192 ;
              02193 ;              Title text line, contains ATASCII-coded characters (20 bytes)
              02194 ;
              02195 ; $0D35..$0DE8 GCPFMEM
              02196 ;
              02197 ;              Galactic Chart PLAYFIELD memory (20 characters x 9 rows = 180
              02198 ;              bytes)
              02199 ;
              02200 ; $0DE9..$0EE8 MAPTO80
              02201 ;
              02202 ;              Lookup table to convert values in $00..$FF to values of 0..80
              02203 ;              (255 bytes). Used to map position vector components (coordinates)
              02204 ;              to pixel row or column numbers relative to the PLAYFIELD center.
              02205 ;
              02206 ; $0EE9..$0FE8 MAPTOBCD99
              02207 ;
              02208 ;              Lookup table to convert values in $00..$FF to BCD-values of
              02209 ;              00..99 (255 bytes). Used in subroutines UPDPANEL ($B804) and
              02210 ;              SHOWDIGITS ($B8CD) to convert values to a 2-digit decimal readout
              02211 ;              value of the Control Panel Display.
              02212 ;
              02213 ; $1000..$1F77 PFMEM
              02214 ;
              02215 ;              PLAYFIELD graphics memory (40 bytes x 100 rows = 4000 bytes, 1
              02216 ;              byte stores 4 pixels, 40 bytes = 160 pixels in GRAPHICS7 mode = 1
              02217 ;              PLAYFIELD row of pixels).
              02218 ;
              02219 ;              NOTE: The Display List displays only PLAYFIELD rows 0..98.
              02220
              02221 ;*******************************************************************************
              02222 ;*                                                                             *
              02223 ;*                         S Y S T E M   S Y M B O L S                         *
              02224 ;*                                                                             *
              02225 ;*******************************************************************************
              02226
    =0200     02227 VDSLST          = $0200                               ; Display List Interrupt (DLI) vector
    =0216     02228 VIMIRQ          = $0216                               ; Interrupt request (IRQ) immediate vector
    =0222     02229 VVBLKI          = $0222                               ; Vertical blank immediate vector
    =D000     02230 HPOSP0          = $D000                               ; Horizontal position of PLAYER0
    =D001     02231 HPOSP1          = $D001                               ; Horizontal position of PLAYER1
    =D002     02232 HPOSP2          = $D002                               ; Horizontal position of PLAYER2
    =D003     02233 HPOSP3          = $D003                               ; Horizontal position of PLAYER3
    =D004     02234 HPOSM0          = $D004                               ; Horizontal position of MISSILE0
    =D005     02235 HPOSM1          = $D005                               ; Horizontal position of MISSILE1
    =D006     02236 HPOSM2          = $D006                               ; Horizontal position of MISSILE2
    =D007     02237 HPOSM3          = $D007                               ; Horizontal position of MISSILE3
    =D008     02238 M0PL            = $D008                               ; MISSILE0 to PLAYER collisions
    =D009     02239 M1PL            = $D009                               ; MISSILE1 to PLAYER collisions
    =D00A     02240 M2PL            = $D00A                               ; MISSILE2 to PLAYER collisions
    =D00B     02241 M3PL            = $D00B                               ; MISSILE3 to PLAYER collisions
    =D00F     02242 P3PL            = $D00F                               ; PLAYER3 to PLAYER collisions
    =D010     02243 TRIG0           = $D010                               ; Joystick 0 trigger
    =D012     02244 COLPM0          = $D012                               ; Color and brightness of PLAYER0
    =D016     02245 COLPF0          = $D016                               ; Color and brightness of PLAYFIELD0
    =D01B     02246 PRIOR           = $D01B                               ; Priority selection register
    =D01D     02247 GRACTL          = $D01D                               ; Graphics control register
    =D01E     02248 HITCLR          = $D01E                               ; Clear collision register
    =D01F     02249 CONSOL          = $D01F                               ; Function keys register
    =D200     02250 AUDF1           = $D200                               ; Audio channel 1 frequency
    =D202     02251 AUDF2           = $D202                               ; Audio channel 2 frequency
    =D203     02252 AUDC2           = $D203                               ; Audio channel 2 control
    =D204     02253 AUDF3           = $D204                               ; Audio channel 3 frequency
    =D205     02254 AUDC3           = $D205                               ; Audio channel 3 control
    =D206     02255 AUDF4           = $D206                               ; Audio channel 4 frequency
    =D207     02256 AUDC4           = $D207                               ; Audio channel 4 control
    =D208     02257 AUDCTL          = $D208                               ; Audio control
    =D209     02258 KBCODE          = $D209                               ; Keyboard code
    =D209     02259 STIMER          = $D209                               ; Start POKEY timers
    =D20A     02260 RANDOM          = $D20A                               ; Random number generator
    =D20E     02261 IRQEN           = $D20E                               ; Interrupt request (IRQ) enable
    =D20F     02262 SKCTL           = $D20F                               ; Serial port control
    =D300     02263 PORTA           = $D300                               ; Port A
    =D302     02264 PACTL           = $D302                               ; Port A control
    =D400     02265 DMACTL          = $D400                               ; Direct Memory Access (DMA) control
    =D402     02266 DLIST           = $D402                               ; Display List pointer
    =D407     02267 PMBASE          = $D407                               ; Player/Missile base address (high byte)
    =D409     02268 CHBASE          = $D409                               ; Character set base address (high byte)
    =D40A     02269 WSYNC           = $D40A                               ; Wait for horizontal synchronization
    =D40B     02270 VCOUNT          = $D40B                               ; Vertical line counter
    =D40E     02271 NMIEN           = $D40E                               ; Non-maskable interrupt (NMI) enable
    =E000     02272 ROMCHARSET      = $E000                               ; ROM character set
              02273
              02274 ;*******************************************************************************
              02275 ;*                                                                             *
              02276 ;*                           G A M E   S Y M B O L S                           *
              02277 ;*                                                                             *
              02278 ;*******************************************************************************
              02279
    =0062     02280 MISSIONLEVEL    = $62
    =0063     02281 FKEYCODE        = $63
    =0064     02282 ISDEMOMODE      = $64
    =0065     02283 NEWTITLEPHR     = $65
    =0066     02284 IDLECNTHI       = $66
    =0067     02285 ISVBISYNC       = $67
    =0068     02286 MEMPTR          = $68
              02287
    =006A     02288 DIVIDEND        = $6A
    =006D     02289 JOYSTICKDELTA   = $6D
              02290
              02291
    =0070     02292 VELOCITYLO      = $70
    =0071     02293 NEWVELOCITY     = $71
    =0072     02294 COUNT8          = $72
    =0073     02295 EXPLLIFE        = $73
    =0074     02296 CLOCKTIM        = $74
    =0075     02297 DOCKSTATE       = $75
    =0076     02298 COUNT256        = $76
    =0077     02299 IDLECNTLO       = $77
    =0078     02300 ZYLONUNITTIM    = $78
    =0079     02301 MAXSPCOBJIND    = $79
    =007A     02302 OLDMAXSPCOBJIND = $7A
    =007B     02303 ISSTARBASESECT  = $7B
    =007C     02304 ISTRACKCOMPON   = $7C
    =007D     02305 DRAINSHIELDS    = $7D
    =007E     02306 DRAINATTCOMP    = $7E
    =007F     02307 ENERGYCNT       = $7F
    =0080     02308 DRAINENGINES    = $80
    =0081     02309 SHIELDSCOLOR    = $81
    =0082     02310 PL3HIT          = $82
    =0083     02311 PL4HIT          = $83
    =0084     02312 OLDTRIG0        = $84
              02313
    =0086     02314 ISTRACKING      = $86
    =0087     02315 BARRELNR        = $87
    =0088     02316 LOCKONLIFE      = $88
    =0089     02317 PLTRACKED       = $89
    =008A     02318 HITBADNESS      = $8A
    =008B     02319 REDALERTLIFE    = $8B
    =008C     02320 WARPDEPRROW     = $8C
    =008D     02321 WARPDEPRCOLUMN  = $8D
    =008E     02322 WARPARRVROW     = $8E
    =008F     02323 WARPARRVCOLUMN  = $8F
    =0090     02324 CURRSECTOR      = $90
    =0091     02325 WARPENERGY      = $91
    =0092     02326 ARRVSECTOR      = $92
    =0093     02327 HUNTSECTOR      = $93
    =0094     02328 HUNTSECTCOLUMN  = $94
    =0095     02329 HUNTSECTROW     = $95
    =0096     02330 NEWZYLONDIST    = $96
    =009E     02331 OLDZYLONDIST    = $9E
    =009F     02332 HUNTTIM         = $9F
    =00A0     02333 BLIPCOLUMN      = $A0
    =00A1     02334 BLIPROW         = $A1
    =00A2     02335 BLIPCYCLECNT    = $A2
    =00A3     02336 ISINLOCKON      = $A3
    =00A4     02337 DIRLEN          = $A4
    =00A5     02338 PENROW          = $A5
    =00A6     02339 PENCOLUMN       = $A6
    =00A7     02340 CTRLDZYLON      = $A7
    =00A8     02341 ZYLONFLPAT0     = $A8
    =00A9     02342 ZYLONFLPAT1     = $A9
    =00AA     02343 MILESTTIM0      = $AA
    =00AB     02344 MILESTTIM1      = $AB
    =00AC     02345 MILESTVELINDZ0  = $AC
    =00AD     02346 MILESTVELINDZ1  = $AD
    =00AE     02347 MILESTVELINDX0  = $AE
    =00AF     02348 MILESTVELINDX1  = $AF
    =00B0     02349 MILESTVELINDY0  = $B0
    =00B1     02350 MILESTVELINDY1  = $B1
    =00B2     02351 ZYLONVELINDZ0   = $B2
    =00B3     02352 ZYLONVELINDZ1   = $B3
    =00B4     02353 ZYLONVELINDX0   = $B4
    =00B5     02354 ZYLONVELINDX1   = $B5
    =00B6     02355 ZYLONVELINDY0   = $B6
    =00B7     02356 ZYLONVELINDY1   = $B7
    =00B8     02357 ISBACKATTACK0   = $B8
    =00B9     02358 ISBACKATTACK1   = $B9
    =00BA     02359 ZYLONTIMX0      = $BA
    =00BB     02360 ZYLONTIMX1      = $BB
    =00BC     02361 ZYLONTIMY0      = $BC
    =00BD     02362 ZYLONTIMY1      = $BD
    =00BE     02363 TORPEDODELAY    = $BE
    =00BF     02364 ZYLONATTACKER   = $BF
    =00C0     02365 WARPSTATE       = $C0
    =00C1     02366 VELOCITYHI      = $C1
    =00C2     02367 TRAILDELAY      = $C2
    =00C3     02368 TRAILIND        = $C3
    =00C4     02369 WARPTEMPCOLUMN  = $C4
    =00C5     02370 WARPTEMPROW     = $C5
    =00C6     02371 VEERMASK        = $C6
    =00C7     02372 VICINITYMASK    = $C7
    =00C8     02373 JOYSTICKX       = $C8
    =00C9     02374 JOYSTICKY       = $C9
    =00CA     02375 KEYCODE         = $CA
    =00CB     02376 SCORE           = $CB
    =00CD     02377 SCOREDRANKIND   = $CD
    =00CE     02378 SCOREDCLASSIND  = $CE
    =00CF     02379 TITLELIFE       = $CF
    =00D0     02380 SHIPVIEW        = $D0
    =00D1     02381 TITLEPHR        = $D1
    =00D2     02382 BEEPFRQIND      = $D2
    =00D3     02383 BEEPREPEAT      = $D3
    =00D4     02384 BEEPTONELIFE    = $D4
    =00D5     02385 BEEPPAUSELIFE   = $D5
    =00D6     02386 BEEPPRIORITY    = $D6
    =00D7     02387 BEEPFRQSTART    = $D7
    =00D8     02388 BEEPLIFE        = $D8
    =00D9     02389 BEEPTOGGLE      = $D9
    =00DA     02390 NOISETORPTIM    = $DA
    =00DB     02391 NOISEEXPLTIM    = $DB
    =00DC     02392 NOISEAUDC2      = $DC
    =00DD     02393 NOISEAUDC3      = $DD
    =00DE     02394 NOISEAUDF1      = $DE
    =00DF     02395 NOISEAUDF2      = $DF
    =00E0     02396 NOISEFRQINC     = $E0
    =00E1     02397 NOISELIFE       = $E1
    =00E2     02398 NOISEZYLONTIM   = $E2
    =00E3     02399 NOISEHITLIFE    = $E3
    =00E4     02400 PL0SHAPOFF      = $E4
    =00E5     02401 PL1SHAPOFF      = $E5
    =00E6     02402 PL2SHAPOFF      = $E6
    =00E7     02403 PL3SHAPOFF      = $E7
    =00E8     02404 PL4SHAPOFF      = $E8
    =00E9     02405 PL0LIFE         = $E9
    =00EA     02406 PL1LIFE         = $EA
    =00EB     02407 PL2LIFE         = $EB
    =00EC     02408 PL3LIFE         = $EC
    =00ED     02409 PL4LIFE         = $ED
    =00EE     02410 PL0COLOR        = $EE
    =00EF     02411 PL1COLOR        = $EF
    =00F0     02412 PL2COLOR        = $F0
    =00F1     02413 PL3COLOR        = $F1
    =00F2     02414 PF0COLOR        = $F2
    =00F3     02415 PF1COLOR        = $F3
    =00F4     02416 PF2COLOR        = $F4
    =00F5     02417 PF3COLOR        = $F5
    =00F6     02418 BGRCOLOR        = $F6
    =00F7     02419 PF0COLORDLI     = $F7
    =00F8     02420 PF1COLORDLI     = $F8
    =00F9     02421 PF2COLORDLI     = $F9
    =00FA     02422 PF3COLORDLI     = $FA
    =00FB     02423 BGRCOLORDLI     = $FB
    =0280     02424 DSPLST          = $0280
    =0300     02425 PL4DATA         = $0300
    =0400     02426 PL0DATA         = $0400
    =0500     02427 PL1DATA         = $0500
    =0600     02428 PL2DATA         = $0600
    =0700     02429 PL3DATA         = $0700
    =0800     02430 PFMEMROWLO      = $0800
    =0864     02431 PFMEMROWHI      = $0864
    =08C9     02432 GCMEMMAP        = $08C9
    =0949     02433 PANELTXT        = $0949
    =094B     02434 VELOCD1         = $094B
    =0950     02435 KILLCNTD1       = $0950
    =0955     02436 ENERGYD1        = $0955
    =095A     02437 TRACKC1         = $095A
    =095C     02438 TRACKDIGIT      = $095C
    =0960     02439 THETAC1         = $0960
    =0966     02440 PHIC1           = $0966
    =096C     02441 RANGEC1         = $096C
    =0971     02442 GCTXT           = $0971
    =097D     02443 GCWARPD1        = $097D
    =098D     02444 GCTRGCNT        = $098D
    =0992     02445 GCSTATPHO       = $0992
    =0993     02446 GCSTATENG       = $0993
    =0994     02447 GCSTATSHL       = $0994
    =0995     02448 GCSTATCOM       = $0995
    =0996     02449 GCSTATLRS       = $0996
    =0997     02450 GCSTATRAD       = $0997
    =09A3     02451 GCSTARDAT       = $09A3
    =09AD     02452 ZPOSSIGN        = $09AD
    =09AF     02453 PL2ZPOSSIGN     = $09AF
    =09B0     02454 PL3ZPOSSIGN     = $09B0
    =09B1     02455 PL4ZPOSSIGN     = $09B1
    =09DE     02456 XPOSSIGN        = $09DE
    =09E0     02457 PL2XPOSSIGN     = $09E0
    =09E1     02458 PL3XPOSSIGN     = $09E1
    =09E2     02459 PL4XPOSSIGN     = $09E2
    =0A0F     02460 YPOSSIGN        = $0A0F
    =0A11     02461 PL2YPOSSIGN     = $0A11
    =0A12     02462 PL3YPOSSIGN     = $0A12
    =0A13     02463 PL4YPOSSIGN     = $0A13
    =0A40     02464 ZPOSHI          = $0A40
    =0A40     02465 PL0ZPOSHI       = $0A40
    =0A42     02466 PL2ZPOSHI       = $0A42
    =0A43     02467 PL3ZPOSHI       = $0A43
    =0A44     02468 PL4ZPOSHI       = $0A44
    =0A71     02469 XPOSHI          = $0A71
    =0A73     02470 PL2XPOSHI       = $0A73
    =0A74     02471 PL3XPOSHI       = $0A74
    =0A75     02472 PL4XPOSHI       = $0A75
    =0AA2     02473 YPOSHI          = $0AA2
    =0AA4     02474 PL2YPOSHI       = $0AA4
    =0AA5     02475 PL3YPOSHI       = $0AA5
    =0AA6     02476 PL4YPOSHI       = $0AA6
    =0AD3     02477 ZPOSLO          = $0AD3
    =0AD5     02478 PL2ZPOSLO       = $0AD5
    =0AD6     02479 PL3ZPOSLO       = $0AD6
    =0AD7     02480 PL4ZPOSLO       = $0AD7
    =0B04     02481 XPOSLO          = $0B04
    =0B06     02482 PL2XPOSLO       = $0B06
    =0B07     02483 PL3XPOSLO       = $0B07
    =0B08     02484 PL4XPOSLO       = $0B08
    =0B35     02485 YPOSLO          = $0B35
    =0B37     02486 PL2YPOSLO       = $0B37
    =0B38     02487 PL3YPOSLO       = $0B38
    =0B39     02488 PL4YPOSLO       = $0B39
    =0B66     02489 ZVEL            = $0B66
    =0B66     02490 PL0ZVEL         = $0B66
    =0B67     02491 PL1ZVEL         = $0B67
    =0B68     02492 PL2ZVEL         = $0B68
    =0B69     02493 PL3ZVEL         = $0B69
    =0B6A     02494 PL4ZVEL         = $0B6A
    =0B97     02495 XVEL            = $0B97
    =0B97     02496 PL0XVEL         = $0B97
    =0B98     02497 PL1XVEL         = $0B98
    =0B99     02498 PL2XVEL         = $0B99
    =0B9A     02499 PL3XVEL         = $0B9A
    =0B9B     02500 PL4XVEL         = $0B9B
    =0BC8     02501 YVEL            = $0BC8
    =0BC8     02502 PL0YVEL         = $0BC8
    =0BC9     02503 PL1YVEL         = $0BC9
    =0BCA     02504 PL2YVEL         = $0BCA
    =0BCB     02505 PL3YVEL         = $0BCB
    =0BCC     02506 PL4YVEL         = $0BCC
    =0BF9     02507 PIXELROWNEW     = $0BF9
    =0BF9     02508 PL0ROWNEW       = $0BF9
    =0BFA     02509 PL1ROWNEW       = $0BFA
    =0BFB     02510 PL2ROWNEW       = $0BFB
    =0BFC     02511 PL3ROWNEW       = $0BFC
    =0BFD     02512 PL4ROWNEW       = $0BFD
    =0C2A     02513 PIXELCOLUMN     = $0C2A
    =0C2A     02514 PL0COLUMN       = $0C2A
    =0C2B     02515 PL1COLUMN       = $0C2B
    =0C2C     02516 PL2COLUMN       = $0C2C
    =0C2D     02517 PL3COLUMN       = $0C2D
    =0C2E     02518 PL4COLUMN       = $0C2E
    =0C5B     02519 PIXELROW        = $0C5B
    =0C5B     02520 PL0ROW          = $0C5B
    =0C5C     02521 PL1ROW          = $0C5C
    =0C5D     02522 PL2ROW          = $0C5D
    =0C5E     02523 PL3ROW          = $0C5E
    =0C5F     02524 PL4ROW          = $0C5F
    =0C8C     02525 PIXELBYTEOFF    = $0C8C
    =0C8C     02526 PL0SHAPTYPE     = $0C8C
    =0C8D     02527 PL1SHAPTYPE     = $0C8D
    =0C8E     02528 PL2SHAPTYPE     = $0C8E
    =0C8F     02529 PL3SHAPTYPE     = $0C8F
    =0C90     02530 PL4SHAPTYPE     = $0C90
    =0CBD     02531 PIXELSAVE       = $0CBD
    =0CBD     02532 PL0HEIGHT       = $0CBD
    =0CBE     02533 PL1HEIGHT       = $0CBE
    =0CBF     02534 PL2HEIGHT       = $0CBF
    =0CC0     02535 PL3HEIGHT       = $0CC0
    =0CC1     02536 PL4HEIGHT       = $0CC1
    =0CEE     02537 PIXELBYTE       = $0CEE
    =0CEE     02538 PL0HEIGHTNEW    = $0CEE
    =0CEF     02539 PL1HEIGHTNEW    = $0CEF
    =0CF0     02540 PL2HEIGHTNEW    = $0CF0
    =0CF1     02541 PL3HEIGHTNEW    = $0CF1
    =0CF2     02542 PL4HEIGHTNEW    = $0CF2
    =0D1F     02543 TITLETXT        = $0D1F
    =0D35     02544 GCPFMEM         = $0D35
    =0DE9     02545 MAPTO80         = $0DE9
    =0EE9     02546 MAPTOBCD99      = $0EE9
    =1000     02547 PFMEM           = $1000
              02548
              02549                 *= $A000
              02550
              02551 ;*******************************************************************************
              02552 ;*                                                                             *
              02553 ;*                G A M E   D A T A   ( P A R T   1   O F   2 )                *
              02554 ;*                                                                             *
              02555 ;*******************************************************************************
              02556
              02557 ;*** Number of space objects ***************************************************
              02558
    =0005     02559 NUMSPCOBJ.PL    = 5                                   ; Number of PLAYER space objects
    =000C     02560 NUMSPCOBJ.STARS = 12                                  ; Number of PLAYFIELD space objects (stars only)
    =0011     02561 NUMSPCOBJ.NORM  = NUMSPCOBJ.PL+NUMSPCOBJ.STARS        ; Normal number of space objects
    =0031     02562 NUMSPCOBJ.ALL   = 49                                  ; Maximum number of space objects
              02563
              02564 ;*** PLAYER shape data offsets *************************************************
              02565
    =0000     02566 SHAP.TORPEDO    = $00                                 ; Photon torpedo
    =0010     02567 SHAP.ZFIGHTER   = $10                                 ; Zylon fighter
    =0020     02568 SHAP.STARBASEL  = $20                                 ; Starbase (left part)
    =0030     02569 SHAP.STARBASEC  = $30                                 ; Starbase (center part)
    =0040     02570 SHAP.STARBASER  = $40                                 ; Starbase (right part)
    =0050     02571 SHAP.TRANSVSSL  = $50                                 ; Transfer vessel
    =0060     02572 SHAP.METEOR     = $60                                 ; Meteor
    =0070     02573 SHAP.ZCRUISER   = $70                                 ; Zylon cruiser
    =0080     02574 SHAP.ZBASESTAR  = $80                                 ; Zylon basestar
    =0090     02575 SHAP.HYPERWARP  = $90                                 ; Hyperwarp Target Marker
              02576
              02577 ;*** ROM character set constants ***********************************************
    =0000     02578 ROM.SPC         = $00                                 ; ROM character ' '
    =000E     02579 ROM.DOT         = $0E                                 ; ROM character '.'
    =0010     02580 ROM.0           = $10                                 ; ROM character '0'
    =0011     02581 ROM.1           = $11                                 ; ROM character '1'
    =0012     02582 ROM.2           = $12                                 ; ROM character '2'
    =0013     02583 ROM.3           = $13                                 ; ROM character '3'
    =0014     02584 ROM.4           = $14                                 ; ROM character '4'
    =0015     02585 ROM.5           = $15                                 ; ROM character '5'
    =0019     02586 ROM.9           = $19                                 ; ROM character '9'
    =001A     02587 ROM.COLON       = $1A                                 ; ROM character ':'
    =0021     02588 ROM.A           = $21                                 ; ROM character 'A'
    =0023     02589 ROM.C           = $23                                 ; ROM character 'C'
    =0024     02590 ROM.D           = $24                                 ; ROM character 'D'
    =0025     02591 ROM.E           = $25                                 ; ROM character 'E'
    =0027     02592 ROM.G           = $27                                 ; ROM character 'G'
    =002C     02593 ROM.L           = $2C                                 ; ROM character 'L'
    =002E     02594 ROM.N           = $2E                                 ; ROM character 'N'
    =0030     02595 ROM.P           = $30                                 ; ROM character 'P'
    =0032     02596 ROM.R           = $32                                 ; ROM character 'R'
    =0033     02597 ROM.S           = $33                                 ; ROM character 'S'
    =0034     02598 ROM.T           = $34                                 ; ROM character 'T'
    =0037     02599 ROM.W           = $37                                 ; ROM character 'W'
    =0039     02600 ROM.Y           = $39                                 ; ROM character 'Y'
              02601
              02602 ;*** Custom character set constants ********************************************
    =0040     02603 CCS.COL1        = $40                                 ; COLOR1 bits for text in GR1/2 text mode
    =0080     02604 CCS.COL2        = $80                                 ; COLOR2 bits for text in GR1/2 text mode
    =00C0     02605 CCS.COL3        = $C0                                 ; COLOR3 bits for text in GR1/2 text mode
              02606
    =0000     02607 CCS.0           = 0                                   ; Custom character '0'
    =0001     02608 CCS.1           = 1                                   ; Custom character '1'
    =0002     02609 CCS.2           = 2                                   ; Custom character '2'
    =0003     02610 CCS.3           = 3                                   ; Custom character '3'
    =0004     02611 CCS.4           = 4                                   ; Custom character '4'
    =0005     02612 CCS.5           = 5                                   ; Custom character '5'
    =0006     02613 CCS.6           = 6                                   ; Custom character '6'
    =0007     02614 CCS.7           = 7                                   ; Custom character '7'
    =0008     02615 CCS.8           = 8                                   ; Custom character '8'
    =0009     02616 CCS.9           = 9                                   ; Custom character '9'
    =000A     02617 CCS.SPC         = 10                                  ; Custom character ' '
    =000B     02618 CCS.COLON       = 11                                  ; Custom character ':'
    =000C     02619 CCS.BORDERSW    = 12                                  ; Custom character 'BORDER SOUTHWEST'
    =000D     02620 CCS.E           = 13                                  ; Custom character 'E'
    =000E     02621 CCS.INF         = 14                                  ; Custom character 'INFINITY'
    =000F     02622 CCS.MINUS       = 15                                  ; Custom character '-'
    =0010     02623 CCS.PLUS        = 16                                  ; Custom character '+'
    =0011     02624 CCS.PHI         = 17                                  ; Custom character 'PHI'
    =0012     02625 CCS.V           = 18                                  ; Custom character 'V'
    =0013     02626 CCS.R           = 19                                  ; Custom character 'R'
    =0014     02627 CCS.THETA       = 20                                  ; Custom character 'THETA'
    =0015     02628 CCS.K           = 21                                  ; Custom character 'K'
    =0016     02629 CCS.T           = 22                                  ; Custom character 'T'
    =0017     02630 CCS.C           = 23                                  ; Custom character 'C'
    =0018     02631 CCS.BORDERS     = 24                                  ; Custom character 'BORDER SOUTH'
    =0019     02632 CCS.BORDERW     = 25                                  ; Custom character 'BORDER WEST'
    =001A     02633 CCS.CORNERSW    = 26                                  ; Custom character 'CORNER SOUTHWEST'
    =001B     02634 CCS.STARBASE    = 27                                  ; Custom character 'STARBASE SECTOR'
    =001C     02635 CCS.4ZYLONS     = 28                                  ; Custom character '4-ZYLON SECTOR'
    =001D     02636 CCS.3ZYLONS     = 29                                  ; Custom character '3-ZYLON SECTOR'
    =001E     02637 CCS.2ZYLONS     = 30                                  ; Custom character '2-ZYLON SECTOR'
              02638
              02639 ;*** Custom character set ******************************************************
              02640 ;
              02641 ; 0        1        2        3        4        5        6        7
              02642 ; ........ ........ ........ ........ ........ ........ ........ ........
              02643 ; .####### ..##.... .####... .####... .##..... .####... .####... .#####..
              02644 ; .#...### ...#.... ....#... ....#... .##..... .#...... .#..#... .#...#..
              02645 ; .#...### ...#.... ....#... ....#... .##..... .#...... .#...... .....#..
              02646 ; .#...### ...#.... .####... .#####.. .##.##.. .####... .#...... ...###..
              02647 ; .#...### ..###... .#...... ....##.. .#####.. ....#... .######. ...#....
              02648 ; .#...### ..###... .#...... ....##.. ....##.. ....#... .#....#. ...#....
              02649 ; .####### ..###... .####... .#####.. ....##.. .####... .######. ...#....
              02650 ;
              02651 ; 8        9        10       11       12       13       14       15
              02652 ; ........ ........ ........ ..###... #....... ........ ........ ........
              02653 ; ..###... .#####.. ........ ..###... #....... ..####.. .##..##. ........
              02654 ; ..#.#... .#...#.. ........ ..###... #....... ..#..... #..##..# ........
              02655 ; ..#.#... .#...#.. ........ ........ #....... ..#..... #..##..# .######.
              02656 ; .#####.. .#####.. ........ ........ #....... .####... #..##..# ........
              02657 ; .##.##.. ....##.. ........ ..###... #....... .##..... .##..##. ........
              02658 ; .##.##.. ....##.. ........ ..###... #....... .##..... ........ ........
              02659 ; .#####.. ....##.. ........ ..###... ######## .#####.. ........ ........
              02660 ;
              02661 ; 16       17       18       19       20       21       22       23
              02662 ; ........ ........ .##..##. ........ ........ ........ #######. ######..
              02663 ; ...##... ...##... .##..##. .#####.. ...###.. .#...##. #..#..#. #...##..
              02664 ; ...##... .######. .##..##. .#...#.. ..#####. .#...##. ...#.... #...##..
              02665 ; ...##... ##.##.## .##..##. .#...#.. .##...## .#...#.. ...##... #.......
              02666 ; .######. #..##..# .##..##. .#####.. .#.###.# .#####.. ...##... #.......
              02667 ; ...##... ##.##.## ..#.##.. .##.#... .##...## .##..#.. ...##... #.......
              02668 ; ...##... .######. ..###... .##.##.. ..#####. .##..##. ...##... #....#..
              02669 ; ...##... ...##... ..##.... .##.##.. ...###.. .##..##. ...##... ######..
              02670 ;
              02671 ; 24       25       26       27       28       29       30
              02672 ; ........ #....... ........ #....... #....... #....... #.......
              02673 ; ........ #....... ........ #.#.#.#. #..##... #...###. #.##....
              02674 ; ........ #....... ........ #..###.. #....... #....... #..##...
              02675 ; ........ #....... ........ #.#####. #.##.##. #.###... #.#####.
              02676 ; ........ #....... ........ #..###.. #....... #....... #..##...
              02677 ; ........ #....... ........ #.#.#.#. #...##.. #..###.. #.##....
              02678 ; ........ #....... ........ #....... #....... #....... #.......
              02679 ; ######## #....... #....... ######## ######## ######## ########
              02680
A000 007F4747 02681 CHARSET         .BYTE $00,$7F,$47,$47,$47,$47,$47,$7F ; Custom character '0'
A004 4747477F
A008 00301010 02682                 .BYTE $00,$30,$10,$10,$10,$38,$38,$38 ; Custom character '1'
A00C 10383838
A010 00780808 02683                 .BYTE $00,$78,$08,$08,$78,$40,$40,$78 ; Custom character '2'
A014 78404078
A018 00780808 02684                 .BYTE $00,$78,$08,$08,$7C,$0C,$0C,$7C ; Custom character '3'
A01C 7C0C0C7C
A020 00606060 02685                 .BYTE $00,$60,$60,$60,$6C,$7C,$0C,$0C ; Custom character '4'
A024 6C7C0C0C
A028 00784040 02686                 .BYTE $00,$78,$40,$40,$78,$08,$08,$78 ; Custom character '5'
A02C 78080878
A030 00784840 02687                 .BYTE $00,$78,$48,$40,$40,$7E,$42,$7E ; Custom character '6'
A034 407E427E
A038 007C4404 02688                 .BYTE $00,$7C,$44,$04,$1C,$10,$10,$10 ; Custom character '7'
A03C 1C101010
A040 00382828 02689                 .BYTE $00,$38,$28,$28,$7C,$6C,$6C,$7C ; Custom character '8'
A044 7C6C6C7C
A048 007C4444 02690                 .BYTE $00,$7C,$44,$44,$7C,$0C,$0C,$0C ; Custom character '9'
A04C 7C0C0C0C
A050 00000000 02691                 .BYTE $00,$00,$00,$00,$00,$00,$00,$00 ; Custom character ' '
A054 00000000
A058 38383800 02692                 .BYTE $38,$38,$38,$00,$00,$38,$38,$38 ; Custom character ':'
A05C 00383838
A060 80808080 02693                 .BYTE $80,$80,$80,$80,$80,$80,$80,$FF ; Custom character 'BORDER SOUTHWEST'
A064 808080FF
A068 003C2020 02694                 .BYTE $00,$3C,$20,$20,$78,$60,$60,$7C ; Custom character 'E'
A06C 7860607C
A070 00669999 02695                 .BYTE $00,$66,$99,$99,$99,$66,$00,$00 ; Custom character 'INFINITY'
A074 99660000
A078 0000007E 02696                 .BYTE $00,$00,$00,$7E,$00,$00,$00,$00 ; Custom character '-'
A07C 00000000
A080 00181818 02697                 .BYTE $00,$18,$18,$18,$7E,$18,$18,$18 ; Custom character '+'
A084 7E181818
A088 00187EDB 02698                 .BYTE $00,$18,$7E,$DB,$99,$DB,$7E,$18 ; Custom character 'PHI'
A08C 99DB7E18
A090 66666666 02699                 .BYTE $66,$66,$66,$66,$66,$2C,$38,$30 ; Custom character 'V'
A094 662C3830
A098 007C4444 02700                 .BYTE $00,$7C,$44,$44,$7C,$68,$6C,$6C ; Custom character 'R'
A09C 7C686C6C
A0A0 001C3E63 02701                 .BYTE $00,$1C,$3E,$63,$5D,$63,$3E,$1C ; Custom character 'THETA'
A0A4 5D633E1C
A0A8 00464644 02702                 .BYTE $00,$46,$46,$44,$7C,$64,$66,$66 ; Custom character 'K'
A0AC 7C646666
A0B0 FE921018 02703                 .BYTE $FE,$92,$10,$18,$18,$18,$18,$18 ; Custom character 'T'
A0B4 18181818
A0B8 FC8C8C80 02704                 .BYTE $FC,$8C,$8C,$80,$80,$80,$84,$FC ; Custom character 'C'
A0BC 808084FC
A0C0 00000000 02705                 .BYTE $00,$00,$00,$00,$00,$00,$00,$FF ; Custom character 'BORDER SOUTH'
A0C4 000000FF
A0C8 80808080 02706                 .BYTE $80,$80,$80,$80,$80,$80,$80,$80 ; Custom character 'BORDER WEST'
A0CC 80808080
A0D0 00000000 02707                 .BYTE $00,$00,$00,$00,$00,$00,$00,$80 ; Custom character 'CORNER SOUTHWEST'
A0D4 00000080
A0D8 80AA9CBE 02708                 .BYTE $80,$AA,$9C,$BE,$9C,$AA,$80,$FF ; Custom character 'STARBASE SECTOR'
A0DC 9CAA80FF
A0E0 809880B6 02709                 .BYTE $80,$98,$80,$B6,$80,$8C,$80,$FF ; Custom character '4-ZYLON SECTOR'
A0E4 808C80FF
A0E8 808E80B8 02710                 .BYTE $80,$8E,$80,$B8,$80,$9C,$80,$FF ; Custom character '3-CYCLON SECTOR'
A0EC 809C80FF
A0F0 80B098BE 02711                 .BYTE $80,$B0,$98,$BE,$98,$B0,$80,$FF ; Custom character '2-ZYLON SECTOR'
A0F4 98B080FF
              02712
              02713 ;*** Header text of Long-Range Scan view (shares spaces with following header) *
A0F8 00006C6F 02714 LRSHEADER       .BYTE $00,$00,$6C,$6F,$6E,$67,$00,$72 ; "  LONG RANGE SCAN"
A0FC 6E670072
A100 616E6765 02715                 .BYTE $61,$6E,$67,$65,$00,$73,$63,$61
A104 00736361
A108 6E       02716                 .BYTE $6E
              02717
              02718 ;*** Header text of Aft view (shares spaces with following header) *************
A109 00000000 02719 AFTHEADER       .BYTE $00,$00,$00,$00,$00,$00,$61,$66 ; "      AFT VIEW   "
A10D 00006166
A111 74007669 02720                 .BYTE $74,$00,$76,$69,$65,$77,$00,$00
A115 65770000
A119 00       02721                 .BYTE $00
              02722
              02723 ;*** Header text of Galactic Chart view ****************************************
A11A 00000067 02724 GCHEADER        .BYTE $00,$00,$00,$67,$61,$6C,$61,$63 ; "   GALACTIC CHART   "
A11E 616C6163
A122 74696300 02725                 .BYTE $74,$69,$63,$00,$63,$68,$61,$72
A126 63686172
A12A 74000000 02726                 .BYTE $74,$00,$00,$00
              02727
              02728 ;*** Display List of Galactic Chart view ***************************************
A12E 60       02729 DLSTGC          .BYTE $60                             ; BLK7
A12F 461AA1   02730                 .BYTE $46,<GCHEADER,>GCHEADER         ; GR2 @ GCHEADER
A132 F0       02731                 .BYTE $F0                             ; BLK8 + DLI
A133 47350D   02732                 .BYTE $47,<GCPFMEM,>GCPFMEM           ; GR1 @ GCPFMEM
A136 07       02733                 .BYTE $07                             ; GR1
A137 07       02734                 .BYTE $07                             ; GR1
A138 07       02735                 .BYTE $07                             ; GR1
A139 07       02736                 .BYTE $07                             ; GR1
A13A 07       02737                 .BYTE $07                             ; GR1
A13B 07       02738                 .BYTE $07                             ; GR1
A13C 07       02739                 .BYTE $07                             ; GR1
A13D 07       02740                 .BYTE $07                             ; GR1
A13E 80       02741                 .BYTE $80                             ; BLK1 + DLI
A13F 461F0D   02742                 .BYTE $46,<TITLETXT,>TITLETXT         ; GR2 @ TITLETXT
A142 467109   02743                 .BYTE $46,<GCTXT,>GCTXT               ; GR2 @ GCTXT
A145 06       02744                 .BYTE $06                             ; GR2
A146 06       02745                 .BYTE $06                             ; GR2
A147 418002   02746                 .BYTE $41,<DSPLST,>DSPLST             ; JMP @ DSPLST
              02747
              02748 ;*******************************************************************************
              02749 ;*                                                                             *
              02750 ;*                              G A M E   C O D E                              *
              02751 ;*                                                                             *
              02752 ;*******************************************************************************
              02753
              02754 ;*******************************************************************************
              02755 ;*                                                                             *
              02756 ;*                                  INITCOLD                                   *
              02757 ;*                                                                             *
              02758 ;*                       Initialize program (Cold start)                       *
              02759 ;*                                                                             *
              02760 ;*******************************************************************************
              02761
              02762 ; DESCRIPTION
              02763 ;
              02764 ; Initializes the program, then continues into the game loop at GAMELOOP
              02765 ; ($A1F3).
              02766 ;
              02767 ; There are four entry points to initialization:
              02768 ;
              02769 ; (1)  INITCOLD ($A14A) is entered at initial cartridge startup (cold start).
              02770 ;      This initializes POKEY, resets the idle counter, sets the mission level
              02771 ;      to NOVICE mission, and clears the function key code. POKEY is enabled to
              02772 ;      receive keyboard input. Code execution continues into INITSELECT ($A15A)
              02773 ;      below.
              02774 ;
              02775 ; (2)  INITSELECT ($A15A) is entered from GAMELOOP ($A1F3) after the SELECT
              02776 ;      function key has been pressed. This loads the title phrase offset for the
              02777 ;      copyright notice. Code execution continues into INITDEMO ($A15C) below.
              02778 ;
              02779 ; (3)  INITDEMO ($A15C) is entered when the program switches into demo mode.
              02780 ;      This loads the demo mode flag. Code execution continues into INITSTART
              02781 ;      ($A15E) below.
              02782 ;
              02783 ; (4)  INITSTART ($A15E) is entered from GAMELOOP ($A1F3) after the START
              02784 ;      function key has been pressed. This enqueues the new title phrase and
              02785 ;      enables or disables demo mode, depending on the preloaded value.
              02786 ;
              02787 ; Initialization continues with the following steps:
              02788 ;
              02789 ; (1)  Clear the custom chip registers and zero-page program variables from
              02790 ;      ISVBISYNC ($0067) on.
              02791 ;
              02792 ;      NOTE: Because of loop jamming there is a loop index overshoot. Instead of
              02793 ;      clearing memory at addresses $0067..$00FB, the memory at addresses
              02794 ;      $0067..$0166 is cleared. This does no harm because $0100..$0166 is a yet
              02795 ;      unused part of the 6502 CPU stack.
              02796 ;
              02797 ;      NOTE: At address $A175 a hack is necessary in the source code to fake a
              02798 ;      STA ISVBISYNC,X instruction with a 16-bit address. ISVBISYNC ($0067) is a
              02799 ;      zero-page address and regular assemblers would translate STA ISVBISYNC,X
              02800 ;      into the byte sequence $95 $67, not $9D $67 $00. This indicates that the
              02801 ;      original ROM was maybe created using a special assembler, perhaps a
              02802 ;      cross-assembler.
              02803 ;
              02804 ; (2)  Initialize the 6502 CPU (reset the stack pointer, disable decimal mode).
              02805 ;
              02806 ; (3)  Clear program memory from $0200..$1FFF in subroutine CLRMEM ($AE0F).
              02807 ;
              02808 ; (4)  Set the address vectors of the IRQ, VBI, and DLI handlers.
              02809 ;
              02810 ; (5)  Enable input from Joystick 0.
              02811 ;
              02812 ; (6)  Enable Player/Missile graphics, providing a fifth PLAYER.
              02813 ;
              02814 ;      BUG (at $A1A6): The set PLAYER-PLAYFIELD priority arranges PLAYERs in
              02815 ;      front of the PLAYFIELD. This makes sense as space objects represented by
              02816 ;      PLAYERs (for example, Zylon ships, photon torpedoes, and meteors) move in
              02817 ;      front of the stars, which are part of the PLAYFIELD. However, PLAYERs
              02818 ;      also move in front of the cross hairs, which are also part of the
              02819 ;      PLAYFIELD. Suggested fix: None, technically not possible.
              02820 ;
              02821 ; (7)  Do more initialization in subroutine INITIALIZE ($B3BA).
              02822 ;
              02823 ; (8)  Set display to Front view.
              02824 ;
              02825 ; (9)  Show or hide the Control Panel Display (bottom text window) in subroutine
              02826 ;      MODDLST ($ADF1), depending on the demo mode flag.
              02827 ;
              02828 ; (10) Initialize our starship's velocity equivalent to speed key '6'.
              02829 ;
              02830 ; (11) Enable the Display List.
              02831 ;
              02832 ; (12) Initialize the number of space objects to 16 (5 PLAYER space objects + 12
              02833 ;      PLAYFIELD space objects (stars)).
              02834 ;
              02835 ; (13) Set the title phrase to the selected mission level in subroutine SETTITLE
              02836 ;      ($B223).
              02837 ;
              02838 ; (14) Enable the IRQ, DLI, and VBI interrupts.
              02839 ;
              02840 ; Code execution continues into the game loop at GAMELOOP ($A1F3).
              02841
A14A A900     02842 INITCOLD        LDA #0                  ;
A14C 8D0FD2   02843                 STA SKCTL               ; POKEY: Initialization
A14F 8566     02844                 STA IDLECNTHI           ; Reset idle counter
A151 8562     02845                 STA MISSIONLEVEL        ; Mission level := NOVICE mission
A153 8563     02846                 STA FKEYCODE            ; Clear function key code
A155 A903     02847                 LDA #$03                ; POKEY: Enable keyboard scan and debounce
A157 8D0FD2   02848                 STA SKCTL               ;
              02849
              02850 ;*** Entry point when SELECT function key was pressed **************************
A15A A02F     02851 INITSELECT      LDY #$2F                ; Prep title phrase "COPYRIGHT ATARI 1979"
              02852
              02853 ;*** Entry point when program switches into demo mode **************************
A15C A9FF     02854 INITDEMO        LDA #$FF                ; Prep demo mode flag
              02855
              02856 ;*** Entry point when START function key was pressed ***************************
A15E 8465     02857 INITSTART       STY NEWTITLEPHR         ; Enqueue new title phrase
A160 8564     02858                 STA ISDEMOMODE          ; Store demo mode flag
              02859
              02860 ;*** More initialization *******************************************************
A162 A900     02861                 LDA #0                  ; Clear custom chip registers, zero-page variables
A164 AA       02862                 TAX                     ;
A165 9D00D0   02863 LOOP001         STA HPOSP0,X            ; Clear $D000..$D0FF (GTIA registers)
A168 9D00D4   02864                 STA DMACTL,X            ; Clear $D400..$D4FF (ANTIC registers)
A16B E00F     02865                 CPX #$0F                ;
A16D B003     02866                 BCS SKIP001             ;
A16F 9D00D2   02867                 STA AUDF1,X             ; Clear $D200..$D20E (POKEY registers)
              02868
A172 9D00D3   02869 SKIP001         STA PORTA,X             ; Clear $D300..$D3FF (PIA registers)
              02870                                         ; Clear $0067..$0166 (zero-page program variables)
A175 9D       02871                 .BYTE $9D               ; HACK: Fake STA ISVBISYNC,X with 16-bit address
A176 6700     02872                 .WORD ISVBISYNC         ;
A178 E8       02873                 INX                     ;
A179 D0EA     02874                 BNE LOOP001             ;
              02875
A17B CA       02876                 DEX                     ; Reset 6502 CPU stack pointer
A17C 9A       02877                 TXS                     ;
              02878
A17D D8       02879                 CLD                     ; Clear 6502 CPU decimal mode
              02880
A17E A902     02881                 LDA #$02                ; Clear $0200..$1FFF (program memory)
A180 200FAE   02882                 JSR CLRMEM              ;
              02883
A183 A951     02884                 LDA #<IRQHNDLR          ; Set IRQ handler (VIMIRQ)
A185 8D1602   02885                 STA VIMIRQ              ;
A188 A9A7     02886                 LDA #>IRQHNDLR          ;
A18A 8D1702   02887                 STA VIMIRQ+1            ;
              02888
A18D A9D1     02889                 LDA #<VBIHNDLR          ; Set VBI and DLI handler (VVBLKI and VDSLST)
A18F 8D2202   02890                 STA VVBLKI              ;
A192 A918     02891                 LDA #<DLSTHNDLR         ;
A194 8D0002   02892                 STA VDSLST              ;
A197 A9A6     02893                 LDA #>VBIHNDLR          ;
A199 8D2302   02894                 STA VVBLKI+1            ;
A19C A9A7     02895                 LDA #>DLSTHNDLR         ;
A19E 8D0102   02896                 STA VDSLST+1            ;
              02897
A1A1 A904     02898                 LDA #$04                ; PIA: Enable PORTA (Joystick 0)
A1A3 8D02D3   02899                 STA PACTL               ;
A1A6 A911     02900                 LDA #$11                ; GTIA: Enable PLAYER4, prio: PLs > PFs > BGR (!)
A1A8 8D1BD0   02901                 STA PRIOR               ; (PLAYERs appear behind cross hairs)
A1AB A903     02902                 LDA #$03                ; GTIA: Enable DMA for PLAYERs and MISSILEs
A1AD 8D1DD0   02903                 STA GRACTL              ;
              02904
A1B0 20BAB3   02905                 JSR INITIALIZE          ; Init Display List, tables, Galactic Chart, etc.
              02906
A1B3 A20A     02907                 LDX #$0A                ; Set Front view
A1B5 2045B0   02908                 JSR SETVIEW             ;
              02909
A1B8 A564     02910                 LDA ISDEMOMODE          ; If in/not in demo mode hide/show...
A1BA 2980     02911                 AND #$80                ; ...Control Panel Display (bottom text window)
A1BC A8       02912                 TAY                     ;
A1BD A25F     02913                 LDX #$5F                ;
A1BF A908     02914                 LDA #$08                ;
A1C1 20F1AD   02915                 JSR MODDLST             ;
              02916
A1C4 A920     02917                 LDA #32                 ; Init our starship's velocity (= speed key '6')
A1C6 8571     02918                 STA NEWVELOCITY         ;
              02919
A1C8 A980     02920                 LDA #<DSPLST            ; ANTIC: Set Display List
A1CA 8D02D4   02921                 STA DLIST               ;
A1CD A902     02922                 LDA #>DSPLST            ;
A1CF 8D03D4   02923                 STA DLIST+1             ;
              02924
A1D2 A93E     02925                 LDA #$3E                ; ANTIC: Enable Display List DMA, single-line PM
A1D4 8D00D4   02926                 STA DMACTL              ; resolution, PM DMA, normal-width PLAYFIELD
              02927
A1D7 A900     02928                 LDA #0                  ; ANTIC: Set PM memory base address
A1D9 8D07D4   02929                 STA PMBASE              ;
              02930
A1DC A910     02931                 LDA #NUMSPCOBJ.NORM-1   ; Set normal number of space objects
A1DE 8579     02932                 STA MAXSPCOBJIND        ; (5 PLAYER spc objs + 12 PLAYFIELD spc objs (stars))
              02933
A1E0 A662     02934                 LDX MISSIONLEVEL        ; Set title phrase
A1E2 BC0CBF   02935                 LDY MISSIONPHRTAB,X     ; NOVICE, PILOT, WARRIOR, or COMMANDER MISSION
A1E5 2023B2   02936                 JSR SETTITLE            ;
              02937
A1E8 A940     02938                 LDA #$40                ; POKEY: Enable keyboard interrupt (IRQ)
A1EA 8D0ED2   02939                 STA IRQEN               ;
              02940
A1ED 58       02941                 CLI                     ; Enable all IRQs
              02942
A1EE A9C0     02943                 LDA #$C0                ; ANTIC: Enable DLI and VBI
A1F0 8D0ED4   02944                 STA NMIEN               ;
              02945
              02946 ;*******************************************************************************
              02947 ;*                                                                             *
              02948 ;*                                  GAMELOOP                                   *
              02949 ;*                                                                             *
              02950 ;*******************************************************************************
              02951
              02952 ; DESCRIPTION
              02953 ;
              02954 ; The game loop is the main part of the program. It is basically an infinite
              02955 ; loop that collects input, computes the game state, and updates the display. It
              02956 ; executes the following steps:
              02957 ;
              02958 ; (1)  Synchronize the start of the game loop with the vertical blank phase of
              02959 ;      the TV beam, which flagged by the Vertical Blank Interrupt handler
              02960 ;      VBIHNDLR ($A6D1). This prevents screen flicker while the PLAYFIELD is
              02961 ;      redrawn at the begin of the game loop, because during the vertical blank
              02962 ;      phase the TV beam is turned off and nothing is rendered on the TV
              02963 ;      display.
              02964 ;
              02965 ; (2)  Erase all PLAYFIELD space objects (stars, explosion fragments) from the
              02966 ;      PLAYFIELD that were drawn in the previous game loop iteration.
              02967 ;
              02968 ; (3)  Draw the updated PLAYFIELD space objects (stars, explosion fragments)
              02969 ;      into the PLAYFIELD (skip this if in hyperspace).
              02970 ;
              02971 ; (4)  If the idle counter has reached its trigger value then clear the center
              02972 ;      of the PLAYFIELD, an 8 x 2 pixel rectangle with a top-left position at
              02973 ;      pixel column number 76 and pixel row number 49 (?).
              02974 ;
              02975 ; (5)  Clear all PLAYER shapes.
              02976 ;
              02977 ; (6)  Update the vertical position of all PLAYERs and update all PLAYER shapes.
              02978 ;
              02979 ; (7)  Update the horizontal position of all PLAYERs.
              02980 ;
              02981 ; (8)  Rotate the position vector of all space objects horizontally and
              02982 ;      vertically, according to the saved joystick position (skip this if in
              02983 ;      Galactic Chart view) using subroutine ROTATE ($B69B).
              02984 ;
              02985 ; (9)  Move our starship forward in space. Our starship is always located at the
              02986 ;      center of the program's 3D coordinate system, so all space objects are
              02987 ;      moved along the z-axis toward our starship by subtracting a displacement
              02988 ;      from their z-coordinate. The amount of the displacement depends on our
              02989 ;      starship's velocity.
              02990 ;
              02991 ;      BUG (at $A3C1): This operation is not applied to Photon torpedoes (?).
              02992 ;      Suggested fix: Remove LDA PL0SHAPTYPE,X and BEQ SKIP011.
              02993 ;
              02994 ; (10) Add the proper velocity vector of all space objects to their position
              02995 ;      vector (except for stars, which do not have any proper motion).
              02996 ;
              02997 ;      BUG (at $A419): The correct maximum loop index is NUMSPCOBJ.ALL*3 = 147
              02998 ;      instead of 144. Suggested fix: Replace CMP #144 with CMP #147.
              02999 ;
              03000 ; (11) Correct the position vector components (coordinates) of all PLAYER space
              03001 ;      objects if they have over- or underflowed during the calculations of the
              03002 ;      previous steps.
              03003 ;
              03004 ; (12) Calculate the perspective projection of the position vectors of all space
              03005 ;      objects and from that their pixel row and column number (applies to Front
              03006 ;      and Aft view) using subroutines PROJECTION ($AA21), SCREENCOLUMN ($B6FB),
              03007 ;      and SCREENROW ($B71E). If a space object (star, explosion fragment) moved
              03008 ;      offscreen then a new space object is automatically created in subroutine
              03009 ;      SCREENCOLUMN ($B6FB).
              03010 ;
              03011 ; (13) Handle hyperwarp marker selection in the Galactic Chart view in
              03012 ;      subroutine SELECTWARP ($B162).
              03013 ;
              03014 ; (14) If in Long-Range Scan view, compute the pixel column number and the pixel
              03015 ;      row number of all PLAYFIELD space objects (stars, explosion fragments) on
              03016 ;      the plane established by the z and x axis of the 3D coordinate system
              03017 ;      using subroutines SCREENCOLUMN ($B6FB) and SCREENROW ($B71E). Our
              03018 ;      starship's shape is drawn using subroutine DRAWLINES ($A76F). If the
              03019 ;      Long-Range Scan is OK then PLAYFIELD space object pixel numbers are
              03020 ;      computed and drawn. This is skipped if the Long-Range Scan is destroyed.
              03021 ;
              03022 ; (15) Update all PLAYER shapes, heights, and colors (see detailed description
              03023 ;      below).
              03024 ;
              03025 ; (16) Flash a red alert when leaving hyperspace into a sector containing Zylon
              03026 ;      ships by setting appropriate colors to PLAYFIELD2 and BACKGROUND.
              03027 ;
              03028 ; (17) Update the color of all PLAYFIELD space objects (stars, explosion
              03029 ;      fragments). The color calculation is similar to that of the PLAYER color
              03030 ;      calculation in (15). It also computes a range index and uses the same
              03031 ;      color lookup table FOURCOLORPIXEL ($BA90). If a star in the Aft view
              03032 ;      became too distant (z-coordinate < -$F000 (-4096) <KM>) its position is
              03033 ;      re-initialized in subroutine INITPOSVEC ($B764).
              03034 ;
              03035 ; (18) If in demo mode skip input handling and jump directly to function key
              03036 ;      handling (28).
              03037 ;
              03038 ; (19) Handle keyboard input in subroutine KEYBOARD ($AFFE).
              03039 ;
              03040 ; (20) Handle joystick input. Store the current joystick directions in JOYSTICKX
              03041 ;      ($C8) and JOYSTICKY ($C9).
              03042 ;
              03043 ; (21) Check if our starship's photon torpedoes have hit a target in subroutine
              03044 ;      COLLISION ($AF3D). This subroutine triggers a game over if all Zylon
              03045 ;      ships have been destroyed.
              03046 ;
              03047 ; (22) Handle the joystick trigger in subroutine TRIGGER ($AE29).
              03048 ;
              03049 ; (23) Handle the Attack Computer and Tracking Computer. If the Attack Computer
              03050 ;      is neither destroyed nor switched off then execute the following steps:
              03051 ;
              03052 ;      o   Update the Attack Computer Display's blip and lock-on markers in
              03053 ;          subroutine UPDATTCOMP ($A7BF) (if in Front view).
              03054 ;
              03055 ;      o   Update the tracking index of the currently tracked PLAYER space
              03056 ;          object. If a Zylon ship is tracked, then make sure to always track
              03057 ;          the Zylon ship that launched the last Zylon photon torpedo. If this
              03058 ;          Zylon ship is not alive then track the other Zylon ship - if alive.
              03059 ;
              03060 ;      o   If the Tracking Computer is on then switch to the view that shows the
              03061 ;          tracked PLAYER space object by emulating pressing the 'F' (Front
              03062 ;          view) or 'A' (Aft view) key (only if in Front or Aft view).
              03063 ;
              03064 ; (24) Handle docking at a starbase in subroutine DOCKING ($ACE6).
              03065 ;
              03066 ; (25) Handle maneuvering both of our starship's photon torpedoes, the single
              03067 ;      Zylon photon torpedo, and the attacking Zylon ships in subroutine
              03068 ;      MANEUVER ($AA79). This subroutine also automatically creates meteors and
              03069 ;      new Zylon ships.
              03070 ;
              03071 ; (26) Check if our starship was hit by a Zylon photon torpedo (skip this if in
              03072 ;      a starbase sector): Its x, y, and z coordinates must be within a range of
              03073 ;      -($0100)..+$00FF (-256..+255) <KM> of our starship.
              03074 ;
              03075 ; (27) If our starship was hit then execute the following steps:
              03076 ;
              03077 ;      o   Damage or destroy one of our starship's subsystems in subroutine
              03078 ;          DAMAGE ($AEE1).
              03079 ;
              03080 ;      o   Trigger an explosion in subroutine INITEXPL ($AC6B),
              03081 ;
              03082 ;      o   Store the severity of the hit.
              03083 ;
              03084 ;      o   End the lifetime of the Zylon photon torpedo.
              03085 ;
              03086 ;      o   Subtract 100 energy units for being hit by the Zylon photon torpedo
              03087 ;          in subroutine DECENERGY ($B86F).
              03088 ;
              03089 ;      o   Trigger the noise sound pattern SHIELD EXPLOSION in subroutine NOISE
              03090 ;          ($AEA8).
              03091 ;
              03092 ;      If the Shields were down during the hit, our starship is destroyed.
              03093 ;      Execute the following steps:
              03094 ;
              03095 ;      o   Switch to Front view.
              03096 ;
              03097 ;      o   Flash the title phrase "SHIP DESTROYED BY ZYLON FIRE".
              03098 ;
              03099 ;      o   Add the mission bonus to the internal game score in subroutine
              03100 ;          GAMEOVER ($B10A).
              03101 ;
              03102 ;      o   Hide the Control Panel Display (bottom text window) in subroutine
              03103 ;          MODDLST ($ADF1).
              03104 ;
              03105 ;      o   Clear the PLAYFIELD in subroutine CLRPLAYFIELD ($AE0D).
              03106 ;
              03107 ;      o   Enable the STARSHIP EXPLOSION noise.
              03108 ;
              03109 ; (28) Handle the function keys START and SELECT. If SELECT has been pressed
              03110 ;      cycle through the next of the 4 mission levels. If either START or SELECT
              03111 ;      have been pressed, reset the idle counter, then jump to the corresponding
              03112 ;      program initialization subroutines INITSTART ($A15E) or INITSELECT
              03113 ;      ($A15A), respectively.
              03114 ;
              03115 ; (29) Update the Control Panel Display in subroutine UPDPANEL ($B804).
              03116 ;
              03117 ; (30) Handle hyperwarp in subroutine HYPERWARP ($A89B).
              03118 ;
              03119 ; (31) Update the text in the title line in subroutine UPDTITLE ($B216).
              03120 ;
              03121 ; (32) Move Zylon units, decrease lifetime of photon torpedoes, elapse game
              03122 ;      time, etc. in subroutine FLUSHGAMELOOP ($B4E4). This subroutine also
              03123 ;      triggers a game over if our starship's energy is zero.
              03124 ;
              03125 ; (33) Jump back to the start of the game loop for the next game loop iteration.
              03126
    =006A     03127 L.HEIGHTCNT     = $6A                   ; Height counter during copying a PLAYER shape
    =006E     03128 L.ZPOSOFF       = $6E                   ; Offset to z-coordinate
    =006B     03129 L.VELOCITYHI    = $6B                   ; Velocity vector component (high byte)
    =006A     03130 L.VECCOMPIND    = $6A                   ; Position vector component index. Used values are:
              03131                                         ;   0 -> z-component
              03132                                         ;   1 -> x-component
              03133                                         ;   2 -> y-component
    =006A     03134 L.RANGEINDEX    = $6A                   ; Range index for space object, computed from the
              03135                                         ; distance to our starship. Used to pick the shape
              03136                                         ; cell index of the PLAYERs shape data and shape
              03137                                         ; height. Used values are: 0..15.
    =006A     03138 L.FOURCOLORPIX  = $6A                   ; 1-byte bit pattern for 4 pixels of same color
    =006B     03139 L.COLORMASK     = $6B                   ; Color/brightness to modify PLAYER color
              03140
              03141 ;*** (1) Synchronize game loop with execution of VBI ***************************
A1F3 A567     03142 GAMELOOP        LDA ISVBISYNC           ; Wait for execution of VBI
A1F5 F0FC     03143                 BEQ GAMELOOP            ;
              03144
A1F7 A900     03145                 LDA #0                  ; VBI is executed, clear VBI sync flag
A1F9 8567     03146                 STA ISVBISYNC           ;
              03147
              03148 ;*** (2) Erase PLAYFIELD space objects (stars, explosion fragments) ************
A1FB A57A     03149                 LDA OLDMAXSPCOBJIND     ; Skip if no space objects in use
A1FD F020     03150                 BEQ SKIP002             ;
              03151
A1FF A204     03152                 LDX #NUMSPCOBJ.PL-1     ; Loop over all PLAYFIELD space objs (X index > 4)
A201 E8       03153 LOOP002         INX                     ;
A202 BC5B0C   03154                 LDY PIXELROW,X          ; Load pixel row number of PLAYFIELD space object
              03155
A205 B90008   03156                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pixel's row...
A208 8568     03157                 STA MEMPTR              ; ...in PLAYFIELD memory
A20A B96408   03158                 LDA PFMEMROWHI,Y        ;
A20D 8569     03159                 STA MEMPTR+1            ;
              03160
A20F BC8C0C   03161                 LDY PIXELBYTEOFF,X      ; Get within-row-offset to byte with space obj pixel
A212 BDBD0C   03162                 LDA PIXELSAVE,X         ; Load saved byte
A215 9168     03163                 STA (MEMPTR),Y          ; Restore byte of PLAYFIELD memory
              03164
A217 E47A     03165                 CPX OLDMAXSPCOBJIND     ;
A219 90E6     03166                 BCC LOOP002             ; Next PLAYFIELD space object
              03167
A21B A900     03168                 LDA #0                  ; Clear number of space objects
A21D 857A     03169                 STA OLDMAXSPCOBJIND     ;
              03170
              03171 ;*** (3) Draw PLAYFIELD space objects (stars, explosion fragments) *************
A21F A5C0     03172 SKIP002         LDA WARPSTATE           ; Skip during hyperspace
A221 302D     03173                 BMI SKIP003             ;
              03174
A223 A679     03175                 LDX MAXSPCOBJIND        ; Update number of space objects
A225 867A     03176                 STX OLDMAXSPCOBJIND     ;
              03177
A227 BDF90B   03178 LOOP003         LDA PIXELROWNEW,X       ; Loop over all PLAYFIELD space objs (X index > 4)
A22A 9D5B0C   03179                 STA PIXELROW,X          ; Update pixel row number of PLAYFIELD space object
              03180
A22D A8       03181                 TAY                     ;
A22E B90008   03182                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pixel's row...
A231 8568     03183                 STA MEMPTR              ; ...in PLAYFIELD memory
A233 B96408   03184                 LDA PFMEMROWHI,Y        ;
A236 8569     03185                 STA MEMPTR+1            ;
              03186
A238 BD2A0C   03187                 LDA PIXELCOLUMN,X       ; Convert pixel column number to within-row-offset
A23B 4A       03188                 LSR A                   ; ...of byte with space obj pixel (4 pixels = 1 byte)
A23C 4A       03189                 LSR A                   ;
A23D 9D8C0C   03190                 STA PIXELBYTEOFF,X      ; Store within-row-offset
              03191
A240 A8       03192                 TAY                     ;
A241 B168     03193                 LDA (MEMPTR),Y          ; Load pixel's byte from PLAYFIELD memory
A243 9DBD0C   03194                 STA PIXELSAVE,X         ; Save it (for restoring it in next game loop)
A246 1DEE0C   03195                 ORA PIXELBYTE,X         ; Blend with pixel's color bit-pattern
A249 9168     03196                 STA (MEMPTR),Y          ; Store byte in PLAYFIELD memory
              03197
A24B CA       03198                 DEX                     ;
A24C E004     03199                 CPX #NUMSPCOBJ.PL-1     ;
A24E D0D7     03200                 BNE LOOP003             ; Next PLAYFIELD space object
              03201
              03202 ;*** (4) Clear PLAYFIELD center if idle counter is up (?) **********************
              03203                                         ; PLAYFIELD addresses of...
    =17BB     03204 PFMEM.C76R49    = PFMEM+49*40+76/4      ; ...pixel column number 76, row number 49
    =17BC     03205 PFMEM.C80R49    = PFMEM+49*40+80/4      ; ...pixel column number 80, row number 49
    =17E3     03206 PFMEM.C76R50    = PFMEM+50*40+76/4      ; ...pixel column number 76, row number 50
    =17E4     03207 PFMEM.C80R50    = PFMEM+50*40+80/4      ; ...pixel column number 80, row number 50
              03208
A250 A566     03209 SKIP003         LDA IDLECNTHI           ; Skip if idle counter not negative
A252 100E     03210                 BPL SKIP004             ;
              03211
A254 A900     03212                 LDA #0                  ; Clear pixels of 8 x 2 pixel rectangle...
A256 8DE317   03213                 STA PFMEM.C76R50        ; ...@ column number 76, row number 49 (?)
A259 8DE417   03214                 STA PFMEM.C80R50        ;
A25C 8DBC17   03215                 STA PFMEM.C80R49        ;
A25F 8DBB17   03216                 STA PFMEM.C76R49        ;
              03217
              03218 ;*** (5) Clear all PLAYER shapes ***********************************************
A262 A900     03219 SKIP004         LDA #0                  ; Clear shape of PLAYER4
A264 AC5F0C   03220                 LDY PL4ROW              ;
A267 AEC10C   03221                 LDX PL4HEIGHT           ;
A26A 990003   03222 LOOP004         STA PL4DATA,Y           ;
A26D C8       03223                 INY                     ;
A26E CA       03224                 DEX                     ;
A26F 10F9     03225                 BPL LOOP004             ;
              03226
A271 AC5E0C   03227                 LDY PL3ROW              ; Clear shape of PLAYER3
A274 AEC00C   03228                 LDX PL3HEIGHT           ;
A277 990007   03229 LOOP005         STA PL3DATA,Y           ;
A27A C8       03230                 INY                     ;
A27B CA       03231                 DEX                     ;
A27C 10F9     03232                 BPL LOOP005             ;
              03233
A27E AC5D0C   03234                 LDY PL2ROW              ; Clear shape of PLAYER2
A281 AEBF0C   03235                 LDX PL2HEIGHT           ;
A284 990006   03236 LOOP006         STA PL2DATA,Y           ;
A287 C8       03237                 INY                     ;
A288 CA       03238                 DEX                     ;
A289 10F9     03239                 BPL LOOP006             ;
              03240
A28B AC5C0C   03241                 LDY PL1ROW              ; Clear shape of PLAYER1
A28E AEBE0C   03242                 LDX PL1HEIGHT           ;
A291 990005   03243 LOOP007         STA PL1DATA,Y           ;
A294 C8       03244                 INY                     ;
A295 CA       03245                 DEX                     ;
A296 10F9     03246                 BPL LOOP007             ;
              03247
A298 AC5B0C   03248                 LDY PL0ROW              ; Clear shape of PLAYER0
A29B AEBD0C   03249                 LDX PL0HEIGHT           ;
A29E 990004   03250 LOOP008         STA PL0DATA,Y           ;
A2A1 C8       03251                 INY                     ;
A2A2 CA       03252                 DEX                     ;
A2A3 10F9     03253                 BPL LOOP008             ;
              03254
              03255 ;*** (6) Update PLAYER vertical positions and update PLAYER shapes *************
A2A5 AD900C   03256                 LDA PL4SHAPTYPE         ; CARRY := PLAYER4 a PHOTON TORPEDO (shape type 0)?
A2A8 C901     03257                 CMP #1                  ;
A2AA A4E8     03258                 LDY PL4SHAPOFF          ; Load PLAYER4 shape data offset
              03259
A2AC AEFD0B   03260                 LDX PL4ROWNEW           ; Update vertical position of PLAYER4
A2AF 8E5F0C   03261                 STX PL4ROW              ;
              03262
A2B2 ADF20C   03263                 LDA PL4HEIGHTNEW        ; Update PLAYER4 shape height
A2B5 856A     03264                 STA L.HEIGHTCNT         ;
A2B7 8DC10C   03265                 STA PL4HEIGHT           ;
              03266
A2BA B9E4B8   03267 LOOP009         LDA PLSHAP1TAB,Y        ; Load PLAYER4 shape byte from shape data table
A2BD B003     03268                 BCS SKIP005             ; Skip if PLAYER4 not PHOTON TORPEDO (shape type 0)
A2BF 2D0AD2   03269                 AND RANDOM              ; AND random bits to shape byte
A2C2 9D0003   03270 SKIP005         STA PL4DATA,X           ; Store shape byte in PLAYER4 data area
A2C5 C8       03271                 INY                     ;
A2C6 E8       03272                 INX                     ;
A2C7 C66A     03273                 DEC L.HEIGHTCNT         ;
A2C9 10EF     03274                 BPL LOOP009             ; Next row of PLAYER4 shape
              03275
A2CB AD8F0C   03276                 LDA PL3SHAPTYPE         ; Repeat above with PLAYER3
A2CE C901     03277                 CMP #1                  ;
A2D0 A4E7     03278                 LDY PL3SHAPOFF          ;
A2D2 AEFC0B   03279                 LDX PL3ROWNEW           ;
A2D5 8E5E0C   03280                 STX PL3ROW              ;
A2D8 ADF10C   03281                 LDA PL3HEIGHTNEW        ;
A2DB 856A     03282                 STA L.HEIGHTCNT         ;
A2DD 8DC00C   03283                 STA PL3HEIGHT           ;
A2E0 B9E4B8   03284 LOOP010         LDA PLSHAP1TAB,Y        ;
A2E3 B003     03285                 BCS SKIP006             ;
A2E5 2D0AD2   03286                 AND RANDOM              ;
A2E8 9D0007   03287 SKIP006         STA PL3DATA,X           ;
A2EB E8       03288                 INX                     ;
A2EC C8       03289                 INY                     ;
A2ED C66A     03290                 DEC L.HEIGHTCNT         ;
A2EF 10EF     03291                 BPL LOOP010             ;
              03292
A2F1 AD8E0C   03293                 LDA PL2SHAPTYPE         ; Repeat above with PLAYER2
A2F4 C901     03294                 CMP #1                  ;
A2F6 A4E6     03295                 LDY PL2SHAPOFF          ;
A2F8 AEFB0B   03296                 LDX PL2ROWNEW           ;
A2FB 8E5D0C   03297                 STX PL2ROW              ;
A2FE ADF00C   03298                 LDA PL2HEIGHTNEW        ;
A301 856A     03299                 STA L.HEIGHTCNT         ;
A303 8DBF0C   03300                 STA PL2HEIGHT           ;
A306 B9E4B8   03301 LOOP011         LDA PLSHAP1TAB,Y        ;
A309 B003     03302                 BCS SKIP007             ;
A30B 2D0AD2   03303                 AND RANDOM              ;
A30E 9D0006   03304 SKIP007         STA PL2DATA,X           ;
A311 E8       03305                 INX                     ;
A312 C8       03306                 INY                     ;
A313 C66A     03307                 DEC L.HEIGHTCNT         ;
A315 10EF     03308                 BPL LOOP011             ;
              03309
A317 A4E5     03310                 LDY PL1SHAPOFF          ; Repeat above with PLAYER1 (without torpedo part)
A319 AEFA0B   03311                 LDX PL1ROWNEW           ;
A31C 8E5C0C   03312                 STX PL1ROW              ;
A31F ADEF0C   03313                 LDA PL1HEIGHTNEW        ;
A322 856A     03314                 STA L.HEIGHTCNT         ;
A324 8DBE0C   03315                 STA PL1HEIGHT           ;
A327 B9B1B9   03316 LOOP012         LDA PLSHAP2TAB,Y        ;
A32A 9D0005   03317                 STA PL1DATA,X           ;
A32D E8       03318                 INX                     ;
A32E C8       03319                 INY                     ;
A32F C66A     03320                 DEC L.HEIGHTCNT         ;
A331 10F4     03321                 BPL LOOP012             ;
              03322
A333 A4E4     03323                 LDY PL0SHAPOFF          ; Repeat above with PLAYER0 (without torpedo part)
A335 AEF90B   03324                 LDX PL0ROWNEW           ;
A338 8E5B0C   03325                 STX PL0ROW              ;
A33B ADEE0C   03326                 LDA PL0HEIGHTNEW        ;
A33E 856A     03327                 STA L.HEIGHTCNT         ;
A340 8DBD0C   03328                 STA PL0HEIGHT           ;
A343 B9B1B9   03329 LOOP013         LDA PLSHAP2TAB,Y        ;
A346 9D0004   03330                 STA PL0DATA,X           ;
A349 E8       03331                 INX                     ;
A34A C8       03332                 INY                     ;
A34B C66A     03333                 DEC L.HEIGHTCNT         ;
A34D 10F4     03334                 BPL LOOP013             ;
              03335
              03336 ;*** (7) Update PLAYER horizontal positions ************************************
A34F AD2A0C   03337                 LDA PL0COLUMN           ; Update horizontal position of PLAYER0
A352 8D00D0   03338                 STA HPOSP0              ;
A355 AD2B0C   03339                 LDA PL1COLUMN           ; Update horizontal position of PLAYER1
A358 8D01D0   03340                 STA HPOSP1              ;
A35B AD2C0C   03341                 LDA PL2COLUMN           ; Update horizontal position of PLAYER2
A35E 8D02D0   03342                 STA HPOSP2              ;
A361 AD2D0C   03343                 LDA PL3COLUMN           ; Update horizontal position of PLAYER3
A364 8D03D0   03344                 STA HPOSP3              ;
A367 AD2E0C   03345                 LDA PL4COLUMN           ; Update horizontal position of PLAYER4
A36A 8D07D0   03346                 STA HPOSM3              ;
A36D 18       03347                 CLC                     ;
A36E 6902     03348                 ADC #2                  ;
A370 8D06D0   03349                 STA HPOSM2              ;
A373 6902     03350                 ADC #2                  ;
A375 8D05D0   03351                 STA HPOSM1              ;
A378 6902     03352                 ADC #2                  ;
A37A 8D04D0   03353                 STA HPOSM0              ;
              03354
              03355 ;*** (8) Rotate space objects horizontally and vertically **********************
A37D 24D0     03356                 BIT SHIPVIEW            ; Skip if in Galactic Chart view
A37F 303A     03357                 BMI SKIP009             ;
              03358
              03359 ;*** Rotate horizontally *******************************************************
A381 A5C8     03360                 LDA JOYSTICKX           ; Skip if joystick centered horizontally
A383 F019     03361                 BEQ SKIP008             ;
              03362
A385 856D     03363                 STA JOYSTICKDELTA       ; Save JOYSTICKX (used in subroutine ROTATE)
A387 A479     03364                 LDY MAXSPCOBJIND        ; Loop over all space objects in use
A389 846E     03365 LOOP014         STY L.ZPOSOFF           ; Save offset to z-coordinate
A38B 18       03366                 CLC                     ;
              03367
A38C 98       03368                 TYA                     ;
A38D AA       03369                 TAX                     ; X := offset to z-coordinate
A38E 6931     03370                 ADC #NUMSPCOBJ.ALL      ;
A390 A8       03371                 TAY                     ; Y := offset to x-coordinate
A391 209BB6   03372                 JSR ROTATE              ; Calc new x-coordinate (horizontal rot @ y-axis)
              03373
A394 98       03374                 TYA                     ;
A395 AA       03375                 TAX                     ; X := offset to x-coordinate
A396 A46E     03376                 LDY L.ZPOSOFF           ; Y := offset to z-coordinate
A398 209BB6   03377                 JSR ROTATE              ; Calc new z-coordinate (horizontal rot @ y-axis)
A39B 88       03378                 DEY                     ;
A39C 10EB     03379                 BPL LOOP014             ; Next space object
              03380
              03381 ;*** Rotate vertically *********************************************************
A39E A5C9     03382 SKIP008         LDA JOYSTICKY           ; Skip if joystick centered vertically
A3A0 F019     03383                 BEQ SKIP009             ;
              03384
A3A2 856D     03385                 STA JOYSTICKDELTA       ; Save JOYSTICKY (used in subroutine ROTATE)
A3A4 A479     03386                 LDY MAXSPCOBJIND        ; Loop over all space objects in use
A3A6 846E     03387 LOOP015         STY L.ZPOSOFF           ; Save offset to z-coordinate
A3A8 18       03388                 CLC                     ;
              03389
A3A9 98       03390                 TYA                     ;
A3AA AA       03391                 TAX                     ; X := offset to z-coordinate
A3AB 6962     03392                 ADC #NUMSPCOBJ.ALL*2    ;
A3AD A8       03393                 TAY                     ; Y := offset to y-coordinate
A3AE 209BB6   03394                 JSR ROTATE              ; Calc new y-coordinate (vertical rot @ x-axis)
              03395
A3B1 98       03396                 TYA                     ;
A3B2 AA       03397                 TAX                     ; X := offset to y-coordinate
A3B3 A46E     03398                 LDY L.ZPOSOFF           ; Y := offset to z-coordinate
A3B5 209BB6   03399                 JSR ROTATE              ; Calc new z-coordinate (vertical rot @ x-axis)
A3B8 88       03400                 DEY                     ;
A3B9 10EB     03401                 BPL LOOP015             ; Next space object
              03402
              03403 ;*** (9) Move all space objects along z-axis (toward our starship) *************
A3BB A679     03404 SKIP009         LDX MAXSPCOBJIND        ; Loop over all space objects in use
A3BD E005     03405 LOOP016         CPX #NUMSPCOBJ.PL       ; Skip if PLAYFIELD space object (X index > 4)
A3BF B005     03406                 BCS SKIP010             ;
              03407
A3C1 BD8C0C   03408                 LDA PL0SHAPTYPE,X       ; Skip if next PLAYER space obj is PHOTON TORPEDO (!)
A3C4 F019     03409                 BEQ SKIP011             ;
              03410
A3C6 38       03411 SKIP010         SEC                     ; New z-coordinate := old z-coordinate -
A3C7 BDD30A   03412                 LDA ZPOSLO,X            ; ...our starship's velocity
A3CA E570     03413                 SBC VELOCITYLO          ; (signed 24-bit subtraction)
A3CC 9DD30A   03414                 STA ZPOSLO,X            ;
A3CF BD400A   03415                 LDA ZPOSHI,X            ;
A3D2 E5C1     03416                 SBC VELOCITYHI          ;
A3D4 9D400A   03417                 STA ZPOSHI,X            ;
A3D7 BDAD09   03418                 LDA ZPOSSIGN,X          ;
A3DA E900     03419                 SBC #0                  ;
A3DC 9DAD09   03420                 STA ZPOSSIGN,X          ;
              03421
A3DF CA       03422 SKIP011         DEX                     ;
A3E0 10DB     03423                 BPL LOOP016             ; Next space object
              03424
              03425 ;*** (10) Add space object's velocity vector to space object's position vector *
A3E2 A679     03426                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A3E4 E010     03427 LOOP017         CPX #NUMSPCOBJ.NORM-1   ; Skip if space object is star (X index 5..16)...
A3E6 D002     03428                 BNE SKIP012             ; ...because stars don't move by themselves
A3E8 A204     03429                 LDX #4                  ;
              03430
A3EA 8A       03431 SKIP012         TXA                     ;
A3EB A8       03432 LOOP018         TAY                     ; Loop over all 3 coordinates
              03433
A3EC A900     03434                 LDA #0                  ; Expand 8-bit velocity vector component to 16-bit:
A3EE 856B     03435                 STA L.VELOCITYHI        ; ...16-bit velocity (high byte) = L.VELOCITYHI := 0
A3F0 B9660B   03436                 LDA ZVEL,Y              ; ...16-bit velocity (low byte)  = A := ZVEL,Y
A3F3 1009     03437                 BPL SKIP013             ; Skip if 16-bit velocity >= 0 (positive)
              03438
A3F5 497F     03439                 EOR #$7F                ; 16-bit velocity < 0 (negative)...
A3F7 18       03440                 CLC                     ; ...calculate two's-complement of 16-bit velocity
A3F8 6901     03441                 ADC #1                  ;
A3FA B002     03442                 BCS SKIP013             ;
A3FC C66B     03443                 DEC L.VELOCITYHI        ;
              03444
A3FE 18       03445 SKIP013         CLC                     ; New coordinate := old coordinate + 16-bit velocity
A3FF 79D30A   03446                 ADC ZPOSLO,Y            ; (signed 24-bit addition)
A402 99D30A   03447                 STA ZPOSLO,Y            ;
A405 B9400A   03448                 LDA ZPOSHI,Y            ;
A408 656B     03449                 ADC L.VELOCITYHI        ;
A40A 99400A   03450                 STA ZPOSHI,Y            ;
A40D B9AD09   03451                 LDA ZPOSSIGN,Y          ;
A410 656B     03452                 ADC L.VELOCITYHI        ;
A412 99AD09   03453                 STA ZPOSSIGN,Y          ;
              03454
A415 98       03455                 TYA                     ;
A416 18       03456                 CLC                     ;
A417 6931     03457                 ADC #NUMSPCOBJ.ALL      ;
A419 C990     03458                 CMP #144                ; (!)
A41B 90CE     03459                 BCC LOOP018             ; Next coordinate
              03460
A41D CA       03461                 DEX                     ;
A41E 10C4     03462                 BPL LOOP017             ; Next space object
              03463
              03464 ;*** (11) Correct over/underflow of PLAYER space objects' position vector ******
A420 A004     03465                 LDY #NUMSPCOBJ.PL-1     ;
A422 98       03466 LOOP019         TYA                     ; Loop over all PLAYER space objects (X index < 5)
A423 AA       03467                 TAX                     ;
              03468
A424 A902     03469                 LDA #2                  ; Loop over all 3 coordinates
A426 856A     03470                 STA L.VECCOMPIND        ;
              03471
A428 BDAD09   03472 LOOP020         LDA ZPOSSIGN,X          ; Load sign of coordinate
A42B C902     03473                 CMP #2                  ;
A42D 9010     03474                 BCC SKIP015             ; Skip if sign = 0 (negative) or 1 (positive)
              03475
A42F 0A       03476                 ASL A                   ; SUMMARY: Space object out-of-bounds correction
A430 A900     03477                 LDA #0                  ; If new coordinate > +65535 <KM> subtract 256 <KM>
A432 9DAD09   03478                 STA ZPOSSIGN,X          ; ...until new coordinate <= +65535 <KM>
A435 B005     03479                 BCS SKIP014             ; If new coordinate < -65536 <KM> add 256 <KM>
A437 FEAD09   03480                 INC ZPOSSIGN,X          ; ...until new coordinate >= -65536 <KM>
A43A 49FF     03481                 EOR #$FF                ;
A43C 9D400A   03482 SKIP014         STA ZPOSHI,X            ;
              03483
A43F 8A       03484 SKIP015         TXA                     ;
A440 18       03485                 CLC                     ;
A441 6931     03486                 ADC #NUMSPCOBJ.ALL      ;
A443 AA       03487                 TAX                     ;
A444 C66A     03488                 DEC L.VECCOMPIND        ;
A446 10E0     03489                 BPL LOOP020             ; Next coordinate
              03490
A448 88       03491                 DEY                     ;
A449 10D7     03492                 BPL LOOP019             ; Next space object
              03493
              03494 ;*** (12) Calc perspective projection of space objects *************************
A44B A5D0     03495                 LDA SHIPVIEW            ; Skip if in Long-Range Scan or Galactic Chart view
A44D C902     03496                 CMP #$02                ;
A44F B05C     03497                 BCS SKIP019             ;
              03498
A451 A679     03499                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A453 A9FF     03500 LOOP021         LDA #255                ; Prep magic offscreen pixel number value
A455 BCAD09   03501                 LDY ZPOSSIGN,X          ; Compare sign of z-coordinate with view mode
A458 C4D0     03502                 CPY SHIPVIEW            ;
A45A F04B     03503                 BEQ SKIP018             ; Equal? Space object is offscreen -> New space obj!
              03504
A45C BD0F0A   03505                 LDA YPOSSIGN,X          ; Prepare projection division...
A45F D012     03506                 BNE SKIP016             ; DIVIDEND (16-bit value) := ABS(y-coordinate)
A461 38       03507                 SEC                     ; (used in subroutine PROJECTION)
A462 A900     03508                 LDA #0                  ;
A464 FD350B   03509                 SBC YPOSLO,X            ;
A467 856A     03510                 STA DIVIDEND            ;
A469 A900     03511                 LDA #0                  ;
A46B FDA20A   03512                 SBC YPOSHI,X            ;
A46E 856B     03513                 STA DIVIDEND+1          ;
A470 4C7DA4   03514                 JMP JUMP001             ;
A473 BD350B   03515 SKIP016         LDA YPOSLO,X            ;
A476 856A     03516                 STA DIVIDEND            ;
A478 BDA20A   03517                 LDA YPOSHI,X            ;
A47B 856B     03518                 STA DIVIDEND+1          ;
              03519
A47D 2021AA   03520 JUMP001         JSR PROJECTION          ; Calc pixel row number rel. to screen center
A480 201EB7   03521                 JSR SCREENROW           ; Calc pixel row number rel. to top-left of screen
              03522
A483 BDDE09   03523                 LDA XPOSSIGN,X          ; Prepare projection division...
A486 D012     03524                 BNE SKIP017             ; DIVIDEND (16-bit value) := ABS(x-coordinate)
A488 38       03525                 SEC                     ; (used in subroutine PROJECTION)
A489 A900     03526                 LDA #0                  ;
A48B FD040B   03527                 SBC XPOSLO,X            ;
A48E 856A     03528                 STA DIVIDEND            ;
A490 A900     03529                 LDA #0                  ;
A492 FD710A   03530                 SBC XPOSHI,X            ;
A495 856B     03531                 STA DIVIDEND+1          ;
A497 4CA4A4   03532                 JMP JUMP002             ;
A49A BD040B   03533 SKIP017         LDA XPOSLO,X            ;
A49D 856A     03534                 STA DIVIDEND            ;
A49F BD710A   03535                 LDA XPOSHI,X            ;
A4A2 856B     03536                 STA DIVIDEND+1          ;
              03537
A4A4 2021AA   03538 JUMP002         JSR PROJECTION          ; Calc pixel column number rel. to screen center
A4A7 20FBB6   03539 SKIP018         JSR SCREENCOLUMN        ; Calc pixel column number rel. to top-left of screen
A4AA CA       03540                 DEX                     ;
A4AB 10A6     03541                 BPL LOOP021             ; Next space object
              03542
              03543 ;*** (13) Handle hyperwarp marker selection in Galactic Chart view *************
A4AD 2062B1   03544 SKIP019         JSR SELECTWARP          ; Handle hyperwarp marker in Galactic Chart view
              03545
              03546 ;*** (14) Compute and draw Long-Range Scan view star field on z-x plane ********
A4B0 24D0     03547                 BIT SHIPVIEW            ; Skip if not in Long-Range Scan view
A4B2 5031     03548                 BVC SKIP022             ;
              03549
A4B4 A231     03550                 LDX #$31                ; Draw our starship's shape
A4B6 206FA7   03551                 JSR DRAWLINES           ;
              03552
A4B9 2C9609   03553                 BIT GCSTATLRS           ; Skip if Long-Range Scan destroyed
A4BC 7027     03554                 BVS SKIP022             ;
              03555
A4BE A679     03556                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A4C0 BD400A   03557 LOOP022         LDA ZPOSHI,X            ; Load z-coordinate (high byte)
A4C3 BCAD09   03558                 LDY ZPOSSIGN,X          ; Load sign of z-coordinate
A4C6 D002     03559                 BNE SKIP020             ;
A4C8 49FF     03560                 EOR #$FF                ; A := ABS(z-coordinate (high byte))
A4CA A8       03561 SKIP020         TAY                     ;
A4CB B9E90D   03562                 LDA MAPTO80,Y           ; Calc pixel row number rel. to screen center
A4CE 201EB7   03563                 JSR SCREENROW           ; Calc pixel row number rel. to top-left of screen
              03564
A4D1 BD710A   03565                 LDA XPOSHI,X            ; Load x-coordinate (high byte)
A4D4 BCDE09   03566                 LDY XPOSSIGN,X          ; Load sign of x-coordinate
A4D7 D002     03567                 BNE SKIP021             ;
A4D9 49FF     03568                 EOR #$FF                ; A := ABS(x-coordinate (high byte))
A4DB A8       03569 SKIP021         TAY                     ;
A4DC B9E90D   03570                 LDA MAPTO80,Y           ; Calc pixel column number rel. to screen center
A4DF 20FBB6   03571                 JSR SCREENCOLUMN        ; Calc pixel column number rel. to top-left of screen
              03572
A4E2 CA       03573                 DEX                     ;
A4E3 10DB     03574                 BPL LOOP022             ; Next space object
              03575
              03576 ;*** (15) Update PLAYER shapes, heights, and colors ****************************
              03577
              03578 ; DESCRIPTION
              03579 ;
              03580 ; In a loop over all PLAYERs, the following steps are executed:
              03581 ;
              03582 ; o   Clear the PLAYER shape offset and height.
              03583 ;
              03584 ; o   If in Galactic Chart view or in Long-Range Scan view, preload a random
              03585 ;     color and a magic z-coordinate (distance value) for PLAYER3..4
              03586 ;     (representing hyperwarp markers in Galactic Chart view and blips in the
              03587 ;     Long-Range Scan view, like, for example, Zylon ships, meteors - or even
              03588 ;     the Hyperwarp Target Marker during hyperwarp!).
              03589 ;
              03590 ; o   If in Front or Aft view, execute the following steps:
              03591 ;
              03592 ;      o   Skip dead PLAYERs.
              03593 ;
              03594 ;      o   Preload the distance value for the remaining live PLAYERs.
              03595 ;
              03596 ;      o   If we are in a starbase sector, combine PLAYER0..2 into a three-part
              03597 ;          starbase shape. Compute the pixel column numbers and pixel row
              03598 ;          numbers of PLAYER0..1 such that they are arranged left (PLAYER0) and
              03599 ;          right (PLAYER1) of PLAYER2. In addition, preload a color mask, a
              03600 ;          counter actually, that will make the starbase pulsate in brightness.
              03601 ;
              03602 ;     BUG (at $A512): The code at $A512 that skips the combination operation for
              03603 ;     PLAYER2..4 jumps for PLAYER3..4 to SKIP025 at $A52A instead of SKIP026 at
              03604 ;     $A52E. Thus it stores a color mask which does not only make the starbase
              03605 ;     PLAYER0..2 pulsate in brightness but also PLAYER3..4 in a starbase sector,
              03606 ;     for example the transfer vessel, photon torpedoes, etc. - or even the
              03607 ;     Hyperwarp Target Marker when hyperwarping out of such a sector! Suggested
              03608 ;     fix: None, code hard to untwist.
              03609 ;
              03610 ; o   After storing the color mask, check if the PLAYER shape is still above the
              03611 ;     bottom edge of the PLAYFIELD.
              03612 ;
              03613 ;     BUG (at $A534): The test checks the vertical position of the top edge of
              03614 ;     the PLAYER against the bottom edge of the PLAYFIELD above the Console
              03615 ;     Panel Display (= Player/Missile pixel row number 204). This is not
              03616 ;     completely accurate as the Console Panel Display starts at PM pixel row
              03617 ;     number 208. For example, if you carefully navigate a starbase to the
              03618 ;     bottom edge of the PLAYFIELD, at a certain point the center of the
              03619 ;     starbase shape bleeds over the bottom edge of the PLAYFIELD (while
              03620 ;     sometimes even losing its left and right wings!). Suggested fix: None, as
              03621 ;     a more elaborate test may consume too many bytes of the cartridge ROM
              03622 ;     memory in order to fix a rarely noticed visual glitch.
              03623 ;
              03624 ; o   Convert the preloaded distance value of a PLAYER space object closer than
              03625 ;     $2000 (8192) <KM> into a range index of 0..15. PLAYER space objects more
              03626 ;     distant than $2000 (8192) <KM> are skipped and not displayed.
              03627 ;
              03628 ;     Later, this range index will pick not only the correct brightness for the
              03629 ;     PLAYER (the closer the space object the brighter its PLAYER) but also the
              03630 ;     correct PLAYER shape cell and height (the closer the space object the
              03631 ;     larger the PLAYER shape and height).
              03632 ;
              03633 ; o   Update the PLAYER's shape offset and height. On the way to the shape
              03634 ;     offset and height add the PLAYER's shape type to the range index and
              03635 ;     divide it by 2 to arrive at the shape offset index and height index (the
              03636 ;     same value). Use this index to pick the correct shape data and shape
              03637 ;     heights from a set of shape cells and their corresponding heights, stored
              03638 ;     in tables PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB ($BE7F), respectively.
              03639 ;
              03640 ;     Remember that magic distance value used in the Galactic Chart and
              03641 ;     Long-Range Scan view? Its value of $F2 is actually part of a negative
              03642 ;     z-coordinate which is inverted to $0D00, leading to a range index of 13,
              03643 ;     which, after the division by 2, picks shape cell 6. Shape cell 6 (the
              03644 ;     seventh shape cell) of all space objects (except the starbase) is the
              03645 ;     Long-Range Scan blip's dot (see PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB
              03646 ;     ($BE7F)).
              03647 ;
              03648 ; o   Update the PLAYER's color/brightness by picking the appropriate values
              03649 ;     with the range index from lookup tables PLSHAPCOLORTAB ($BFD1) and
              03650 ;     PLSHAPBRITTAB ($BFDB). Apply some special effects to the color/brightness
              03651 ;     of certain PLAYERs, such as using random colors for Zylon basestars, or
              03652 ;     using the precomputed pulsating brightness value for a starbase.
              03653
A4E5 A205     03654 SKIP022         LDX #NUMSPCOBJ.PL       ; Loop over all PLAYER space objects (X index < 5)
A4E7 CA       03655 LOOP023         DEX                     ;
A4E8 1003     03656                 BPL SKIP023             ; Jump into loop body below
A4EA 4C79A5   03657                 JMP JUMP003             ; Loop is finished, skip loop body
              03658
              03659 ;*** Clear PLAYER shape offsets and heights ************************************
A4ED A900     03660 SKIP023         LDA #0                  ;
A4EF 95E4     03661                 STA PL0SHAPOFF,X        ; Clear PLAYER shape offset
A4F1 9DEE0C   03662                 STA PL0HEIGHTNEW,X      ; Clear new PLAYER shape height
              03663
              03664 ;*** Preload stuff for hyperwarp markers and Long-Range Scan blips *************
A4F4 24D0     03665                 BIT SHIPVIEW            ; Skip if not in Galactic Chart view
A4F6 100B     03666                 BPL SKIP024             ;
              03667
A4F8 E003     03668                 CPX #3                  ; Next PLAYER space object if PLAYER0..2
A4FA 90EB     03669                 BCC LOOP023             ;
              03670
A4FC AD0AD2   03671 LOOP024         LDA RANDOM              ; Prep random color mask for warp markers/LRS blips
A4FF A0F2     03672                 LDY #$F2                ; Prep magic z-coordinate for warp markers/LRS blips
A501 302B     03673                 BMI SKIP026             ; Unconditional jump
              03674
A503 D5E9     03675 SKIP024         CMP PL0LIFE,X           ; Next PLAYER space object if this PLAYER not alive
A505 F0E0     03676                 BEQ LOOP023             ;
              03677
A507 70F3     03678                 BVS LOOP024             ; Skip back if in Long-Range Scan view
              03679
              03680 ;*** Preload stuff for other views *********************************************
              03681
A509 BC400A   03682                 LDY PL0ZPOSHI,X         ; Prep z-coordinate (high byte)
              03683
              03684 ;*** Combine PLAYER0..2 to starbase shape **************************************
A50C 247B     03685                 BIT ISSTARBASESECT      ; Skip if no starbase in this sector
A50E 501E     03686                 BVC SKIP026             ;
              03687
A510 E002     03688                 CPX #2                  ; Skip if PLAYER2..4
A512 B016     03689                 BCS SKIP025             ; (!)
              03690
A514 AD2C0C   03691                 LDA PL2COLUMN           ; Calc new PM pixel column number for PLAYER0..1:
A517 18       03692                 CLC                     ; Load PLAYER2 (starbase center) pixel column number
A518 7DDBBE   03693                 ADC PLSTARBAOFFTAB,X    ; ...add PLAYER left/right offset (starbase wings)
A51B 9D2A0C   03694                 STA PL0COLUMN,X         ; Store new PM pixel column number of starbase wing
              03695
A51E ADFB0B   03696                 LDA PL2ROWNEW           ; Calc new PM pixel row number for PLAYER0..1:
A521 18       03697                 CLC                     ; Add vertical offset (= 4 PM pixels) to PLAYER2's
A522 6904     03698                 ADC #4                  ;
A524 9DF90B   03699                 STA PL0ROWNEW,X         ; Store new PM pixel row number of starbase wing
              03700
A527 AC420A   03701                 LDY PL2ZPOSHI           ; Prep Y with z-coordinate (high byte) of starbase
              03702
A52A A576     03703 SKIP025         LDA COUNT256            ; Prep color mask with B3..0 of counter
A52C 290F     03704                 AND #$0F                ; ...(= brightness bits cause pulsating brightness)
              03705
A52E 856B     03706 SKIP026         STA L.COLORMASK         ; Store color mask
              03707
              03708 ;*** Check if PLAYER is below PLAYFIELD bottom edge ****************************
A530 98       03709                 TYA                     ; A := z-coordinate (high byte)
              03710
A531 BCF90B   03711                 LDY PL0ROWNEW,X         ; Next PLAYER space object if top of PM shape...
A534 C0CC     03712                 CPY #204                ; ...is below PLAYFIELD bottom... (!)
A536 B0AF     03713                 BCS LOOP023             ; ...(PM pixel row number >= 204)
              03714
              03715 ;*** Convert PLAYER z-coordinate to range index in 0..15 ***********************
A538 A4D0     03716                 LDY SHIPVIEW            ; Skip if in Front view...
A53A F002     03717                 BEQ SKIP027             ;
A53C 49FF     03718                 EOR #$FF                ; ...else invert z-coordinate (high byte)
              03719
A53E C920     03720 SKIP027         CMP #$20                ; Next PLAYER space object if this one too far away
A540 B0A5     03721                 BCS LOOP023             ; ...(z-coordinate >= $20** (8192) <KM>)
              03722
A542 C910     03723                 CMP #16                 ; Load z-coordinate (high byte) and...
A544 9002     03724                 BCC SKIP028             ;
A546 A90F     03725                 LDA #15                 ;
A548 856A     03726 SKIP028         STA L.RANGEINDEX        ; ...trim to range index in 0..15
              03727
              03728 ;*** Update PLAYER shape offset and height *************************************
A54A 1D8C0C   03729                 ORA PL0SHAPTYPE,X       ; Calc offset to shape table (shape type+range index)
A54D 4A       03730                 LSR A                   ;
A54E A8       03731                 TAY                     ; Divide by 2 to get offset in 0..7 into shape data
A54F B92FBE   03732                 LDA PLSHAPOFFTAB,Y      ; Update new PLAYER shape offset
A552 95E4     03733                 STA PL0SHAPOFF,X        ;
A554 B97FBE   03734                 LDA PLSHPHEIGHTTAB,Y    ; Update new PLAYER shape height
A557 9DEE0C   03735                 STA PL0HEIGHTNEW,X      ;
              03736
              03737 ;*** Calculate PLAYER color/brightness value ***********************************
A55A 98       03738                 TYA                     ; Pick color (B7..4) using PLAYER shape type
A55B 4A       03739                 LSR A                   ;
A55C 4A       03740                 LSR A                   ;
A55D 4A       03741                 LSR A                   ;
A55E A8       03742                 TAY                     ;
A55F B9D1BF   03743                 LDA PLSHAPCOLORTAB,Y    ;
A562 C008     03744                 CPY #8                  ; Pick random color if ZYLON BASESTAR (shape type 8)
A564 D003     03745                 BNE SKIP029             ;
A566 4D0AD2   03746                 EOR RANDOM              ;
A569 A46A     03747 SKIP029         LDY L.RANGEINDEX        ;
A56B 59DBBF   03748                 EOR PLSHAPBRITTAB,Y     ; Pick brightness (B3..0) using range index and merge
              03749
A56E 456B     03750                 EOR L.COLORMASK         ; Modify color/brightness of PLAYER
              03751
A570 BCDFB8   03752                 LDY PLCOLOROFFTAB,X     ; Get PLAYER color offset
A573 99EE00   03753                 STA PL0COLOR,Y          ; Store color in PLAYER color register
A576 4CE7A4   03754                 JMP LOOP023             ; Next PLAYER space object
              03755
              03756 ;*** (16) Flash red alert ******************************************************
A579 A0AF     03757 JUMP003         LDY #$AF                ; Prep PLAYFIELD2 color {BRIGHT BLUE-GREEN}
A57B A681     03758                 LDX SHIELDSCOLOR        ; Prep Shields color {DARK GREEN} or {BLACK}
              03759
A57D A58B     03760                 LDA REDALERTLIFE        ; Skip if red alert is over
A57F F00C     03761                 BEQ SKIP030             ;
              03762
A581 C68B     03763                 DEC REDALERTLIFE        ; Decrement lifetime of red alert
A583 A04F     03764                 LDY #$4F                ; Prep PLAYFIELD2 color {BRIGHT ORANGE}
              03765
A585 2920     03766                 AND #$20                ; Switch colors every 64 game loops
A587 F004     03767                 BEQ SKIP030             ;
              03768
A589 A242     03769                 LDX #$42                ; Load BACKGROUND color {DARK ORANGE}
A58B A060     03770                 LDY #$60                ; Load PLAYFIELD2 color {DARK PURPLE BLUE}
              03771
A58D 84F4     03772 SKIP030         STY PF2COLOR            ; Store PLAYFIELD2 color
A58F 86F6     03773                 STX BGRCOLOR            ; Store BACKGROUND color
              03774
              03775 ;*** (17) Update color of PLAYFIELD space objects (stars, explosion fragments) *
A591 A679     03776                 LDX MAXSPCOBJIND        ; Loop over all PLAYFIELD space objs (X index > 4)
A593 BD400A   03777 LOOP025         LDA ZPOSHI,X            ; Prep z-coordinate (high byte)
A596 A4D0     03778                 LDY SHIPVIEW            ;
A598 C001     03779                 CPY #1                  ; Skip if not in Aft view
A59A D009     03780                 BNE SKIP032             ;
              03781
A59C C9F0     03782                 CMP #$F0                ; Skip if star not too far (z < $F0** (-4096) <KM>)
A59E B003     03783                 BCS SKIP031             ;
A5A0 2064B7   03784                 JSR INITPOSVEC          ; Re-init position vector
A5A3 49FF     03785 SKIP031         EOR #$FF                ; Invert z-coordinate (high byte)
              03786
A5A5 C910     03787 SKIP032         CMP #16                 ; Convert z-coordinate (high byte)
A5A7 9002     03788                 BCC SKIP033             ; ...into range index 0..15
A5A9 A90F     03789                 LDA #15                 ;
              03790
A5AB 0A       03791 SKIP033         ASL A                   ; Compute index to pixel color table:
A5AC 291C     03792                 AND #$1C                ; Use bits B3..1 from range index as B4..2.
A5AE 0572     03793                 ORA COUNT8              ; Combine with random bits B3..0 from counter
              03794
A5B0 A8       03795                 TAY                     ;
A5B1 B990BA   03796                 LDA FOURCOLORPIXEL,Y    ; Load 1-byte bit pattern for 4 pixels of same color
A5B4 856A     03797                 STA L.FOURCOLORPIX      ; ...and temporarily save it
              03798
A5B6 BD2A0C   03799                 LDA PIXELCOLUMN,X       ; Load pixel mask to mask 1 pixel out of 4 pixels:
A5B9 2903     03800                 AND #$03                ; Use B1..0 from pixel column number...
A5BB A8       03801                 TAY                     ;
A5BC B9B0BA   03802                 LDA PIXELMASKTAB,Y      ; ...to pick mask to filter pixel in byte
A5BF 256A     03803                 AND L.FOURCOLORPIX      ; ...AND with 1-byte bit pattern for 4 pixels
A5C1 9DEE0C   03804                 STA PIXELBYTE,X         ; ...store byte (used in repaint step of game loop)
              03805
A5C4 CA       03806                 DEX                     ;
A5C5 E005     03807                 CPX #NUMSPCOBJ.PL       ;
A5C7 B0CA     03808                 BCS LOOP025             ; Next PLAYFIELD space object
              03809
              03810 ;*** (18) Skip input handling if in demo mode **********************************
A5C9 2464     03811                 BIT ISDEMOMODE          ; If in demo mode skip to function keys
A5CB 5003     03812                 BVC SKIP034             ;
A5CD 4C9BA6   03813                 JMP SKIP040             ;
              03814
              03815 ;*** (19) Handle keyboard input ************************************************
A5D0 20FEAF   03816 SKIP034         JSR KEYBOARD            ; Handle keyboard input
              03817
              03818 ;*** (20) Handle joystick input ************************************************
A5D3 AD00D3   03819                 LDA PORTA               ; Load Joystick 0 directions
A5D6 A8       03820                 TAY                     ; ...Bits B0..3 -> Right, left, down, up.
A5D7 2903     03821                 AND #$03                ; ...Bit = 0/1 -> Stick pressed/not pressed
A5D9 AA       03822                 TAX                     ; JOYSTICKY := +1 -> Up
A5DA BDF5BA   03823                 LDA STICKINCTAB,X       ; JOYSTICKY :=  0 -> Centered
A5DD 85C9     03824                 STA JOYSTICKY           ; JOYSTICKY := -1 -> Down
A5DF 98       03825                 TYA                     ;
A5E0 4A       03826                 LSR A                   ;
A5E1 4A       03827                 LSR A                   ;
A5E2 2903     03828                 AND #$03                ;
A5E4 AA       03829                 TAX                     ; JOYSTICKX := -1 -> Left
A5E5 BDF5BA   03830                 LDA STICKINCTAB,X       ; JOYSTICKX :=  0 -> Centered
A5E8 85C8     03831                 STA JOYSTICKX           ; JOYSTICKX := +1 -> Right
              03832
              03833 ;*** (21) Check if our starship's photon torpedoes have hit a target ***********
A5EA 203DAF   03834                 JSR COLLISION           ; Check if our starship's photon torpedoes have hit
              03835
              03836 ;*** (22) Handle joystick trigger **********************************************
A5ED 2029AE   03837                 JSR TRIGGER             ; Handle joystick trigger
              03838
              03839 ;*** (23) Handle Attack Computer and Tracking Computer *************************
A5F0 2C9509   03840                 BIT GCSTATCOM           ; Skip if Attack Computer destroyed
A5F3 7040     03841                 BVS SKIP038             ;
              03842
A5F5 A57E     03843                 LDA DRAINATTCOMP        ; Skip if Attack Computer off
A5F7 F03C     03844                 BEQ SKIP038             ;
              03845
A5F9 A5D0     03846                 LDA SHIPVIEW            ; Skip if not in Front view
A5FB D003     03847                 BNE SKIP035             ;
              03848
A5FD 20BFA7   03849                 JSR UPDATTCOMP          ; Update Attack Computer Display
              03850
A600 AE5C09   03851 SKIP035         LDX TRACKDIGIT          ; Load index of tracked space object
              03852
A603 A5BF     03853                 LDA ZYLONATTACKER       ; Skip if ship of current Zylon torpedo is tracked
A605 3005     03854                 BMI SKIP036             ;
A607 AA       03855                 TAX                     ; ...else override Tracking Computer...
A608 0980     03856                 ORA #$80                ;
A60A 85BF     03857                 STA ZYLONATTACKER       ; ...and mark Zylon torpedo's ship as being tracked
              03858
A60C B5E9     03859 SKIP036         LDA PL0LIFE,X           ; Skip if tracked space object still alive
A60E D00B     03860                 BNE SKIP037             ;
              03861
A610 8A       03862                 TXA                     ;
A611 4901     03863                 EOR #$01                ;
A613 AA       03864                 TAX                     ;
A614 B5E9     03865                 LDA PL0LIFE,X           ; Check if other Zylon ship still alive
A616 D003     03866                 BNE SKIP037             ; ...yes -> Keep new index
A618 AE5C09   03867                 LDX TRACKDIGIT          ; ...no  -> Revert to old index of tracked space obj
              03868
A61B 8E5C09   03869 SKIP037         STX TRACKDIGIT          ; Store index of tracked space object
              03870
A61E A57C     03871                 LDA ISTRACKCOMPON       ; Skip if tracking computer is turned off
A620 F013     03872                 BEQ SKIP038             ;
              03873
A622 A5D0     03874                 LDA SHIPVIEW            ; Skip if in Long-Range Scan or Galactic Chart view
A624 C902     03875                 CMP #2                  ;
A626 B00D     03876                 BCS SKIP038             ;
              03877
A628 4901     03878                 EOR #$01                ;
A62A DDAD09   03879                 CMP ZPOSSIGN,X          ; Skip if tracked space object in our starship's...
A62D F006     03880                 BEQ SKIP038             ; ...view direction
              03881
A62F AA       03882                 TAX                     ;
A630 BDCFBE   03883                 LDA TRACKKEYSTAB,X      ; Pick 'F' or 'A' (Front or Aft view) keyboard code
A633 85CA     03884                 STA KEYCODE             ; ...and store it (= emulate pressing 'F' or 'A' key)
              03885
              03886 ;*** (24) Handle docking to starbase *******************************************
A635 20E6AC   03887 SKIP038         JSR DOCKING             ; Handle docking to starbase
              03888
              03889 ;*** (25) Handle maneuvering ***************************************************
A638 2079AA   03890                 JSR MANEUVER            ; Handle maneuvering photon torpedoes and Zylon ships
              03891
              03892 ;*** (26) Was our starship hit by Zylon photon torpedo? ************************
A63B A57B     03893                 LDA ISSTARBASESECT      ; Skip hit check if in starbase sector
A63D D05C     03894                 BNE SKIP040             ;
              03895
A63F A5EB     03896                 LDA PL2LIFE             ; Skip hit check if PLAYER2 (Zylon photon torpedo)...
A641 F058     03897                 BEQ SKIP040             ; ...not alive
              03898
A643 AC420A   03899                 LDY PL2ZPOSHI           ; Our starship was not hit if Zylon photon torpedo's
A646 C8       03900                 INY                     ; ...z-coordinate is not in -256..255 <KM> or...
A647 C002     03901                 CPY #$02                ;
A649 B050     03902                 BCS SKIP040             ;
              03903
A64B AC730A   03904                 LDY PL2XPOSHI           ; ...x-coordinate is not in -256..255 <KM> or...
A64E C8       03905                 INY                     ;
A64F C002     03906                 CPY #$02                ;
A651 B048     03907                 BCS SKIP040             ;
              03908
A653 ACA40A   03909                 LDY PL2YPOSHI           ; ...y-coordinate is not in -256..255 <KM>.
A656 C8       03910                 INY                     ;
A657 C002     03911                 CPY #$02                ;
A659 B040     03912                 BCS SKIP040             ;
              03913
              03914 ;*** (27) Our starship was hit! ************************************************
A65B 20E1AE   03915                 JSR DAMAGE              ; Damage or destroy some subsystem
              03916
A65E A002     03917                 LDY #2                  ; Trigger explosion at PLAYER2 (Zylon photon torpedo)
A660 206BAC   03918                 JSR INITEXPL            ;
              03919
A663 A27F     03920                 LDX #$7F                ; Prep HITBADNESS := SHIELDS HIT
A665 A581     03921                 LDA SHIELDSCOLOR        ; Skip if Shields are up (SHIELDSCOLOR not {BLACK}).
A667 D01E     03922                 BNE SKIP039             ;
              03923
A669 A20A     03924                 LDX #$0A                ; Set Front view
A66B 2045B0   03925                 JSR SETVIEW             ;
              03926
A66E A023     03927                 LDY #$23                ; Set title phrase "SHIP DESTROYED BY ZYLON FIRE"
A670 A208     03928                 LDX #8                  ; Set mission bonus offset
A672 200AB1   03929                 JSR GAMEOVER            ; Game over
              03930
A675 A25F     03931                 LDX #$5F                ; Hide Control Panel Display (bottom text window)
A677 A080     03932                 LDY #$80                ;
A679 A908     03933                 LDA #$08                ;
A67B 20F1AD   03934                 JSR MODDLST             ;
              03935
A67E 200DAE   03936                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
              03937
A681 A240     03938                 LDX #64                 ; Enable STARSHIP EXPLOSION noise (see SOUND)
A683 86E3     03939                 STX NOISEHITLIFE        ;
              03940
A685 A2FF     03941                 LDX #$FF                ; Prep HITBADNESS := STARSHIP DESTROYED
              03942
A687 868A     03943 SKIP039         STX HITBADNESS          ; Store HITBADNESS
A689 A900     03944                 LDA #0                  ; Zylon photon torpedo lifetime := 0 game loops
A68B 85EB     03945                 STA PL2LIFE             ;
A68D A902     03946                 LDA #2                  ; Init Zylon photon torpedo trigger
A68F 85BE     03947                 STA TORPEDODELAY        ;
              03948
A691 A201     03949                 LDX #1                  ; ENERGY := ENERGY - 100 after photon torpedo hit
A693 206FB8   03950                 JSR DECENERGY           ;
              03951
A696 A20A     03952                 LDX #$0A                ; Play noise sound pattern SHIELD EXPLOSION
A698 20A8AE   03953                 JSR NOISE               ;
              03954
              03955 ;*** (28) Handle function keys *************************************************
A69B A463     03956 SKIP040         LDY FKEYCODE            ; Prep old function key code
A69D AD1FD0   03957                 LDA CONSOL              ; POKEY: Load function key code
              03958
A6A0 49FF     03959                 EOR #$FF                ; Store inverted and masked function key code
A6A2 2903     03960                 AND #$03                ;
A6A4 8563     03961                 STA FKEYCODE            ;
A6A6 F01A     03962                 BEQ SKIP042             ; Skip if no function key pressed
              03963
A6A8 88       03964                 DEY                     ;
A6A9 1017     03965                 BPL SKIP042             ; Skip if SELECT or START still pressed
A6AB 8566     03966                 STA IDLECNTHI           ; Reset idle counter to a value in 1..3 (?)
A6AD C902     03967                 CMP #2                  ; Skip if SELECT function key pressed
A6AF B006     03968                 BCS SKIP041             ;
              03969
A6B1 A900     03970                 LDA #0                  ; START function key pressed:
A6B3 A8       03971                 TAY                     ; Prep empty title phrase offset
A6B4 4C5EA1   03972                 JMP INITSTART           ; Reenter game loop via INITSTART
              03973
A6B7 E662     03974 SKIP041         INC MISSIONLEVEL        ; SELECT function key pressed:
A6B9 A562     03975                 LDA MISSIONLEVEL        ; Cycle through next of 4 mission levels
A6BB 2903     03976                 AND #$03                ;
A6BD 8562     03977                 STA MISSIONLEVEL        ;
A6BF 4C5AA1   03978                 JMP INITSELECT          ; Reenter game loop via INITSELECT
              03979
              03980 ;*** (29) Update Control Panel Display *****************************************
A6C2 2004B8   03981 SKIP042         JSR UPDPANEL            ; Update Control Panel Display
              03982
              03983 ;*** (30) Handle hyperwarp *****************************************************
A6C5 209BA8   03984                 JSR HYPERWARP           ; Handle hyperwarp
              03985
              03986 ;*** (31) Update title line ****************************************************
A6C8 2016B2   03987                 JSR UPDTITLE            ; Update title line
              03988
              03989 ;*** (32) Flush game loop iteration ********************************************
A6CB 20E4B4   03990                 JSR FLUSHGAMELOOP       ; Move Zylon units, age torpedoes, elapse time
              03991
              03992 ;*** (33) Jump back to begin of game loop **************************************
A6CE 4CF3A1   03993                 JMP GAMELOOP            ; Next game loop iteration
              03994
              03995 ;*******************************************************************************
              03996 ;*                                                                             *
              03997 ;*                                  VBIHNDLR                                   *
              03998 ;*                                                                             *
              03999 ;*                      Vertical Blank Interrupt Handler                       *
              04000 ;*                                                                             *
              04001 ;*******************************************************************************
              04002
              04003 ; DESCRIPTION
              04004 ;
              04005 ; This subroutine is executed during the Vertical Blank Interrupt (VBI) when the
              04006 ; TV beam has reached the bottom-right corner of the TV screen and is switched
              04007 ; off to return to the top-left position. This situation is called the "vertical
              04008 ; blank phase".
              04009 ;
              04010 ; This subroutine signals its execution with flag ISVBISYNC ($67) (which is
              04011 ; examined by GAMELOOP ($A1F3) to synchronize the execution of the game loop
              04012 ; with the start of this subroutine). Then it switches the character set to the
              04013 ; ROM character set, sets the BACKGROUND color depending on the severity of a
              04014 ; Zylon photon torpedo hit and view mode, copies PLAYER and PLAYFIELD color
              04015 ; registers to their corresponding hardware registers, clears the Player/Missile
              04016 ; collision registers, calls the sound effects code in subroutine SOUND ($B2AB),
              04017 ; and increments the idle counter. If the idle counter reaches the value $8000
              04018 ; the title phrase is cleared and the program is switched to demo mode.
              04019 ;
              04020 ; BUG (at $A6EC): Because the values of SHIPVIEW ($D0) are $00, $01, $40, and
              04021 ; $80, a value of 3 overspecifies the comparison. Suggested fix: Replace CMP #3
              04022 ; with CMP #2, which may make the code clearer.
              04023 ;
              04024 ; BUG (at $A712): Demo mode is entered via a JMP instruction, which proceeds
              04025 ; directly into GAMELOOP ($A1F3). Thus code execution never returns to pop the
              04026 ; registers pushed on the stack during entry of this subroutine. Suggested fix:
              04027 ; None.
              04028
A6D1 A9FF     04029 VBIHNDLR        LDA #$FF                ; Signals entering Vertical Blank Interrupt
A6D3 8567     04030                 STA ISVBISYNC           ;
              04031
A6D5 A9E0     04032                 LDA #>ROMCHARSET        ; Switch character set to ROM character set
A6D7 8D09D4   04033                 STA CHBASE              ;
              04034
A6DA A6F6     04035                 LDX BGRCOLOR            ; Preload BACKGROUND color
A6DC AD0AD2   04036                 LDA RANDOM              ; Preload random number
A6DF 248A     04037                 BIT HITBADNESS          ; Check if our starship was hit
A6E1 5007     04038                 BVC SKIP044             ; If HITBADNESS has a value of...
A6E3 3004     04039                 BMI SKIP043             ; $00 -> NO HIT             (BGR color := unchanged)
A6E5 2972     04040                 AND #$72                ; $7F -> SHIELDS HIT        (BGR color := %01rr00r0)
A6E7 0940     04041                 ORA #$40                ; $FF -> STARSHIP DESTROYED (BGR color := %01rr00r0)
A6E9 AA       04042 SKIP043         TAX                     ;
A6EA A5D0     04043 SKIP044         LDA SHIPVIEW            ; Skip if in Front or Aft view
A6EC C903     04044                 CMP #3                  ; (!)
A6EE 9002     04045                 BCC SKIP045             ;
A6F0 A2A0     04046                 LDX #$A0                ; Preload BACKGROUND color {DARK BLUE GREEN}...
A6F2 86F6     04047 SKIP045         STX BGRCOLOR            ; Store BACKGROUND color
              04048
A6F4 A208     04049                 LDX #8                  ; Copy all color registers to hardware registers
A6F6 B5EE     04050 LOOP026         LDA PL0COLOR,X          ;
A6F8 9D12D0   04051                 STA COLPM0,X            ;
A6FB CA       04052                 DEX                     ;
A6FC 10F8     04053                 BPL LOOP026             ;
              04054
A6FE 8D1ED0   04055                 STA HITCLR              ; Clear Player/Missile collision registers
              04056
A701 20ABB2   04057                 JSR SOUND               ; Call sound effects
              04058
A704 E677     04059                 INC IDLECNTLO           ; Increment 16-bit idle counter
A706 D00D     04060                 BNE SKIP046             ;
A708 A566     04061                 LDA IDLECNTHI           ;
A70A 3009     04062                 BMI SKIP046             ;
A70C E666     04063                 INC IDLECNTHI           ;
A70E 1005     04064                 BPL SKIP046             ; Skip if idle counter value of $8000 not reached yet
              04065
A710 A000     04066                 LDY #$00                ; Prep empty title phrase offset
A712 4C5CA1   04067                 JMP INITDEMO            ; Enter demo mode (!)
              04068
A715 4C4BA7   04069 SKIP046         JMP JUMP004             ; Return via DLI return code
              04070
              04071 ;*******************************************************************************
              04072 ;*                                                                             *
              04073 ;*                                  DLSTHNDLR                                  *
              04074 ;*                                                                             *
              04075 ;*                       Display List Interrupt Handler                        *
              04076 ;*                                                                             *
              04077 ;*******************************************************************************
              04078
              04079 ; DESCRIPTION
              04080 ;
              04081 ; This subroutine is executed during the Display List Interrupt (DLI). It
              04082 ; switches the character set to the ROM character set if the DLI occurs at ANTIC
              04083 ; line 96 (video line 192), otherwise to the custom character set. The former
              04084 ; happens in the Galactic Chart view where the ROM character set is used in the
              04085 ; Galactic Chart Panel Display.
              04086 ;
              04087 ; Then, the DLI PLAYFIELD colors are copied to the corresponding hardware
              04088 ; registers and the values of the collision hardware registers for PLAYER3..4
              04089 ; (our starship's photon torpedoes) are copied to the corresponding zero-page
              04090 ; variables PL3HIT ($82) and PL4HIT ($83).
              04091
A718 48       04092 DLSTHNDLR       PHA                     ; Push A
A719 8A       04093                 TXA                     ;
A71A 48       04094                 PHA                     ; Push X
A71B 98       04095                 TYA                     ;
A71C 48       04096                 PHA                     ; Push Y
              04097
A71D A9E0     04098                 LDA #>ROMCHARSET        ; Switch to ROM charset if ANTIC line counter = 96
A71F AC0BD4   04099                 LDY VCOUNT              ; ...else switch to custom character set
A722 C060     04100                 CPY #96                 ;
A724 F002     04101                 BEQ SKIP047             ;
A726 A9A0     04102                 LDA #>CHARSET           ;
A728 8D09D4   04103 SKIP047         STA CHBASE              ;
              04104
A72B A204     04105                 LDX #4                  ; Loop over all PLAYFIELD colors
A72D 8D0AD4   04106                 STA WSYNC               ; Stop and wait for horizontal TV beam sync
A730 B5F7     04107 LOOP027         LDA PF0COLORDLI,X       ; Copy DLI PLAYFIELD colors to hardware registers
A732 9D16D0   04108                 STA COLPF0,X            ;
A735 CA       04109                 DEX                     ;
A736 10F8     04110                 BPL LOOP027             ; Next PLAYFIELD color
              04111
A738 AD08D0   04112                 LDA M0PL                ; Merge MISSILE-to-PLAYER collision registers...
A73B 0D09D0   04113                 ORA M1PL                ;
A73E 0D0AD0   04114                 ORA M2PL                ;
A741 0D0BD0   04115                 ORA M3PL                ;
A744 8583     04116                 STA PL4HIT              ; ...and store them in PL4HIT
A746 AD0FD0   04117                 LDA P3PL                ; Copy PLAYER3-to-PLAYER coll. register to PL3HIT
A749 8582     04118                 STA PL3HIT              ;
              04119
A74B 68       04120 JUMP004         PLA                     ; Pop Y
A74C A8       04121                 TAY                     ;
A74D 68       04122                 PLA                     ; Pop X
A74E AA       04123                 TAX                     ;
A74F 68       04124                 PLA                     ; Pop A
A750 40       04125                 RTI                     ; Return from interrupt
              04126
              04127 ;*******************************************************************************
              04128 ;*                                                                             *
              04129 ;*                                  IRQHNDLR                                   *
              04130 ;*                                                                             *
              04131 ;*                       Interrupt Request (IRQ) Handler                       *
              04132 ;*                                                                             *
              04133 ;*******************************************************************************
              04134
              04135 ; DESCRIPTION
              04136 ;
              04137 ; This subroutine is executed during immediate interrupt requests (IRQs), such
              04138 ; as after pressing a key on the keyboard. It clears and disables all IRQs
              04139 ; except the interrupt raised by a pressed key. If a key has been pressed, its
              04140 ; hardware code is collected and the bits of the SHIFT and CONTROL keys are
              04141 ; added. The resulting keyboard code is stored in KEYCODE ($CA).
              04142
A751 48       04143 IRQHNDLR        PHA                     ; Push A
A752 A900     04144                 LDA #0                  ; POKEY: Disable all IRQs
A754 8D0ED2   04145                 STA IRQEN               ;
A757 A940     04146                 LDA #$40                ; POKEY: Enable keyboard interrupt (IRQ)
A759 8D0ED2   04147                 STA IRQEN               ;
A75C AD09D2   04148                 LDA KBCODE              ; POKEY: Load keyboard key code
A75F 09C0     04149                 ORA #$C0                ; Combine with SHIFT and CONTROL key bits
A761 85CA     04150                 STA KEYCODE             ; Store keyboard code
A763 68       04151                 PLA                     ; Pop A
A764 40       04152                 RTI                     ; Return from interrupt
              04153
              04154 ;*******************************************************************************
              04155 ;*                                                                             *
              04156 ;*                                  DRAWLINES                                  *
              04157 ;*                                                                             *
              04158 ;*                     Draw horizontal and vertical lines                      *
              04159 ;*                                                                             *
              04160 ;*******************************************************************************
              04161
              04162 ; DESCRIPTION
              04163 ;
              04164 ; Draws the Attack Computer Display (in Front view), cross hairs (in Front and
              04165 ; Aft view), and our starship's shape (in Long-Range Scan view) on the PLAYFIELD
              04166 ; (if the Attack Computer is not destroyed) by being passed an offset to table
              04167 ; DRAWLINESTAB ($BAF9). This table consists of a list of 3-byte elements,
              04168 ; terminated by an end marker byte ($FE). Each such element defines a single
              04169 ; horizontal or vertical line, and is passed via memory addresses DIRLEN ($A4),
              04170 ; PENROW ($A5), and PENCOLUMN ($A6) to subroutine DRAWLINE ($A782), which
              04171 ; executes the actual drawing. See subroutine DRAWLINE ($A782) and table
              04172 ; DRAWLINESTAB ($BAF9) for a description of the 3-byte elements.
              04173 ;
              04174 ; With every call of this subroutine the blip cycle counter is initialized to
              04175 ; the start of the DELAY phase (see subroutine UPDATTCOMP ($A7BF)).
              04176 ;
              04177 ; NOTE: The entry to this subroutine is in mid-code, not at the beginning.
              04178 ;
              04179 ; INPUT
              04180 ;
              04181 ;   X = Offset into DRAWLINESTAB ($BAF9). Used values are:
              04182 ;     $00 -> Draw Attack Computer Display and cross hairs (Front view)
              04183 ;     $2A -> Draw Aft view cross hairs (Aft view)
              04184 ;     $31 -> Draw our starship's shape (Long-Range Scan view)
              04185
A765 99A400   04186 LOOP028         STA DIRLEN,Y            ; Store byte of 3-byte element
A768 E8       04187                 INX                     ;
A769 88       04188                 DEY                     ;
A76A 100E     04189                 BPL SKIP048             ; Next byte of 3-byte element until 3 bytes copied
A76C 2082A7   04190                 JSR DRAWLINE            ; Draw line on PLAYFIELD
              04191
A76F A905     04192 DRAWLINES       LDA #5                  ; Init blip cycle to DELAY phase...
A771 85A2     04193                 STA BLIPCYCLECNT        ; ...delays drawing each row
              04194
A773 2C9509   04195                 BIT GCSTATCOM           ; Return if Attack Computer destroyed
A776 7009     04196                 BVS SKIP049             ;
              04197
A778 A002     04198                 LDY #2                  ;
A77A BDF9BA   04199 SKIP048         LDA DRAWLINESTAB,X      ; Load byte of 3-byte element
A77D C9FE     04200                 CMP #$FE                ; Loop until end marker byte ($FE) encountered
A77F D0E4     04201                 BNE LOOP028             ;
A781 60       04202 SKIP049         RTS                     ; Return
              04203
              04204 ;*******************************************************************************
              04205 ;*                                                                             *
              04206 ;*                                  DRAWLINE                                   *
              04207 ;*                                                                             *
              04208 ;*                  Draw a single horizontal or vertical line                  *
              04209 ;*                                                                             *
              04210 ;*******************************************************************************
              04211
              04212 ; DESCRIPTION
              04213 ;
              04214 ; Draws a single horizontal or vertical transparent line.
              04215 ;
              04216 ; There are two entries to this subroutine:
              04217 ;
              04218 ; (1)  DRAWLINE ($A782) is entered from subroutine DRAWLINES ($A76F) to draw a
              04219 ;      line in COLOR1.
              04220 ;
              04221 ; (2)  DRAWLINE2 ($A784) is entered from subroutine UPDATTCOMP ($A7BF) to draw
              04222 ;      the blip in COLOR2 in the Attack Computer Display.
              04223 ;
              04224 ; The position, direction, and length of the line is defined by three bytes
              04225 ; passed in memory addresses DIRLEN ($A4), PENROW ($A5), and PENCOLUMN ($A6).
              04226 ;
              04227 ; A drawing operation draws one transparent line. It uses both the color
              04228 ; register number of the overwritten (old) and the overwriting (new) pixel to
              04229 ; decide on the new pixel color register number. This results in a transparent
              04230 ; drawing effect. See the table below for all resulting combinations of color
              04231 ; registers.
              04232 ;
              04233 ; +-----------+---------------+
              04234 ; |           |   Old Color   |
              04235 ; |           |   Register    |
              04236 ; | New Color +---------------+
              04237 ; | Register  | 0 | 1 | 2 | 3 |
              04238 ; +-----------+---+---+---+---+
              04239 ; |         0 | 0 | 1 | 2 | 3 |
              04240 ; +-----------+---+---+---+---+
              04241 ; |         1 | 1 | 1 | 3 | 3 |
              04242 ; +-----------+---+---+---+---+
              04243 ; |         2 | 2 | 3 | 2 | 3 |
              04244 ; +-----------+---+---+---+---+
              04245 ; |         3 | 3 | 3 | 3 | 3 |
              04246 ; +-----------+---+---+---+---+
              04247 ;
              04248 ; For example, COLOR1 overwritten by COLOR2 yields COLOR3. If you look closely
              04249 ; at the blip (in COLOR2) on the Attack Computer Display (in COLOR1) the lines
              04250 ; of the Attack Computer Display shine through (in COLOR3) where they overlap.
              04251 ;
              04252 ; INPUT
              04253 ;
              04254 ;   DIRLEN    ($A4) = B7 = 0 -> Draw line to the right
              04255 ;                     B7 = 1 -> Draw line downward
              04256 ;                     B6..0  -> Length of line in pixels
              04257 ;   PENROW    ($A5) = Start pixel row number of line
              04258 ;   PENCOLUMN ($A6) = Start pixel column number of line
              04259
    =006A     04260 L.PIXELBYTEOFF  = $6A                   ; Within-row-offset to byte with pixel in PLAYFIELD
    =006B     04261 L.BITPAT        = $6B                   ; 1-byte bit pattern for 4 pixels of same color
    =006E     04262 L.DIRSAV        = $6E                   ; Saves DIRLEN
              04263
A782 A955     04264 DRAWLINE        LDA #$55                ; Copy 1-byte bit pattern for 4 pixels of COLOR1
A784 856B     04265 DRAWLINE2       STA L.BITPAT            ;
A786 A5A4     04266                 LDA DIRLEN              ; Copy direction (and length) of line
A788 856E     04267                 STA L.DIRSAV            ;
A78A 297F     04268                 AND #$7F                ; Strip direction bit
A78C 85A4     04269                 STA DIRLEN              ; Store length of line
              04270
A78E A4A5     04271 LOOP029         LDY PENROW              ; Loop over length of line to be drawn
A790 B90008   04272                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pen's pixel row...
A793 8568     04273                 STA MEMPTR              ; ...in PLAYFIELD memory
A795 B96408   04274                 LDA PFMEMROWHI,Y        ;
A798 8569     04275                 STA MEMPTR+1            ;
              04276
A79A A5A6     04277                 LDA PENCOLUMN           ; Calc and store pen's byte-within-row offset
A79C 4A       04278                 LSR A                   ;
A79D 4A       04279                 LSR A                   ;
A79E 856A     04280                 STA L.PIXELBYTEOFF      ;
              04281
A7A0 A5A6     04282                 LDA PENCOLUMN           ; Calc pixel-within-byte index
A7A2 2903     04283                 AND #$03                ;
A7A4 A8       04284                 TAY                     ;
              04285
A7A5 B9B0BA   04286                 LDA PIXELMASKTAB,Y      ; Pick mask to filter pixel in byte
A7A8 256B     04287                 AND L.BITPAT            ; ...AND with bit pattern for 4 pixels of same color
A7AA A46A     04288                 LDY L.PIXELBYTEOFF      ;
A7AC 1168     04289                 ORA (MEMPTR),Y          ; Blend byte with new pixel and PLAYFIELD byte
A7AE 9168     04290                 STA (MEMPTR),Y          ; ...and store it back in PLAYFIELD memory
              04291
A7B0 246E     04292                 BIT L.DIRSAV            ; Check direction bit B7
A7B2 1004     04293                 BPL SKIP050             ;
A7B4 E6A5     04294                 INC PENROW              ; If B7 = 1 -> Increment pen's pixel row number
A7B6 D002     04295                 BNE SKIP051             ;
A7B8 E6A6     04296 SKIP050         INC PENCOLUMN           ; If B7 = 0 -> Increment pen's pixel column number
              04297
A7BA C6A4     04298 SKIP051         DEC DIRLEN              ;
A7BC D0D0     04299                 BNE LOOP029             ; Next pixel of line
A7BE 60       04300                 RTS                     ; Return
              04301
              04302 ;*******************************************************************************
              04303 ;*                                                                             *
              04304 ;*                                 UPDATTCOMP                                  *
              04305 ;*                                                                             *
              04306 ;*                       Update Attack Computer Display                        *
              04307 ;*                                                                             *
              04308 ;*******************************************************************************
              04309
              04310 ; DESCRIPTION
              04311 ;
              04312 ; Draws the blip of the tracked space object and the lock-on markers into the
              04313 ; Attack Computer Display. The actual drawing follows a cycle of 11 game loop
              04314 ; iterations (numbered by this subroutine as "blip cycles" 0..10), which can be
              04315 ; divided into three phases:
              04316 ;
              04317 ; (1)  Blip cycle 0..4: Draw blip shape row-by-row
              04318 ;
              04319 ;      Draw the blip's shape into the Attack Computer Display, one row each blip
              04320 ;      cycle. After 5 blip cycles the blip shape is complete and completely
              04321 ;      visible because between blip cycles, that is, game loop iterations, the
              04322 ;      PLAYFIELD is not erased (only the PLAYFIELD space objects are). Drawing
              04323 ;      is executed by branching to entry DRAWLINE2 ($A784) of subroutine
              04324 ;      DRAWLINE ($A782). The blip shape is retrieved from table BLIPSHAPTAB
              04325 ;      ($BF6E).
              04326 ;
              04327 ; (2)  Blip cycle 5..9: Delay
              04328 ;
              04329 ;      Delay the execution of blip cycle 10.
              04330 ;
              04331 ; (3)  Blip cycle 10: Update Attack Computer Display
              04332 ;
              04333 ;      After verifying that the tracked space object is alive, calculate the
              04334 ;      blip's relative top-left pixel column and row number. Resulting values
              04335 ;      are in -11..11 and -6..4, relative to the blip's top-left reference
              04336 ;      position at pixel column number 131 and pixel row number 77,
              04337 ;      respectively.
              04338 ;
              04339 ;      Filter the Attack Computer Display area: Only pixels of COLOR1 within the
              04340 ;      inner frame area (a 28 pixel wide x 15 pixel high rectangle with its
              04341 ;      top-left corner at pixel column number 120 and pixel row number 71) pass
              04342 ;      the filter operation. This effectively erases the blip.
              04343 ;
              04344 ;      If the blip is within -2..+2 pixels off its horizontal reference position
              04345 ;      (pixel column numbers 129..132) then the tracked space object is in x
              04346 ;      lock-on. Draw the x lock-on marker.
              04347 ;
              04348 ;      If the tracked space object is in x lock-on and the blip is within -2..+1
              04349 ;      pixels off its vertical reference position (pixel column numbers 75..78)
              04350 ;      then the tracked space object is in x and y lock-on. Draw also the y
              04351 ;      lock-on marker.
              04352 ;
              04353 ;      If the tracked space object is in x and y lock-on and the tracked space
              04354 ;      object's z-coordinate < +3072 (+$0C**) <KM> then the tracked space object
              04355 ;      is in x, y and z lock-on. Draw also the z lock-on marker.
              04356 ;
              04357 ;      If the tracked space object is in x, y, and z lock-on (and thus in
              04358 ;      optimal firing range) set the ISINLOCKON ($A3) flag.
              04359 ;
              04360 ;      The following sketches show the Attack Computer Display area overlaid
              04361 ;      with the Attack Computer Display frame:
              04362 ;
              04363 ;          119                                 119
              04364 ;      70 ##############################    70 ##############################
              04365 ;         #         ....#....          #       #             #              #
              04366 ;         #         ....#....          #       #             #              #
              04367 ;         #         ....#....          #       #             #              #
              04368 ;         #         ....#....          #       #             #              #
              04369 ;         #      ###############       #       #......###############.......#
              04370 ;         #XXXX  #  .........  #   XXXX#       #......#.............#.......#
              04371 ;         #      #  ..$......  #       #       #......#....$........#.......#
              04372 ;         ########  .........  #########       ########.............#########
              04373 ;         #      #  .........  #       #       #......#.............#.......#
              04374 ;         #      #  .........  #       #       #YYYY..#.............#...YYYY#
              04375 ;         #      ###############       #       #......###############.......#
              04376 ;         #         ....#....          #       #.............#..............#
              04377 ;         #         ....#....          #       #             #              #
              04378 ;         #         ....#....          #       #             #              #
              04379 ;         #         ....#....          #       #             #              #
              04380 ;         ##############################       ##############################
              04381 ;
              04382 ;         X = x lock-on marker                 Y = y lock-on marker
              04383 ;         . = x lock-on blip zone              . = y lock-on blip zone
              04384 ;         $ = Blip's top-left reference        $ = Blip's top-left reference
              04385 ;             position                             position
              04386 ;
              04387 ;         119
              04388 ;      70 ##############################
              04389 ;         #             #              #
              04390 ;         #             #              #
              04391 ;         #             #              #
              04392 ;         #             #              #
              04393 ;         #      ###############       #
              04394 ;         #      #             #       #
              04395 ;         #      #    $        #       #
              04396 ;         ########             #########
              04397 ;         #      #             #       #
              04398 ;         #      #             #       #
              04399 ;         #      ###############       #
              04400 ;         #             #              #
              04401 ;         #             #              #
              04402 ;         #        ZZ   #  ZZ          #
              04403 ;         #        ZZ   #  ZZ          #
              04404 ;         ##############################
              04405 ;
              04406 ;         Z = z lock-on marker
              04407 ;         $ = Blip's top-left reference
              04408 ;             position
              04409
    =006C     04410 L.SHIFTSHAPE    = $6C                   ; Saves shifted byte of blip shape bit pattern
              04411
A7BF AE5C09   04412 UPDATTCOMP      LDX TRACKDIGIT          ; Load index of tracked space object
A7C2 A4A2     04413                 LDY BLIPCYCLECNT        ; Load blip cycle counter
A7C4 C005     04414                 CPY #5                  ;
A7C6 B024     04415                 BCS SKIP054             ; Skip drawing blip if blip cycle > 5
              04416
              04417 ;*** Blip cycle 0..4: Draw blip shape one row each cycle ***********************
A7C8 A5A0     04418                 LDA BLIPCOLUMN          ; Init pen's pixel column number...
A7CA 85A6     04419                 STA PENCOLUMN           ; ...with top position of blip shape
A7CC B96EBF   04420                 LDA BLIPSHAPTAB,Y       ; Load bit pattern of one row of blip shape
A7CF 0A       04421 LOOP030         ASL A                   ; Shift bit pattern one position to the left
A7D0 856C     04422                 STA L.SHIFTSHAPE        ; Temporarily save shifted shape byte
A7D2 900D     04423                 BCC SKIP052             ; Skip if shifted-out bit = 0
              04424
A7D4 A981     04425                 LDA #$81                ; Store "draw a line of 1 pixel length downward"
A7D6 85A4     04426                 STA DIRLEN              ; ...for call to DRAWLINE2
              04427
A7D8 A5A1     04428                 LDA BLIPROW             ; Init pen's pixel row number...
A7DA 85A5     04429                 STA PENROW              ; ...with leftmost position of blip shape
A7DC A9AA     04430                 LDA #$AA                ; Load 1-byte bit pattern for 4 pixels of COLOR2
A7DE 2084A7   04431                 JSR DRAWLINE2           ; Draw pixel on PLAYFIELD
              04432
A7E1 E6A6     04433 SKIP052         INC PENCOLUMN           ; Move pen one pixel to the right
A7E3 A56C     04434                 LDA L.SHIFTSHAPE        ; Reload shifted shape byte
A7E5 D0E8     04435                 BNE LOOP030             ; Next horizontal pixel of blip shape
              04436
A7E7 E6A1     04437                 INC BLIPROW             ; Move pen one pixel downward
A7E9 E6A2     04438 SKIP053         INC BLIPCYCLECNT        ; Increment blip cycle counter
A7EB 60       04439                 RTS                     ; Return
              04440
              04441 ;*** Blip cycle 5..9: Delay ****************************************************
A7EC C00A     04442 SKIP054         CPY #10                 ; Return if blip cycle < 10
A7EE 90F9     04443                 BCC SKIP053             ;
              04444
              04445 ;*** Blip cycle 10: Calculate new blip pixel row and column numbers ************
A7F0 B5E9     04446                 LDA PL0LIFE,X           ; Skip if tracked object not alive
A7F2 F03C     04447                 BEQ SKIP059             ;
              04448
A7F4 BD710A   04449                 LDA XPOSHI,X            ; Map x-coordinate of tracked space obj to -11..11:
A7F7 BCDE09   04450                 LDY XPOSSIGN,X          ; Skip if tracked object on left screen half (x >= 0)
A7FA F008     04451                 BEQ SKIP055             ;
              04452
A7FC C90C     04453                 CMP #12                 ; Skip if x of tracked obj < +$0C** (< 3327) <KM>
A7FE 900A     04454                 BCC SKIP056             ;
A800 A90B     04455                 LDA #11                 ; Prep relative pixel column number of 11, skip
A802 1006     04456                 BPL SKIP056             ;
              04457
A804 C9F5     04458 SKIP055         CMP #-11                ; Skip if x of tracked obj >= -($0B**) (>=-2816) <KM>
A806 B002     04459                 BCS SKIP056             ;
A808 A9F5     04460                 LDA #-11                ; Prep relative pixel column number of -11
              04461
A80A 18       04462 SKIP056         CLC                     ; Add 131 (= blip's top-left reference pixel column)
A80B 6983     04463                 ADC #131                ;
A80D 85A0     04464                 STA BLIPCOLUMN          ; BLIPCOLUMN := 131 + -11..11
              04465
A80F BDA20A   04466                 LDA YPOSHI,X            ; Map y-coordinate of tracked space obj to -6..4:
A812 49FF     04467                 EOR #$FF                ; Mirror y-coordinate on y-axis (displacement of +1)
A814 BC0F0A   04468                 LDY YPOSSIGN,X          ; Skip if tracked obj on lower screen half (y < 0)
A817 D008     04469                 BNE SKIP057             ;
              04470
A819 C905     04471                 CMP #5                  ; Skip if mirrored y of tracked obj < +$05** <KM>
A81B 900A     04472                 BCC SKIP058             ;
A81D A904     04473                 LDA #4                  ; Prep relative pixel row number of 4, skip
A81F 1006     04474                 BPL SKIP058             ;
              04475
A821 C9FA     04476 SKIP057         CMP #-6                 ; Skip if mirrored y of tracked obj >= -($06**) <KM>
A823 B002     04477                 BCS SKIP058             ;
A825 A9FA     04478                 LDA #-6                 ; Prep relative pixel row number of -6
              04479
A827 18       04480 SKIP058         CLC                     ; Add 77 (= blip's top-left ref. pixel row number)
A828 694D     04481                 ADC #77                 ;
A82A 85A1     04482                 STA BLIPROW             ; BLIPROW := 77 + -6..4
              04483
A82C A900     04484                 LDA #0                  ; Reset blip cycle
A82E 85A2     04485                 STA BLIPCYCLECNT        ;
              04486
              04487 ;*** Filter Attack Computer Display frame area *********************************
              04488                                         ; PLAYFIELD address of top-left of Attack Computer
    =1B36     04489 PFMEM.C120R71   = PFMEM+71*40+120/4     ; Display's inner frame @ pixel column 120, row 71
              04490
A830 A936     04491 SKIP059         LDA #<PFMEM.C120R71     ; Point MEMPTR to start of frame's...
A832 8568     04492                 STA MEMPTR              ; ...inner top-left corner at column 120, row 71...
A834 A91B     04493                 LDA #>PFMEM.C120R71     ; ...in PLAYFIELD memory
A836 8569     04494                 STA MEMPTR+1            ;
              04495
A838 A20E     04496                 LDX #14                 ; Traverse a 28 x 15 pixel rect of PLAYFIELD memory
A83A A006     04497 LOOP031         LDY #6                  ;
A83C B168     04498 LOOP032         LDA (MEMPTR),Y          ; Load byte (4 pixels) from PLAYFIELD memory
A83E 2955     04499                 AND #$55                ; Filter COLOR1 pixels
A840 9168     04500                 STA (MEMPTR),Y          ; Store byte (4 pixels) back to PLAYFIELD memory
A842 88       04501                 DEY                     ;
A843 10F7     04502                 BPL LOOP032             ; Next 4 pixels in x-direction
              04503
A845 18       04504                 CLC                     ; Add 40 to MEMPTR
A846 A568     04505                 LDA MEMPTR              ; (40 bytes = 160 pixels = 1 PLAYFIELD row of pixels)
A848 6928     04506                 ADC #40                 ;
A84A 8568     04507                 STA MEMPTR              ;
A84C 9002     04508                 BCC SKIP060             ;
A84E E669     04509                 INC MEMPTR+1            ;
              04510
A850 CA       04511 SKIP060         DEX                     ;
A851 10E7     04512                 BPL LOOP031             ; Next row of pixels in y-direction
              04513
              04514 ;*** Prepare lock-on marker checks *********************************************
A853 AE5C09   04515                 LDX TRACKDIGIT          ; Preload index of tracked space obj to check z-range
A856 C8       04516                 INY                     ; Y := 0, preloaded value of ISINLOCKON
              04517
              04518 ;*** Draw lock-on markers ******************************************************
              04519                                         ; PLAYFIELD addresses of
    =1BFE     04520 PFMEM.C120R76   = PFMEM+76*40+120/4     ; ...x lock-on marker @ pixel column 120, row 76
    =1C04     04521 PFMEM.C144R76   = PFMEM+76*40+144/4     ; ...x lock-on marker @ pixel column 144, row 76
    =1C9E     04522 PFMEM.C120R80   = PFMEM+80*40+120/4     ; ...y lock-on marker @ pixel column 120, row 80
    =1CA4     04523 PFMEM.C144R80   = PFMEM+80*40+144/4     ; ...y lock-on marker @ pixel column 144, row 80
    =1D40     04524 PFMEM.C128R84   = PFMEM+84*40+128/4     ; ...z lock-on marker @ pixel column 128, row 84
    =1D68     04525 PFMEM.C128R85   = PFMEM+85*40+128/4     ; ...z lock-on marker @ pixel column 128, row 85
    =1D42     04526 PFMEM.C136R84   = PFMEM+84*40+136/4     ; ...z lock-on marker @ pixel column 136, row 84
    =1D6A     04527 PFMEM.C136R85   = PFMEM+85*40+136/4     ; ...z lock-on marker @ pixel column 136, row 85
              04528
A857 A588     04529                 LDA LOCKONLIFE          ; If lock-on lifetime expired redraw lock-on markers
A859 F004     04530                 BEQ SKIP061             ;
              04531
A85B C688     04532                 DEC LOCKONLIFE          ; else decr lock-on lifetime, skip drawing markers
A85D D039     04533                 BNE SKIP062             ;
              04534
A85F A5A0     04535 SKIP061         LDA BLIPCOLUMN          ; Skip x, y, and z lock-on marker if blip's...
A861 C981     04536                 CMP #129                ; ...top-left pixel column number not in 129..132
A863 9033     04537                 BCC SKIP062             ;
A865 C985     04538                 CMP #133                ;
A867 B02F     04539                 BCS SKIP062             ;
              04540
A869 A9AA     04541                 LDA #$AA                ; Draw x lock-on marker (4 horiz. pixels of COLOR2)
A86B 8DFE1B   04542                 STA PFMEM.C120R76       ; ...at pixel column 120, row 76
A86E 8D041C   04543                 STA PFMEM.C144R76       ; ...at pixel column 144, row 76
              04544
A871 A5A1     04545                 LDA BLIPROW             ; Skip y and z lock-on marker if blip's...
A873 C94B     04546                 CMP #75                 ; ...top-left pixel row number not in 75...78
A875 9021     04547                 BCC SKIP062             ;
A877 C94F     04548                 CMP #79                 ;
A879 B01D     04549                 BCS SKIP062             ;
              04550
A87B A9AA     04551                 LDA #$AA                ; Draw y lock-on marker (4 horiz. pixels of COLOR2)
A87D 8D9E1C   04552                 STA PFMEM.C120R80       ; ...at pixel column 120, row 80
A880 8DA41C   04553                 STA PFMEM.C144R80       ; ...at pixel column 144, row 80
              04554
A883 BD400A   04555                 LDA ZPOSHI,X            ; Skip z lock-on marker if z >= +$0C** (>= 3072) <KM>
A886 C90C     04556                 CMP #12                 ;
A888 B00E     04557                 BCS SKIP062             ;
              04558
A88A A0A0     04559                 LDY #$A0                ; Draw z lock-on marker (2 horiz. pixels of COLOR2)
A88C 8C401D   04560                 STY PFMEM.C128R84       ; ...at pixel column 128, row 84 (prep lock-on flag)
A88F 8C681D   04561                 STY PFMEM.C128R85       ; ...at pixel column 128, row 85
A892 8C421D   04562                 STY PFMEM.C136R84       ; ...at pixel column 136, row 84
A895 8C6A1D   04563                 STY PFMEM.C136R85       ; ...at pixel column 136, row 85
              04564
A898 84A3     04565 SKIP062         STY ISINLOCKON          ; Store lock-on flag (> 0 -> Tracked obj locked on)
A89A 60       04566                 RTS                     ; Return
              04567
              04568 ;*******************************************************************************
              04569 ;*                                                                             *
              04570 ;*                                  HYPERWARP                                  *
              04571 ;*                                                                             *
              04572 ;*                              Handle hyperwarp                               *
              04573 ;*                                                                             *
              04574 ;*******************************************************************************
              04575
              04576 ; DESCRIPTION
              04577 ;
              04578 ; Handles the hyperwarp sequence, which transports our starship from one sector
              04579 ; to another. It can be divided into four phases:
              04580 ;
              04581 ; (1)  ACCELERATION PHASE
              04582 ;
              04583 ;      The ACCELERATION PHASE is entered after the hyperwarp sequence has been
              04584 ;      engaged in subroutine KEYBOARD ($AFFE) by pressing the 'H' key. The
              04585 ;      Hyperwarp Target Marker appears and our starship begins to accelerate.
              04586 ;      When our starship's velocity reaches 128 <KM/H> (the VELOCITY readout of
              04587 ;      the Control Panel Display displays "50"), the STAR TRAIL phase is
              04588 ;      entered.
              04589 ;
              04590 ;      The Hyperwarp Target Marker is represented by a space object some fixed
              04591 ;      distance away in front of our starship as PLAYER3. It has a lifetime of
              04592 ;      144 game loop iterations and is tracked. Thus, tracking handling in
              04593 ;      subroutine UPDATTCOMP ($A7BF) provides drawing the x and y lock-on
              04594 ;      markers in the Attack Computer Display when the Hyperwarp Target Marker
              04595 ;      is centered.
              04596 ;
              04597 ;      A temporary arrival location on the Galactic Chart was saved when the
              04598 ;      hyperwarp was engaged in subroutine KEYBOARD ($AFFE). During the
              04599 ;      ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE) this location is
              04600 ;      constantly updated depending on how much the Hyperwarp Target Marker
              04601 ;      veers off its center position.
              04602 ;
              04603 ;      The actual arrival hyperwarp marker row and column numbers on the
              04604 ;      Galactic Chart are the sum of the temporary arrival hyperwarp marker row
              04605 ;      and column numbers stored when engaging the hyperwarp in subroutine
              04606 ;      KEYBOARD ($AFFE) and the number of Player/Missile (PM) pixels which the
              04607 ;      Hyperwarp Target Marker is off-center vertically and horizontally,
              04608 ;      respectively, at the end of the STAR TRAIL PHASE.
              04609 ;
              04610 ;      NOTE: The used vertical center value of 119 PM pixels is the PM pixel row
              04611 ;      number of the top edge of the centered Hyperwarp Target Marker (from top
              04612 ;      to bottom: 8 PM pixels to the start of Display List + 16 PM pixels blank
              04613 ;      lines + 100 PM pixels to the vertical PLAYFIELD center - 5 PM pixels
              04614 ;      relative offset of the Hyperwarp Target Marker's shape center to the
              04615 ;      shape's top edge = 119 PM pixels). Recall also that PLAYERs at
              04616 ;      single-line resolution have PM pixels that are half as high as they are
              04617 ;      wide.
              04618 ;
              04619 ;      NOTE: The used horizontal center value of 125 PM pixels is the PM pixel
              04620 ;      row number of the left edge of the centered Hyperwarp Target Marker (from
              04621 ;      left to right: 127 PM pixels to the PLAYFIELD center - 3 PM pixels
              04622 ;      relative offset of the Hyperwarp Target Marker's shape center to the
              04623 ;      shape's left edge = 125 PM pixels).
              04624 ;
              04625 ;      If during the ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE)
              04626 ;      you switch the Front view to another view, the Hyperwarp Target Marker
              04627 ;      changes to a random position which results in arriving at a random
              04628 ;      destination sector.
              04629 ;
              04630 ;      During the ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE) in
              04631 ;      all but NOVICE missions, the Hyperwarp Target Marker veers off with
              04632 ;      random velocity in x and y direction, which is changed during 6% of game
              04633 ;      loop iterations. Table VEERMASKTAB ($BED7) limits the maximum veer-off
              04634 ;      velocity depending on the mission level:
              04635 ;
              04636 ;      +-----------+-----------------------------+
              04637 ;      |  Mission  |      Veer-Off Velocity      |
              04638 ;      +-----------+-----------------------------+
              04639 ;      | NOVICE    |                   0  <KM/H> |
              04640 ;      | PILOT     |  -63..-16, +16..+63  <KM/H> |
              04641 ;      | WARRIOR   |  -95..-16, +16..+95  <KM/H> |
              04642 ;      | COMMANDER | -127..-16, +16..+127 <KM/H> |
              04643 ;      +-----------+-----------------------------+
              04644 ;
              04645 ; (2)  STAR TRAIL PHASE
              04646 ;
              04647 ;      When our starship's velocity reaches a velocity of 128 <KM/H> (the
              04648 ;      VELOCITY readout of the Control Panel Display displays "50"), in addition
              04649 ;      to all effects of the ACCELERATION PHASE, multiple star trails begin to
              04650 ;      appear while our starship continues to accelerate. Each star trail is
              04651 ;      initialized in subroutine INITTRAIL ($A9B4).
              04652 ;
              04653 ; (3)  HYPERSPACE PHASE
              04654 ;
              04655 ;      When our starship's velocity reaches a velocity of 254 <KM/H> (the
              04656 ;      VELOCITY readout of the Control Panel Display displays "99") our starship
              04657 ;      enters the HYPERSPACE PHASE (the VELOCITY readout of the Control Panel
              04658 ;      Display displays the infinity symbol).
              04659 ;
              04660 ;      During the first pass of the HYPERSPACE PHASE the hyperwarp state is set
              04661 ;      to HYPERSPACE. This makes the stars and the Hyperwarp Target Marker
              04662 ;      disappear in GAMELOOP ($A1F3). Then, the beeper sound pattern HYPERWARP
              04663 ;      TRANSIT is played in subroutine BEEP ($B3A6), the hyperwarp distance and
              04664 ;      required hyperwarp energy is calculated in subroutine CALCWARP ($B1A7),
              04665 ;      and the title line is preloaded with "HYPERSPACE". Code execution returns
              04666 ;      via calling subroutine CLEANUPWARP ($A98D) where program variables are
              04667 ;      already initialized to their post-hyperwarp values.
              04668 ;
              04669 ;      During subsequent passes of the HYPERSPACE PHASE, the calculated
              04670 ;      hyperwarp energy is decremented in chunks of 10 energy units. Code
              04671 ;      execution returns via calling subroutine DECENERGY ($B86F), which
              04672 ;      decrements our starship's energy. After the calculated hyperwarp energy
              04673 ;      is spent the DECELERATION PHASE is entered.
              04674 ;
              04675 ; (4)  DECELERATION PHASE
              04676 ;
              04677 ;      The title line flashes "HYPERWARP COMPLETE", the star field reappears and
              04678 ;      our starship decelerates to a stop. The Engines and the hyperwarp are
              04679 ;      disengaged and stopped in subroutine ENDWARP ($A987), the arrival
              04680 ;      coordinates on the Galactic Chart are initialized, as well as the
              04681 ;      vicinity mask.
              04682 ;
              04683 ;      The vicinity mask limits the position vector components (coordinates) of
              04684 ;      space objects in the arrival sector relative to our starship. The
              04685 ;      vicinity mask is picked from table VICINITYMASKTAB ($BFB3) by an index
              04686 ;      calculated by the arrival y-coordinate modulo 8: The more you have placed
              04687 ;      the arrival hyperwarp marker in the vertical center of a sector on the
              04688 ;      Galactic Chart, the closer space objects in this sector will be to our
              04689 ;      starship. For example, if you placed the arrival hyperwarp marker exactly
              04690 ;      in the vertical middle of the sector the index will be 3, thus the space
              04691 ;      objects inside the arrival sector will be in the vicinity of <= 4095 <KM>
              04692 ;      of our starship. The following table lists the possible coordinates
              04693 ;      depending on the calculated index:
              04694 ;
              04695 ;      +-------+-----------------------+
              04696 ;      | Index |    ABS(Coordinate)    |
              04697 ;      +-------+-----------------------+
              04698 ;      |   0   | <= 65535 ($FF**) <KM> |
              04699 ;      |   1   | <= 65535 ($FF**) <KM> |
              04700 ;      |   2   | <= 16383 ($3F**) <KM> |
              04701 ;      |   3   | <=  4095 ($0F**) <KM> |
              04702 ;      |   4   | <= 16383 ($3F**) <KM> |
              04703 ;      |   5   | <= 32767 ($7F**) <KM> |
              04704 ;      |   6   | <= 65535 ($FF**) <KM> |
              04705 ;      |   7   | <= 65535 ($FF**) <KM> |
              04706 ;      +-------+-----------------------+
              04707 ;
              04708 ;      If there is a starbase in the arrival sector, its x and y coordinates are
              04709 ;      initialized to random values within the interval defined by the vicinity
              04710 ;      mask by using subroutine RNDINVXY ($B7BE). Its z-coordinate is forced to
              04711 ;      a value >= +$71** (+28928) <KM>. Its velocity vector components are set
              04712 ;      to 0 <KM/H>.
              04713 ;
              04714 ;      If there are Zylon ships in the arrival sector then a red alert is
              04715 ;      initialized by setting the red alert lifetime to 255 game loop
              04716 ;      iterations, playing the beeper sound pattern RED ALERT in subroutine BEEP
              04717 ;      ($B3A6) and setting the title phrase to "RED ALERT".
              04718
A89B A4C0     04719 HYPERWARP       LDY WARPSTATE           ; Return if hyperwarp not engaged
A89D F061     04720                 BEQ SKIP066             ;
              04721
A89F A570     04722                 LDA VELOCITYLO          ; If velocity >= 254 <KM/H> skip to HYPERSPACE PHASE
A8A1 C9FE     04723                 CMP #254                ;
A8A3 B05C     04724                 BCS SKIP067             ;
              04725
A8A5 C980     04726                 CMP #128                ; If velocity < 128 <KM/H> skip to ACCELERATION PHASE
A8A7 9003     04727                 BCC SKIP063             ;
              04728
              04729 ;*** STAR TRAIL PHASE **********************************************************
A8A9 20B4A9   04730                 JSR INITTRAIL           ; Init star trail
              04731
              04732 ;*** ACCELERATION PHASE ********************************************************
A8AC A903     04733 SKIP063         LDA #3                  ; Track Hyperwarp Target Marker (PLAYER3)
A8AE 8D5C09   04734                 STA TRACKDIGIT          ;
              04735
A8B1 A990     04736                 LDA #SHAP.HYPERWARP     ; PLAYER3 is HYPERWARP TARGET MARKER (shape type 9)
A8B3 8D8F0C   04737                 STA PL3SHAPTYPE         ;
A8B6 85EC     04738                 STA PL3LIFE             ; PLAYER3 lifetime := 144 game loops
              04739
A8B8 A91F     04740                 LDA #$1F                ; PLAYER3 z-coordinate := $1F** (7936..8191) <KM>
A8BA 8D430A   04741                 STA PL3ZPOSHI           ;
              04742
A8BD 38       04743                 SEC                     ; New arrival hyperwarp marker row number is...
A8BE ADFC0B   04744                 LDA PL3ROWNEW           ; WARPARRVROW := WARPTEMPROW + PL3ROWNEW...
A8C1 E977     04745                 SBC #119                ; ... - 119 PM pixels (top edge of centered...
A8C3 18       04746                 CLC                     ; ...Hyperwarp Target Marker)
A8C4 65C5     04747                 ADC WARPTEMPROW         ;
A8C6 297F     04748                 AND #$7F                ; Limit WARPARRVROW to 0..127
A8C8 858E     04749                 STA WARPARRVROW         ;
              04750
A8CA 38       04751                 SEC                     ; New arrival hyperwarp marker column number is...
A8CB AD2D0C   04752                 LDA PL3COLUMN           ; WARPARRVCOLUMN := WARPTEMPCOLUMN + PL3COLUMN...
A8CE E97D     04753                 SBC #125                ; ... - 125 PM pixels (left edge of centered...
A8D0 18       04754                 CLC                     ; ...Hyperwarp Target Marker)
A8D1 65C4     04755                 ADC WARPTEMPCOLUMN      ;
A8D3 297F     04756                 AND #$7F                ; Limit WARPARRVCOLUMN to 0..127
A8D5 858F     04757                 STA WARPARRVCOLUMN      ;
              04758
A8D7 A562     04759                 LDA MISSIONLEVEL        ; Skip if NOVICE mission
A8D9 F011     04760                 BEQ SKIP065             ;
              04761
A8DB AD0AD2   04762                 LDA RANDOM              ; Prep random number
A8DE A4D0     04763                 LDY SHIPVIEW            ; Skip if in Front view
A8E0 F006     04764                 BEQ SKIP064             ;
              04765
A8E2 8D2D0C   04766                 STA PL3COLUMN           ; Randomize PM pixel row and column number...
A8E5 8DFC0B   04767                 STA PL3ROWNEW           ; ...of Hyperwarp Target Marker
              04768
A8E8 C910     04769 SKIP064         CMP #16                 ; Return in 94% (240:256) of game loops
A8EA B014     04770                 BCS SKIP066             ;
              04771
              04772 ;*** Veer off Hyperwarp Target Marker and return *******************************
A8EC AD0AD2   04773 SKIP065         LDA RANDOM              ; Prep random x-velocity of Hyperwarp Target Marker
A8EF 0910     04774                 ORA #$10                ; Velocity value >= 16 <KM/H>
A8F1 25C6     04775                 AND VEERMASK            ; Limit velocity value by mission level
A8F3 8D9A0B   04776                 STA PL3XVEL             ; PLAYER3 x-velocity := velocity value
              04777
A8F6 AD0AD2   04778                 LDA RANDOM              ; Prep random y-velocity of Hyperwarp Target Marker
A8F9 0910     04779                 ORA #$10                ; Velocity value >= 16 <KM/H>
A8FB 25C6     04780                 AND VEERMASK            ; Limit velocity value by mission level
A8FD 8DCB0B   04781                 STA PL3YVEL             ; PLAYER3 y-velocity := velocity value
A900 60       04782 SKIP066         RTS                     ; Return
              04783
              04784 ;*** HYPERSPACE PHASE **********************************************************
A901 98       04785 SKIP067         TYA                     ; Skip if already in HYPERSPACE PHASE
A902 3011     04786                 BMI SKIP068             ;
              04787
              04788 ;*** HYPERSPACE PHASE (First pass) *********************************************
A904 A9FF     04789                 LDA #$FF                ; Set hyperwarp state to HYPERSPACE PHASE
A906 85C0     04790                 STA WARPSTATE           ;
              04791
A908 A200     04792                 LDX #$00                ; Play beeper sound pattern HYPERWARP TRANSIT
A90A 20A6B3   04793                 JSR BEEP                ;
              04794
A90D 20A7B1   04795                 JSR CALCWARP            ; Calc hyperwarp energy
              04796
A910 A01B     04797                 LDY #$1B                ; Prep title phrase "HYPERSPACE"
A912 4C8DA9   04798                 JMP CLEANUPWARP         ; Return via CLEANUPWARP
              04799
              04800 ;*** HYPERSPACE PHASE (Second and later passes) ********************************
A915 C691     04801 SKIP068         DEC WARPENERGY          ; Decrement energy in chunks of 10 energy units
A917 F005     04802                 BEQ SKIP069             ; Skip to DECELERATION PHASE if hyperwarp energy zero
              04803
A919 A202     04804                 LDX #2                  ; ENERGY := ENERGY - 10 and return
A91B 4C6FB8   04805                 JMP DECENERGY           ;
              04806
              04807 ;*** DECELERATION PHASE ********************************************************
A91E A019     04808 SKIP069         LDY #$19                ; Prep title phrase "HYPERWARP COMPLETE"
A920 2087A9   04809                 JSR ENDWARP             ; Stop our starship
              04810
A923 A58F     04811                 LDA WARPARRVCOLUMN      ; Make the arrival hyperwarp marker column number...
A925 858D     04812                 STA WARPDEPRCOLUMN      ; ...the departure hyperwarp marker column number
A927 A58E     04813                 LDA WARPARRVROW         ; Make the arrival hyperwarp marker row number...
A929 858C     04814                 STA WARPDEPRROW         ; ...the departure hyperwarp marker row number
              04815
A92B 4A       04816                 LSR A                   ; B3..1 of arrival hyperwarp marker row number...
A92C 2907     04817                 AND #$07                ; ...pick vicinity mask
A92E AA       04818                 TAX                     ;
A92F BDB3BF   04819                 LDA VICINITYMASKTAB,X   ;
A932 85C7     04820                 STA VICINITYMASK        ; Store vicinity mask (limits space obj coordinates)
              04821
A934 A492     04822                 LDY ARRVSECTOR          ; Make the arrival sector the current sector
A936 8490     04823                 STY CURRSECTOR          ;
              04824
              04825 ;*** Init starbase in arrival sector *******************************************
A938 A900     04826                 LDA #0                  ; Clear starbase-in-sector flag
A93A 857B     04827                 STA ISSTARBASESECT      ;
              04828
A93C BEC908   04829                 LDX GCMEMMAP,Y          ; Skip if no starbase in arrival sector
A93F 102E     04830                 BPL SKIP070             ;
              04831
A941 A9FF     04832                 LDA #$FF                ; Set starbase-in-sector flag
A943 857B     04833                 STA ISSTARBASESECT      ;
              04834
              04835 ;*** Set position vector and velocity vector of starbase ***********************
A945 A000     04836                 LDY #0                  ;
A947 A900     04837 LOOP033         LDA #0                  ; Loop over all coordinates of starbase
A949 99680B   04838                 STA PL2ZVEL,Y           ; Starbase velocity vector component := 0 <KM/H>
A94C A901     04839                 LDA #1                  ;
A94E 99AF09   04840                 STA PL2ZPOSSIGN,Y       ; Starbase coordinate sign := + (positive)
A951 AD0AD2   04841                 LDA RANDOM              ; Prep random number...
A954 25C7     04842                 AND VICINITYMASK        ; ...limit number range by vicinity mask, then...
A956 99420A   04843                 STA PL2ZPOSHI,Y         ; ...store in starbase coordinate (high byte)
              04844
A959 98       04845                 TYA                     ;
A95A 18       04846                 CLC                     ;
A95B 6931     04847                 ADC #NUMSPCOBJ.ALL      ;
A95D A8       04848                 TAY                     ;
A95E C993     04849                 CMP #NUMSPCOBJ.ALL*3    ;
A960 90E5     04850                 BCC LOOP033             ; Next starbase coordinate
              04851
A962 AD420A   04852                 LDA PL2ZPOSHI           ; Force starbase z-coordinate >= +$71** <KM>
A965 0971     04853                 ORA #$71                ;
A967 8D420A   04854                 STA PL2ZPOSHI           ;
A96A A202     04855                 LDX #2                  ; Randomly invert starbase x and y coordinates...
A96C 4CBEB7   04856                 JMP RNDINVXY            ; ...and return
              04857
              04858 ;*** Flash red alert if Zylon sector entered ***********************************
A96F F00E     04859 SKIP070         BEQ SKIP071             ; Skip if no Zylon ships in sector
              04860
A971 A9FF     04861                 LDA #255                ; Red alert lifetime := 255 game loops
A973 858B     04862                 STA REDALERTLIFE        ;
              04863
A975 A206     04864                 LDX #$06                ; Play beeper sound pattern RED ALERT
A977 20A6B3   04865                 JSR BEEP                ;
              04866
A97A A075     04867                 LDY #$75                ; Set title phrase "RED ALERT"
A97C 2023B2   04868                 JSR SETTITLE            ;
              04869
A97F 60       04870 SKIP071         RTS                     ; Return
              04871
              04872 ;*******************************************************************************
              04873 ;*                                                                             *
              04874 ;*                                  ABORTWARP                                  *
              04875 ;*                                                                             *
              04876 ;*                               Abort hyperwarp                               *
              04877 ;*                                                                             *
              04878 ;*******************************************************************************
              04879
              04880 ; DESCRIPTION
              04881 ;
              04882 ; Aborts hyperwarp.
              04883 ;
              04884 ; This subroutine is entered from subroutine KEYBOARD ($AFFE). It subtracts 100
              04885 ; energy units for aborting the hyperwarp and preloads the title phrase with
              04886 ; "HYPERWARP ABORTED". Code execution continues into subroutine ENDWARP
              04887 ; ($A987).
              04888
A980 A201     04889 ABORTWARP       LDX #1                  ; ENERGY := ENERGY - 100 after hyperwarp abort
A982 206FB8   04890                 JSR DECENERGY           ;
              04891
A985 A017     04892                 LDY #$17                ; Prep title phrase "HYPERWARP ABORTED"
              04893
              04894 ;*******************************************************************************
              04895 ;*                                                                             *
              04896 ;*                                   ENDWARP                                   *
              04897 ;*                                                                             *
              04898 ;*                                End hyperwarp                                *
              04899 ;*                                                                             *
              04900 ;*******************************************************************************
              04901
              04902 ; DESCRIPTION
              04903 ;
              04904 ; Ends hyperwarp.
              04905 ;
              04906 ; This subroutine stops our starship's Engines and resets the hyperwarp state.
              04907 ; Code execution continues into subroutine CLEANUPWARP ($A98D).
              04908
A987 A900     04909 ENDWARP         LDA #0                  ; Stop Engines
A989 8571     04910                 STA NEWVELOCITY         ;
A98B 85C0     04911                 STA WARPSTATE           ; Disengage hyperwarp
              04912
              04913 ;*******************************************************************************
              04914 ;*                                                                             *
              04915 ;*                                 CLEANUPWARP                                 *
              04916 ;*                                                                             *
              04917 ;*                        Clean up hyperwarp variables                         *
              04918 ;*                                                                             *
              04919 ;*******************************************************************************
              04920
              04921 ; DESCRIPTION
              04922 ;
              04923 ; Cleans up after a hyperwarp.
              04924 ;
              04925 ; This subroutine restores many hyperwarp related variables to their
              04926 ; post-hyperwarp values: The number of used space objects is set to the regular
              04927 ; value of 16 (5 PLAYER space objects + 12 PLAYFIELD space objects (stars)), our
              04928 ; starship's velocity (high byte) is cleared as well as the explosion lifetime,
              04929 ; the hit badness, the PLAYER3 shape type (Hyperwarp Target Marker), the Engines
              04930 ; energy drain rate, and the lifetimes of the PLAYERs. The docking state is
              04931 ; reset as well as the tracking digit. The title phrase is updated with either
              04932 ; "HYPERSPACE" or "HYPERWARP ABORTED".
              04933 ;
              04934 ; INPUT
              04935 ;
              04936 ;   Y = Title phrase offset. Used values are:
              04937 ;     $17 -> "HYPERWARP ABORTED"
              04938 ;     $1B -> "HYPERSPACE"
              04939
A98D A910     04940 CLEANUPWARP     LDA #NUMSPCOBJ.NORM-1   ; Set normal number of space objects
A98F 8579     04941                 STA MAXSPCOBJIND        ; (5 PLAYER spc objs + 12 PLAYFIELD spc objs (stars))
              04942
A991 A900     04943                 LDA #0                  ;
A993 85C1     04944                 STA VELOCITYHI          ; Turn off hyperwarp velocity
A995 8573     04945                 STA EXPLLIFE            ; Explosion lifetime := 0 game loops
A997 858A     04946                 STA HITBADNESS          ; HITBADNESS := NO HIT
A999 8D8F0C   04947                 STA PL3SHAPTYPE         ; Clear PLAYER3 shape type
A99C 8580     04948                 STA DRAINENGINES        ; Clear Engines energy drain rate
A99E C017     04949                 CPY #$17                ; Skip if hyperwarp was aborted
A9A0 F004     04950                 BEQ SKIP072             ;
              04951
A9A2 85E9     04952                 STA PL0LIFE             ; Zylon ship 0 lifetime := 0 game loops
A9A4 85EA     04953                 STA PL1LIFE             ; Zylon ship 1 lifetime := 0 game loops
              04954
A9A6 85EB     04955 SKIP072         STA PL2LIFE             ; Zylon photon torpedo lifetime := 0 game loops
A9A8 85EC     04956                 STA PL3LIFE             ; Hyperwarp Target Marker lifetime := 0 game loops
A9AA 85ED     04957                 STA PL4LIFE             ; Photon torpedo 1 lifetime := 0  game loops
A9AC 8575     04958                 STA DOCKSTATE           ; DOCKSTATE := NO DOCKING
A9AE 8D5C09   04959                 STA TRACKDIGIT          ; Clear index of tracked space object
A9B1 4C23B2   04960                 JMP SETTITLE            ; Set title phrase and return
              04961
              04962 ;*******************************************************************************
              04963 ;*                                                                             *
              04964 ;*                                  INITTRAIL                                  *
              04965 ;*                                                                             *
              04966 ;*         Initialize star trail during STAR TRAIL PHASE of hyperwarp          *
              04967 ;*                                                                             *
              04968 ;*******************************************************************************
              04969
              04970 ; DESCRIPTION
              04971 ;
              04972 ; BACKGROUND
              04973 ;
              04974 ; Star trails are displayed during the STAR TRAIL PHASE, that is, after the
              04975 ; ACCELERATION PHASE and before the HYPERSPACE PHASE of the hyperwarp.
              04976 ;
              04977 ; A star trail is formed by 6 stars represented by 6 PLAYFIELD space objects
              04978 ; with continuous position vector indices in 17..48 (indices are wrapped around
              04979 ; when greater than 48). Between the creation of two star trails there is delay
              04980 ; of 4 game loop iterations.
              04981 ;
              04982 ; DETAILS
              04983 ;
              04984 ; This subroutine first decrements this star trail creation delay, returning if
              04985 ; the delay is still counting down. If the delay falls below 0 then it continues
              04986 ; accelerating our starship's velocity toward hyperwarp speed and then creates a
              04987 ; new star trail:
              04988 ;
              04989 ; First, it raises the maximum index of used space objects to 48 (increasing the
              04990 ; number of displayed space objects to 49), resets the star trail creation delay
              04991 ; to 4 game loop iterations, then forms a new star trail of 6 stars represented
              04992 ; by 6 PLAYFIELD space objects. The x and y coordinates for all 6 stars are the
              04993 ; same, picked randomly from tables WARPSTARXTAB ($BB3A) and WARPSTARYTAB
              04994 ; ($BB3E), respectively, with their signs changed randomly. Their z-coordinates
              04995 ; are computed in increasing depth from at least +4608 (+$12**) <KM> in
              04996 ; intervals of +80 (+$0050) <KM>. Their velocity vector components are set to 0
              04997 ; <KM/H>.
              04998
    =0068     04999 L.RANGE         = $68                   ; z-coordinate of star in star trail (16-bit value)
    =006E     05000 L.TRAILCNT      = $6E                   ; Star's index in star trail. Used values are: 0..5.
              05001
A9B4 C6C2     05002 INITTRAIL       DEC TRAILDELAY          ; Decrement star trail delay
A9B6 1068     05003                 BPL SKIP074             ; Return if delay still counting
              05004
A9B8 A901     05005                 LDA #1                  ; Turn on hyperwarp velocity
A9BA 85C1     05006                 STA VELOCITYHI          ;
              05007
A9BC A930     05008                 LDA #NUMSPCOBJ.ALL-1    ; Max index of space objects (for star trail stars)
A9BE 8579     05009                 STA MAXSPCOBJIND        ;
              05010
A9C0 A903     05011                 LDA #3                  ; Star trail delay := 3(+1) game loops
A9C2 85C2     05012                 STA TRAILDELAY          ;
              05013
A9C4 A6C3     05014                 LDX TRAILIND            ; Next avail. space obj index for star of star trail
              05015
A9C6 A912     05016                 LDA #$12                ; Star z-coordinate := >= +$12** (+4608) <KM>
A9C8 8569     05017                 STA L.RANGE+1           ;
              05018
A9CA AD0AD2   05019                 LDA RANDOM              ; Calc random index to pick initial star coordinates
A9CD 2903     05020                 AND #$03                ;
A9CF A8       05021                 TAY                     ;
A9D0 B93ABB   05022                 LDA WARPSTARXTAB,Y      ; Pick x-coordinate (high byte) of star from table
A9D3 9D710A   05023                 STA XPOSHI,X            ;
A9D6 B93EBB   05024                 LDA WARPSTARYTAB,Y      ;
A9D9 9DA20A   05025                 STA YPOSHI,X            ; Pick y-coordinate (high byte) of star from table
A9DC 20BEB7   05026                 JSR RNDINVXY            ; Randomize signs of x and y coordinates of star
              05027
A9DF 8A       05028                 TXA                     ; Save space object index
A9E0 A8       05029                 TAY                     ;
A9E1 A905     05030                 LDA #5                  ; Loop over 5(+1) stars that form the star trail
A9E3 856E     05031                 STA L.TRAILCNT          ; Store star counter of star trail
              05032
A9E5 18       05033 LOOP034         CLC                     ; Place stars in z-coordinate intervals of +80 <KM>
A9E6 A568     05034                 LDA L.RANGE             ;
A9E8 6950     05035                 ADC #80                 ;
A9EA 8568     05036                 STA L.RANGE             ;
A9EC 9DD30A   05037                 STA ZPOSLO,X            ;
A9EF A569     05038                 LDA L.RANGE+1           ;
A9F1 6900     05039                 ADC #0                  ;
A9F3 8569     05040                 STA L.RANGE+1           ;
A9F5 9D400A   05041                 STA ZPOSHI,X            ;
              05042
A9F8 A900     05043                 LDA #0                  ; Star's velocity vector components := 0 <KM/H>
A9FA 9D660B   05044                 STA ZVEL,X              ;
A9FD 9D970B   05045                 STA XVEL,X              ;
AA00 9DC80B   05046                 STA YVEL,X              ;
AA03 A901     05047                 LDA #1                  ; Star's z-coordinate sign := + (= ahead of starship)
AA05 9DAD09   05048                 STA ZPOSSIGN,X          ;
              05049
AA08 A963     05050                 LDA #99                 ; Init pixel row and column numbers to magic...
AA0A 9DF90B   05051                 STA PIXELROWNEW,X       ; ...offscreen value (triggers automatic recalc in...
AA0D 9D2A0C   05052                 STA PIXELCOLUMN,X       ; ...GAMELOOP's calls to SCREENCOLUMN and SCREENROW)
              05053
AA10 20C1AC   05054                 JSR COPYPOSXY           ; Copy x and y coordinate from previous star in trail
              05055
AA13 CA       05056                 DEX                     ; Decrement space object index to next star
AA14 E011     05057                 CPX #NUMSPCOBJ.NORM     ; If index reaches minimum value...
AA16 B002     05058                 BCS SKIP073             ;
AA18 A230     05059                 LDX #NUMSPCOBJ.ALL-1    ; ...wrap-around to maximum space object index
AA1A C66E     05060 SKIP073         DEC L.TRAILCNT          ;
AA1C 10C7     05061                 BPL LOOP034             ; Next star of star trail
              05062
AA1E 86C3     05063                 STX TRAILIND            ; Save space object index of star trail's last star
AA20 60       05064 SKIP074         RTS                     ; Return
              05065
              05066 ;*******************************************************************************
              05067 ;*                                                                             *
              05068 ;*                                 PROJECTION                                  *
              05069 ;*                                                                             *
              05070 ;*         Calculate pixel column (or row) number from position vector         *
              05071 ;*                                                                             *
              05072 ;*******************************************************************************
              05073
              05074 ; Calculates the pixel column (or row) number of a position vector x (or y)
              05075 ; component relative to the PLAYFIELD center by computing the perspective
              05076 ; projection quotient
              05077 ;
              05078 ;     QUOTIENT := DIVIDEND / DIVISOR * 128
              05079 ;
              05080 ; with
              05081 ;
              05082 ;     DIVIDEND := ABS(x-coordinate (or y-coordinate)) / 2
              05083 ;     DIVISOR  := ABS(z-coordinate) / 2
              05084 ;
              05085 ; If the QUOTIENT is in 0..255, it is used as an index to pick the pixel column
              05086 ; (or row) number from table MAPTO80 ($0DE9), returning values in 0..80.
              05087 ;
              05088 ; If the QUOTIENT is larger than 255 ("dividend overflow") or if the
              05089 ; z-coordinate = 0 ("division by zero") then the error value 255 is returned.
              05090 ;
              05091 ; INPUT
              05092 ;
              05093 ;   X                   = Position vector index. Used values are: 0..48.
              05094 ;   DIVIDEND ($6A..$6B) = Dividend (positive 16-bit value), contains the
              05095 ;                         absolute value of the x (or y) coordinate.
              05096 ;
              05097 ; OUTPUT
              05098 ;
              05099 ;   A = Pixel column (or row) number relative to PLAYFIELD center. Used values
              05100 ;       are:
              05101 ;     0..80 -> Pixel number
              05102 ;     255   -> Error value indicating "dividend overflow" or "division by zero"
              05103
    =0068     05104 L.DIVISOR       = $68                   ; Divisor (16-bit value)
    =006D     05105 L.QUOTIENT      = $6D                   ; Division result (unsigned 8-bit value)
    =006E     05106 L.LOOPCNT       = $6E                   ; Division loop counter. Used values are: 7..0.
              05107
AA21 A900     05108 PROJECTION      LDA #0                  ; Init quotient result
AA23 856D     05109                 STA L.QUOTIENT          ;
              05110
AA25 A907     05111                 LDA #7                  ; Init division loop counter
AA27 856E     05112                 STA L.LOOPCNT           ;
              05113
AA29 466B     05114                 LSR DIVIDEND+1          ; DIVIDEND := x-coordinate (or y-coordinate) / 2
AA2B 666A     05115                 ROR DIVIDEND            ; (division by 2 to make B15 = 0?) (?)
              05116
AA2D A5D0     05117                 LDA SHIPVIEW            ; Skip if in Aft view
AA2F D00F     05118                 BNE SKIP075             ;
              05119
AA31 BD400A   05120                 LDA ZPOSHI,X            ; If in Front view -> DIVISOR := z-coordinate / 2
AA34 4A       05121                 LSR A                   ; (division by 2 to make B15 = 0?) (?)
AA35 8569     05122                 STA L.DIVISOR+1         ;
AA37 BDD30A   05123                 LDA ZPOSLO,X            ;
AA3A 6A       05124                 ROR A                   ;
AA3B 8568     05125                 STA L.DIVISOR           ;
AA3D 4C52AA   05126                 JMP LOOP035             ;
              05127
AA40 38       05128 SKIP075         SEC                     ; If in Aft view -> DIVISOR := - z-coordinate / 2
AA41 A900     05129                 LDA #0                  ; (division by 2 to make B15 = 0?) (?)
AA43 FDD30A   05130                 SBC ZPOSLO,X            ;
AA46 8568     05131                 STA L.DIVISOR           ;
AA48 A900     05132                 LDA #0                  ;
AA4A FD400A   05133                 SBC ZPOSHI,X            ;
AA4D 4A       05134                 LSR A                   ;
AA4E 8569     05135                 STA L.DIVISOR+1         ;
AA50 6668     05136                 ROR L.DIVISOR           ;
              05137
AA52 066D     05138 LOOP035         ASL L.QUOTIENT          ; QUOTIENT := DIVIDEND / DIVISOR * 128
AA54 38       05139                 SEC                     ;
AA55 A56A     05140                 LDA DIVIDEND            ;
AA57 E568     05141                 SBC L.DIVISOR           ;
AA59 A8       05142                 TAY                     ;
AA5A A56B     05143                 LDA DIVIDEND+1          ;
AA5C E569     05144                 SBC L.DIVISOR+1         ;
AA5E 9006     05145                 BCC SKIP076             ;
              05146
AA60 856B     05147                 STA DIVIDEND+1          ;
AA62 846A     05148                 STY DIVIDEND            ;
AA64 E66D     05149                 INC L.QUOTIENT          ;
              05150
AA66 066A     05151 SKIP076         ASL DIVIDEND            ;
AA68 266B     05152                 ROL DIVIDEND+1          ;
AA6A 9003     05153                 BCC SKIP077             ;
              05154
AA6C A9FF     05155                 LDA #255                ; Return 255 if division by zero or dividend overflow
AA6E 60       05156                 RTS                     ;
              05157
AA6F C66E     05158 SKIP077         DEC L.LOOPCNT           ;
AA71 10DF     05159                 BPL LOOP035             ; Next division loop iteration
              05160
AA73 A46D     05161                 LDY L.QUOTIENT          ; Prep with quotient
AA75 B9E90D   05162                 LDA MAPTO80,Y           ; Pick and return pixel column (or row) number...
AA78 60       05163 SKIP078         RTS                     ; ...relative to PLAYFIELD center
              05164
              05165 ;*******************************************************************************
              05166 ;*                                                                             *
              05167 ;*                                  MANEUVER                                   *
              05168 ;*                                                                             *
              05169 ;*     Maneuver our starship's and Zylon photon torpedoes and Zylon ships      *
              05170 ;*                                                                             *
              05171 ;*******************************************************************************
              05172
              05173 ; DESCRIPTION
              05174 ;
              05175 ; This subroutine maneuvers both of our starship's photon torpedoes, the single
              05176 ; Zylon photon torpedo, and the one or two Zylon ships that are simultaneously
              05177 ; displayed on the screen. It also creates meteors and new Zylon ships. This
              05178 ; subroutine is executed only if our starship is not in a starbase sector and
              05179 ; hyperwarp is not engaged.
              05180 ;
              05181 ; BACKGROUND
              05182 ;
              05183 ; When a Zylon ship is initialized, a "flight pattern" is assigned to it. There
              05184 ; are 3 flight patterns (0, 1, and 4) which are picked from table ZYLONFLPATTAB
              05185 ; ($BF91).
              05186 ;
              05187 ; The flight pattern determines the maximum velocity with which a Zylon ship can
              05188 ; move along each axis of the 3D coordinate system, that is the maximum value of
              05189 ; a velocity vector component. Velocity vector components for Zylon ships are
              05190 ; picked from the Zylon velocity table ZYLONVELTAB ($BF99):
              05191 ;
              05192 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05193 ; | Velocity Index  |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
              05194 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05195 ; | Velocity <KM/H> | +62 | +30 | +16 |  +8 |  +4 |  +2 |  +1 |  0  |
              05196 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05197 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05198 ; | Velocity Index  |  8  |  9  |  10 |  11 |  12 |  13 |  14 |  15 |
              05199 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05200 ; | Velocity <KM/H> |  0  |  -1 |  -2 |  -4 |  -8 | -16 | -30 | -62 |
              05201 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05202 ;
              05203 ; The index into the Zylon velocity table ZYLONVELTAB ($BF99) corresponding to
              05204 ; the maximum velocity is called the "maximum velocity index". The following
              05205 ; table shows the flight patterns, their maximum velocity indices, and their
              05206 ; corresponding velocities:
              05207 ;
              05208 ; +----------------+------------------+------------------+
              05209 ; | Flight Pattern | Maximum Velocity | Maximum Velocity |
              05210 ; |                |      Index       |                  |
              05211 ; +----------------+------------------+------------------+
              05212 ; |       0        |         0        |    +62 <KM/H>    |
              05213 ; |       0        |        15        |    -62 <KM/H>    |
              05214 ; |       1        |         1        |    +30 <KM/H>    |
              05215 ; |       1        |        14        |    -30 <KM/H>    |
              05216 ; |       4        |         4        |     +4 <KM/H>    |
              05217 ; |       4        |        11        |     -4 <KM/H>    |
              05218 ; +----------------+------------------+------------------+
              05219 ;
              05220 ; Because flight pattern 0 produces the fastest-moving Zylon ships, which
              05221 ; maneuver aggressively, it is called the "attack flight pattern".
              05222 ;
              05223 ; Each Zylon ship has a set of 3 maximum velocity indices, one for each of its
              05224 ; velocity vector components.
              05225 ;
              05226 ; Each Zylon ship has also one more set of 3 velocity indices, called "Zylon
              05227 ; velocity indices", one for each of its velocity vector components. They are
              05228 ; used to pick the current values of the velocity vector components from the
              05229 ; Zylon velocity table ZYLONVELTAB ($BF99).
              05230 ;
              05231 ; In order to maneuver Zylon ships this subroutine uses the concept of
              05232 ; "milestone velocity indices". By using delay timers, called "Zylon timers",
              05233 ; this subroutine gradually increases or decreases the Zylon velocity indices
              05234 ; with every game loop iteration to eventually match the corresponding milestone
              05235 ; velocity indices. By incrementing a Zylon velocity index a Zylon ship
              05236 ; accelerates toward the negative direction of a coordinate axis. By
              05237 ; decrementing a Zylon velocity index a Zylon ship accelerates toward the
              05238 ; positive direction of a coordinate axis. If one milestone velocity index is
              05239 ; matched or a "milestone timer" has counted down to 0, a new milestone velocity
              05240 ; index is calculated and the matching of the current Zylon velocity indices
              05241 ; with the new milestone velocity indices repeats.
              05242 ;
              05243 ; DETAILS
              05244 ;
              05245 ; For quick lookup, the following table lists the PLAYERs and what space objects
              05246 ; they represent in this subroutine:
              05247 ;
              05248 ; +--------+---------------------------------+
              05249 ; | PLAYER |           Represents            |
              05250 ; +--------+---------------------------------+
              05251 ; |    0   | Zylon Ship 0                    |
              05252 ; |    1   | Zylon Ship 1                    |
              05253 ; |    2   | Zylon Photon Torpedo, Meteor    |
              05254 ; |    3   | Our starship's Photon Torpedo 0 |
              05255 ; |    4   | Our starship's Photon Torpedo 1 |
              05256 ; +--------+---------------------------------+
              05257 ;
              05258 ; This subroutine executes the following steps:
              05259 ;
              05260 ; (1)  Update the x and y velocity vector components of both of our starship's
              05261 ;      photon torpedoes 0 and 1.
              05262 ;
              05263 ;      The x and y velocity vector components of both of our starship's photon
              05264 ;      torpedoes 0 and 1 are only updated if they are tracking (homing in on) a
              05265 ;      target.
              05266 ;
              05267 ;      To update the y-velocity vector components of both of our starship's
              05268 ;      photon torpedoes 0 and 1 the PLAYER row number difference between the
              05269 ;      PLAYER of tracked target space object and the current location of the
              05270 ;      PLAYER of our starship's photon torpedo 0 is passed to subroutine
              05271 ;      HOMINGVEL ($AECA). It returns the new y-velocity vector component value
              05272 ;      for both of our starship's photon torpedoes in <KM/H>. If the target is
              05273 ;      located below our starship's photon torpedo 0 a value of 0 <KM/H> is
              05274 ;      used.
              05275 ;
              05276 ;      NOTE: The new y-velocity vector components depend only on the PLAYER row
              05277 ;      number of our starship's photon torpedo 0.
              05278 ;
              05279 ;      To update the x-velocity vector components of both of our starship's
              05280 ;      photon torpedoes, the above calculation is repeated for the PLAYER column
              05281 ;      numbers of each of our starship's photon torpedoes 0 and 1.
              05282 ;
              05283 ; (2)  Make the Zylon ships follow the rotation of our starship.
              05284 ;
              05285 ;      If you rotate our starship away from Zylon ships they adjust their course
              05286 ;      such that they reappear in our starship's view.
              05287 ;
              05288 ;      This is achieved by 4 Zylon timers, one for each of both Zylon ships'
              05289 ;      current x and y Zylon velocity indices. The Zylon timers are decremented
              05290 ;      every game loop iteration. If any of them reach a value of 0, the
              05291 ;      corresponding Zylon velocity index is incremented or decremented
              05292 ;      depending on the current joystick position.
              05293 ;
              05294 ;      For example, if the Zylon timer for the x-velocity of Zylon ship 0
              05295 ;      reaches 0 and at the same time the joystick is pushed left then the
              05296 ;      x-Zylon velocity index of this Zylon ship is incremented. This
              05297 ;      accelerates the Zylon ship toward negative x-direction ("left"): The
              05298 ;      Zylon ship follows our starship's rotation. This works in Aft view, too,
              05299 ;      where the direction of change of the Zylon velocity index is reversed.
              05300 ;      After setting the new Zylon velocity index, it is used to pick a new
              05301 ;      Zylon timer value for this Zylon velocity index:
              05302 ;
              05303 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05304 ;      | Velocity Index                 |  0 |  1 |  2 |  3 |  4 |  5 |  6 |  7 |
              05305 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05306 ;      | Zylon Timer Value (Game Loops) |  0 |  2 |  4 |  6 |  8 | 10 | 12 | 14 |
              05307 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05308 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05309 ;      | Velocity Index                 |  8 |  9 | 10 | 11 | 12 | 13 | 14 | 15 |
              05310 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05311 ;      | Zylon Timer Value (Game Loops) | 14 | 12 | 10 |  8 |  6 |  4 |  2 |  0 |
              05312 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05313 ;
              05314 ; (3)  Update the x and y velocity vector components of the single Zylon photon
              05315 ;      torpedo.
              05316 ;
              05317 ;      If a Zylon photon torpedo is moving toward our starship then update its x
              05318 ;      and y velocity vector components. They are picked from table
              05319 ;      ZYLONHOMVELTAB ($BF85) and depend on the mission level. The signs of the
              05320 ;      velocity vector components are always set such that the Zylon photon
              05321 ;      torpedo is guided toward our starship.
              05322 ;
              05323 ; (4)  Create a meteor?
              05324 ;
              05325 ;      If PLAYER2, the PLAYER to represent a meteor, is either initial or not
              05326 ;      alive, then attempt in 7 out of 8 game loop iterations to create a new
              05327 ;      meteor.
              05328 ;
              05329 ;      With a probability of 2% (4:256) a new meteor is created: Its shape type
              05330 ;      is set to METEOR, its position vector components to random coordinates in
              05331 ;      subroutine INITPOSVEC ($B764), its lifetime to 60 game loop iterations,
              05332 ;      and its velocity vector components (velocities) to x-velocity: 0 <KM/H>,
              05333 ;      y-velocity: 0 <KM/H>, z-velocity: -8 <KM/H>. Then code execution returns.
              05334 ;
              05335 ; (5)  Toggle Zylon ship control.
              05336 ;
              05337 ;      Every other game loop iteration, the program takes control of and
              05338 ;      maneuvers the other Zylon ship.
              05339 ;
              05340 ; (6)  Create new Zylon ship?
              05341 ;
              05342 ;      If the program-controlled Zylon ship is not alive, check if both Zylon
              05343 ;      ships are not alive and this is an empty sector. If so, then attempt to
              05344 ;      create a meteor. Otherwise create a new Zylon ship with infinite
              05345 ;      lifetime. Randomly pick its shape type from table ZYLONSHAPTAB ($BF89)
              05346 ;      (BASESTAR, ZYLON CRUISER, or ZYLON FIGHTER) and its flight pattern from
              05347 ;      table ZYLONFLPATTAB ($BF91) (attack flight pattern 0 is always picked in
              05348 ;      a NOVICE mission). Then set the milestone timer to 1 game loop iteration
              05349 ;      and the position vector of the Zylon ship to a position of at least
              05350 ;      +28928 (+$71**) <KM> in front of our starship. The y-coordinate depends
              05351 ;      on the value of VICINITYMASK ($C7). The x-coordinate is the sum of the
              05352 ;      y-coordinate plus at least 4864..5119 ($13**) <KM>. Randomly choose the
              05353 ;      signs of the x and y coordinates.
              05354 ;
              05355 ; (7)  Set the current flight pattern to attack flight pattern?
              05356 ;
              05357 ;      The current flight pattern of the Zylon ship will change to attack flight
              05358 ;      pattern if it is close enough (z-coordinate < +8192 (+$20**) <KM>) and
              05359 ;      one of the following conditions is met:
              05360 ;
              05361 ;      o   The Zylon ship is located behind our starship.
              05362 ;
              05363 ;      o   The shape of the Zylon ship is not initial and does not currently
              05364 ;          appear as a blip in the Long-Range Scan view.
              05365 ;
              05366 ; (8)  Update the back-attack flag and the milestone velocity indices.
              05367 ;
              05368 ;      The milestone timer is decremented for the program-controlled Zylon ship.
              05369 ;      If this timer reaches a value of 0 the following steps are executed:
              05370 ;
              05371 ;      o   The milestone timer is reset to a value of 120 game loop iterations.
              05372 ;
              05373 ;      o   The back-attack flag is updated. It determines if the
              05374 ;          program-controlled Zylon ship not only attacks from the front of our
              05375 ;          starship but also from the back. A back-attack takes place with a
              05376 ;          probability of 19% (48:256) in WARRIOR or COMMANDER missions.
              05377 ;
              05378 ;      o   Course corrections are prepared for the program-controlled Zylon ship
              05379 ;          by computing the new milestone vector indices, resulting in new
              05380 ;          velocity vector components for this Zylon ship. The new milestone
              05381 ;          velocity indices for each velocity vector component are randomly
              05382 ;          chosen depending of the flight pattern. Recall that the Zylon
              05383 ;          velocity index is changed gradually to match the milestone velocity
              05384 ;          index. It corresponds to a maximum velocity vector component when
              05385 ;          using this index to pick a velocity vector component from Zylon
              05386 ;          velocity table ZYLONVELTAB ($BF99):
              05387 ;
              05388 ;          +----------------+----------------+------------------+
              05389 ;          | Flight Pattern | New Milestone  | Maximum Velocity |
              05390 ;          |                | Velocity Index | Vector Component |
              05391 ;          +----------------+----------------+------------------+
              05392 ;          |       0        |        0       |    +62 <KM/H>    |
              05393 ;          |       0        |       15       |    -62 <KM/H>    |
              05394 ;          |       1        |        1       |    +30 <KM/H>    |
              05395 ;          |       1        |       14       |    -30 <KM/H>    |
              05396 ;          |       4        |        4       |     +4 <KM/H>    |
              05397 ;          |       4        |       11       |     -4 <KM/H>    |
              05398 ;          +----------------+----------------+------------------+
              05399 ;
              05400 ; (9)  Update milestone velocity indices in attack flight pattern.
              05401 ;
              05402 ;      If a Zylon ship executes the attack flight pattern, its milestone
              05403 ;      velocity indices are changed depending on the current location of the
              05404 ;      Zylon ship as follows:
              05405 ;
              05406 ;      +--------------+-------------+----------------+------------+----------------+
              05407 ;      | x-Coordinate |  Where on   |   Milestone    |  Velocity  | Zylon Ship     |
              05408 ;      |              |   Screen    | Velocity Index |            | Accelerates... |
              05409 ;      +--------------+-------------+----------------+------------+----------------+
              05410 ;      | x <  0 <KM>  | left half   |       0        | +62 <KM/H> | to the right   |
              05411 ;      | x >= 0 <KM>  | right half  |      15        | -62 <KM/H> | to the left    |
              05412 ;      +--------------+-------------+----------------+------------+----------------+
              05413 ;      +--------------+-------------+----------------+------------+----------------+
              05414 ;      | y-Coordinate |  Where on   |   Milestone    |  Velocity  | Zylon Ship     |
              05415 ;      |              |   Screen    | Velocity Index |            | Accelerates... |
              05416 ;      +--------------+-------------+----------------+------------+----------------+
              05417 ;      | y <  0 <KM>  | bottom half |       0        | +62 <KM/H> | up             |
              05418 ;      | y >= 0 <KM>  | top half    |      15        | -62 <KM/H> | down           |
              05419 ;      +--------------+-------------+----------------+------------+----------------+
              05420 ;
              05421 ;      Thus, with respect to its x and y coordinates, the Zylon ship oscillates
              05422 ;      around the center of the Front or Aft view.
              05423 ;
              05424 ;      This is the behavior of the Zylon ship along the z-axis:
              05425 ;
              05426 ;      If the Zylon ship attacks from the front:
              05427 ;
              05428 ;      +--------------------------+----------------+------------+----------------+
              05429 ;      |       z-Coordinate       |   Milestone    |  Velocity  | Zylon Ship     |
              05430 ;      |                          | Velocity Index |            | Accelerates... |
              05431 ;      +--------------------------+----------------+------------+----------------+
              05432 ;      | z <  +2560 (+$0A00) <KM> |       0        | +62 <KM/H> | outbound       |
              05433 ;      | z >= +2560 (+$0A00) <KM> |      15        | -62 <KM/H> | inbound        |
              05434 ;      +--------------------------+----------------+------------+----------------+
              05435 ;
              05436 ;      In other words, the Zylon ship accelerates into positive z-direction
              05437 ;      (outbound) up to a distance of +2560 (+$0A00) <KM>, then reverses its
              05438 ;      course and returns back to our starship (inbound).
              05439 ;
              05440 ;      If the Zylon ship attacks from the back:
              05441 ;
              05442 ;      +--------------------------+----------------+------------+----------------+
              05443 ;      |       z-Coordinate       |   Milestone    |  Velocity  | Zylon Ship     |
              05444 ;      |                          | Velocity Index |            | Accelerates... |
              05445 ;      +--------------------------+----------------+------------+----------------+
              05446 ;      | z <  -2816 (-$F500) <KM> |       0        | +62 <KM/H> | inbound        |
              05447 ;      | z >= -2816 (-$F500) <KM> |      15        | -62 <KM/H> | outbound       |
              05448 ;      +--------------------------+----------------+------------+----------------+
              05449 ;
              05450 ;      In other words, the Zylon ship accelerates into negative z-direction
              05451 ;      (outbound) up to a distance of -2816 (-$(0B00)) <KM>, then reverses its
              05452 ;      course and returns back to our starship (inbound).
              05453 ;
              05454 ; (10) Change Zylon velocity index toward milestone velocity index.
              05455 ;
              05456 ;      Compare all 3 Zylon velocity indices of the program-controlled Zylon ship
              05457 ;      with their corresponding milestone velocity indices. Increment or
              05458 ;      decrement the former to better match the latter. Use the new Zylon
              05459 ;      velocity indices to pick the current velocity values from Zylon velocity
              05460 ;      table ZYLONVELTAB ($BF99).
              05461 ;
              05462 ; (11) Launch a Zylon photon torpedo?
              05463 ;
              05464 ;      Prepare launching a Zylon photon torpedo if either of the following
              05465 ;      conditions are met:
              05466 ;
              05467 ;      o   PLAYER2 is not used as a photon torpedo
              05468 ;
              05469 ;      o   The y-coordinate of the Zylon ship is in the range of -768..+767
              05470 ;          (-$0300..+$2FF) <KM>.
              05471 ;
              05472 ;      or if
              05473 ;
              05474 ;      o   The Zylon photon torpedo is not alive
              05475 ;
              05476 ;      o   The corresponding Zylon photon torpedo delay timer has reached a
              05477 ;          value of 0
              05478 ;
              05479 ;      o   The y-coordinate of the Zylon ship is in the range of -768..+767
              05480 ;          (-$0300..+$2FF) <KM>.
              05481 ;
              05482 ;      At this point the z-velocity vector component of the Zylon photon torpedo
              05483 ;      is preloaded with a value of -80 or +80 <KM/H> depending on the Zylon
              05484 ;      ship being in front or behind of our starship, respectively.
              05485 ;
              05486 ;      Launch a Zylon photon torpedo if both of the following conditions are
              05487 ;      met:
              05488 ;
              05489 ;      o   The Zylon ship is in front or behind of our starship, with the
              05490 ;          exception of a Zylon ship behind our starship in a NOVICE mission
              05491 ;          (our starship will never be shot in the back in a NOVICE mission).
              05492 ;
              05493 ;      o   The z-coordinate of the Zylon ship (no matter if in front or behind
              05494 ;          our starship) is closer than 8192 ($20**) <KM>.
              05495 ;
              05496 ;      Finally, the Zylon photon torpedo is launched with a lifetime of 62 game
              05497 ;      loop iterations. Its position vector is copied from the launching Zylon
              05498 ;      ship in subroutine COPYPOSVEC ($ACAF). In addition, the Zylon ship is
              05499 ;      earmarked for the tracking computer.
              05500
    =006A     05501 L.CTRLDZYLON    = $6A                   ; Index of currently program-controlled Zylon ship.
              05502                                         ; Used values are:
              05503                                         ;   0 -> Control Zylon ship 0
              05504                                         ;   1 -> Control Zylon ship 1
    =0080     05505 NEG             = $80                   ; Negative sign bit for velocity vector component
              05506
AA79 A5C0     05507 MANEUVER        LDA WARPSTATE           ; Return if in starbase sector or hyperwarp engaged
AA7B 057B     05508                 ORA ISSTARBASESECT      ;
AA7D D0F9     05509                 BNE SKIP078             ;
              05510
              05511 ;*** Update x and y velocity of both our starship's photon torpedoes 0 and 1 ***
AA7F A586     05512                 LDA ISTRACKING          ; Skip this if ship's torpedoes not tracking a target
AA81 F030     05513                 BEQ SKIP080             ;
              05514
AA83 A689     05515                 LDX PLTRACKED           ; Load PLAYER index of tracked target space object
              05516
AA85 38       05517                 SEC                     ; Prep A := PLAYER row number of target...
AA86 BDF90B   05518                 LDA PL0ROWNEW,X         ; ...- PLAYER row number photon torpedo 0
AA89 EDFC0B   05519                 SBC PL3ROWNEW           ;
AA8C 9002     05520                 BCC SKIP079             ; Skip if target above our starship's photon torpedo
AA8E A900     05521                 LDA #0                  ; Prep A := 0
AA90 20CAAE   05522 SKIP079         JSR HOMINGVEL           ; Get y-velocity for homing photon torpedo 0 and 1
AA93 8DCB0B   05523                 STA PL3YVEL             ; Store y-velocity photon torpedo 0
AA96 8DCC0B   05524                 STA PL4YVEL             ; Store y-velocity photon torpedo 1
              05525
AA99 38       05526                 SEC                     ; Prep A := PLAYER column number of target...
AA9A AD2D0C   05527                 LDA PL3COLUMN           ; ...- PLAYER column number of photon torpedo 0
AA9D FD2A0C   05528                 SBC PL0COLUMN,X         ;
AAA0 20CAAE   05529                 JSR HOMINGVEL           ; Get x-velocity for homing photon torpedo 0
AAA3 8D9A0B   05530                 STA PL3XVEL             ; Store x-velocity of photon torpedo 0
              05531
AAA6 38       05532                 SEC                     ; Prep A := PLAYER column number of target...
AAA7 AD2E0C   05533                 LDA PL4COLUMN           ; ...- PLAYER column number of photon torpedo 1
AAAA FD2A0C   05534                 SBC PL0COLUMN,X         ;
AAAD 20CAAE   05535                 JSR HOMINGVEL           ; Get x-velocity for homing photon torpedo 1
AAB0 8D9B0B   05536                 STA PL4XVEL             ; Store x-velocity of photon torpedo 1
              05537
              05538 ;*** Make Zylon ships follow rotation of our starship **************************
AAB3 A203     05539 SKIP080         LDX #3                  ; Loop over x and y velocity indices of both Zylons
AAB5 D6BA     05540 LOOP036         DEC ZYLONTIMX0,X        ; Decrement Zylon timer
AAB7 1027     05541                 BPL SKIP085             ; Next timer if this one still counting down
              05542
AAB9 8A       05543                 TXA                     ; Prep joystick (x or y) value in -1, 0, +1
AABA 4A       05544                 LSR A                   ;
AABB A8       05545                 TAY                     ;
AABC B9C800   05546                 LDA JOYSTICKX,Y         ;
              05547
AABF A4D0     05548                 LDY SHIPVIEW            ; Skip if in Front view
AAC1 F005     05549                 BEQ SKIP081             ;
              05550
AAC3 49FF     05551                 EOR #$FF                ; Invert joystick value (when in Aft view)
AAC5 18       05552                 CLC                     ; (two's-complement)
AAC6 6901     05553                 ADC #1                  ;
              05554
AAC8 18       05555 SKIP081         CLC                     ; Add joystick value to Zylon velocity index
AAC9 75B4     05556                 ADC ZYLONVELINDX0,X     ;
AACB 1002     05557                 BPL SKIP082             ;
AACD A900     05558                 LDA #0                  ;
AACF C910     05559 SKIP082         CMP #16                 ; Limit new Zylon velocity index to 0..15 ...
AAD1 9002     05560                 BCC SKIP083             ;
AAD3 A90F     05561                 LDA #15                 ;
AAD5 95B4     05562 SKIP083         STA ZYLONVELINDX0,X     ; ...and store new Zylon velocity index
              05563
AAD7 C908     05564                 CMP #8                  ; Calc new Zylon timer value in 0, 2, ..., 14
AAD9 9002     05565                 BCC SKIP084             ;
AADB 490F     05566                 EOR #$0F                ;
AADD 0A       05567 SKIP084         ASL A                   ;
AADE 95BA     05568                 STA ZYLONTIMX0,X        ; ...and store new Zylon timer value
              05569
AAE0 CA       05570 SKIP085         DEX                     ;
AAE1 10D2     05571                 BPL LOOP036             ; Next Zylon timer
              05572
              05573 ;*** Update x and y velocity of single Zylon photon torpedo ********************
AAE3 AD8E0C   05574                 LDA PL2SHAPTYPE         ; Skip if PLAYER2 not PHOTON TORPEDO (shape type 0)
AAE6 D01B     05575                 BNE SKIP088             ;
              05576
AAE8 A462     05577                 LDY MISSIONLEVEL        ; Depending on mission level...
AAEA B985BF   05578                 LDA ZYLONHOMVELTAB,Y    ; ...pick (initially negative) Zylon torpedo velocity
              05579
AAED AEA40A   05580                 LDX PL2YPOSHI           ; If photon torpedo in upper screen half (y >= 0)...
AAF0 1002     05581                 BPL SKIP086             ; ...don't toggle velocity sign -> torpedo goes down
AAF2 297F     05582                 AND #$7F                ; ...toggle velocity sign       -> torpedo goes up
AAF4 8DCA0B   05583 SKIP086         STA PL2YVEL             ; Store new y-velocity of Zylon photon torpedo
              05584
AAF7 0980     05585                 ORA #NEG                ; Restore negative sign bit of velocity
              05586
AAF9 AE730A   05587                 LDX PL2XPOSHI           ; If photon torpedo in right screen half (x >= 0)...
AAFC 1002     05588                 BPL SKIP087             ; ...don't toggle velocity sign -> torpedo goes left
AAFE 297F     05589                 AND #$7F                ; ...toggle velocity sign       -> torpedo goes right
AB00 8D990B   05590 SKIP087         STA PL2XVEL             ; Store new x-velocity of Zylon photon torpedo
              05591
              05592 ;*** Create new meteor? ********************************************************
AB03 A576     05593 SKIP088         LDA COUNT256            ; Attempt meteor creation in 7 out of 8 game loops
AB05 2903     05594                 AND #$03                ;
AB07 F02E     05595                 BEQ SKIP092             ;
              05596
AB09 A5E6     05597 SKIP089         LDA PL2SHAPOFF          ; If PLAYER2 shape is initial try to create a meteor
AB0B F004     05598                 BEQ SKIP090             ;
              05599
AB0D A5EB     05600                 LDA PL2LIFE             ; Return if PLAYER2 alive
AB0F D025     05601                 BNE SKIP091             ;
              05602
AB11 AD0AD2   05603 SKIP090         LDA RANDOM              ; Return in 98% (252:256) (do not create meteor)
AB14 C904     05604                 CMP #4                  ;
AB16 B01E     05605                 BCS SKIP091             ;
              05606
              05607 ;*** Create new meteor! ********************************************************
AB18 A960     05608                 LDA #SHAP.METEOR        ; PLAYER2 is METEOR (shape type 6)
AB1A 8D8E0C   05609                 STA PL2SHAPTYPE         ;
AB1D A202     05610                 LDX #2                  ; Randomize position vector of meteor
AB1F 2064B7   05611                 JSR INITPOSVEC          ;
AB22 A93C     05612                 LDA #60                 ; Meteor lifetime := 60 game loops
AB24 85EB     05613                 STA PL2LIFE             ;
AB26 A988     05614                 LDA #NEG!8              ; SUMMARY:
AB28 8D680B   05615                 STA PL2ZVEL             ; x-velocity :=  0 <KM/H>
AB2B A900     05616                 LDA #0                  ; y-velocity :=  0 <KM/H>
AB2D 8D2C0C   05617                 STA PL2COLUMN           ; z-velocity := -8 <KM/H>
AB30 8D990B   05618                 STA PL2XVEL             ;
AB33 8DCA0B   05619                 STA PL2YVEL             ; PLAYER2 column number := 0 (offscreen)
AB36 60       05620 SKIP091         RTS                     ; Return
              05621
              05622 ;*** Toggle Zylon ship control *************************************************
AB37 A5A7     05623 SKIP092         LDA CTRLDZYLON          ; Toggle control to the other Zylon ship
AB39 4901     05624                 EOR #$01                ;
AB3B 85A7     05625                 STA CTRLDZYLON          ;
              05626
              05627 ;*** Create a new Zylon ship? **************************************************
AB3D AA       05628                 TAX                     ; Save index of controlled Zylon ship
AB3E B5E9     05629                 LDA PL0LIFE,X           ; Skip creating Zylon ship if its PLAYER still alive
AB40 D042     05630                 BNE SKIP094             ;
              05631
AB42 A5E9     05632                 LDA PL0LIFE             ; If both Zylon ships are not alive...
AB44 05EA     05633                 ORA PL1LIFE             ;
AB46 2901     05634                 AND #$01                ;
AB48 A490     05635                 LDY CURRSECTOR          ; ...and this an empty sector...
AB4A D9C908   05636                 CMP GCMEMMAP,Y          ;
AB4D B0BA     05637                 BCS SKIP089             ; ...attempt to create meteor and return
              05638
              05639 ;*** Create a new Zylon ship! **************************************************
AB4F A9FF     05640                 LDA #255                ; Zylon ship lifetime := 255 game loops (infinite)
AB51 95E9     05641                 STA PL0LIFE,X           ;
              05642
AB53 AD0AD2   05643                 LDA RANDOM              ; Pick a Zylon ship shape type (1 out of 8)
AB56 2907     05644                 AND #$07                ;
AB58 A8       05645                 TAY                     ;
AB59 B989BF   05646                 LDA ZYLONSHAPTAB,Y      ;
AB5C 9D8C0C   05647                 STA PL0SHAPTYPE,X       ;
              05648
AB5F A562     05649                 LDA MISSIONLEVEL        ; Init Zylon's flight pattern (0 if NOVICE mission)
AB61 F003     05650                 BEQ SKIP093             ;
AB63 B991BF   05651                 LDA ZYLONFLPATTAB,Y     ;
AB66 95A8     05652 SKIP093         STA ZYLONFLPAT0,X       ;
              05653
AB68 A901     05654                 LDA #1                  ; Zylon ship's milestone timer := 1 game loop
AB6A 95AA     05655                 STA MILESTTIM0,X        ;
              05656
AB6C 9DAD09   05657                 STA ZPOSSIGN,X          ; Put Zylon ship in front of our starship
AB6F AD0AD2   05658                 LDA RANDOM              ;
AB72 25C7     05659                 AND VICINITYMASK        ; y-coordinate (high byte) := RND(0..VICINITYMASK)
AB74 9DA20A   05660                 STA YPOSHI,X            ;
AB77 6913     05661                 ADC #19                 ; x-coordinate (high byte) := y (high byte) + 19
AB79 9D710A   05662                 STA XPOSHI,X            ;
AB7C 0971     05663                 ORA #$71                ; z-coordinate (high byte) := >= +28928 (+$71**) <KM>
AB7E 9D400A   05664                 STA ZPOSHI,X            ;
AB81 20BEB7   05665                 JSR RNDINVXY            ; Randomly invert x and y coordinate of pos vector
              05666
              05667 ;*** Set current flight pattern to attack flight pattern? **********************
AB84 BD400A   05668 SKIP094         LDA ZPOSHI,X            ; Skip if Zylon too distant (z >= +$20** <KM>)
AB87 C920     05669                 CMP #$20                ;
AB89 B011     05670                 BCS SKIP096             ;
              05671
AB8B BDAD09   05672                 LDA ZPOSSIGN,X          ; Set attack flight pattern if Zylon is behind
AB8E F008     05673                 BEQ SKIP095             ;
              05674
AB90 B5E4     05675                 LDA PL0SHAPOFF,X        ; Skip if Zylon shape initial
AB92 F008     05676                 BEQ SKIP096             ;
              05677
AB94 C929     05678                 CMP #$29                ; Skip if Zylon shape is Long-Range Scan blip
AB96 F004     05679                 BEQ SKIP096             ;
              05680
AB98 A900     05681 SKIP095         LDA #0                  ; Set attack flight pattern
AB9A 95A8     05682                 STA ZYLONFLPAT0,X       ;
              05683
              05684 ;*** Update back-attack flag and milestone velocity indices ********************
AB9C D6AA     05685 SKIP096         DEC MILESTTIM0,X        ; Skip if milestone timer still counting down
AB9E 1024     05686                 BPL SKIP099             ;
              05687
ABA0 A978     05688                 LDA #120                ; Milestone timer := 120 game loops
ABA2 95AA     05689                 STA MILESTTIM0,X        ;
              05690
ABA4 A562     05691                 LDA MISSIONLEVEL        ; Back-attack flag := 1 in 19% (48:256) of...
ABA6 AC0AD2   05692                 LDY RANDOM              ; ...WARRIOR or COMMANDER missions
ABA9 C030     05693                 CPY #48                 ; ...              := 0 otherwise
ABAB 9001     05694                 BCC SKIP097             ;
ABAD 4A       05695                 LSR A                   ;
ABAE 4A       05696 SKIP097         LSR A                   ;
ABAF 95B8     05697                 STA ISBACKATTACK0,X     ;
              05698
              05699                                         ; Loop over all 3 milestone velocity indices
ABB1 B5A8     05700                 LDA ZYLONFLPAT0,X       ; Set new milestone velocity index:
ABB3 2C0AD2   05701 LOOP037         BIT RANDOM              ; If Zylon flight pattern is...
ABB6 1002     05702                 BPL SKIP098             ; ...0 -> milestone velocity index := either 0 or 15
ABB8 490F     05703                 EOR #$0F                ; ...1 -> milestone velocity index := either 1 or 14
ABBA 95AC     05704 SKIP098         STA MILESTVELINDZ0,X    ; ...4 -> milestone velocity index := either 4 or 11
ABBC E8       05705                 INX                     ;
ABBD E8       05706                 INX                     ;
ABBE E006     05707                 CPX #6                  ;
ABC0 90F1     05708                 BCC LOOP037             ; Next Zylon milestone velocity index
              05709
              05710 ;*** Update milestone velocity indices in attack flight pattern ****************
ABC2 A6A7     05711                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
              05712
ABC4 B5A8     05713 SKIP099         LDA ZYLONFLPAT0,X       ; Skip if not in attack flight pattern
ABC6 D032     05714                 BNE SKIP105             ;
              05715
ABC8 A4A7     05716                 LDY CTRLDZYLON          ; Reload index of controlled Zylon ship
              05717
              05718                                         ; Loop over all 3 milestone velocity indices
ABCA C031     05719 LOOP038         CPY #$31                ; Skip to handle x and y velocity index
ABCC B013     05720                 BCS SKIP101             ;
              05721                                         ; SUMMARY:
ABCE B9B800   05722                 LDA ISBACKATTACK0,Y     ; Handle z-velocity index:
ABD1 4A       05723                 LSR A                   ;
ABD2 B9400A   05724                 LDA ZPOSHI,Y            ; If Zylon attacks from front...
ABD5 B006     05725                 BCS SKIP100             ; z <  $0A00 <KM> -> mil vel index := 0  (+62 <KM/H>)
ABD7 C90A     05726                 CMP #$0A                ; z >= $0A00 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABD9 900E     05727                 BCC SKIP103             ;
ABDB B004     05728                 BCS SKIP101             ; If Zylon attacks from back...
ABDD C9F5     05729 SKIP100         CMP #$F5                ; z >= $F500 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABDF B004     05730                 BCS SKIP102             ; z <  $F500 <KM> -> mil vel index := 0  (+62 <KM/H>)
              05731
ABE1 B9AD09   05732 SKIP101         LDA ZPOSSIGN,Y          ; Handle x and y velocity index:
ABE4 4A       05733                 LSR A                   ;
ABE5 A90F     05734 SKIP102         LDA #15                 ; x >= 0 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABE7 B002     05735                 BCS SKIP104             ; x <  0 <KM> -> mil vel index := 0  (+62 <KM/H>)
ABE9 A900     05736 SKIP103         LDA #0                  ; y >= 0 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABEB 95AC     05737 SKIP104         STA MILESTVELINDZ0,X    ; y <  0 <KM> -> mil vel index := 0  (+62 <KM/H>)
              05738
ABED 18       05739                 CLC                     ; Adjust position vector component index
ABEE 98       05740                 TYA                     ;
ABEF 6931     05741                 ADC #NUMSPCOBJ.ALL      ;
ABF1 A8       05742                 TAY                     ;
              05743
ABF2 E8       05744                 INX                     ;
ABF3 E8       05745                 INX                     ;
ABF4 E006     05746                 CPX #6                  ;
ABF6 90D2     05747                 BCC LOOP038             ; Next milestone velocity index
              05748
              05749 ;*** Acceleration: Change Zylon velocity index toward milestone velocity index *
ABF8 A6A7     05750                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
ABFA A4A7     05751 SKIP105         LDY CTRLDZYLON          ; Reload index of controlled Zylon ship
              05752
              05753                                         ; Loop over all 3 milestone velocity indices
ABFC B5B2     05754 LOOP039         LDA ZYLONVELINDZ0,X     ; Compare Zylon velocity index with milestone index
ABFE D5AC     05755                 CMP MILESTVELINDZ0,X    ;
AC00 F008     05756                 BEQ SKIP107             ; Skip if equal
AC02 B004     05757                 BCS SKIP106             ;
AC04 F6B2     05758                 INC ZYLONVELINDZ0,X     ; Increm. Zylon velocity index if < milestone index
AC06 9002     05759                 BCC SKIP107             ;
AC08 D6B2     05760 SKIP106         DEC ZYLONVELINDZ0,X     ; Decrem. Zylon velocity index if >= milestone index
              05761
AC0A 866A     05762 SKIP107         STX L.CTRLDZYLON        ; Save index of controlled Zylon ship
AC0C AA       05763                 TAX                     ;
AC0D BD99BF   05764                 LDA ZYLONVELTAB,X       ; Pick new velocity value by Zylon velocity index
AC10 A66A     05765                 LDX L.CTRLDZYLON        ; Reload index of controlled Zylon ship
AC12 99660B   05766                 STA ZVEL,Y              ; Store new velocity vector component of Zylon ship
              05767
AC15 98       05768                 TYA                     ; Next velocity vector component
AC16 18       05769                 CLC                     ;
AC17 6931     05770                 ADC #NUMSPCOBJ.ALL      ;
AC19 A8       05771                 TAY                     ;
              05772
AC1A E8       05773                 INX                     ;
AC1B E8       05774                 INX                     ;
AC1C E006     05775                 CPX #6                  ;
AC1E 90DC     05776                 BCC LOOP039             ; Next milestone velocity index
              05777
              05778 ;*** Launch Zylon photon torpedo? **********************************************
              05779
              05780 ;*** Check PLAYER2 shape and lifetime ******************************************
AC20 A6A7     05781                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
              05782
AC22 AD8E0C   05783                 LDA PL2SHAPTYPE         ; Skip if PLAYER2 not PHOTON TORPEDO (shape type 0)
AC25 D00B     05784                 BNE SKIP109             ;
              05785
AC27 A5EB     05786                 LDA PL2LIFE             ; Return if Zylon photon torpedo still alive
AC29 D006     05787                 BNE SKIP108             ;
              05788
AC2B A5BE     05789                 LDA TORPEDODELAY        ; Count down Zylon photon torpedo delay timer...
AC2D F003     05790                 BEQ SKIP109             ; ...before launching next Zylon photon torpedo
AC2F C6BE     05791                 DEC TORPEDODELAY        ;
AC31 60       05792 SKIP108         RTS                     ; Return
              05793
              05794 ;*** Check y-coordinate of Zylon ship ******************************************
AC32 18       05795 SKIP109         CLC                     ; Return if Zylon ship's y-coordinate not...
AC33 BDA20A   05796                 LDA YPOSHI,X            ; ...in -768..+767 (-$(0300)..+$2FF) <KM>.
AC36 6902     05797                 ADC #2                  ;
AC38 C905     05798                 CMP #5                  ;
AC3A B0F5     05799                 BCS SKIP108             ;
              05800
              05801 ;*** Set Zylon photon torpedo's z-velocity *************************************
AC3C A0D0     05802                 LDY #NEG!80             ; Prep Zylon torpedo's z-velocity := -80 <KM/H>
              05803
AC3E BDAD09   05804                 LDA ZPOSSIGN,X          ; Prep Zylon ship's sign of z-coordinate
AC41 4A       05805                 LSR A                   ;
AC42 BD400A   05806                 LDA ZPOSHI,X            ; Prep Zylon ship's z-coordinate
AC45 B008     05807                 BCS SKIP110             ; Skip if Zylon ship in front...
AC47 49FF     05808                 EOR #$FF                ; ...else invert loaded Zylon ship's z-coordinate
              05809
AC49 A462     05810                 LDY MISSIONLEVEL        ; Return (no torpedo from back) if NOVICE mission
AC4B F0E4     05811                 BEQ SKIP108             ;
              05812
AC4D A050     05813                 LDY #80                 ; Preload Zylon torpedo's z-velocity := +80 <KM/H>
              05814
              05815 ;*** Is Zylon ship in range? ***************************************************
AC4F C920     05816 SKIP110         CMP #$20                ; Return if Zylon ship too far...
AC51 B0DE     05817                 BCS SKIP108             ; ... (ABS(z-coordinate) > 8192 ($20**) <KM>)
              05818
AC53 8C680B   05819                 STY PL2ZVEL             ; Store Zylon photon torpedo's z-velocity
              05820
              05821 ;*** Launch Zylon photon torpedo! **********************************************
              05822
AC56 A900     05823                 LDA #0                  ; PLAYER2 is PHOTON TORPEDO (shape type 0)
AC58 8D8E0C   05824                 STA PL2SHAPTYPE         ;
AC5B 8D2C0C   05825                 STA PL2COLUMN           ; Zylon torpedo PLAYER column number := 0 (offscreen)
AC5E A93E     05826                 LDA #62                 ;
AC60 85EB     05827                 STA PL2LIFE             ; Zylon torpedo lifetime := 62 game loops
              05828
AC62 A202     05829                 LDX #2                  ; Prep source index for position vector copy
AC64 A4A7     05830                 LDY CTRLDZYLON          ; Prep destination index for position vector copy
AC66 84BF     05831                 STY ZYLONATTACKER       ; Save Zylon ship index for tracking computer
AC68 4CAFAC   05832                 JMP COPYPOSVEC          ; Copy position vector from Zylon ship to its torpedo
              05833
              05834 ;*******************************************************************************
              05835 ;*                                                                             *
              05836 ;*                                  INITEXPL                                   *
              05837 ;*                                                                             *
              05838 ;*                            Initialize explosion                             *
              05839 ;*                                                                             *
              05840 ;*******************************************************************************
              05841
              05842 ; DESCRIPTION
              05843 ;
              05844 ; Initializes the explosion's lifetime, the explosion fragments' position and
              05845 ; velocity vectors as well as their pixel row and column numbers.
              05846 ;
              05847 ; An explosion has a lifetime of 128 game loop iterations. It consists of 32
              05848 ; explosion fragment space objects with indices 17..48. The position vector of
              05849 ; each explosion fragment is copied from the exploding PLAYER space object.
              05850 ;
              05851 ; The pixel column number of each explosion fragment is initialized to
              05852 ;
              05853 ;     PIXEL COLUMN NUMBER := PLAYER column number - 48 + RND(0..15)
              05854 ;
              05855 ; To convert PLAYER column numbers (in Player/Missile (PM) pixels) into pixel
              05856 ; column numbers, the PLAYER column number of the left PLAYFIELD border (= 48)
              05857 ; is subtracted and a random number is added.
              05858 ;
              05859 ; BUG (at $AC76): The added random number should not be in 0..15 but in 0..7
              05860 ; because the exploding PLAYER is 8 pixels wide. The PLAYER column number
              05861 ; represents the left edge of the PLAYER shape. When using a random number in
              05862 ; 0..15, half of the pixels are located off to the right of the PLAYER, outside
              05863 ; the PLAYER area. Suggested fix: Replace instruction AND #$0F with AND #$07.
              05864 ;
              05865 ; The pixel row number of each explosion fragment is initialized to
              05866 ;
              05867 ;     PIXEL ROW NUMBER := (PLAYER row number - RND(0..15)) / 2 - 16
              05868 ;
              05869 ; BUG (at $AC88): To convert PLAYER row numbers (in PM pixels) into pixel row
              05870 ; numbers, the PLAYER row number to the top PLAYFIELD border (= 16) should be
              05871 ; subtracted first, then the division by 2 (instruction LRS A) should be applied
              05872 ; to reduce the double-line PM resolution to the single-line PLAYFIELD
              05873 ; resolution. Suggested fix: Swap instruction LRS A with SBC #16 which leads to
              05874 ; the following formula for the pixel row number:
              05875 ;
              05876 ;     PIXEL ROW NUMBER := (PLAYER row number - 16 + RND(0..15)) / 2
              05877 ;
              05878 ; Incidentally, adding a random number in 0..15 is correct. PLAYER row number
              05879 ; represents the top edge of the PLAYER shape, which is typically 16 PM pixels
              05880 ; tall when representing a close space object.
              05881 ;
              05882 ; The velocity vector of explosion fragments is set to random x, y, and z
              05883 ; velocity vector components in -7..+7 <KM/H>.
              05884 ;
              05885 ; INPUT
              05886 ;
              05887 ;   Y = PLAYER index from which the explosion originates. Used values are:
              05888 ;     0 -> Explosion of PLAYER0 (Zylon ship 0)
              05889 ;     1 -> Explosion of PLAYER1 (Zylon ship 1)
              05890 ;     2 -> Explosion of PLAYER2 (Zylon photon torpedo, starbase, or meteor)
              05891
AC6B A980     05892 INITEXPL        LDA #128                ; Explosion lifetime := 128 game loops
AC6D 8573     05893                 STA EXPLLIFE            ;
              05894
AC6F A230     05895                 LDX #NUMSPCOBJ.ALL-1    ; Max index of space objects (for explosion frags)
AC71 8679     05896                 STX MAXSPCOBJIND        ;
              05897
              05898                                         ; Loop over all explosion fragment position vectors
              05899                                         ; (index 48..17)
AC73 AD0AD2   05900 LOOP040         LDA RANDOM              ; PIXEL COLUMN NUM := PLAYER column - 48 + RND(0..15)
AC76 290F     05901                 AND #$0F                ; (!)
AC78 792A0C   05902                 ADC PL0COLUMN,Y         ;
AC7B E930     05903                 SBC #48                 ;
AC7D 9D2A0C   05904                 STA PIXELCOLUMN,X       ;
              05905
AC80 AD0AD2   05906                 LDA RANDOM              ; PIXEL ROW NUM := (PLAYER row + RND(0..15)) / 2 - 16
AC83 290F     05907                 AND #$0F                ;
AC85 79F90B   05908                 ADC PL0ROWNEW,Y         ;
AC88 4A       05909                 LSR A                   ; (!)
AC89 E910     05910                 SBC #16                 ;
AC8B 9DF90B   05911                 STA PIXELROWNEW,X       ;
              05912
AC8E 20AFAC   05913                 JSR COPYPOSVEC          ; Copy position vector of PLAYER to explosion frag
              05914
AC91 AD0AD2   05915                 LDA RANDOM              ; z-velocity := RND(-7..+7) <KM/H>
AC94 2987     05916                 AND #NEG!7              ;
AC96 9D660B   05917                 STA ZVEL,X              ;
AC99 AD0AD2   05918                 LDA RANDOM              ; x-velocity := RND(-7..+7) <KM/H>
AC9C 2987     05919                 AND #NEG!7              ;
AC9E 9D970B   05920                 STA XVEL,X              ;
ACA1 AD0AD2   05921                 LDA RANDOM              ; y-velocity := RND(-7..+7) <KM/H>
ACA4 2987     05922                 AND #NEG!7              ;
ACA6 9DC80B   05923                 STA YVEL,X              ;
              05924
ACA9 CA       05925                 DEX                     ; Next explosion fragment position vector
ACAA E010     05926                 CPX #16                 ;
ACAC D0C5     05927                 BNE LOOP040             ;
ACAE 60       05928                 RTS                     ; Return
              05929
              05930 ;*******************************************************************************
              05931 ;*                                                                             *
              05932 ;*                                 COPYPOSVEC                                  *
              05933 ;*                                                                             *
              05934 ;*                           Copy a position vector                            *
              05935 ;*                                                                             *
              05936 ;*******************************************************************************
              05937
              05938 ; DESCRIPTION
              05939 ;
              05940 ; Copies a position vector.
              05941 ;
              05942 ; Actually, this subroutine copies the z-coordinate only, then code execution
              05943 ; continues into subroutine COPYPOSXY ($ACC1) to copy the x and y coordinate.
              05944 ;
              05945 ; INPUT
              05946 ;
              05947 ;   X = Destination position vector index. Used values are: 0..48.
              05948 ;   Y = Source position vector index. Used values are: 0..48.
              05949
ACAF B9AD09   05950 COPYPOSVEC      LDA ZPOSSIGN,Y          ;
ACB2 9DAD09   05951                 STA ZPOSSIGN,X          ;
ACB5 B9400A   05952                 LDA ZPOSHI,Y            ;
ACB8 9D400A   05953                 STA ZPOSHI,X            ;
ACBB B9D30A   05954                 LDA ZPOSLO,Y            ;
ACBE 9DD30A   05955                 STA ZPOSLO,X            ;
              05956
              05957 ;*******************************************************************************
              05958 ;*                                                                             *
              05959 ;*                                  COPYPOSXY                                  *
              05960 ;*                                                                             *
              05961 ;*          Copy x and y components (coordinates) of position vector           *
              05962 ;*                                                                             *
              05963 ;*******************************************************************************
              05964
              05965 ; DESCRIPTION
              05966 ;
              05967 ; Copies the x and y components (coordinates) of a position vector.
              05968 ;
              05969 ; INPUT
              05970 ;
              05971 ;   X = Destination position vector index. Used values are: 0..48.
              05972 ;   Y = Source position vector index. Used values are: 0..48.
              05973
ACC1 B9DE09   05974 COPYPOSXY       LDA XPOSSIGN,Y          ;
ACC4 9DDE09   05975                 STA XPOSSIGN,X          ;
ACC7 B9710A   05976                 LDA XPOSHI,Y            ;
ACCA 9D710A   05977                 STA XPOSHI,X            ;
ACCD B90F0A   05978                 LDA YPOSSIGN,Y          ;
ACD0 9D0F0A   05979                 STA YPOSSIGN,X          ;
ACD3 B9A20A   05980                 LDA YPOSHI,Y            ;
ACD6 9DA20A   05981                 STA YPOSHI,X            ;
ACD9 B9040B   05982                 LDA XPOSLO,Y            ;
ACDC 9D040B   05983                 STA XPOSLO,X            ;
ACDF B9350B   05984                 LDA YPOSLO,Y            ;
ACE2 9D350B   05985                 STA YPOSLO,X            ;
ACE5 60       05986 SKIP111         RTS                     ; Return
              05987
              05988 ;*******************************************************************************
              05989 ;*                                                                             *
              05990 ;*                                   DOCKING                                   *
              05991 ;*                                                                             *
              05992 ;*      Handle docking at starbase, launch and return of transfer vessel       *
              05993 ;*                                                                             *
              05994 ;*******************************************************************************
              05995
              05996 ; DESCRIPTION
              05997 ;
              05998 ; Handles docking at a starbase, launching and returning the transfer vessel,
              05999 ; and repairing our starship's subsystems.
              06000 ;
              06001 ; This subroutine changes, if in Front view, the PLAYER-PLAYFIELD priority such
              06002 ; that PLAYERs like the starbase appear behind the cross hairs, which are part
              06003 ; of the PLAYFIELD.
              06004 ;
              06005 ; BUG (at $ACEE): The starbase also appears behind the stars, which are also
              06006 ; part of the PLAYFIELD - a rarely noticed glitch. In Aft view, the arrangement
              06007 ; is reversed: PLAYERs are arranged in front of the PLAYFIELD. Then the starbase
              06008 ; (and the transfer vessel) appear in front of the cross hairs! Suggested fix:
              06009 ; None, technically not possible.
              06010 ;
              06011 ; The starbase is tracked and the PLAYER0..2 shape types are set to STARBASE
              06012 ; RIGHT, STARBASE LEFT, and STARBASE CENTER, respectively, combining them into a
              06013 ; 3-part starbase shape.
              06014 ;
              06015 ; If this sector is still marked as a starbase sector but no more so on the
              06016 ; Galactic Chart (if in the meantime either Zylon units have surrounded this
              06017 ; sector and destroyed the starbase or you have destroyed the starbase with a
              06018 ; photon torpedo) then the noise sound pattern SHIELD EXPLOSION is played in
              06019 ; subroutine NOISE ($AEA8) and code execution returns.
              06020 ;
              06021 ; Otherwise a minimum distance to the starbase of +32 (+$0020) <KM> is enforced
              06022 ; and the conditions for a successful docking are checked:
              06023 ;
              06024 ; DOCKING CONDITIONS
              06025 ;
              06026 ; A docking is successful if all of the following conditions are met:
              06027 ;
              06028 ; (1)  The PLAYER2 (STARBASE CENTER) column number is in 120..135.
              06029 ;
              06030 ;      BUG (at $AD39): At first glance, the PLAYER column interval of 120..135
              06031 ;      corresponds to an almost symmetric interval of -8..+7 PM pixels relative
              06032 ;      to the horizontal center of the PLAYFIELD, at PLAYER column number 128
              06033 ;      (48 PM pixels offset to left PLAYFIELD border + 80 PM pixels to the
              06034 ;      PLAYFIELD center). This is correct only if the PLAYER column number were
              06035 ;      to designate the horizontal center of the PLAYER. However it designates
              06036 ;      its left edge! Thus the used pixel column number range 120..135 creates
              06037 ;      an asymmetric horizontal docking position: A docking is successful if the
              06038 ;      horizontal position of the starbase shape's center is roughly -5..+10 PM
              06039 ;      pixels relative to the horizontal center of the PLAYFIELD. Suggested fix:
              06040 ;      Replace SBC #120 with SBC #117. This leads to an interval of -8..+7
              06041 ;      pixels relative to the horizontal center of the PLAYFIELD and better
              06042 ;      symmetry in the horizontal docking position.
              06043 ;
              06044 ; (2)  The PLAYER2 (STARBASE CENTER) row number is in 104..119.
              06045 ;
              06046 ;      BUG (at $AD43): The PLAYER row interval of 104..119 corresponds to an
              06047 ;      asymmetric interval of -20..-5 PM pixels relative to the vertical center
              06048 ;      of the PLAYFIELD, at pixel row number 80 or PLAYER row number 124. It
              06049 ;      lets you dock at a starbase that "sits" on top of the horizontal cross
              06050 ;      hairs but not at one that "hangs" from them. Suggested fix: Replace SBC
              06051 ;      #104 with SBC #108. This leads to an interval of -8..+7 pixels relative
              06052 ;      to the vertical center of the PLAYFIELD (assuming a PLAYER2 shape of 16
              06053 ;      pixel height, which is typical during docking) and better symmetry in the
              06054 ;      vertical docking position.
              06055 ;
              06056 ; (3)  The starbase is in correct distance in front of our starship: The
              06057 ;      starbase's z-coordinate must be < +512 (+$02**) <KM>.
              06058 ;
              06059 ; (4)  Our starship is horizontally level with the starbase: The starbase's
              06060 ;      y-coordinate must be < +256 (+$01**) <KM>.
              06061 ;
              06062 ; (5)  Our starship is at a complete halt.
              06063 ;
              06064 ; DOCKING SUCCESSFUL
              06065 ;
              06066 ; If the conditions for a successful docking are met, the subsequent docking and
              06067 ; transfer operation can be divided in the following states, starting with state
              06068 ; NOT DOCKED:
              06069 ;
              06070 ; (1)  NOT DOCKED
              06071 ;
              06072 ;      The docking state is set to ORBIT ESTABLISHED and the title line is
              06073 ;      updated with "ORBIT ESTABLISHED".
              06074 ;
              06075 ; (2)  ORBIT ESTABLISHED
              06076 ;
              06077 ;      After waiting until the title line "ORBIT ESTABLISHED" has disappeared,
              06078 ;      the transfer vessel is initialized and launched: The PLAYER4 shape type
              06079 ;      is set to TRANSFER VESSEL. Its position vector is set to a position above
              06080 ;      and in front of our starship, but behind the starbase:
              06081 ;
              06082 ;          x-coordinate :=     +0..+255 (+$00**) <KM>
              06083 ;          y-coordinate :=   +256..+511 (+$01**) <KM>
              06084 ;          z-coordinate := +4096..+4351 (+$10**) <KM>
              06085 ;
              06086 ;      Its velocity vector is set to
              06087 ;
              06088 ;          x-velocity   := +1 <KM/H>
              06089 ;          y-velocity   := -1 <KM/H>
              06090 ;          z-velocity   := -7 <KM/H>
              06091 ;
              06092 ;      This will move the transfer vessel from behind the starbase into a
              06093 ;      direction toward and a little to the lower right of our starship. The
              06094 ;      lifetime of the transfer vessel (and its return journey) is set to 129
              06095 ;      game loop iterations. Finally, the docking state is set to RETURN
              06096 ;      TRANSFER VESSEL.
              06097 ;
              06098 ; (3)  RETURN TRANSFER VESSEL
              06099 ;
              06100 ;      After checking if the transfer vessel has passed behind our starship, the
              06101 ;      beeper sound pattern ACKNOWLEDGE is played in subroutine BEEP ($B3A6),
              06102 ;      the title line is updated with "TRANSFER COMPLETE", our starship's
              06103 ;      subsystems are repaired, and our starship's ENERGY readout is restored to
              06104 ;      9999 energy units. by inverting the z-velocity the velocity vector of the
              06105 ;      transfer vessel is changed to
              06106 ;
              06107 ;          x-velocity   := +1 <KM/H>
              06108 ;          y-velocity   := -1 <KM/H>
              06109 ;          z-velocity   := +7 <KM/H>
              06110 ;
              06111 ;      thus launching the transfer vessel on its return journey to the starbase.
              06112 ;      The docking state is set to TRANSFER COMPLETE. Finally, the screen is
              06113 ;      updated in subroutine UPDSCREEN ($B07B).
              06114 ;
              06115 ; (4)  TRANSFER COMPLETE
              06116 ;
              06117 ;      This docking state marks the end of a successful docking and transfer
              06118 ;      operation.
              06119 ;
              06120 ; DOCKING ABORTED
              06121 ;
              06122 ; If the docking conditions above are not met and the docking state is already
              06123 ; ORBIT ESTABLISHED or RETURN TRANSFER VESSEL then the message "DOCKING ABORTED"
              06124 ; is displayed and the docking state is set to NOT DOCKED.
              06125
ACE6 A57B     06126 DOCKING         LDA ISSTARBASESECT      ; Return if not in starbase sector
ACE8 F0FB     06127                 BEQ SKIP111             ;
              06128
ACEA A5D0     06129                 LDA SHIPVIEW            ; Skip if not in Front view
ACEC D005     06130                 BNE SKIP112             ;
ACEE A914     06131                 LDA #$14                ; GTIA: enable PLAYER4, prio: PFs > PLs > BGR (!)
ACF0 8D1BD0   06132                 STA PRIOR               ; (Cross hairs appear behind PLAYERs)
              06133
ACF3 A902     06134 SKIP112         LDA #2                  ; Track starbase (PLAYER2)
ACF5 8D5C09   06135                 STA TRACKDIGIT          ;
              06136
              06137 ;** Initialize starbase shape **************************************************
ACF8 A930     06138                 LDA #SHAP.STARBASEC     ; PLAYER2 is STARBASE CENTER (shape type 3)
ACFA 8D8E0C   06139                 STA PL2SHAPTYPE         ;
ACFD A920     06140                 LDA #SHAP.STARBASEL     ; PLAYER1 is STARBASE LEFT (shape type 2)
ACFF 8D8D0C   06141                 STA PL1SHAPTYPE         ;
AD02 A940     06142                 LDA #SHAP.STARBASER     ; PLAYER0 is STARBASE RIGHT (shape type 4)
AD04 8D8C0C   06143                 STA PL0SHAPTYPE         ;
              06144
AD07 A9FF     06145                 LDA #255                ; Prep starbase lifetime := 255 game loops (infinite)
              06146
AD09 A690     06147                 LDX CURRSECTOR          ; Skip if starbase in current sector
AD0B BCC908   06148                 LDY GCMEMMAP,X          ;
AD0E 3002     06149                 BMI SKIP113             ;
              06150
AD10 A900     06151                 LDA #0                  ; Prep starbase lifetime := 0 game loops (fast death)
              06152
AD12 85E9     06153 SKIP113         STA PL0LIFE             ; PLAYER0 lifetime := either 0 or 255 game loops
AD14 85EA     06154                 STA PL1LIFE             ; PLAYER1 lifetime := either 0 or 255 game loops
AD16 85EB     06155                 STA PL2LIFE             ; PLAYER2 lifetime := either 0 or 255 game loops
AD18 857B     06156                 STA ISSTARBASESECT      ; Store starbase-in-sector flag
AD1A 300A     06157                 BMI SKIP114             ; Skip if starbase in current sector
              06158
AD1C A002     06159                 LDY #2                  ; Init explosion at PLAYER2 (STARBASE CENTER)
AD1E 206BAC   06160                 JSR INITEXPL            ;
              06161
AD21 A20A     06162                 LDX #$0A                ; Play noise sound pattern SHIELD EXPLOSION and return
AD23 4CA8AE   06163                 JMP NOISE               ;
              06164
              06165 ;*** Keep minimum distance to starbase *****************************************
AD26 AD420A   06166 SKIP114         LDA PL2ZPOSHI           ; Skip if starbase z-coordinate > +255 (+$00**) <KM>
AD29 D00A     06167                 BNE SKIP115             ;
              06168
AD2B ADD50A   06169                 LDA PL2ZPOSLO           ; Approach starbase not closer than +32 (+$0020) <KM>
AD2E C920     06170                 CMP #32                 ;
AD30 B003     06171                 BCS SKIP115             ;
AD32 EED50A   06172                 INC PL2ZPOSLO           ; ...else push starbase back
              06173
              06174 ;*** Check if in docking range *************************************************
AD35 AD2C0C   06175 SKIP115         LDA PL2COLUMN           ; Abort docking if PLAYER column number of...
AD38 38       06176                 SEC                     ; ...PLAYER2 (STARBASE CENTER) not in 120..135.
AD39 E978     06177                 SBC #120                ; (!)
AD3B C910     06178                 CMP #16                 ;
AD3D B022     06179                 BCS SKIP116             ;
              06180
AD3F ADFB0B   06181                 LDA PL2ROWNEW           ; Abort docking if PLAYER row number of...
AD42 38       06182                 SEC                     ; ...PLAYER2 (STARBASE CENTER) not in 104..119.
AD43 E968     06183                 SBC #104                ; (!)
AD45 C910     06184                 CMP #16                 ;
AD47 B018     06185                 BCS SKIP116             ;
              06186
AD49 AD420A   06187                 LDA PL2ZPOSHI           ; Abort docking if...
AD4C C902     06188                 CMP #2                  ; ... z-coordinate of starbase >= +512 (+$02**) <KM>
AD4E B011     06189                 BCS SKIP116             ;
              06190
AD50 ADAF09   06191                 LDA PL2ZPOSSIGN         ; Abort docking...
AD53 2D110A   06192                 AND PL2YPOSSIGN         ; ...if starbase not in front and upper screen half
AD56 4901     06193                 EOR #$01                ;
AD58 0570     06194                 ORA VELOCITYLO          ; ...if our starship's velocity not zero
AD5A 0DA40A   06195                 ORA PL2YPOSHI           ; ...if starbase not roughly vertically centered
AD5D 0571     06196                 ORA NEWVELOCITY         ; ...if our starship's new velocity not zero
AD5F F010     06197                 BEQ SKIP119             ; Else skip and handle docking
              06198
              06199 ;*** Docking aborted ***********************************************************
AD61 A575     06200 SKIP116         LDA DOCKSTATE           ; Skip if DOCKSTATE is NOT DOCKED, TRANSFER COMPLETE
AD63 C902     06201                 CMP #2                  ;
AD65 9005     06202                 BCC SKIP117             ;
              06203
AD67 A01F     06204                 LDY #$1F                ; Set title phrase "DOCKING ABORTED"
AD69 2023B2   06205                 JSR SETTITLE            ;
              06206
AD6C A900     06207 SKIP117         LDA #0                  ; DOCKSTATE := NOT DOCKED
AD6E 8575     06208                 STA DOCKSTATE           ;
AD70 60       06209 SKIP118         RTS                     ; Return
              06210
              06211 ;*** Docking successful, check docking state ***********************************
AD71 2475     06212 SKIP119         BIT DOCKSTATE           ; Check DOCKSTATE
AD73 700D     06213                 BVS SKIP120             ; If DOCKSTATE = ORBIT ESTABLISHED hide title line
AD75 3042     06214                 BMI SKIP122             ; If DOCKSTATE = RETURN TRANSFER VESSEL return it
AD77 A575     06215                 LDA DOCKSTATE           ;
AD79 D0F5     06216                 BNE SKIP118             ; Return if DOCKSTATE not NOT DOCKED
AD7B C675     06217                 DEC DOCKSTATE           ; DOCKSTATE := ORBIT ESTABLISHED
              06218
AD7D A01C     06219                 LDY #$1C                ; Set title phrase "ORBIT ESTABLISHED" and return
AD7F 4C23B2   06220                 JMP SETTITLE            ;
              06221
              06222 ;*** Orbit established *********************************************************
AD82 A200     06223 SKIP120         LDX #0                  ; Enqueue new, empty title phrase
AD84 8665     06224                 STX NEWTITLEPHR         ;
              06225
AD86 A4D1     06226                 LDY TITLEPHR            ; Return if "ORBIT ESTABLISHED" still displayed
AD88 D0E6     06227                 BNE SKIP118             ;
              06228
              06229 ;*** Launch transfer vessel ****************************************************
AD8A A950     06230                 LDA #SHAP.TRANSVSSL     ; PLAYER4 is TRANSFER VESSEL (shape 5)
AD8C 8D900C   06231                 STA PL4SHAPTYPE         ;
              06232
AD8F A901     06233                 LDA #1                  ; Place transfer vessel behind starbase:
AD91 8DB109   06234                 STA PL4ZPOSSIGN         ; x-coordinate :=    +0..+255  (+$00**) <KM>
AD94 8DE209   06235                 STA PL4XPOSSIGN         ; y-coordinate :=  +256..+511  (+$01**) <KM>
AD97 8D130A   06236                 STA PL4YPOSSIGN         ; z-coordinate := +4096..+4351 (+$10**) <KM>
AD9A 8DA60A   06237                 STA PL4YPOSHI           ;
AD9D 8D9B0B   06238                 STA PL4XVEL             ; Move transfer vessel toward our starship:
ADA0 A910     06239                 LDA #$10                ; x-velocity := +1 <KM/H>
ADA2 8D440A   06240                 STA PL4ZPOSHI           ; y-velocity := -1 <KM/H>
ADA5 A900     06241                 LDA #$00                ; z-velocity := -7 <KM/H>
ADA7 8D750A   06242                 STA PL4XPOSHI           ;
ADAA A987     06243                 LDA #NEG!7              ;
ADAC 8D6A0B   06244                 STA PL4ZVEL             ;
ADAF A981     06245                 LDA #NEG!1              ; DOCKSTATE := RETURN TRANSFER VESSEL
ADB1 8575     06246                 STA DOCKSTATE           ;
ADB3 8DCC0B   06247                 STA PL4YVEL             ;
ADB6 85ED     06248                 STA PL4LIFE             ; Transfer vessel lifetime := 129 game loops
ADB8 60       06249 SKIP121         RTS                     ; Return
              06250
              06251 ;*** Return transfer vessel ****************************************************
ADB9 ADB109   06252 SKIP122         LDA PL4ZPOSSIGN         ; Return if transfer vessel in front of our starship
ADBC D0FA     06253                 BNE SKIP121             ;
              06254
ADBE A20C     06255                 LDX #$0C                ; Play beeper sound pattern ACKNOWLEGDE
ADC0 20A6B3   06256                 JSR BEEP                ;
              06257
ADC3 A021     06258                 LDY #$21                ; Set title phrase "TRANSFER COMPLETE"
ADC5 2023B2   06259                 JSR SETTITLE            ;
              06260
ADC8 A205     06261                 LDX #5                  ; Repair all 6 subsystems
ADCA BD8BBB   06262 LOOP041         LDA PANELTXTTAB+73,X    ;
ADCD 9D9209   06263                 STA GCSTATPHO,X         ;
ADD0 CA       06264                 DEX                     ;
ADD1 10F7     06265                 BPL LOOP041             ;
              06266
ADD3 A989     06267                 LDA #CCS.COL2!CCS.9     ; Set starship's ENERGY readout to "9999" in COLOR2
ADD5 A203     06268                 LDX #3                  ;
ADD7 9D5509   06269 LOOP042         STA ENERGYD1,X          ;
ADDA CA       06270                 DEX                     ;
ADDB 10FA     06271                 BPL LOOP042             ;
              06272
ADDD A907     06273                 LDA #7                  ; Move transfer vessel back toward starbase:
ADDF 8D6A0B   06274                 STA PL4ZVEL             ; x-velocity := -1 <KM/H>
ADE2 A981     06275                 LDA #NEG!1              ; y-velocity := +1 <KM/H>
ADE4 8D9B0B   06276                 STA PL4XVEL             ; z-velocity := +7 <KM/H>
ADE7 A901     06277                 LDA #1                  ;
ADE9 8DCC0B   06278                 STA PL4YVEL             ;
              06279
ADEC 8575     06280                 STA DOCKSTATE           ; DOCKSTATE := TRANSFER COMPLETE
ADEE 4C7BB0   06281                 JMP UPDSCREEN           ; Update screen and return
              06282
              06283 ;*******************************************************************************
              06284 ;*                                                                             *
              06285 ;*                                   MODDLST                                   *
              06286 ;*                                                                             *
              06287 ;*                             Modify Display List                             *
              06288 ;*                                                                             *
              06289 ;*******************************************************************************
              06290
              06291 ; DESCRIPTION
              06292 ;
              06293 ; Modifies the Display List to show and hide title, headers, and the Control
              06294 ; Panel Display.
              06295 ;
              06296 ; INPUT
              06297 ;
              06298 ;   A = Number of bytes to copy into the Display List
              06299 ;   X = Offset into Display List DSPLST ($0280)
              06300 ;   Y = Offset into Display List fragment table DLSTFRAG ($BA62). If Y = $80
              06301 ;       then no bytes are copied but the specified locations of the Display List
              06302 ;       are overwritten with Display List instruction $0D (one row of
              06303 ;       GRAPHICS7).
              06304 ;
              06305 ;   Used values are:
              06306 ;
              06307 ;    A    X    Y
              06308 ;   $08  $5F  $00 -> Show Control Panel Display (bottom text window)
              06309 ;   $08  $5F  $80 -> Hide Control Panel Display (bottom text window)
              06310 ;   $07  $0F  $23 -> Show title line
              06311 ;   $07  $0F  $80 -> Hide title line
              06312 ;   $08  $02  $1B -> Show Display List header line of Front view
              06313 ;   $08  $02  $13 -> Show Display List header line of Aft view
              06314 ;   $08  $02  $0B -> Show Display List header line of Long-Range Scan view
              06315 ;   $08  $02  $08 -> Show Display List header line of Galactic Chart view
              06316
    =006A     06317 L.NUMBYTES      = $6A                   ; Number of bytes to copy
              06318
ADF1 78       06319 MODDLST         SEI                     ; Disable IRQ
ADF2 856A     06320                 STA L.NUMBYTES          ; Save number of bytes to copy
              06321
ADF4 AD0BD4   06322 LOOP043         LDA VCOUNT              ; Wait for ANTIC line counter >= 124 (PLAYFIELD...
ADF7 C97C     06323                 CMP #124                ; ...bottom) before changing the Display List
ADF9 90F9     06324                 BCC LOOP043             ;
              06325
ADFB B962BA   06326 LOOP044         LDA DLSTFRAG,Y          ; Load byte from Display List fragment table
ADFE C8       06327                 INY                     ;
ADFF 1002     06328                 BPL SKIP123             ; Skip if fragment table index < $80
AE01 A90D     06329                 LDA #$0D                ; Prep Display List instruction $0D (GRAPHICS7)
AE03 9D8002   06330 SKIP123         STA DSPLST,X            ; Store byte in Display List
AE06 E8       06331                 INX                     ;
AE07 C66A     06332                 DEC L.NUMBYTES          ;
AE09 D0F0     06333                 BNE LOOP044             ; Copy next byte
              06334
AE0B 58       06335                 CLI                     ; Enable IRQ
AE0C 60       06336                 RTS                     ; Return
              06337
              06338 ;*******************************************************************************
              06339 ;*                                                                             *
              06340 ;*                                CLRPLAYFIELD                                 *
              06341 ;*                                                                             *
              06342 ;*                           Clear PLAYFIELD memory                            *
              06343 ;*                                                                             *
              06344 ;*******************************************************************************
              06345
              06346 ; DESCRIPTION
              06347 ;
              06348 ; Clears PLAYFIELD memory from $1000 to $1FFF.
              06349 ;
              06350 ; This subroutine sets the start address of the memory to be cleared then code
              06351 ; execution continues into subroutine CLRMEM ($AE0F) where the memory is
              06352 ; actually cleared.
              06353
AE0D A910     06354 CLRPLAYFIELD    LDA #$10
              06355
              06356 ;*******************************************************************************
              06357 ;*                                                                             *
              06358 ;*                                   CLRMEM                                    *
              06359 ;*                                                                             *
              06360 ;*                                Clear memory                                 *
              06361 ;*                                                                             *
              06362 ;*******************************************************************************
              06363
              06364 ; DESCRIPTION
              06365 ;
              06366 ; Clears memory from a given start address to memory address $1FFF. This
              06367 ; subroutine is called in the following situations:
              06368 ;
              06369 ; (1)  In routine INITCOLD ($A14A) at the beginning of the program to initialize
              06370 ;      the program's variables
              06371 ;
              06372 ; (2)  In subroutine CLRPLAYFIELD ($AE0D) to clear PLAYFIELD memory.
              06373 ;
              06374 ; As a side effect this subroutine also clears the saved number of space objects
              06375 ; and the lock-on flag.
              06376 ;
              06377 ; INPUT
              06378 ;
              06379 ;   A = Start address (high byte) of memory to be cleared. Used values are:
              06380 ;     $02 -> Clear memory $0200..$1FFF during program initialization
              06381 ;     $10 -> Clear PLAYFIELD memory $1000..$1FFF
              06382
AE0F 8569     06383 CLRMEM          STA MEMPTR+1            ; Store start address (high byte) to be cleared
AE11 A900     06384                 LDA #0                  ; Store start address (low byte) to be cleared
AE13 A8       06385                 TAY                     ;
AE14 8568     06386                 STA MEMPTR              ;
              06387
AE16 85A3     06388                 STA ISINLOCKON          ; Clear lock-on flag
AE18 857A     06389                 STA OLDMAXSPCOBJIND     ; Clear saved number of space objects
              06390
AE1A 9168     06391 LOOP045         STA (MEMPTR),Y          ; Clear memory location
AE1C C8       06392                 INY                     ;
AE1D D0FB     06393                 BNE LOOP045             ;
              06394
AE1F E669     06395                 INC MEMPTR+1            ; Next page (= 256-byte block)
AE21 A469     06396                 LDY MEMPTR+1            ;
AE23 C020     06397                 CPY #$20                ;
AE25 A8       06398                 TAY                     ;
AE26 90F2     06399                 BCC LOOP045             ; Loop until memory address $2000 reached
AE28 60       06400                 RTS                     ; Return
              06401
              06402 ;*******************************************************************************
              06403 ;*                                                                             *
              06404 ;*                                   TRIGGER                                   *
              06405 ;*                                                                             *
              06406 ;*                           Handle joystick trigger                           *
              06407 ;*                                                                             *
              06408 ;*******************************************************************************
              06409
              06410 ; DESCRIPTION
              06411 ;
              06412 ; This subroutine handles the joystick trigger and launches one of our
              06413 ; starship's photon torpedo. If a target is in full lock-on then a second photon
              06414 ; torpedo is prepared for automatic launch in the next game loop iteration.
              06415 ;
              06416 ; DETAILS
              06417 ;
              06418 ; If the trigger is pressed then reset the idle counter and, if not in
              06419 ; hyperwarp, launch a photon torpedo with the following steps:
              06420 ;
              06421 ; (1)  If the trigger was pressed in this game loop iteration, a photon torpedo
              06422 ;      will be launched if a previously launched photon torpedo is already under
              06423 ;      way for at least 255 - 232 = 23 game loop iterations. This avoids firing
              06424 ;      photon torpedoes too rapidly.
              06425 ;
              06426 ; (2)  Start tracking a space object. If it is in full lock-on, set up the
              06427 ;      lock-on timer, activate photon torpedo tracking, and tweak the last saved
              06428 ;      trigger state such that our other photon torpedo (if available) is
              06429 ;      launched automatically in the next game loop iteration.
              06430 ;
              06431 ; (3)  If the Photon Torpedoes are destroyed, do nothing.
              06432 ;
              06433 ; (4)  If the Photon Torpedoes are damaged, launch a photon torpedo from the
              06434 ;      same barrel than the previous one.
              06435 ;
              06436 ; (5)  If the Photon Torpedoes are not damaged, launch a photon torpedo from the
              06437 ;      other barrel.
              06438 ;
              06439 ; (6)  Set the lifetime of our starship's photon torpedo to infinite, set the
              06440 ;      PLAYER shape to PHOTON TORPEDO.
              06441 ;
              06442 ; (7)  Initialize the position vector of our starship's photon torpedo to:
              06443 ;
              06444 ;          x-coordinate := +256 (+$0100) <KM> (Right barrel)
              06445 ;                          -256 (-$FF00) <KM> (Left barrel)
              06446 ;          y-coordinate := -256 (-$FF00) <KM>
              06447 ;          z-coordinate :=   +1 (+$0001) <KM>
              06448 ;
              06449 ; (8)  Initialize the velocity vector of our starship's photon torpedo to:
              06450 ;
              06451 ;          x-velocity   :=   +0 <KM/H>
              06452 ;          y-velocity   :=   +0 <KM/H>
              06453 ;          z-velocity   := +102 <KM/H> (All views but Aft view)
              06454 ;                          -102 <KM/H> (Aft view)
              06455 ;
              06456 ; (9)  Subtract 10 energy units for launching our starship's photon torpedo.
              06457 ;
              06458 ; (10) Play the noise sound pattern PHOTON TORPEDO LAUNCHED by continuing code
              06459 ;      execution into subroutine NOISE ($AEA8).
              06460
AE29 A584     06461 TRIGGER         LDA OLDTRIG0            ; Prep last trigger state
              06462
AE2B AC10D0   06463                 LDY TRIG0               ; Copy current trigger state
AE2E 8484     06464                 STY OLDTRIG0            ;
AE30 D00E     06465                 BNE SKIP124             ; Return if trigger currently not pressed
              06466
AE32 8466     06467                 STY IDLECNTHI           ; Reset idle counter
              06468
AE34 A6C0     06469                 LDX WARPSTATE           ; Return if hyperwarp engaged
AE36 D008     06470                 BNE SKIP124             ;
              06471
AE38 A687     06472                 LDX BARRELNR            ; Prep barrel number (0 -> left, 1 -> right)
              06473
AE3A C901     06474                 CMP #1                  ; If trigger is newly pressed -> handle tracking...
AE3C F003     06475                 BEQ SKIP125             ; ...and launch our starship's photon torpedo...
AE3E B018     06476                 BCS SKIP127             ; ...else launch our starship's photon torpedo only
AE40 60       06477 SKIP124         RTS                     ; Return
              06478
              06479 ;*** Set up our starship's photon torpedo tracking *****************************
AE41 B5EC     06480 SKIP125         LDA PL3LIFE,X           ; Return if torpedo's lifetime >= 232 game loops
AE43 C9E8     06481                 CMP #232                ;
AE45 B0F9     06482                 BCS SKIP124             ;
              06483
AE47 AC5C09   06484                 LDY TRACKDIGIT          ; Store index of tracked space object
AE4A 8489     06485                 STY PLTRACKED           ;
              06486
AE4C A90C     06487                 LDA #12                 ; Prep lock-on lifetime := 12 game loops
AE4E A4A3     06488                 LDY ISINLOCKON          ; If target is in full lock-on...
AE50 8486     06489                 STY ISTRACKING          ; ...activate photon torpedo tracking
              06490
AE52 F002     06491                 BEQ SKIP126             ; Skip if target not in full lock-on
AE54 A900     06492                 LDA #0                  ; Prep lock-on lifetime := 0 game loops
AE56 8588     06493 SKIP126         STA LOCKONLIFE          ; Store lock-on lifetime (either 0 or 12 game loops)
              06494
              06495 ;*** Launch our starship's photon torpedo **************************************
AE58 8484     06496 SKIP127         STY OLDTRIG0            ; Update last trigger state
AE5A 2C9209   06497                 BIT GCSTATPHO           ; Return if Photon Torpedoes are destroyed
AE5D 70E1     06498                 BVS SKIP124             ;
              06499
AE5F 3005     06500                 BMI SKIP128             ; If Photon Torpedoes damaged launch from same barrel
AE61 8A       06501                 TXA                     ; ...else switch barrel from which to launch torpedo
AE62 4901     06502                 EOR #$01                ;
AE64 8587     06503                 STA BARRELNR            ;
              06504
AE66 8A       06505 SKIP128         TXA                     ; SUMMARY: Our starship's photon torpedo's...
AE67 9DE109   06506                 STA PL3XPOSSIGN,X       ; x-coordinate := +256 (+$0100) <KM> (right barrel)
AE6A BD73BF   06507                 LDA BARRELXTAB,X        ; x-coordinate := -256 (-$FF00) <KM> (left barrel)
AE6D 9D740A   06508                 STA PL3XPOSHI,X         ; y-coordinate := -256 (-$FF00) <KM>
AE70 A9FF     06509                 LDA #255                ; z-coordinate :=   +1 (+$0001) <KM>
AE72 95EC     06510                 STA PL3LIFE,X           ; ...lifetime := 255 game loops
AE74 9DA50A   06511                 STA PL3YPOSHI,X         ;
AE77 A900     06512                 LDA #0                  ;
AE79 9D8F0C   06513                 STA PL3SHAPTYPE,X       ; PLAYER3 or PLAYER4 is PHOTON TORPEDO (shape type 0)
AE7C 9D430A   06514                 STA PL3ZPOSHI,X         ;
AE7F 9D070B   06515                 STA PL3XPOSLO,X         ;
AE82 9D120A   06516                 STA PL3YPOSSIGN,X       ;
AE85 9D380B   06517                 STA PL3YPOSLO,X         ;
AE88 A901     06518                 LDA #1                  ;
AE8A 9DB009   06519                 STA PL3ZPOSSIGN,X       ;
AE8D 9DD60A   06520                 STA PL3ZPOSLO,X         ;
              06521
AE90 A5D0     06522                 LDA SHIPVIEW            ; SUMMARY: Our starship's photon torpedo's...
AE92 4A       06523                 LSR A                   ; x-velocity :=   +0 <KM/H>
AE93 6A       06524                 ROR A                   ; y-velocity :=   +0 <KM/H>
AE94 0966     06525                 ORA #102                ; z-velocity := +102 <KM/H> (Other views)
AE96 9D690B   06526                 STA PL3ZVEL,X           ; z-velocity := -102 <KM/H> (Aft view)
AE99 A900     06527                 LDA #0                  ;
AE9B 9D9A0B   06528                 STA PL3XVEL,X           ;
AE9E 9DCB0B   06529                 STA PL3YVEL,X           ;
              06530
AEA1 A202     06531                 LDX #2                  ; ENERGY := ENERGY - 10 for launching photon torpedo
AEA3 206FB8   06532                 JSR DECENERGY           ;
              06533
AEA6 A200     06534                 LDX #$00                ; Play noise sound pattern PHOTON TORPEDO LAUNCHED
              06535
              06536 ;*******************************************************************************
              06537 ;*                                                                             *
              06538 ;*                                    NOISE                                    *
              06539 ;*                                                                             *
              06540 ;*                          Copy noise sound pattern                           *
              06541 ;*                                                                             *
              06542 ;*******************************************************************************
              06543
              06544 ; DESCRIPTION
              06545 ;
              06546 ; Copies a 10-byte noise sound pattern from table NOISEPATTAB ($BF20). The first
              06547 ; 8 bytes are copied to the noise sound pattern area NOISETORPTIM
              06548 ; ($DA)..NOISELIFE ($E1), the remaining 2 bytes are copied to audio registers
              06549 ; AUDCTL ($D208) and AUDF3 ($D204). The noise sound pattern is automatically
              06550 ; played in subroutine SOUND ($B2AB).
              06551 ;
              06552 ; NOTE: the first 8 bytes of each pattern in table NOISEPATTAB ($BF20) are
              06553 ; copied in reverse order from memory. See subroutine SOUND ($B2AB) for details
              06554 ; on the noise sound patterns stored in NOISEPATTAB ($BF20).
              06555 ;
              06556 ; Playing a SHIELD EXPLOSION or ZYLON EXPLOSION noise sound pattern overrides a
              06557 ; currently playing PHOTON TORPEDO LAUNCHED noise sound pattern.
              06558 ;
              06559 ; Playing a PHOTON TORPEDO LAUNCHED noise sound pattern overrides a currently
              06560 ; playing PHOTON TORPEDO LAUNCHED noise sound pattern if the latter has < 24
              06561 ; TICKs to play.
              06562 ;
              06563 ; INPUT
              06564 ;
              06565 ;   X = Offset into table NOISEPATTAB ($BF20) to index noise sound patterns.
              06566 ;       Used values are:
              06567 ;     $00 -> PHOTON TORPEDO LAUNCHED
              06568 ;     $0A -> SHIELD EXPLOSION (either our starship or a starbase explodes)
              06569 ;     $14 -> ZYLON EXPLOSION
              06570
AEA8 8A       06571 NOISE           TXA                     ; Skip if SHIELD EXPLOSION or ZYLON EXPLOSION playing
AEA9 D006     06572                 BNE SKIP129             ;
              06573
AEAB A5E1     06574                 LDA NOISELIFE           ; Return if PHOTON TORPEDO LAUNCHED noise sound pat.
AEAD C918     06575                 CMP #24                 ; ...playing for yet more than 24 TICKs
AEAF B018     06576                 BCS SKIP130             ;
              06577
AEB1 A007     06578 SKIP129         LDY #7                  ; Copy noise sound pattern (in reverse order)
AEB3 BD20BF   06579 LOOP046         LDA NOISEPATTAB,X       ;
AEB6 99DA00   06580                 STA NOISETORPTIM,Y      ;
AEB9 E8       06581                 INX                     ;
AEBA 88       06582                 DEY                     ;
AEBB 10F6     06583                 BPL LOOP046             ;
              06584
AEBD BD20BF   06585                 LDA NOISEPATTAB,X       ; Copy AUDCTL from noise sound pattern table
AEC0 8D08D2   06586                 STA AUDCTL              ;
AEC3 BD21BF   06587                 LDA NOISEPATTAB+1,X     ; Copy AUDF3 from noise sound pattern table
AEC6 8D04D2   06588                 STA AUDF3               ;
              06589
AEC9 60       06590 SKIP130         RTS                     ; Return
              06591
              06592 ;*******************************************************************************
              06593 ;*                                                                             *
              06594 ;*                                  HOMINGVEL                                  *
              06595 ;*                                                                             *
              06596 ;*      Calculate homing velocity of our starship's photon torpedo 0 or 1      *
              06597 ;*                                                                             *
              06598 ;*******************************************************************************
              06599
              06600 ; DESCRIPTION
              06601 ;
              06602 ; Calculates the x (or y) velocity vector component of our starship's photon
              06603 ; torpedo 0 or 1 when it is tracking (homing in on) a target space object.
              06604 ;
              06605 ; Our starship's photon torpedo's x (or y) velocity vector component depends on
              06606 ; the PLAYER column (or row) number difference between the target PLAYER and our
              06607 ; starship's photon torpedo PLAYER in Player/Missile (PM) pixels. This
              06608 ; difference is used as an index to pick the new x (or y) velocity vector
              06609 ; component of out starship's photon torpedo from table HOMVELTAB ($BFC9):
              06610 ;
              06611 ; +---------------+--------------+
              06612 ; | Difference in | New Velocity |
              06613 ; |   PM Pixels   |  Component   |
              06614 ; +---------------+--------------+
              06615 ; |    >= +7      |   -64 <KM/H> |
              06616 ; |       +6      |   -56 <KM/H> |
              06617 ; |       +5      |   -48 <KM/H> |
              06618 ; |       +4      |   -40 <KM/H> |
              06619 ; |       +3      |   -24 <KM/H> |
              06620 ; |       +2      |   -16 <KM/H> |
              06621 ; |       +1      |    -8 <KM/H> |
              06622 ; |        0      |     0 <KM/H> |
              06623 ; |       -1      |    +8 <KM/H> |
              06624 ; |       -2      |   +16 <KM/H> |
              06625 ; |       -3      |   +24 <KM/H> |
              06626 ; |       -4      |   +40 <KM/H> |
              06627 ; |       -5      |   +48 <KM/H> |
              06628 ; |       -6      |   +56 <KM/H> |
              06629 ; |    <= -7      |   +64 <KM/H> |
              06630 ; +---------------+--------------+
              06631 ;
              06632 ; INPUT
              06633 ;
              06634 ;   A     = PLAYER column (or row) number difference between the target PLAYER
              06635 ;           and our starship's photon torpedo PLAYER in Player/Missile pixels
              06636 ;
              06637 ;   CARRY = Sign of the PLAYER column (or row) number difference. Used values
              06638 ;           are:
              06639 ;     0 -> Negative difference (target PLAYER column (or row) number < our
              06640 ;          starship's photon torpedo PLAYER column (or row) number
              06641 ;     1 -> Positive difference (target PLAYER column (or row) number >= our
              06642 ;          starship's photon torpedo PLAYER column (or row) number
              06643 ;
              06644 ; OUTPUT
              06645 ;
              06646 ;   A = New velocity vector component of our starship's photon torpedo in <KM/H>
              06647
    =006A     06648 L.VELSIGN       = $6A                   ; Saves velocity sign
              06649
AECA A080     06650 HOMINGVEL       LDY #NEG                ; Preload negative velocity sign
AECC B004     06651                 BCS SKIP131             ; Skip if difference is positive
              06652
AECE 49FF     06653                 EOR #$FF                ; Invert to get absolute value of difference
AED0 A000     06654                 LDY #0                  ; Preload positive velocity sign
              06655
AED2 846A     06656 SKIP131         STY L.VELSIGN           ; Save velocity sign
AED4 C908     06657                 CMP #8                  ;
AED6 9002     06658                 BCC SKIP132             ;
AED8 A907     06659                 LDA #7                  ; Limit difference to 0..7
AEDA A8       06660 SKIP132         TAY                     ;
AEDB A56A     06661                 LDA L.VELSIGN           ; Reload velocity sign
AEDD 19C9BF   06662                 ORA HOMVELTAB,Y         ; Combine with homing velocity from table
AEE0 60       06663                 RTS                     ; Return
              06664
              06665 ;*******************************************************************************
              06666 ;*                                                                             *
              06667 ;*                                   DAMAGE                                    *
              06668 ;*                                                                             *
              06669 ;*             Damage or destroy one of our starship's subsystems              *
              06670 ;*                                                                             *
              06671 ;*******************************************************************************
              06672
              06673 ; DESCRIPTION
              06674 ;
              06675 ; Damages or destroys one of our starship's subsystems. There are 6 subsystems:
              06676 ;
              06677 ; (1)  Photon Torpedoes
              06678 ; (2)  Engines
              06679 ; (3)  Shields
              06680 ; (4)  Attack Computer
              06681 ; (5)  Long-Range Scan
              06682 ; (6)  Subspace Radio
              06683 ;
              06684 ; Their status is stored and displayed in the Galactic Chart Panel Display by
              06685 ; the colored letters PESCLR. The color of each letter represents the
              06686 ; subsystem's status:
              06687 ;
              06688 ; +---------------+------------------+
              06689 ; | Letter Color  | Subsystem Status |
              06690 ; +---------------+------------------+
              06691 ; | {LIGHT GREEN} | OK               |
              06692 ; | {CORN YELLOW} | Damaged          |
              06693 ; | {PINK}        | Destroyed        |
              06694 ; +---------------+------------------+
              06695 ;
              06696 ; This subroutine first makes sure that we are not in demo mode. Then it picks a
              06697 ; random value in 0..255 and the damage probability value. The latter value
              06698 ; depends on the mission level and is picked from table DAMAGEPROBTAB ($BF10):
              06699 ;
              06700 ; +-----------+-------------------+---------------+
              06701 ; |  Mission  |       Damage      |    Damage     |
              06702 ; |   Level   | Probability Value |  Probability  |
              06703 ; +-----------+-------------------+---------------+
              06704 ; | NOVICE    |          0        |  0% (  0:256) |
              06705 ; | PILOT     |         80        | 31% ( 80:256) |
              06706 ; | WARRIOR   |        180        | 70% (180:256) |
              06707 ; | COMMANDER |        254        | 99% (254:256) |
              06708 ; +-----------+-------------------+---------------+
              06709 ;
              06710 ; If the random number is lower than the damage probability value, a randomly
              06711 ; picked subsystem is about to get damaged (or destroyed). There is a built-in
              06712 ; upfront probability of 25% (2:8) that no subsystem gets harmed.
              06713 ;
              06714 ; If the picked subsystem is already destroyed then another subsystem is picked.
              06715 ;
              06716 ; Then the title phrase offset is picked from table DAMAGEPHRTAB ($BF14) to
              06717 ; display the damaged subsystem in the title line. Next, color bits are picked
              06718 ; that indicate a damaged system.
              06719 ;
              06720 ; If the Zylon photon torpedo's lifetime >= 30 game loop iterations the
              06721 ; subsystem will not only be damaged but destroyed.
              06722 ;
              06723 ; NOTE: The Zylon photon torpedo lifetime decreases from 62 to 0 game loop
              06724 ; iterations. With a remaining lifetime >= 30 game loop iterations it is
              06725 ; considered strong enough to destroy one of our starship's subsystems. There
              06726 ; are two exceptions to this rule: If the Attack Computer was picked to be
              06727 ; destroyed it will be damaged only - not destroyed - if the Long-Range Scan has
              06728 ; been already destroyed, and vice versa.
              06729 ;
              06730 ; Then the title phrase offset from table DESTROYPHRTAB ($BF1A) is picked to
              06731 ; display the destroyed subsystem in the title line. Next, color bits are picked
              06732 ; that indicate a destroyed system.
              06733 ;
              06734 ; The color of the subsystem's status letter is adjusted in the Galactic Chart
              06735 ; Panel Display. Next, the title phrase describing the subsystem's status is
              06736 ; enqueued for display in the title line. If the Attack Computer has been
              06737 ; destroyed it is switched off and the PLAYFIELD is cleared. The title line is
              06738 ; updated with the "DAMAGE CONTROL" message. Finally, the beeper sound pattern
              06739 ; DAMAGE REPORT is played in subroutine BEEP ($B3A6).
              06740
AEE1 2464     06741 DAMAGE          BIT ISDEMOMODE          ; Return if in demo mode
AEE3 3057     06742                 BMI SKIP137             ;
              06743
              06744 ;*** Damage some subsystem *****************************************************
AEE5 A662     06745                 LDX MISSIONLEVEL        ; Prep mission level
AEE7 AD0AD2   06746 LOOP047         LDA RANDOM              ; Return if random number >= damage probability
AEEA DD10BF   06747                 CMP DAMAGEPROBTAB,X     ; ...(the latter depends on mission level)
AEED B04D     06748                 BCS SKIP137             ;
              06749
AEEF 2907     06750                 AND #$07                ; Randomly pick 1 of 6 subsystems
AEF1 C906     06751                 CMP #6                  ; Return if no subsystem picked
AEF3 B047     06752                 BCS SKIP137             ;
              06753
AEF5 AA       06754                 TAX                     ;
AEF6 BD9209   06755                 LDA GCSTATPHO,X         ; Get picked subsystem status letter
AEF9 0A       06756                 ASL A                   ; Check bit B6 (= destroyed) of letter code
AEFA 30EB     06757                 BMI LOOP047             ; Try again if subsystem already destroyed
              06758
AEFC A5EB     06759                 LDA PL2LIFE             ; Load Zylon photon torpedo lifetime...
AEFE C91E     06760                 CMP #30                 ; ...and compare it to 30 game loops
              06761
AF00 A980     06762                 LDA #CCS.COL2           ; Preload COLOR2 text color bits (= damaged status)
AF02 BC14BF   06763                 LDY DAMAGEPHRTAB,X      ; Preload title phrase offset of damaged subsystem
              06764
AF05 9017     06765                 BCC SKIP135             ; Skip if Zylon torpedo lifetime < 30 game loops
              06766
AF07 E003     06767                 CPX #3                  ; Skip if selected subsystem not Attack Computer
AF09 D005     06768                 BNE SKIP133             ;
AF0B 2C9609   06769                 BIT GCSTATLRS           ; Skip if Long-Range Scan already destroyed
AF0E 700E     06770                 BVS SKIP135             ;
AF10 E004     06771 SKIP133         CPX #4                  ; Skip if selected subsystem is not Long-Range Scan
AF12 D005     06772                 BNE SKIP134             ;
AF14 2C9509   06773                 BIT GCSTATCOM           ; Skip if Attack Computer already destroyed
AF17 7005     06774                 BVS SKIP135             ;
              06775
AF19 A9C0     06776 SKIP134         LDA #CCS.COL3           ; Preload COLOR3 text color bits (= destroyed status)
AF1B BC1ABF   06777                 LDY DESTROYPHRTAB,X     ; Preload title phrase offset of destroyed subsystem
              06778
AF1E 1D9209   06779 SKIP135         ORA GCSTATPHO,X         ; Combine status letter with new color
AF21 9D9209   06780                 STA GCSTATPHO,X         ;
AF24 8465     06781                 STY NEWTITLEPHR         ; Enqueue damage status title phrase
AF26 2C9509   06782                 BIT GCSTATCOM           ; Skip if Attack Computer OK or damaged
AF29 5007     06783                 BVC SKIP136             ;
              06784
AF2B A900     06785                 LDA #0                  ; Switch Attack Computer off
AF2D 857E     06786                 STA DRAINATTCOMP        ;
AF2F 200DAE   06787                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
              06788
AF32 A052     06789 SKIP136         LDY #$52                ; Set title phrase "DAMAGE CONTROL..."
AF34 2023B2   06790                 JSR SETTITLE            ;
              06791
AF37 A212     06792                 LDX #$12                ; Play beeper sound pattern DAMAGE REPORT
AF39 20A6B3   06793                 JSR BEEP                ;
              06794
AF3C 60       06795 SKIP137         RTS                     ; Return
              06796
              06797 ;*******************************************************************************
              06798 ;*                                                                             *
              06799 ;*                                  COLLISION                                  *
              06800 ;*                                                                             *
              06801 ;*            Detect a collision of our starship's photon torpedoes            *
              06802 ;*                                                                             *
              06803 ;*******************************************************************************
              06804
              06805 ; DESCRIPTION
              06806 ;
              06807 ; Both of our starship's photon torpedoes are checked if they have collided with
              06808 ; a space object represented by PLAYER0..2, such as a Zylon ship, a Zylon photon
              06809 ; torpedo, a starbase, or a meteor.
              06810 ;
              06811 ; For quick lookup, the following table lists the PLAYERs and what space objects
              06812 ; they represent:
              06813 ;
              06814 ; +--------+--------------------------------------------------+
              06815 ; | PLAYER |                   Represents                     |
              06816 ; +--------+--------------------------------------------------+
              06817 ; |   0    | Zylon ship 0, Starbase Left                      |
              06818 ; |   1    | Zylon ship 1, Starbase Right                     |
              06819 ; |   2    | Zylon photon torpedo, Starbase Center, Meteor    |
              06820 ; |   3    | Our starship's photon torpedo 0                  |
              06821 ; |   4    | Our starship's photon torpedo 1, Transfer Vessel |
              06822 ; +--------+--------------------------------------------------+
              06823 ;
              06824 ; NOTE: Only space objects represented by PLAYER0..2 are checked for collisions.
              06825 ; The transfer vessel of the starbase, represented by PLAYER4, is not checked
              06826 ; and therefore cannot be destroyed by one of our starship's photon torpedoes.
              06827 ;
              06828 ; This subroutine first checks if our starship's photon torpedoes are
              06829 ; represented by alive PLAYERs with PHOTON TORPEDO shape.
              06830 ;
              06831 ; In order to detect a collision with a space object, our starship's photon
              06832 ; torpedo must compare its x, y, and z coordinates with the ones of the space
              06833 ; object.
              06834 ;
              06835 ; Instead of comparing the x and y coordinates, however, this subroutines uses a
              06836 ; much more efficient method by inspecting the Player/Missile collision
              06837 ; registers, as the x and y axis of the 3D coordinate system establish the plane
              06838 ; in which the TV screen lies. Each of our starship's photon torpedoes has its
              06839 ; own Player/Missile collision register: PL3HIT ($82) for our starship's photon
              06840 ; torpedo 0 and PL4HIT ($83) for our starship's photon torpedo 1. By inspecting
              06841 ; these registers the hit space object is determined:
              06842 ;
              06843 ; +---------------------------------------------------+-------------------------+
              06844 ; |          Bits B2..0 of Collision Register         |        Hit PLAYER       |
              06845 ; |              (0 -> Not Hit, 1 -> Hit)             |                         |
              06846 ; +-----------------+----------------+----------------+                         |
              06847 ; |     PLAYER2     |     PLAYER1    |    PLAYER0     |                         |
              06848 ; | (Zylon torpedo) | (Zylon ship 1) | (Zylon ship 0) |                         |
              06849 ; +-----------------+----------------+----------------+-------------------------+
              06850 ; |        0        |        0       |        0       | None                    |
              06851 ; |        0        |        0       |        1       | PLAYER0 (Zylon ship 0)  |
              06852 ; |        0        |        1       |        0       | PLAYER1 (Zylon ship 1)  |
              06853 ; |        0        |        1       |        1       | PLAYER1 (Zylon ship 1)  |
              06854 ; |        1        |        0       |        0       | PLAYER2 (Zylon torpedo) |
              06855 ; |        1        |        0       |        1       | PLAYER2 (Zylon torpedo) |
              06856 ; |        1        |        1       |        0       | PLAYER1 (Zylon ship 1)  |
              06857 ; |        1        |        1       |        1       | PLAYER1 (Zylon ship 1)  |
              06858 ; +-----------------+----------------+----------------+-------------------------+
              06859 ;
              06860 ; If the lifetime of the hit space object has already expired, then the hit is
              06861 ; ignored.
              06862 ;
              06863 ; A collision along the z-axis happens if the z-coordinate of our starship's
              06864 ; photon torpedo is close enough to the z-coordinate of the space object:
              06865 ;
              06866 ; The absolute value of the z-coordinate of the space object is converted into a
              06867 ; range index in 0..7. This index picks a minimum and a maximum z-coordinate
              06868 ; from tables HITMINZTAB ($BF7D) and HITMAXZTAB ($BF75). If the absolute value
              06869 ; of the z-coordinate of our starship's photon torpedo is inside this interval,
              06870 ; then our starship's photon torpedo has hit the space object. The following
              06871 ; table lists the relevant values:
              06872 ;
              06873 ; +-----------------------+-------+--------------------------+--------------------------+
              06874 ; | ABS(z-Coordinate)     | Range | Min ABS(z-Coordinate)    | Max ABS(z-Coordinate)    |
              06875 ; | of Space Object       | Index | of Photon Torpedo to Hit | of Photon Torpedo to Hit |
              06876 ; +-----------------------+-------+--------------------------+--------------------------+
              06877 ; | <=   511 ($01**) <KM> |   0   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06878 ; | <=  1023 ($03**) <KM> |   1   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06879 ; | <=  1535 ($05**) <KM> |   2   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06880 ; | <=  2047 ($07**) <KM> |   3   |         512 ($02**) <KM> |      < 3328 ($0C**) <KM> |
              06881 ; | <=  2559 ($09**) <KM> |   4   |        1024 ($04**) <KM> |      < 3840 ($0E**) <KM> |
              06882 ; | <=  3071 ($0B**) <KM> |   5   |        1536 ($06**) <KM> |      < 3840 ($0E**) <KM> |
              06883 ; | <=  3583 ($0D**) <KM> |   6   |        2048 ($08**) <KM> |      < 3840 ($0E**) <KM> |
              06884 ; | <= 65535 ($FF**) <KM> |   7   |        3072 ($0C**) <KM> |      < 8448 ($20**) <KM> |
              06885 ; +-----------------------+-------+--------------------------+--------------------------+
              06886 ;
              06887 ; if a collision has been detected, the "age" (= initial lifetime - remaining
              06888 ; lifetime) of our starship's photon torpedo is calculated. This age is used to
              06889 ; delay playing the ZYLON EXPLOSION noise sound pattern but also to determine
              06890 ; the strength of our starship's photon torpedo. Only photon torpedoes of an age
              06891 ; < 15 game loop iterations can destroy a Zylon basestar.
              06892 ;
              06893 ; Some clean-up work is done before the actual explosion: The lock-on timer, our
              06894 ; starship's photon torpedo lifetime, and the hit space object's PLAYER lifetime
              06895 ; is set to 0.
              06896 ;
              06897 ; If a meteor or a Zylon photon torpedo have been hit, then the score is not
              06898 ; changed, skipping right to the explosion part. Otherwise, our starship's
              06899 ; photon torpedo tracking flag is cleared and the Galactic Chart Map is updated.
              06900 ; If a starbase was destroyed, then 3 points are added to the score. If a Zylon
              06901 ; ship was destroyed, then 6 points are added to the score and the Zylon KILL
              06902 ; COUNTER readout of the Control Panel Display is incremented. Next, the
              06903 ; explosion is initialized in subroutine INITEXPL ($AC6B).
              06904 ;
              06905 ; NOTE: This subroutine lacks proper explosion initialization if the starbase
              06906 ; was hit. The actual explosion initialization is done in subroutine DOCKING
              06907 ; ($ACE6) when the code finds out that the starbase sector is no more marked as
              06908 ; such in the Galactic Chart.
              06909 ;
              06910 ; Finally, the Galactic Chart Map is searched for a remaining Zylon unit. If
              06911 ; none is found then the mission is complete and code execution continues into
              06912 ; subroutine GAMEOVER2 ($B121), ending the game.
              06913
    =006B     06914 L.PLHIT         = $6B                   ; Saves PLAYER (and space object) index of hit PLAYER
    =006C     06915 L.VIEWDIR       = $6C                   ; Saves view direction. Used values are:
              06916                                         ;   $00 -> Front view
              06917                                         ;   $FF -> Aft view
              06918
AF3D A202     06919 COLLISION       LDX #2                  ; Loop over our starship's two photon torpedoes
AF3F CA       06920 LOOP048         DEX                     ;
AF40 1001     06921                 BPL SKIP138             ; Branch into loop body below
AF42 60       06922                 RTS                     ; Return
              06923
              06924 ;*** Photon torpedo sanity checks **********************************************
AF43 BD8F0C   06925 SKIP138         LDA PL3SHAPTYPE,X       ; Next photon torpedo if PLAYER not a PHOTON TORPEDO
AF46 D0F7     06926                 BNE LOOP048             ;
              06927
AF48 B5EC     06928                 LDA PL3LIFE,X           ; Next photon torpedo if PLAYER not alive
AF4A F0F3     06929                 BEQ LOOP048             ;
              06930
              06931 ;*** Check if our starship's photon torpedo has hit in x-y plane ***************
AF4C B582     06932                 LDA PL3HIT,X            ; Check Player/Missile collision register
AF4E 2907     06933                 AND #$07                ; Next torpedo if no torpedo-to-PLAYER collision
AF50 F0ED     06934                 BEQ LOOP048             ;
              06935
AF52 4A       06936                 LSR A                   ; Find out which of PLAYER0..2 was hit in PLAYFIELD
AF53 C903     06937                 CMP #3                  ;
AF55 D001     06938                 BNE SKIP139             ;
AF57 4A       06939                 LSR A                   ;
AF58 A8       06940 SKIP139         TAY                     ; Save resulting index of hit PLAYER
              06941
AF59 B9E900   06942                 LDA PL0LIFE,Y           ; Next torpedo if PLAYER0..2 (= targets) not alive
AF5C F0E1     06943                 BEQ LOOP048             ;
              06944
              06945 ;*** Has our starship's photon torpedo hit within valid z-coordinate interval? *
AF5E A5D0     06946                 LDA SHIPVIEW            ; Skip if in Front view
AF60 F002     06947                 BEQ SKIP140             ;
AF62 A9FF     06948                 LDA #$FF                ; Calculate range index...
AF64 856C     06949 SKIP140         STA L.VIEWDIR           ; Saves view direction
AF66 59400A   06950                 EOR ZPOSHI,Y            ; Calc ABS(z-coordinate (high byte)) of hit object
AF69 C910     06951                 CMP #16                 ; Limit range index to 0..7
AF6B 9002     06952                 BCC SKIP141             ;
AF6D A90F     06953                 LDA #15                 ;
AF6F 4A       06954 SKIP141         LSR A                   ;
AF70 846B     06955                 STY L.PLHIT             ; Save index of hit PLAYER
              06956
AF72 A8       06957                 TAY                     ;
AF73 A56C     06958                 LDA L.VIEWDIR           ; Reload view direction
AF75 5D430A   06959                 EOR PL3ZPOSHI,X         ; Calc ABS(z-coordinate (high byte)) of torpedo
              06960
AF78 D975BF   06961                 CMP HITMAXZTAB,Y        ; Next torpedo if torpedo >= max hit z-coordinate
AF7B B0C2     06962                 BCS LOOP048             ;
              06963
AF7D D97DBF   06964                 CMP HITMINZTAB,Y        ; Next torpedo if torpedo < min hit z-coordinate
AF80 90BD     06965                 BCC LOOP048             ;
              06966
              06967 ;*** Our starship's photon torpedo has hit within valid z-coordinate interval! *
AF82 A46B     06968                 LDY L.PLHIT             ; Reload index of hit PLAYER
AF84 38       06969                 SEC                     ; Calc "age" of photon torpedo in game loops to...
AF85 A9FF     06970                 LDA #255                ; delay playing ZYLON EXPLOSION noise sound pattern
AF87 F5EC     06971                 SBC PL3LIFE,X           ;
AF89 85E2     06972                 STA NOISEZYLONTIM       ;
              06973
AF8B C90F     06974                 CMP #15                 ; Skip if photon torpedo "age" < 15
AF8D 9005     06975                 BCC SKIP142             ;
AF8F B98C0C   06976                 LDA PL0SHAPTYPE,Y       ; CARRY := PLAYER is ZYLON BASESTAR (shape type 8)
AF92 C980     06977                 CMP #SHAP.ZBASESTAR     ; (and torpedo "age" good to destroy ZYLON BASESTAR)
              06978
              06979 ;*** Clean up our starship's photon torpedo and hit PLAYER *********************
AF94 A900     06980 SKIP142         LDA #0                  ; Lock-on lifetime := 0 game loops
AF96 8588     06981                 STA LOCKONLIFE          ;
AF98 95EC     06982                 STA PL3LIFE,X           ; Photon torpedo's lifetime := 0 game loops
AF9A B04B     06983                 BCS SKIP144             ; If CARRY set do not score, just do explosion
              06984
AF9C 99E900   06985                 STA PL0LIFE,Y           ; Hit PLAYER lifetime := 0 game loops
              06986
AF9F B98C0C   06987                 LDA PL0SHAPTYPE,Y       ; If hit PLAYER is...
AFA2 F043     06988                 BEQ SKIP144             ; ...a PHOTON TORPEDO (shape type 0)...
AFA4 C960     06989                 CMP #SHAP.METEOR        ; ...or a METEOR (shape type 6)...
AFA6 F03F     06990                 BEQ SKIP144             ; ...do not score, just do explosion
              06991
AFA8 A900     06992                 LDA #0                  ; Clear photon torpedo tracking flag
AFAA 8586     06993                 STA ISTRACKING          ;
              06994
              06995 ;*** Zylon ship (or starbase) destroyed! ***************************************
AFAC A690     06996                 LDX CURRSECTOR          ; Decrement Zylon count on Galactic Chart
AFAE DEC908   06997                 DEC GCMEMMAP,X          ;
AFB1 1013     06998                 BPL SKIP143             ; Skip if destroyed space object was Zylon ship
              06999
              07000 ;*** Starbase destroyed! *******************************************************
AFB3 A900     07001                 LDA #0                  ; Remove destroyed starbase from Galactic Chart
AFB5 9DC908   07002                 STA GCMEMMAP,X          ;
AFB8 38       07003                 SEC                     ; SCORE := SCORE - 3 for destroying starbase
AFB9 A5CB     07004                 LDA SCORE               ;
AFBB E903     07005                 SBC #3                  ;
AFBD 85CB     07006                 STA SCORE               ;
AFBF A5CC     07007                 LDA SCORE+1             ;
AFC1 E900     07008                 SBC #0                  ;
AFC3 85CC     07009                 STA SCORE+1             ;
AFC5 60       07010                 RTS                     ; Return
              07011
              07012 ;*** Zylon ship destroyed! *****************************************************
AFC6 18       07013 SKIP143         CLC                     ; SCORE := SCORE + 6 for destroying Zylon ship
AFC7 A5CB     07014                 LDA SCORE               ;
AFC9 6906     07015                 ADC #6                  ;
AFCB 85CB     07016                 STA SCORE               ;
AFCD A5CC     07017                 LDA SCORE+1             ;
AFCF 6900     07018                 ADC #0                  ;
AFD1 85CC     07019                 STA SCORE+1             ;
              07020
AFD3 A201     07021                 LDX #1                  ; Increment Zylon KILL COUNTER readout...
AFD5 FE5009   07022 LOOP049         INC KILLCNTD1,X         ; ...of Control Panel Display
AFD8 BD5009   07023                 LDA KILLCNTD1,X         ;
AFDB C94A     07024                 CMP #[CCS.COL1!CCS.9]+1 ;
AFDD 9008     07025                 BCC SKIP144             ;
AFDF A940     07026                 LDA #[CCS.COL1!CCS.0]   ;
AFE1 9D5009   07027                 STA KILLCNTD1,X         ;
AFE4 CA       07028                 DEX                     ;
AFE5 10EE     07029                 BPL LOOP049             ;
              07030
AFE7 206BAC   07031 SKIP144         JSR INITEXPL            ; Init explosion at hit PLAYER
              07032
              07033 ;*** Any Zylon ships left? *****************************************************
AFEA A27F     07034                 LDX #127                ; Scan all sectors of Galactic Chart
AFEC BDC908   07035 LOOP050         LDA GCMEMMAP,X          ;
AFEF 3002     07036                 BMI SKIP145             ;
AFF1 D00A     07037                 BNE SKIP146             ; Return if Zylon sector found
AFF3 CA       07038 SKIP145         DEX                     ;
AFF4 10F6     07039                 BPL LOOP050             ;
              07040
              07041 ;*** Game over (Mission Complete) **********************************************
AFF6 A03F     07042                 LDY #$3F                ; Set title phrase "MISSION COMPLETE"
AFF8 A200     07043                 LDX #0                  ; Set mission bonus offset
AFFA 2021B1   07044                 JSR GAMEOVER2           ; Game over
AFFD 60       07045 SKIP146         RTS                     ; Return
              07046
              07047 ;*******************************************************************************
              07048 ;*                                                                             *
              07049 ;*                                  KEYBOARD                                   *
              07050 ;*                                                                             *
              07051 ;*                            Handle Keyboard Input                            *
              07052 ;*                                                                             *
              07053 ;*******************************************************************************
              07054
              07055 ; DESCRIPTION
              07056 ;
              07057 ; If a keyboard code has been collected during a keyboard IRQ in the Immediate
              07058 ; Interrupt Request handler IRQHNDLR ($A751), the idle counter is reset and the
              07059 ; PLAYER-PLAYFIELD priority arranges the PLAYERs in front of the PLAYFIELD.
              07060 ; Then, the keyboard code is compared with keyboard codes of table KEYTAB
              07061 ; ($BABE). If no match is found the "WHAT'S WRONG" message is displayed in the
              07062 ; title line and code execution returns.
              07063 ;
              07064 ; If one of the speed keys '0'..'9' has been pressed, a pending hyperwarp is
              07065 ; aborted in subroutine ABORTWARP ($A980) and code execution returns. Otherwise
              07066 ; the Engines drain rate is adjusted as well as the new velocity of our
              07067 ; starship. If the Engines are damaged, a maximum speed is possible equivalent
              07068 ; to speed key '5'.
              07069 ;
              07070 ; If one of our starship's view keys 'F' (Front), 'A' (Aft), 'G' (Galactic
              07071 ; Chart), or 'L' (Long-Range Scan) have been pressed, the Display List is
              07072 ; modified accordingly in subroutine MODDLST ($ADF1) and a new star field of 12
              07073 ; stars is created with the help of subroutine INITPOSVEC ($B764). Code
              07074 ; execution returns via subroutine UPDSCREEN ($B07B).
              07075 ;
              07076 ; If one of the 'T' (Tracking Computer), 'S' (Shields) or 'C' (Attack Computer)
              07077 ; keys have been pressed, the corresponding status bits are toggled and the
              07078 ; title line is updated with the corresponding title phrase. The beeper sound
              07079 ; pattern ACKNOWLEDGE is played in subroutine BEEP ($B3A6). The tracking letter
              07080 ; of the Control Panel Display is updated and the PLAYFIELD is cleared in
              07081 ; subroutine CLRPLAYFIELD ($AE0D). If the Attack Computer is on, the Front or
              07082 ; Aft view cross hairs are drawn, depending on the current view of our starship,
              07083 ; via subroutine DRAWLINES ($A76F).
              07084 ;
              07085 ; If the 'H' (Hyperwarp) key has been pressed then the hyperwarp is engaged. Our
              07086 ; starship's velocity is set to the maximum value, the Engines drain rate is
              07087 ; increased to the equivalent of speed key '7'. Star trails are prepared. The
              07088 ; position vector of the Hyperwarp Target Marker (PLAYER3) is set to the
              07089 ; following values:
              07090 ;
              07091 ;     x-coordinate :=   +0 (+$0000) <KM>
              07092 ;     y-coordinate := +256 (+$0100) <KM>
              07093 ;     z-coordinate :=    + (+$****) <KM> (sign only)
              07094 ;
              07095 ; The velocity vector is set to the following values:
              07096 ;
              07097 ;     x-velocity   :=  (not initialized)
              07098 ;     y-velocity   :=  (not initialized)
              07099 ;     z-velocity   :=          +0 <KM/H>
              07100 ;
              07101 ; The temporary arrival hyperwarp marker column and row numbers are saved. If
              07102 ; not in a NOVICE mission, the maximum veer-off velocity of the Hyperwarp Target
              07103 ; Marker during hyperwarp is picked from table VEERMASKTAB ($BED7). This value
              07104 ; depends on the selected hyperwarp energy (and thus on the distance to
              07105 ; hyperwarp). Finally, the title line displays the "HYPERWARP ENGAGED" message.
              07106 ;
              07107 ; If the 'M' (Manual target selector) key has been pressed, the tracked target
              07108 ; space object is swapped and the corresponding digit of the Control Panel
              07109 ; Display is toggled between 0 and 1.
              07110 ;
              07111 ; If the 'P' (Pause) key has been pressed, an endless loop waits until the
              07112 ; joystick is pushed.
              07113 ;
              07114 ; BUG (at $B103): The endless loop branches back one instruction too far.
              07115 ; Suggested fix: Branch to instruction LDA PORTA at $B0FE.
              07116 ;
              07117 ; If the 'INV' (Abort mission) key has been pressed, the mission is aborted by
              07118 ; setting the mission bonus offset, then displaying the "MISSION ABORTED"
              07119 ; message in the title line. Code execution continues into subroutine GAMEOVER
              07120 ; ($B10A).
              07121 ;
              07122 ; NOTE: This subroutine has two additional entry points:
              07123 ;
              07124 ; (1)  SETVIEW ($B045), which is used to enforce the Front view. It is entered
              07125 ;      from the game loop GAMELOOP ($A1F3) and subroutines INITSTART ($A15E) and
              07126 ;      DECENERGY ($B86F).
              07127 ;
              07128 ; (2)  UPDSCREEN ($B07B), which draws the cross hairs, the Attack Computer
              07129 ;      Display and sets the tracking letter of the Control Panel Display. It is
              07130 ;      entered from subroutine DOCKING ($ACE6).
              07131
    =006A     07132 L.KEYCODE       = $6A                   ; Saves pressed keyboard code
              07133
AFFE A5CA     07134 KEYBOARD        LDA KEYCODE             ; Return if no keyboard code collected
B000 F03E     07135                 BEQ SKIP150             ;
              07136
B002 A214     07137                 LDX #20                 ; Prep keyboard code table loop index
B004 856A     07138                 STA L.KEYCODE           ; Save keyboard code
              07139
B006 A900     07140                 LDA #0                  ; Reset idle counter
B008 8566     07141                 STA IDLECNTHI           ;
B00A 85CA     07142                 STA KEYCODE             ; Clear keyboard code
              07143
B00C A911     07144                 LDA #$11                ; GTIA: enable PLAYER4, prio: PLs > PFs > BGR
B00E 8D1BD0   07145                 STA PRIOR               ; (PLAYERs appear behind cross hairs)
              07146
              07147 ;*** Search keyboard code in lookup table **************************************
              07148
B011 BDBEBA   07149 LOOP051         LDA KEYTAB,X            ; Loop over all valid keyboard codes
B014 C56A     07150                 CMP L.KEYCODE           ;
B016 F008     07151                 BEQ SKIP147             ; Branch if matching entry found
B018 CA       07152                 DEX                     ;
B019 10F6     07153                 BPL LOOP051             ; Next keyboard code
              07154
B01B A010     07155                 LDY #$10                ; No match found...
B01D 4C23B2   07156                 JMP SETTITLE            ; ...set title phrase "WHATS WRONG?" and return
              07157
              07158 ;*** Handle '0'..'9' keyboard keys (speed) *************************************
B020 E00A     07159 SKIP147         CPX #10                 ; Skip section if keyboard code does not match
B022 B01D     07160                 BCS SKIP151             ;
              07161
B024 A5C0     07162                 LDA WARPSTATE           ; Skip if hyperwarp disengaged...
B026 F003     07163                 BEQ SKIP148             ;
B028 4C80A9   07164                 JMP ABORTWARP           ; ...else abort hyperwarp
              07165
B02B 2C9309   07166 SKIP148         BIT GCSTATENG           ; Skip if Engines are OK or destroyed
B02E 5006     07167                 BVC SKIP149             ;
B030 E006     07168                 CPX #6                  ; Allow max velocity equivalent to speed key '5'
B032 9002     07169                 BCC SKIP149             ;
B034 A205     07170                 LDX #5                  ;
              07171
B036 BDD3BA   07172 SKIP149         LDA DRAINRATETAB,X      ; Set Engines energy drain rate
B039 8580     07173                 STA DRAINENGINES        ;
B03B BDB4BA   07174                 LDA VELOCITYTAB,X       ; Set new velocity
B03E 8571     07175                 STA NEWVELOCITY         ;
B040 60       07176 SKIP150         RTS                     ; Return
              07177
              07178 ;*** Handle 'F', 'A', 'L', 'G' keyboard keys (our starship's views) ************
B041 E00E     07179 SKIP151         CPX #14                 ; Skip section if keyboard code does not match
B043 B01B     07180                 BCS SKIP152             ;
              07181
              07182 ;*** Entry to force Front view after program init and failed missions **********
B045 BD18BE   07183 SETVIEW         LDA VIEWMODETAB-10,X    ; Store our starship's view type
B048 85D0     07184                 STA SHIPVIEW            ;
              07185
B04A BC82BA   07186                 LDY DLSTFRAGOFFTAB-10,X ; Get DL fragment offset (Front, Aft, LRS, GC)
B04D A202     07187                 LDX #$02                ; Switch to corresponding view
B04F A908     07188                 LDA #$08                ;
B051 20F1AD   07189                 JSR MODDLST             ;
              07190
B054 A210     07191                 LDX #NUMSPCOBJ.NORM-1   ; Create new star field of 12 stars
B056 2064B7   07192 LOOP052         JSR INITPOSVEC          ;
B059 CA       07193                 DEX                     ;
B05A E005     07194                 CPX #NUMSPCOBJ.PL       ;
B05C B0F8     07195                 BCS LOOP052             ;
              07196
B05E 901B     07197                 BCC UPDSCREEN           ; Return via updating screen (below)
              07198
              07199 ;*** Handle 'T', 'S', 'C' keyboard keys (Tracking, Shields, Attack Computer) ***
B060 E011     07200 SKIP152         CPX #17                 ; Skip section if keyboard code does not match
B062 B035     07201                 BCS SKIP156             ;
              07202
B064 BC18BE   07203                 LDY MSGOFFTAB-14,X      ; Prep title phrase offset "... OFF"
B067 B56E     07204                 LDA ISTRACKCOMPON-14,X  ; Toggle status bits (also energy consumption values)
B069 5D1BBE   07205                 EOR MSGBITTAB-14,X      ;
B06C 956E     07206                 STA ISTRACKCOMPON-14,X  ;
B06E F003     07207                 BEQ SKIP153             ;
B070 BC1EBE   07208                 LDY MSGONTAB-14,X       ; Prep title phrase offset "... ON"
B073 2023B2   07209 SKIP153         JSR SETTITLE            ; Set title phrase to "... ON" or "... OFF" version
              07210
B076 A20C     07211                 LDX #$0C                ; Play beeper sound pattern ACKNOWLEDGE
B078 20A6B3   07212                 JSR BEEP                ;
              07213
              07214 ;*** Update PLAYFIELD (Cross hairs, Attack Computer, set tracking letter) ******
B07B A216     07215 UPDSCREEN       LDX #CCS.T              ; Get custom char 'T' (entry point TRANSFER COMPLETE)
B07D A47C     07216                 LDY ISTRACKCOMPON       ;
B07F F001     07217                 BEQ SKIP154             ; Skip if Tracking Computer is on
              07218
B081 E8       07219                 INX                     ; Get custom char 'C'
              07220
B082 8E5A09   07221 SKIP154         STX TRACKC1             ; Store tracking character in Control Panel Display
B085 200DAE   07222                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
B088 A57E     07223                 LDA DRAINATTCOMP        ; Return if Attack Computer off
B08A F0B4     07224                 BEQ SKIP150             ;
              07225
B08C A6D0     07226                 LDX SHIPVIEW            ; If Aft view   -> Draw Aft cross hairs and return
B08E F006     07227                 BEQ SKIP155             ; If Front view -> Draw Front cross hairs and ...
B090 E001     07228                 CPX #$01                ;                  ...Attack Computer and return
B092 D0AC     07229                 BNE SKIP150             ;
B094 A22A     07230                 LDX #$2A                ;
B096 4C6FA7   07231 SKIP155         JMP DRAWLINES           ;
              07232
              07233 ;*** Handle 'H' keyboard key (Hyperwarp) ***************************************
B099 E011     07234 SKIP156         CPX #17                 ; Skip if keyboard code does not match
B09B D050     07235                 BNE SKIP158             ;
              07236
              07237 ;*** Engage Hyperwarp **********************************************************
B09D A5C0     07238                 LDA WARPSTATE           ; Return if hyperwarp engaged
B09F D05A     07239                 BNE SKIP159             ;
              07240
B0A1 A97F     07241                 LDA #$7F                ; Engage hyperwarp
B0A3 85C0     07242                 STA WARPSTATE           ;
B0A5 A9FF     07243                 LDA #255                ; Set new velocity
B0A7 8571     07244                 STA NEWVELOCITY         ;
B0A9 A91E     07245                 LDA #30                 ; Set Engines energy drain rate (= speed key '7')
B0AB 8580     07246                 STA DRAINENGINES        ;
              07247
B0AD A930     07248                 LDA #NUMSPCOBJ.ALL-1    ; Set space obj index of first star of star trail
B0AF 85C3     07249                 STA TRAILIND            ;
B0B1 A900     07250                 LDA #0                  ; Clear star trail delay
B0B3 85C2     07251                 STA TRAILDELAY          ;
              07252
B0B5 8D740A   07253                 STA PL3XPOSHI           ; Init position vector and velocity vector of...
B0B8 8D070B   07254                 STA PL3XPOSLO           ; ... Hyperwarp Target Marker (PLAYER3):
B0BB 8D380B   07255                 STA PL3YPOSLO           ; x-coordinate :=   +0 (+$0000) <KM>
B0BE 8D690B   07256                 STA PL3ZVEL             ; y-coordinate := +256 (+$0100) <KM>
B0C1 A901     07257                 LDA #1                  ; z-coordinate :=    + (+$****) <KM> (sign only)
B0C3 8DB009   07258                 STA PL3ZPOSSIGN         ; z-velocity := +0 <KM/H>
B0C6 8DE109   07259                 STA PL3XPOSSIGN         ;
B0C9 8D120A   07260                 STA PL3YPOSSIGN         ;
B0CC 8DA50A   07261                 STA PL3YPOSHI           ;
              07262
B0CF A58F     07263                 LDA WARPARRVCOLUMN      ; Store temp arrival hyperwarp marker column number
B0D1 85C4     07264                 STA WARPTEMPCOLUMN      ;
B0D3 A58E     07265                 LDA WARPARRVROW         ; Store temp arrival hyperwarp marker row number
B0D5 85C5     07266                 STA WARPTEMPROW         ;
              07267
B0D7 A562     07268                 LDA MISSIONLEVEL        ; Skip if NOVICE mission
B0D9 F00B     07269                 BEQ SKIP157             ;
              07270
B0DB A591     07271                 LDA WARPENERGY          ; Bits B0..1 of hyperwarp energy index a table...
B0DD 2A       07272                 ROL A                   ; ...containing the maximum value of how much the...
B0DE 2A       07273                 ROL A                   ; ...Hyperwarp Target Marker will veer off during...
B0DF 2A       07274                 ROL A                   ; ...hyperwarp
B0E0 2903     07275                 AND #$03                ;
B0E2 A8       07276                 TAY                     ;
B0E3 B9D7BE   07277                 LDA VEERMASKTAB,Y       ;
              07278
B0E6 85C6     07279 SKIP157         STA VEERMASK            ; Store veer-off velocity limitation mask
              07280
B0E8 A011     07281                 LDY #$11                ; Set title phrase "HYPERWARP ENGAGED" and return
B0EA 4C23B2   07282                 JMP SETTITLE            ;
              07283
              07284 ;*** Handle 'M' keyboard key (Manual Target Selector) key **********************
B0ED E013     07285 SKIP158         CPX #19                 ; Skip if keyboard code does not match
B0EF B00B     07286                 BCS SKIP160             ;
              07287
B0F1 AD5C09   07288                 LDA TRACKDIGIT          ; Toggle digit of tracked space object of...
B0F4 4901     07289                 EOR #$01                ; ... Control Panel Display
B0F6 2901     07290                 AND #$01                ;
B0F8 8D5C09   07291                 STA TRACKDIGIT          ;
B0FB 60       07292 SKIP159         RTS                     ; Return
              07293
              07294 ;*** Handle 'P' keyboard key (Pause) *******************************************
B0FC D008     07295 SKIP160         BNE SKIP161             ; Skip if keyboard code does not match
              07296
B0FE AD00D3   07297                 LDA PORTA               ; Push joystick to resume action
B101 C9FF     07298                 CMP #$FF                ;
B103 F0F7     07299                 BEQ SKIP160             ; (!)
B105 60       07300                 RTS                     ; Return
              07301
              07302 ;*** Handle 'INV' keyboard key (Abort Mission) *********************************
B106 A076     07303 SKIP161         LDY #$76                ; Preload title phrase "MISSION ABORTED..."
B108 A204     07304                 LDX #$04                ; Set mission bonus offset
              07305
              07306 ;*******************************************************************************
              07307 ;*                                                                             *
              07308 ;*                                  GAMEOVER                                   *
              07309 ;*                                                                             *
              07310 ;*                              Handle game over                               *
              07311 ;*                                                                             *
              07312 ;*******************************************************************************
              07313
              07314 ; DESCRIPTION
              07315 ;
              07316 ; Handles game over, including calculating the scored rank and class.
              07317 ;
              07318 ; This subroutine has two entry points:
              07319 ;
              07320 ; (1)  GAMEOVER ($B10A) is entered at the end of a failed mission (mission
              07321 ;      aborted, zero energy, or starship destroyed by Zylon fire). Essentially,
              07322 ;      our starship is shut down. Code execution continues into GAMEOVER2
              07323 ;      ($B121) below.
              07324 ;
              07325 ; (2)  GAMEOVER2 ($B121) is entered at the end of a successful mission (all
              07326 ;      Zylon ships destroyed). It puts the program in demo mode, enqueues the
              07327 ;      corresponding game over message, and calculates the scored rank and
              07328 ;      class.
              07329 ;
              07330 ;      The scored rank and class are based on the total score: the score
              07331 ;      accumulated during the game plus a mission bonus, which depends on the
              07332 ;      mission level and how the mission ended (mission complete, mission
              07333 ;      aborted, or starship destroyed by Zylon fire). The mission bonus is
              07334 ;      picked from table BONUSTAB ($BEDD).
              07335 ;
              07336 ;      The scored rank index is taken from bits B8..4 of the total score and
              07337 ;      limited to values of 0..18. It indexes table RANKTAB ($BEE9) for the rank
              07338 ;      string. The rank string is displayed in subroutine SETTITLE ($B223).
              07339 ;
              07340 ;      The scored class index is taken from bits B3..0 (for rank indices 0,
              07341 ;      11..14) and computed from bits B4..1 (for rank indices 1..10 and 15..18).
              07342 ;      It takes values of 0..15. It indexes table CLASSTAB ($BEFC) for the class
              07343 ;      digit. The class digit is displayed in subroutine SETTITLE ($B223).
              07344 ;
              07345 ;      For quick lookup, the following table lists rank and class from the total
              07346 ;      score. Pick the cell with the closest value <= your score then read the
              07347 ;      rank and class off the left and the top of the table, respectively.
              07348 ;
              07349 ;      For example, a score of 90 results in a ranking of "Novice Class 4", a
              07350 ;      score of 161 results in a ranking of "Pilot Class 3".
              07351 ;
              07352 ; +------------------------------+---------------------------------------------------------------+
              07353 ; |     Minimum Total Score      |                        Class Index                            |
              07354 ; |                              |  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15|
              07355 ; +-------+----------------------+---------------------------------------------------------------+
              07356 ; | Rank  |                      |                           Class                               |
              07357 ; | Index |         Rank         |  5   5   5   4   4   4   4   3   3   3   2   2   2   1   1   1|
              07358 ; +-------+----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
              07359 ; |     0 | Galactic Cook        |  0|  1|  2|  3|  4|  5|  6|  7|  8|  9| 10| 11| 12| 13| 14| 15|
              07360 ; |     1 | Garbage Scow Captain | 16| 18| 20| 22| 24| 26| 28| 30|   |   |   |   |   |   |   |   |
              07361 ; |     2 | Garbage Scow Captain |   |   |   |   |   |   |   |   | 32| 34| 36| 38| 40| 42| 44| 46|
              07362 ; |     3 | Rookie               | 48| 50| 52| 54| 56| 58| 60| 62|   |   |   |   |   |   |   |   |
              07363 ; |     4 | Rookie               |   |   |   |   |   |   |   |   | 64| 66| 68| 70| 72| 74| 76| 78|
              07364 ; |     5 | Novice               | 80| 82| 84| 86| 88| 90| 92| 94|   |   |   |   |   |   |   |   |
              07365 ; |     6 | Novice               |   |   |   |   |   |   |   |   | 96| 98|100|102|104|106|108|110|
              07366 ; |     7 | Ensign               |112|114|116|118|120|122|124|126|   |   |   |   |   |   |   |   |
              07367 ; |     8 | Ensign               |   |   |   |   |   |   |   |   |128|130|132|134|136|138|140|142|
              07368 ; |     9 | Pilot                |144|146|148|150|152|154|156|158|   |   |   |   |   |   |   |   |
              07369 ; |    10 | Pilot                |   |   |   |   |   |   |   |   |160|162|164|166|168|170|172|174|
              07370 ; |    11 | Ace                  |176|177|178|179|180|181|182|183|184|185|186|187|188|189|190|191|
              07371 ; |    12 | Lieutenant           |192|193|194|195|196|197|198|199|200|201|202|203|204|205|206|207|
              07372 ; |    13 | Warrior              |208|209|210|211|212|213|214|215|216|217|218|219|220|221|222|223|
              07373 ; |    14 | Captain              |224|225|226|227|228|229|230|231|232|233|234|235|236|237|238|239|
              07374 ; |    15 | Commander            |240|242|244|246|248|250|252|254|   |   |   |   |   |   |   |   |
              07375 ; |    16 | Commander            |   |   |   |   |   |   |   |   |256|258|260|262|264|266|268|270|
              07376 ; |    17 | Star Commander       |272|274|276|278|280|282|284|286|   |   |   |   |   |   |   |   |
              07377 ; |    18 | Star Commander       |   |   |   |   |   |   |   |   |288|290|292|294|296|298|300|302|
              07378 ; +-------+----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
              07379 ;
              07380 ;      NOTE: This subroutine also clears the vertical and horizontal joystick
              07381 ;      directions.
              07382 ;
              07383 ; INPUT
              07384 ;
              07385 ;   X = Offset to index table BONUSTAB ($BEDD) of mission bonus values. Used
              07386 ;       values are:
              07387 ;     $00 -> Mission complete
              07388 ;     $04 -> Mission was aborted due to zero energy
              07389 ;     $08 -> Our starship was destroyed by Zylon fire
              07390 ;
              07391 ;   Y = Title phrase offset. Used values are:
              07392 ;     $3F -> "MISSION COMPLETE"
              07393 ;     $31 -> "MISSION ABORTED ZERO ENERGY"
              07394 ;     $23 -> "SHIP DESTROYED BY ZYLON FIRE"
              07395
              07396 ;*** Game over (Mission failed) ************************************************
B10A A900     07397 GAMEOVER        LDA #0                  ;
B10C 85EC     07398                 STA PL3LIFE             ; PLAYER3 lifetime := 0 game loops
B10E 85D6     07399                 STA BEEPPRIORITY        ; Mute beeper
B110 85D1     07400                 STA TITLEPHR            ; Clear title line
B112 858B     07401                 STA REDALERTLIFE        ; Red alert flash lifetime := 0 game loops
B114 8D07D2   07402                 STA AUDC4               ; Mute audio channel 4
B117 8571     07403                 STA NEWVELOCITY         ; Shut down Engines
B119 8581     07404                 STA SHIELDSCOLOR        ; Set Shields color to {BLACK}
B11B 857D     07405                 STA DRAINSHIELDS        ; Switch off Shields
B11D 85C0     07406                 STA WARPSTATE           ; Disengage hyperwarp
B11F 85C1     07407                 STA VELOCITYHI          ; Turn off hyperwarp velocity
              07408
              07409 ;*** Game over (Mission successful) ********************************************
B121 A9FF     07410 GAMEOVER2       LDA #$FF                ; Enter demo mode
B123 8564     07411                 STA ISDEMOMODE          ;
              07412
B125 8465     07413                 STY NEWTITLEPHR         ; Enqueue title phrase
              07414
              07415 ;*** Calculate total score *****************************************************
B127 8A       07416                 TXA                     ;
B128 0562     07417                 ORA MISSIONLEVEL        ;
B12A AA       07418                 TAX                     ;
B12B BDDDBE   07419                 LDA BONUSTAB,X          ; Retrieve mission bonus
B12E 18       07420                 CLC                     ; Add mission bonus and game score
B12F 65CB     07421                 ADC SCORE               ;
B131 AA       07422                 TAX                     ;
B132 A900     07423                 LDA #0                  ;
              07424
B134 85C9     07425                 STA JOYSTICKY           ; Clear vertical joystick delta
B136 85C8     07426                 STA JOYSTICKX           ; Clear horizontal joystick delta
              07427
B138 65CC     07428                 ADC SCORE+1             ;
B13A 3025     07429                 BMI SKIP165             ; Return if total score < 0 (= total score of 0)
              07430
              07431 ;*** Calculate scored rank *****************************************************
B13C 4A       07432                 LSR A                   ;
B13D 8A       07433                 TXA                     ;
B13E 6A       07434                 ROR A                   ;
B13F 4A       07435                 LSR A                   ;
B140 4A       07436                 LSR A                   ;
B141 4A       07437                 LSR A                   ; Use bits B8..4 of total score as rank index
B142 C913     07438                 CMP #19                 ; Limit scored rank index to 0..18
B144 9004     07439                 BCC SKIP162             ;
B146 A912     07440                 LDA #18                 ;
B148 A20F     07441                 LDX #15                 ; Prep class index of 15
B14A 85CD     07442 SKIP162         STA SCOREDRANKIND       ; Store scored rank index
              07443
              07444 ;*** Calculate scored class ****************************************************
B14C A8       07445                 TAY                     ;
B14D 8A       07446                 TXA                     ;
B14E C000     07447                 CPY #0                  ;
B150 F00B     07448                 BEQ SKIP164             ;
B152 C00B     07449                 CPY #11                 ;
B154 9004     07450                 BCC SKIP163             ;
B156 C00F     07451                 CPY #15                 ;
B158 9003     07452                 BCC SKIP164             ;
B15A 4A       07453 SKIP163         LSR A                   ;
B15B 4908     07454                 EOR #$08                ;
B15D 290F     07455 SKIP164         AND #$0F                ;
B15F 85CE     07456                 STA SCOREDCLASSIND      ; Store scored class index, is 0..15
              07457
B161 60       07458 SKIP165         RTS                     ; Return
              07459
              07460 ;*******************************************************************************
              07461 ;*                                                                             *
              07462 ;*                                 SELECTWARP                                  *
              07463 ;*                                                                             *
              07464 ;*             Select hyperwarp arrival location on Galactic Chart             *
              07465 ;*                                                                             *
              07466 ;*******************************************************************************
              07467
              07468 ; DESCRIPTION
              07469 ;
              07470 ; This subroutine executes the following steps:
              07471 ;
              07472 ; (1)  Check if we are in Galactic Chart view and not in hyperwarp.
              07473 ;
              07474 ; (2)  Update the Galactic Chart in subroutine DRAWGC ($B4B9) if the Subspace
              07475 ;      Radio is not damaged.
              07476 ;
              07477 ; (3)  Move the arrival hyperwarp marker (PLAYER4) across the Galactic Chart
              07478 ;      every other game loop iteration. The current location of our starship is
              07479 ;      indicated by the departure hyperwarp marker (PLAYER3).
              07480 ;
              07481 ; Code execution continues into subroutine CALCWARP ($B1A7) to calculate the
              07482 ; required hyperwarp energy.
              07483 ;
              07484 ; NOTE: To calculate the horizontal position of PLAYER3..4 an offset of 61 is
              07485 ; added (from left to right: 48 Player/Missile (PM) pixels to the left edge of
              07486 ; the screen + 16 PM pixels to the left border of the Galactic Chart - 3 PM
              07487 ; pixels relative offset of the PLAYER shape's horizontal center to its left
              07488 ; edge = 61 PM pixels).
              07489 ;
              07490 ; NOTE: To calculate the vertical position of PLAYER3..4 an offset of 63 is
              07491 ; added (from top to bottom: 8 Player/Missile (PM) pixels to the start of the
              07492 ; Display List + 56 PM pixels to the first row of sectors - 1 PM pixel relative
              07493 ; offset of the PLAYER shape's vertical center to its top edge (?) = 63 PM
              07494 ; pixels).
              07495
B162 A5C0     07496 SELECTWARP      LDA WARPSTATE           ; Return if hyperwarp engaged
B164 D004     07497                 BNE SKIP166             ;
              07498
B166 A5D0     07499                 LDA SHIPVIEW            ; Return if not in Galactic Chart view
B168 3001     07500                 BMI SKIP167             ;
B16A 60       07501 SKIP166         RTS                     ; Return
              07502
B16B 2C9709   07503 SKIP167         BIT GCSTATRAD           ; Skip if Subspace Radio is damaged or destroyed
B16E 3003     07504                 BMI SKIP168             ;
              07505
B170 20B9B4   07506                 JSR DRAWGC              ; Redraw Galactic Chart
              07507
B173 A572     07508 SKIP168         LDA COUNT8              ; Move hyperwarp markers only every other game loop
B175 2901     07509                 AND #$01                ; (slowing down movement of hyperwarp markers)
B177 D02E     07510                 BNE CALCWARP            ;
              07511
              07512 ;*** Calc arrival hyperwarp marker column and row numbers, update PLAYER4 pos **
B179 18       07513                 CLC                     ;
B17A A58F     07514                 LDA WARPARRVCOLUMN      ; Load arrival hyperwarp marker column number
B17C 65C8     07515                 ADC JOYSTICKX           ; Add joystick x-delta
B17E 297F     07516                 AND #$7F                ; Limit value to 0..127
B180 858F     07517                 STA WARPARRVCOLUMN      ; Save new arrival hyperwarp marker column number
B182 18       07518                 CLC                     ;
B183 693D     07519                 ADC #61                 ; Add offset of 61
B185 8D2E0C   07520                 STA PL4COLUMN           ; Store as PLAYER4 column number
              07521
B188 18       07522                 CLC                     ;
B189 A58E     07523                 LDA WARPARRVROW         ; Load arrival hyperwarp marker row number
B18B 65C9     07524                 ADC JOYSTICKY           ; Add joystick y-delta
B18D 297F     07525                 AND #$7F                ; Limit value to 0..127
B18F 858E     07526                 STA WARPARRVROW         ; Save new arrival hyperwarp marker row number
B191 18       07527                 CLC                     ;
B192 693F     07528                 ADC #63                 ; Add offset of 63
B194 8DFD0B   07529                 STA PL4ROWNEW           ; Store as PLAYER4 row number
              07530
              07531 ;*** Calc departure hyperwarp marker column and row numbers, update PLAYER3 pos
B197 A58C     07532                 LDA WARPDEPRROW         ; Load departure hyperwarp marker row number
B199 18       07533                 CLC                     ;
B19A 693F     07534                 ADC #63                 ; Add offset of 63
B19C 8DFC0B   07535                 STA PL3ROWNEW           ; Store as PLAYER3 row number
              07536
B19F A58D     07537                 LDA WARPDEPRCOLUMN      ; Load departure hyperwarp marker column number
B1A1 18       07538                 CLC                     ;
B1A2 693D     07539                 ADC #61                 ; Add offset of 61
B1A4 8D2D0C   07540                 STA PL3COLUMN           ; Store as PLAYER3 column number
              07541
              07542 ;*******************************************************************************
              07543 ;*                                                                             *
              07544 ;*                                  CALCWARP                                   *
              07545 ;*                                                                             *
              07546 ;*                   Calculate and display hyperwarp energy                    *
              07547 ;*                                                                             *
              07548 ;*******************************************************************************
              07549
              07550 ; DESCRIPTION
              07551 ;
              07552 ; Calculates and displays the hyperwarp energy in the Galactic Chart view.
              07553 ;
              07554 ; This subroutine executes the following steps:
              07555 ;
              07556 ; (1)  Determine the arrival sector from the arrival hyperwarp marker position.
              07557 ;
              07558 ; (2)  If the Subspace Radio is not destroyed, update the target number digit of
              07559 ;      the Galactic Chart Panel Display.
              07560 ;
              07561 ; (3)  Calculate the hyperwarp energy that is required to hyperwarp from the
              07562 ;      departure hyperwarp marker to the arrival hyperwarp marker based on the
              07563 ;      "block-distance":
              07564 ;
              07565 ;          DISTANCE := DELTAC + DELTAR / 2
              07566 ;
              07567 ;          where
              07568 ;
              07569 ;          DELTAC := ABS(WARPARRVCOLUMN - WARPDEPRCOLUMN)
              07570 ;          DELTAR := ABS(WARPARRVROW - WARPDEPRROW)
              07571 ;
              07572 ;      NOTE: Dividing DELTAR by 2 is because PLAYERs at single-line resolution
              07573 ;      have Player/Missile pixels that are half as high as they are wide.
              07574 ;
              07575 ;      The hyperwarp energy, divided by 10, is the sum of a value picked from
              07576 ;      the hyperwarp energy table WARPENERGYTAB ($BADD) indexed by DISTANCE / 8)
              07577 ;      plus a remainder computed from Bits B1..0 of DISTANCE.
              07578 ;
              07579 ; (4)  Store the hyperwarp energy value in WARPENERGY ($91).
              07580 ;
              07581 ; (5)  Update the HYPERWARP ENERGY readout of the Galactic Chart Panel Display.
              07582
    =006A     07583 L.WARPARRVCOL   = $6A                   ; Saves arrival sector column number
    =006A     07584 L.DIFFC         = $6A                   ; Saves diff column value
              07585
              07586 ;*** Calculate arrival sector **************************************************
B1A7 A58F     07587 CALCWARP        LDA WARPARRVCOLUMN      ;
B1A9 4A       07588                 LSR A                   ;
B1AA 4A       07589                 LSR A                   ;
B1AB 4A       07590                 LSR A                   ;
B1AC 856A     07591                 STA L.WARPARRVCOL       ; A := arrival sector column 0..15
B1AE A58E     07592                 LDA WARPARRVROW         ;
B1B0 2970     07593                 AND #$70                ; A := arrival sector row (0..7) * 16
B1B2 056A     07594                 ORA L.WARPARRVCOL       ;
B1B4 8592     07595                 STA ARRVSECTOR          ; Save arrival sector (format %0rrrcccc)
              07596
              07597 ;*** Update target number digit of Galactic Chart Panel Display ****************
B1B6 AA       07598                 TAX                     ;
B1B7 BDC908   07599                 LDA GCMEMMAP,X          ; Get number of Zylon ships in arrival sector
B1BA 1002     07600                 BPL SKIP169             ; Skip if no starbase in arrival sector
B1BC A900     07601                 LDA #0                  ; Clear number of Zylon ships
B1BE 0990     07602 SKIP169         ORA #CCS.COL2!ROM.0     ; Merge COLOR2 bits with number of Zylon ships
B1C0 2C9709   07603                 BIT GCSTATRAD           ; Skip if Subspace Radio destroyed
B1C3 7003     07604                 BVS SKIP170             ;
              07605
B1C5 8D8D09   07606                 STA GCTRGCNT            ; Set target number digit of Galactic Chart Panel
              07607
              07608 ;*** Calculate energy to hyperwarp between hyperwarp markers *******************
B1C8 38       07609 SKIP170         SEC                     ; A := DIFFC := ABS(WARPARRVCOLUMN - WARPDEPRCOLUMN)
B1C9 A58F     07610                 LDA WARPARRVCOLUMN      ; (Column value difference)
B1CB E58D     07611                 SBC WARPDEPRCOLUMN      ;
B1CD B004     07612                 BCS SKIP171             ;
B1CF 49FF     07613                 EOR #$FF                ;
B1D1 6901     07614                 ADC #1                  ;
B1D3 856A     07615 SKIP171         STA L.DIFFC             ;
              07616
B1D5 38       07617                 SEC                     ; A := DIFFR := ABS(WARPARRVROW - WARPDEPRROW)
B1D6 A58E     07618                 LDA WARPARRVROW         ; (Row value difference)
B1D8 E58C     07619                 SBC WARPDEPRROW         ;
B1DA B004     07620                 BCS SKIP172             ;
B1DC 49FF     07621                 EOR #$FF                ;
B1DE 6901     07622                 ADC #1                  ;
              07623
B1E0 4A       07624 SKIP172         LSR A                   ; A := DISTANCE := DIFFR / 2 + DIFFC
B1E1 18       07625                 CLC                     ;
B1E2 656A     07626                 ADC L.DIFFC             ;
              07627
B1E4 A8       07628                 TAY                     ; Save DISTANCE
B1E5 4A       07629                 LSR A                   ; Calc index into hyperwarp energy table
B1E6 4A       07630                 LSR A                   ;
B1E7 4A       07631                 LSR A                   ;
B1E8 AA       07632                 TAX                     ;
              07633
B1E9 98       07634                 TYA                     ; Load DISTANCE value
B1EA 2903     07635                 AND #$03                ; Get DISTANCE bits B1..0
B1EC 18       07636                 CLC                     ;
B1ED 7DDDBA   07637                 ADC WARPENERGYTAB,X     ; Add hyperwarp energy from table
B1F0 8591     07638                 STA WARPENERGY          ; Save hyperwarp energy
              07639
              07640 ;*** Update HYPERWARP ENERGY readout of Galactic Chart Panel Display ***********
B1F2 A8       07641                 TAY                     ; Prep with hyperwarp energy value
              07642
B1F3 A910     07643                 LDA #ROM.0              ; Set HYPERWARP ENERGY readout digit1..3 to '0'
B1F5 8D7D09   07644                 STA GCWARPD1            ;
B1F8 8D7E09   07645                 STA GCWARPD1+1          ;
B1FB 8D7F09   07646                 STA GCWARPD1+2          ;
              07647
B1FE A202     07648 LOOP053         LDX #2                  ; Loop over HYPERWARP ENERGY readout digit3..1
B200 FE7D09   07649 LOOP054         INC GCWARPD1,X          ; Increment digit value
B203 BD7D09   07650                 LDA GCWARPD1,X          ;
B206 C91A     07651                 CMP #ROM.9+1            ;
B208 9008     07652                 BCC SKIP173             ; Skip if energy digit <= '9'
              07653
B20A A910     07654                 LDA #ROM.0              ; Replace energy digit with '0'
B20C 9D7D09   07655                 STA GCWARPD1,X          ;
B20F CA       07656                 DEX                     ;
B210 10EE     07657                 BPL LOOP054             ; Next energy digit
              07658
B212 88       07659 SKIP173         DEY                     ; Decrement HYPERWARP ENERGY readout value
B213 D0E9     07660                 BNE LOOP053             ;
B215 60       07661                 RTS                     ; Return
              07662
              07663 ;*******************************************************************************
              07664 ;*                                                                             *
              07665 ;*                                  UPDTITLE                                   *
              07666 ;*                                                                             *
              07667 ;*                              Update title line                              *
              07668 ;*                                                                             *
              07669 ;*******************************************************************************
              07670
              07671 ; DESCRIPTION
              07672 ;
              07673 ; Updates the title phrase displayed in the title line.
              07674 ;
              07675 ; If no title phrase has been set then fetch the offset of the next ("enqueued")
              07676 ; title phrase to be displayed. If one has been set then code execution
              07677 ; continues into subroutine SETTITLE ($B223), otherwise code execution returns.
              07678 ;
              07679 ; If a title phrase has been set then decrement the lifetime of the currently
              07680 ; displayed title phrase segment. If its lifetime has reached a value of 0 then
              07681 ; branch to subroutine SETTITLE ($B223) to display the next segment.
              07682
B216 A5D1     07683 UPDTITLE        LDA TITLEPHR            ; Skip if no title phrase set
B218 F005     07684                 BEQ SKIP175             ;
              07685
B21A C6CF     07686                 DEC TITLELIFE           ; Decrement title phrase segment lifetime
B21C F010     07687                 BEQ SKIP176             ; If lifetime expired show next title segment
              07688
B21E 60       07689 SKIP174         RTS                     ; Return
              07690
B21F A465     07691 SKIP175         LDY NEWTITLEPHR         ; Prep enqueued new title phrase
B221 F0FB     07692                 BEQ SKIP174             ; Return if not set
              07693
              07694 ;*******************************************************************************
              07695 ;*                                                                             *
              07696 ;*                                  SETTITLE                                   *
              07697 ;*                                                                             *
              07698 ;*                       Set title phrase in title line                        *
              07699 ;*                                                                             *
              07700 ;*******************************************************************************
              07701
              07702 ; DESCRIPTION
              07703 ;
              07704 ; Displays a title phrase in the title line.
              07705 ;
              07706 ; INTRODUCTION
              07707 ;
              07708 ; Title phrases are picked from the title phrase table PHRASETAB ($BBAA). They
              07709 ; consist of one or more phrase tokens. Each token is a byte representing a word
              07710 ; in word table WORDTAB ($BC2B). Two special tokens are placeholders for the
              07711 ; scored class ($FC) and scored rank ($FD) strings.
              07712 ;
              07713 ; A title phrase is split up into one or more title phrase segments, each
              07714 ; fitting into the title line. One title phrase segment is displayed after the
              07715 ; other after a delay called the "title segment lifetime".
              07716 ;
              07717 ; Phrase tokens, except the tokens for the scored class ($FC) and for the scored
              07718 ; rank ($FD), contain the number of a word in word table WORDTAB ($BC2B) and may
              07719 ; contain an end-of-segment or end-of-phrase marker bit.
              07720 ;
              07721 ; DETAILS
              07722 ;
              07723 ; The Display List is modified by subroutine MODDLST ($ADF1) to display the
              07724 ; title line. Then, the title line is cleared and the words of the title phrase
              07725 ; are copied into it using the passed offset into title phrase table PHRASETAB
              07726 ; ($BBAA). If the offset has a value of $FF the title line is hidden in
              07727 ; subroutine MODDLST ($ADF1).
              07728 ;
              07729 ; INPUT
              07730 ;
              07731 ;   Y = Offset into title phrase table PHRASETAB ($BBAA). Used values are:
              07732 ;     $FF  -> Hide title line
              07733 ;     else -> Offset into title phrase table PHRASETAB ($BBAA), with explicitly
              07734 ;             used values:
              07735 ;
              07736 ;     $01 -> "COMPUTER ON"
              07737 ;     $04 -> "COMPUTER OFF"
              07738 ;     $07 -> "SHIELDS ON"
              07739 ;     $09 -> "SHIELDS OFF"
              07740 ;     $0B -> "COMPUTER TRACKING ON"
              07741 ;     $0E -> "TRACKING OFF"
              07742 ;     $13 -> "STARBASE SURROUNDED"
              07743 ;     $15 -> "STARBASE DESTROYED"
              07744 ;     $1F -> "DOCKING ABORTED"
              07745 ;     $21 -> "TRANSFER COMPLETE"
              07746 ;     $4A -> "NOVICE MISSION"
              07747 ;     $4C -> "PILOT MISSION"
              07748 ;     $4E -> "WARRIOR MISSION"
              07749 ;     $50 -> "COMMANDER MISSION"
              07750 ;     $52 -> "DAMAGE CONTROL..."
              07751 ;     $75 -> "RED ALERT"
              07752
    =006A     07753 L.WORD          = $6A                   ; Saves word number of WORDTAB ($BC2A). Used values
              07754                                         ; are $00..$3F.
    =006B     07755 L.COLUMNPOS     = $6B                   ; Saves cursor column position during copying text
              07756                                         ; into title line
    =006C     07757 L.TOKEN         = $6C                   ; Saves title phrase token from PHRASETAB ($BBAA),
              07758                                         ; contains bit-encoded information about one word in
              07759                                         ; the title phrase:
              07760                                         ; B7..6 = %00 -> Copy next word to title line
              07761                                         ; B7..6 = %01 -> End-of-phrase reached, apply short
              07762                                         ;                delay, then hide title line. Title
              07763                                         ;                segment lifetime = 60 game loops.
              07764                                         ; B7..6 = %10 -> End-of-segment reached. Title
              07765                                         ;                segment lifetime = 60 game loops
              07766                                         ; B7..6 = %11 -> End-of-phrase reached, apply long
              07767                                         ;                delay, then hide title line. Title
              07768                                         ;                segment lifetime = 254 game loops.
              07769                                         ;                Used with title phrases
              07770                                         ;                  "STARBASE SURROUNDED"
              07771                                         ;                  "STARBASE DESTROYED"
              07772                                         ;                  "HYPERSPACE"
              07773                                         ;                  "RED ALERT"
              07774                                         ; B5..0       -> Word number of WORDTAB ($BC2A)
              07775
B223 84D1     07776 SETTITLE        STY TITLEPHR            ; Save title phrase offset
              07777
B225 A023     07778                 LDY #$23                ; Show title line
B227 A20F     07779                 LDX #$0F                ;
B229 A907     07780                 LDA #$07                ;
B22B 20F1AD   07781                 JSR MODDLST             ;
              07782
              07783 ;*** Init cursor column position and clear title line **************************
B22E A213     07784 SKIP176         LDX #19                 ; There are 19(+1) characters to clear
B230 A900     07785                 LDA #0                  ;
B232 856B     07786                 STA L.COLUMNPOS         ; Init cursor column position
              07787
B234 9D1F0D   07788 LOOP055         STA TITLETXT,X          ; Clear character in title line
B237 CA       07789                 DEX                     ;
B238 10FA     07790                 BPL LOOP055             ;
              07791
              07792 ;*** If title phrase offset = $FF then hide title line *************************
B23A A6D1     07793 SKIP177         LDX TITLEPHR            ; Load title phrase offset
B23C E6D1     07794                 INC TITLEPHR            ; Prepare title phrase offset for next word
B23E D009     07795                 BNE SKIP178             ; ...skip if it turned 0
              07796
B240 A20F     07797                 LDX #$0F                ; Remove title line and return
B242 A080     07798                 LDY #$80                ;
B244 A907     07799                 LDA #$07                ;
B246 4CF1AD   07800                 JMP MODDLST             ;
              07801
B249 BDAABB   07802 SKIP178         LDA PHRASETAB,X         ; Get phrase token
              07803
              07804 ;*** Display scored class? *****************************************************
B24C C9FC     07805                 CMP #$FC                ; Skip if not "scored class" token
B24E D00F     07806                 BNE SKIP179             ;
              07807
B250 A4CE     07808                 LDY SCOREDCLASSIND      ; Get scored class index, is in 0..15
B252 B9FCBE   07809                 LDA CLASSTAB,Y          ; Load scored class number digit
B255 A66B     07810                 LDX L.COLUMNPOS         ; Load cursor position
B257 9D1F0D   07811                 STA TITLETXT,X          ; Store class in title line
B25A A93C     07812                 LDA #60                 ; Title segment lifetime := 60 game loops
B25C 85CF     07813                 STA TITLELIFE           ;
B25E 60       07814                 RTS                     ; Return
              07815
              07816 ;*** Display scored rank? ******************************************************
B25F C9FD     07817 SKIP179         CMP #$FD                ; Skip if not "scored rank" token
B261 D005     07818                 BNE SKIP180             ;
              07819
B263 A4CD     07820                 LDY SCOREDRANKIND       ; Get scored rank index, is in 0..18
B265 B9E9BE   07821                 LDA RANKTAB,Y           ; Load rank word number
              07822
              07823 ;*** Search word of token in word table ****************************************
B268 856C     07824 SKIP180         STA L.TOKEN             ; Save phrase token
B26A 293F     07825                 AND #$3F                ; Strip bits B6..7 from phrase token
B26C 856A     07826                 STA L.WORD              ; Store word number (bits B5..0)
              07827
B26E A92A     07828                 LDA #<[WORDTAB-1]       ; Point MEMPTR to WORDTAB-1
B270 8568     07829                 STA MEMPTR              ;
B272 A9BC     07830                 LDA #>[WORDTAB-1]       ;
B274 8569     07831                 STA MEMPTR+1            ;
              07832
B276 E668     07833 LOOP056         INC MEMPTR              ; Increment MEMPTR
B278 D002     07834                 BNE SKIP181             ;
B27A E669     07835                 INC MEMPTR+1            ;
              07836
B27C A000     07837 SKIP181         LDY #0                  ;
B27E B168     07838                 LDA (MEMPTR),Y          ; Load character of word
B280 10F4     07839                 BPL LOOP056             ; Loop until end-of-word marker (bit B7) found
B282 C66A     07840                 DEC L.WORD              ;
B284 D0F0     07841                 BNE LOOP056             ; Loop until word found
              07842
              07843 ;*** Copy word to title line, add space ****************************************
B286 293F     07844 LOOP057         AND #$3F                ; Strip color bits B6..7 from character
B288 49A0     07845                 EOR #CCS.COL2!$20       ; Merge COLOR2 bits and convert to ATASCII
B28A A66B     07846                 LDX L.COLUMNPOS         ; Copy character to title line
B28C E66B     07847                 INC L.COLUMNPOS         ; Increment cursor column position
B28E 9D1F0D   07848                 STA TITLETXT,X          ;
B291 C8       07849                 INY                     ;
B292 B168     07850                 LDA (MEMPTR),Y          ; Load next character of word
B294 10F0     07851                 BPL LOOP057             ; Next character of word if no end-of-word marker
B296 E66B     07852                 INC L.COLUMNPOS         ; Word was copied. Add space after word.
              07853
              07854 ;*** Decide to copy another word, etc. *****************************************
B298 A93C     07855                 LDA #60                 ; SUMMARY:
B29A 246C     07856                 BIT L.TOKEN             ; If bits B7..6 of phrase token...
B29C 1004     07857                 BPL SKIP182             ; %00 -> Copy next word to title line
B29E 5008     07858                 BVC SKIP183             ; %01 -> End-of-phrase, short delay, hide title line
B2A0 A9FE     07859                 LDA #254                ;        Title segment lifetime := 60 game loops
B2A2 5096     07860 SKIP182         BVC SKIP177             ; %10 -> End-of-segment.
B2A4 A0FF     07861                 LDY #$FF                ;        Title segment lifetime := 60 game loops
B2A6 84D1     07862                 STY TITLEPHR            ; %11 -> End-of-phrase, long delay, hide title line
B2A8 85CF     07863 SKIP183         STA TITLELIFE           ;        Title segment lifetime := 254 game loops
B2AA 60       07864                 RTS                     ; Return
              07865
              07866 ;*******************************************************************************
              07867 ;*                                                                             *
              07868 ;*                                    SOUND                                    *
              07869 ;*                                                                             *
              07870 ;*                            Handles sound effects                            *
              07871 ;*                                                                             *
              07872 ;*******************************************************************************
              07873
              07874 ; DESCRIPTION
              07875 ;
              07876 ; This subroutine handles the sound effects. It is called every vertical blank
              07877 ; phase, that is, every TICK (1/60 s on an NTSC ATARI Home Computer system, 1/50
              07878 ; s on a PAL ATARI Home Computer system) from the Vertical Blank Interrupt
              07879 ; handler VBIHNDLR ($A6D1).
              07880 ;
              07881 ; The program uses all of the available 4 audio channels: Audio channels 1, 2,
              07882 ; and 3 are shared among the Engines sound effects and the "noise sound
              07883 ; patterns" (explosion and photon torpedo sound effects), while audio channel 4
              07884 ; is used for "beeper sound patterns" (status report sound effects). The
              07885 ; following sections explain the beeper sound patterns and the noise sound
              07886 ; patterns:
              07887 ;
              07888 ; o   BEEPER SOUND PATTERNS
              07889 ;
              07890 ;     There are the following beeper sound patterns:
              07891 ;
              07892 ;     (1)  HYPERWARP TRANSIT
              07893 ;     (2)  RED ALERT
              07894 ;     (3)  ACKNOWLEDGE
              07895 ;     (4)  DAMAGE REPORT
              07896 ;     (5)  MESSAGE FROM STARBASE
              07897 ;
              07898 ;     They are encoded in table BEEPPATTAB ($BF3E) in 6-byte long "beeper sound
              07899 ;     patterns".
              07900 ;
              07901 ;     Another table, BEEPFRQTAB ($BF5C), stores the frequencies for the tones
              07902 ;     of each beeper sound pattern, terminated by a marker byte ($FF).
              07903 ;
              07904 ;     BUG (at $BF5C): The pattern frequencies in table BEEPFRQTAB ($BF5C) at
              07905 ;     offset $00 are unused. Suggested Fix: Remove from code.
              07906 ;
              07907 ;     Whenever the program calls subroutine BEEP ($B3A6), that subroutine sets
              07908 ;     up a beeper sound pattern for playing by copying 6 bytes from the pattern
              07909 ;     table BEEPPATTAB ($BF3E) to BEEPFRQIND ($D2)..BEEPFRQSTART ($D7).
              07910 ;     Subroutine SOUND ($B2AB) detects the copied beeper sound pattern and plays
              07911 ;     the encoded tones and pauses.
              07912 ;
              07913 ;     The relevant variables for playing a beeper sound pattern are the
              07914 ;     following (see also figures at BEEPPATTAB ($BF3E)):
              07915 ;
              07916 ;     BEEPFRQIND    ($D2)   = Running index into table BEEPFRQTAB ($BF5C)
              07917 ;     BEEPREPEAT    ($D3)   = Number of times that the beeper sound pattern is
              07918 ;                             repeated - 1
              07919 ;     BEEPTONELIFE  ($D4)   = Lifetime of tone in TICKs - 1
              07920 ;     BEEPPAUSELIFE ($D5)   = Lifetime of pause in TICKs - 1 ($FF -> No pause)
              07921 ;     BEEPPRIORITY  ($D6)   = Beeper sound pattern priority. A playing beeper
              07922 ;                             sound pattern is stopped if a beeper sound pattern
              07923 ;                             of higher priority is about to be played. A value
              07924 ;                             of 0 indicates that no beeper sound pattern is
              07925 ;                             playing at the moment.
              07926 ;     BEEPFRQSTART  ($D7)   = Index to first byte of the beeper sound pattern in
              07927 ;                             table BEEPFRQTAB ($BF5C)
              07928 ;
              07929 ;     BEEPLIFE      ($D8)   = Lifetime of the current tone or pause in TICKs
              07930 ;     BEEPTOGGLE    ($D9)   = Indicates that either a tone (0) or a pause (not
              07931 ;                             0) is currently playing.
              07932 ;
              07933 ; o   NOISE SOUND PATTERNS
              07934 ;
              07935 ;     There are the following noise sound patterns:
              07936 ;
              07937 ;     (1)  PHOTON TORPEDO LAUNCHED
              07938 ;     (2)  SHIELD EXPLOSION
              07939 ;     (3)  ZYLON EXPLOSION
              07940 ;
              07941 ;     They are encoded in table NOISEPATTAB ($BF20) in 10-byte long "noise sound
              07942 ;     patterns".
              07943 ;
              07944 ;     Whenever the program calls subroutine NOISE ($AEA8), that subroutine  sets
              07945 ;     up a noise sound pattern for being played by copying 10 bytes from the
              07946 ;     pattern table NOISEPATTAB ($BF20) to NOISETORPTIM ($DA)..NOISELIFE ($E1)
              07947 ;     and hardware sound registers AUDCTL ($D208) and AUDF3 ($D204).
              07948 ;
              07949 ;     The relevant variables for playing a noise sound pattern are the
              07950 ;     following:
              07951 ;
              07952 ;     NOISETORPTIM  ($DA)   = Delay timer for PHOTON TORPEDO LAUNCHED noise
              07953 ;                             sound pattern
              07954 ;     NOISEEXPLTIM  ($DB)   = Delay timer for SHIELD EXPLOSION and ZYLON
              07955 ;                             EXPLOSION noise sound patterns
              07956 ;     NOISEAUDC2    ($DC)   = Audio channel 1/2 control shadow register
              07957 ;     NOISEAUDC3    ($DD)   = Audio channel 3   control shadow register
              07958 ;     NOISEAUDF1    ($DE)   = Audio channel 1 frequency shadow register
              07959 ;     NOISEAUDF2    ($DF)   = Audio channel 2 frequency shadow register
              07960 ;     NOISEFRQINC   ($E0)   = Audio channel 1/2 frequency increment
              07961 ;     NOISELIFE     ($E1)   = Noise sound pattern lifetime
              07962 ;
              07963 ;     AUDCTL        ($D208) = POKEY: Audio control
              07964 ;     AUDF3         ($D204) = POKEY: Audio channel 3 frequency audio register
              07965 ;
              07966 ;     There are two more variables that trigger noise effects. They are not part
              07967 ;     of the noise sound pattern table:
              07968 ;
              07969 ;     NOISEZYLONTIM ($E2)  = Delay timer to trigger the ZYLON EXPLOSION noise
              07970 ;                            sound pattern. It is set in subroutine COLLISION
              07971 ;                            ($AF3D) when the impact of one of our starship's
              07972 ;                            photon torpedoes with a target is imminent. The
              07973 ;                            timer is decremented every TICK. When it reaches a
              07974 ;                            value of 0 the ZYLON EXPLOSION noise sound pattern
              07975 ;                            is played in subroutine SOUND ($B2AB).
              07976 ;     NOISEHITLIFE ($E3)   = Lifetime of the STARSHIP EXPLOSION noise when our
              07977 ;                            starship was destroyed by a Zylon photon torpedo.
              07978 ;                            It is set in GAMELOOP ($A1F3) to a value of 64
              07979 ;                            TICKs. When it reaches a value of 0 the STARSHIP
              07980 ;                            EXPLOSION noise is played in subroutine SOUND
              07981 ;                            ($B2AB).
              07982 ;
              07983 ; SUBROUTINE DETAILS
              07984 ;
              07985 ; This subroutine executes the following steps:
              07986 ;
              07987 ; (1)  Play beeper sound pattern
              07988 ;
              07989 ;      The playing of a beeper sound pattern is started, continued, or stopped.
              07990 ;
              07991 ; (2)  Play ZYLON EXPLOSION noise sound pattern
              07992 ;
              07993 ;      If the explosion of a target space object is imminent (subroutine
              07994 ;      COLLISION ($AF3D) has set NOISEZYLONTIM ($E2) to the number of game loop
              07995 ;      iterations that will pass until our starship's photon torpedo will hit
              07996 ;      the target), the timer NOISEZYLONTIM ($E2) is decremented every TICK. If
              07997 ;      it reaches a value of 0, then the noise sound pattern ZYLON EXPLOSION is
              07998 ;      played.
              07999 ;
              08000 ; (3)  Play starship's Engines sound
              08001 ;
              08002 ;      If the Engines are louder than the current noise sound pattern then the
              08003 ;      noise sound pattern is terminated and the values for the audio channels
              08004 ;      1..3 are updated:
              08005 ;
              08006 ;      The velocity of our starship determines the pitch and the volume of the
              08007 ;      Engines: the higher the velocity, the higher the pitch and the volume of
              08008 ;      the Engines. The incremented value of VELOCITYLO ($70) is used as a "base
              08009 ;      value" %abcdefgh.
              08010 ;
              08011 ;      Audio channels 1 and 2 are combined to a 16-bit audio channel 1/2,
              08012 ;      clocked at 1.79 MHz. The inverted bits (represented by an overscore)
              08013 ;      B7..0 of the base value form bits B12..5 of the 16-bit frequency value of
              08014 ;      audio channel 1/2. Bits B7..4 of the base value form bits B3..0 of the
              08015 ;      volume of audio channel 1/2, with noise distortion bit B7 set:
              08016 ;                               ________
              08017 ;      AUDF1/2 ($D202..3) := %000abcdefgh00000
              08018 ;      AUDC2   ($D203)    := %1000abcd
              08019 ;
              08020 ;      Audio channel 3 is also clocked at 1.79 MHz. The inverted bits B7..0 of
              08021 ;      the base value form bits B7..0 of the frequency value of audio channel 3.
              08022 ;      Bits B6..4 of the base value form bits B3..0 of the volume of audio
              08023 ;      channel 3, with noise distortion bit B7 set:
              08024 ;                            ________
              08025 ;      AUDF3   ($D204)    := %abcdefgh
              08026 ;      AUDC3   ($D205)    := %10000bcd
              08027 ;
              08028 ;      Code execution returns at this point.
              08029 ;
              08030 ; (4)  Play ZYLON EXPLOSION or SHIELD EXPLOSION noise sound pattern
              08031 ;
              08032 ;      If the ZYLON EXPLOSION or SHIELD EXPLOSION noise sound pattern was set
              08033 ;      up, the explosion noise timer NOISEEXPLTIM ($DB) is decremented every
              08034 ;      TICK. It starts either with a value of 4 TICKs with a ZYLON EXPLOSION
              08035 ;      noise sound pattern or with a value of 8 TICKs with a SHIELD EXPLOSION
              08036 ;      noise sound pattern, set up in subroutine NOISE ($AEA8). If it reaches a
              08037 ;      value of 0, then the shadow control register of audio channel 1/2
              08038 ;      switches to "noise distortion" at maximum volume.
              08039 ;
              08040 ; (5)  Play PHOTON TORPEDO LAUNCHED noise sound pattern
              08041 ;
              08042 ;      If the PHOTON TORPEDO LAUNCHED noise sound pattern was set up, the photon
              08043 ;      torpedo noise timer NOISETORPTIM ($DA) is decremented every TICK. It
              08044 ;      starts with a value of 8 TICKs, set in subroutine TRIGGER ($AE29). The
              08045 ;      noise distortion and volume for the shadow control register of audio
              08046 ;      channel 3 is picked from table NOISETORPVOLTAB ($BFEB), the noise
              08047 ;      frequency for audio channel 3 is picked from table NOISETORPFRQTAB
              08048 ;      ($BFF3). If the photon torpedo noise timer reaches a value of 0, then the
              08049 ;      shadow control registers of audio channel 1/2 switch to "tone distortion"
              08050 ;      at maximum volume and a frequency of $0202.
              08051 ;
              08052 ;      NOTE: Using a real-time volume envelope stored in table NOISETORPVOLTAB
              08053 ;      ($BFEB) for a launched photon torpedo results in the distinctive
              08054 ;      "whooshing" photon torpedo sound.
              08055 ;
              08056 ; (6)  Play STARSHIP EXPLOSION noise
              08057 ;
              08058 ;      If our starship was hit by a Zylon photon torpedo then NOISEHITLIFE ($E3)
              08059 ;      was set to 64 TICKs in routine GAMELOOP ($A1F3). While this value is
              08060 ;      decremented every TICK, a random frequency value is stored to audio
              08061 ;      channel 3 and the distortion bit of the shadow control register of audio
              08062 ;      channel 3 is randomly toggled.
              08063 ;
              08064 ; (7)  Increase audio channels 1/2 frequency
              08065 ;
              08066 ;      The 16-bit frequency value of audio channels 1/2 (both shadow registers
              08067 ;      and audio registers) is increased every TICK by an increment picked from
              08068 ;      the currently playing noise sound pattern.
              08069 ;
              08070 ; (8)  Mute audio channels gradually
              08071 ;
              08072 ;      Toward the end of a noise sound pattern's lifetime all audio channels
              08073 ;      gradually mute their volume every other TICK until completely silent.
              08074
              08075 ;*** Play beeper sound pattern *************************************************
B2AB A5D6     08076 SOUND           LDA BEEPPRIORITY        ; Skip if beeper sound pattern not in use
B2AD F037     08077                 BEQ SKIP185             ;
              08078
B2AF C6D8     08079                 DEC BEEPLIFE            ; Decrement beeper lifetime
B2B1 1033     08080                 BPL SKIP185             ; Skip if beeper lifetime still counting down
              08081
B2B3 A5D9     08082                 LDA BEEPTOGGLE          ; Load tone/pause toggle
B2B5 F00A     08083                 BEQ LOOP058             ; Skip if a tone is playing or is to be played
              08084
B2B7 A5D5     08085                 LDA BEEPPAUSELIFE       ; Load pause lifetime
B2B9 3006     08086                 BMI LOOP058             ; Skip if duration = $FF (no pause)
B2BB 85D8     08087                 STA BEEPLIFE            ; Store pause lifetime as beeper lifetime
B2BD A000     08088                 LDY #0                  ; Prep AUDC4 (zero volume)
B2BF F020     08089                 BEQ SKIP184             ; Skip unconditionally
              08090
B2C1 A5D4     08091 LOOP058         LDA BEEPTONELIFE        ; Load tone lifetime
B2C3 85D8     08092                 STA BEEPLIFE            ; Store tone lifetime as beeper lifetime
B2C5 A6D2     08093                 LDX BEEPFRQIND          ; Load frequency index
B2C7 E6D2     08094                 INC BEEPFRQIND          ; Increment frequency index
B2C9 BD5CBF   08095                 LDA BEEPFRQTAB,X        ; Store tone frequency from frequency table in AUDF4
B2CC 8D06D2   08096                 STA AUDF4               ;
B2CF A0A8     08097                 LDY #$A8                ; Prep AUDC4 (tone distortion + medium volume)
B2D1 C9FF     08098                 CMP #$FF                ; Skip if frequency not $FF (there are more tones)
B2D3 D00C     08099                 BNE SKIP184             ;
              08100
B2D5 A5D7     08101                 LDA BEEPFRQSTART        ; Rewind pattern frequency pointer
B2D7 85D2     08102                 STA BEEPFRQIND          ;
B2D9 C6D3     08103                 DEC BEEPREPEAT          ; Decrement sequence counter
B2DB 10E4     08104                 BPL LOOP058             ; Keep playing until sequence counter < 0
              08105
B2DD A000     08106                 LDY #0                  ; Prep AUDC4 with zero volume
B2DF 84D6     08107                 STY BEEPPRIORITY        ; Stop playing beeper sound pattern
              08108
B2E1 8C07D2   08109 SKIP184         STY AUDC4               ; Store in AUDC4
B2E4 84D9     08110                 STY BEEPTOGGLE          ; Store in BEEPTOGGLE
              08111
              08112 ;*** Play ZYLON EXPLOSION noise sound pattern **********************************
B2E6 A5E2     08113 SKIP185         LDA NOISEZYLONTIM       ; Skip if ZYLON EXPLOSION timer not in use
B2E8 F009     08114                 BEQ SKIP186             ;
              08115
B2EA C6E2     08116                 DEC NOISEZYLONTIM       ; Decrement ZYLON EXPLOSION timer
B2EC D005     08117                 BNE SKIP186             ; Skip if ZYLON EXPLOSION timer still counting down
              08118
B2EE A214     08119                 LDX #$14                ; Play noise sound pattern ZYLON EXPLOSION
B2F0 20A8AE   08120                 JSR NOISE               ;
              08121
              08122 ;*** Play our starship's Engines sound *****************************************
B2F3 A670     08123 SKIP186         LDX VELOCITYLO          ; Skip if Engines softer than noise sound pattern
B2F5 8A       08124                 TXA                     ;
B2F6 4A       08125                 LSR A                   ;
B2F7 4A       08126                 LSR A                   ;
B2F8 4A       08127                 LSR A                   ;
B2F9 4A       08128                 LSR A                   ;
B2FA 4A       08129                 LSR A                   ;
B2FB C5E1     08130                 CMP NOISELIFE           ;
B2FD 902C     08131                 BCC SKIP187             ;
              08132
B2FF A900     08133                 LDA #0                  ; Terminate noise sound pattern
B301 85E1     08134                 STA NOISELIFE           ;
              08135
B303 E8       08136                 INX                     ;
B304 8A       08137                 TXA                     ; A := %abcdefgh = VELOCITYLO + 1
B305 49FF     08138                 EOR #$FF                ;           ________
B307 8D04D2   08139                 STA AUDF3               ; AUDF3 := %abcdefgh
              08140
B30A AA       08141                 TAX                     ;                ________
B30B 0A       08142                 ASL A                   ; AUDF2/1 := %000abcdefgh00000
B30C 0A       08143                 ASL A                   ;
B30D 0A       08144                 ASL A                   ;
B30E 0A       08145                 ASL A                   ;
B30F 0A       08146                 ASL A                   ;
B310 8D00D2   08147                 STA AUDF1               ;
B313 8A       08148                 TXA                     ;
B314 4A       08149                 LSR A                   ;
B315 4A       08150                 LSR A                   ;
B316 4A       08151                 LSR A                   ;
B317 8D02D2   08152                 STA AUDF2               ;
              08153
B31A 4A       08154                 LSR A                   ; AUDC2 := %1000abcd
B31B 498F     08155                 EOR #$8F                ; (noise distortion + B7..B4 bits for volume)
B31D 8D03D2   08156                 STA AUDC2               ;
              08157
B320 2987     08158                 AND #$87                ; AUDC3 := %10000bcd
B322 8D05D2   08159                 STA AUDC3               ; (noise distortion + B6..B4 bits for volume)
              08160
B325 A970     08161                 LDA #$70                ; Clock audio channel 1 and 3 @ 1.79 MHz and...
B327 8D08D2   08162                 STA AUDCTL              ; ...combine audio channel 1/2 to 16-bit channel
              08163
B32A 60       08164                 RTS                     ; Return
              08165
              08166 ;*** Play ZYLON EXPLOSION or SHIELD EXPLOSION noise ****************************
B32B A5DB     08167 SKIP187         LDA NOISEEXPLTIM        ; Skip if explosion noise timer not in use
B32D F008     08168                 BEQ SKIP188             ;
              08169
B32F C6DB     08170                 DEC NOISEEXPLTIM        ; Decrement explosion noise timer (4 or 8 TICKs long)
B331 D004     08171                 BNE SKIP188             ; Skip if explosion noise timer still counting down
              08172
B333 A98F     08173                 LDA #$8F                ; Shadow register AUDC2 := (noise dist. + max volume)
B335 85DC     08174                 STA NOISEAUDC2          ;
              08175
              08176 ;*** Play PHOTON TORPEDO LAUNCHED noise sound **********************************
B337 A6DA     08177 SKIP188         LDX NOISETORPTIM        ; Skip if photon torpedo noise timer not in use
B339 F01C     08178                 BEQ SKIP190             ;
              08179
B33B C6DA     08180                 DEC NOISETORPTIM        ; Decrement photon torpedo noise timer (8 TICKs long)
B33D D00A     08181                 BNE SKIP189             ; Skip if torpedo noise timer still counting down
              08182
B33F A9AF     08183                 LDA #$AF                ; Shadow register AUDC2 := (tone dist. + max volume)
B341 85DC     08184                 STA NOISEAUDC2          ;
B343 A902     08185                 LDA #$02                ; Set frequency $0202 to AUDF1/2's shadow...
B345 85DE     08186                 STA NOISEAUDF1          ; ...registers
B347 85DF     08187                 STA NOISEAUDF2          ;
              08188
B349 BDEABF   08189 SKIP189         LDA NOISETORPVOLTAB-1,X ; Pick torpedo noise + volume shape (X in 1..8)...
B34C 85DD     08190                 STA NOISEAUDC3          ; ...and store it in AUDC3's shadow register
B34E BDF2BF   08191                 LDA NOISETORPFRQTAB-1,X ; Pick photon torpedo noise frequency (X in 1..8)...
B351 8D04D2   08192                 STA AUDF3               ; ...and store it in AUDF3
B354 8D09D2   08193                 STA STIMER              ; Reset POKEY audio timers
              08194
              08195 ;*** Play STARSHIP EXPLOSION noise when our starship is hit ********************
B357 A5E3     08196 SKIP190         LDA NOISEHITLIFE        ; Skip if STARSHIP EXPLOSION noise not in use
B359 F00E     08197                 BEQ SKIP191             ;
              08198
B35B C6E3     08199                 DEC NOISEHITLIFE        ; Decrement STARSHIP EXPLOSION noise lifetime
B35D AD0AD2   08200                 LDA RANDOM              ; Set random frequency to AUDF3
B360 8D04D2   08201                 STA AUDF3               ;
B363 2920     08202                 AND #$20                ; Toggle noise/tone dist. of AUDC3's shadow register
B365 45DD     08203                 EOR NOISEAUDC3          ; ...randomly
B367 85DD     08204                 STA NOISEAUDC3          ;
              08205
              08206 ;*** Increase 16-bit frequency of audio channels 1/2 (shadow registers also) ***
B369 18       08207 SKIP191         CLC                     ; Increase 16-bit frequency value of AUDF1/2...
B36A A5DE     08208                 LDA NOISEAUDF1          ; ...and its shadow register by...
B36C 65E0     08209                 ADC NOISEFRQINC         ; ...noise sound pattern frequency increment
B36E 85DE     08210                 STA NOISEAUDF1          ; AUDF1/2 := NOISEAUDF1/2 := ...
B370 8D00D2   08211                 STA AUDF1               ; ...NOISEAUDF1/2 + NOISEFRQINC
B373 A5DF     08212                 LDA NOISEAUDF2          ;
B375 6900     08213                 ADC #0                  ;
B377 85DF     08214                 STA NOISEAUDF2          ;
B379 8D02D2   08215                 STA AUDF2               ;
              08216
              08217 ;*** Gradually mute audio channels while noise sound pattern expires ***********
B37C A6DC     08218                 LDX NOISEAUDC2          ; Prep AUDC2's shadow register value
B37E A4DD     08219                 LDY NOISEAUDC3          ; Prep AUDC3's shadow register value
              08220
B380 A572     08221                 LDA COUNT8              ; Decrement volumes every other TICK
B382 4A       08222                 LSR A                   ;
B383 901A     08223                 BCC SKIP193             ;
              08224
B385 A5E1     08225                 LDA NOISELIFE           ; Skip if noise sound pattern not in use
B387 F016     08226                 BEQ SKIP193             ;
              08227
B389 C6E1     08228                 DEC NOISELIFE           ; Decrement noise sound pattern lifetime
              08229
B38B C911     08230                 CMP #17                 ; Mute noise sound pattern only in...
B38D B010     08231                 BCS SKIP193             ; ...the last 16 TICKs of its lifetime
              08232
B38F 8A       08233                 TXA                     ; Decrement volume of AUDC2's shadow register
B390 290F     08234                 AND #$0F                ;
B392 F003     08235                 BEQ SKIP192             ;
B394 CA       08236                 DEX                     ;
B395 86DC     08237                 STX NOISEAUDC2          ;
              08238
B397 98       08239 SKIP192         TYA                     ; Decrement volume of AUDC3's shadow register
B398 290F     08240                 AND #$0F                ;
B39A F003     08241                 BEQ SKIP193             ;
B39C 88       08242                 DEY                     ;
B39D 84DD     08243                 STY NOISEAUDC3          ;
              08244
B39F 8E03D2   08245 SKIP193         STX AUDC2               ; Store shadow register values to audio registers
B3A2 8C05D2   08246                 STY AUDC3               ;
              08247
B3A5 60       08248                 RTS                     ; Return
              08249
              08250 ;*******************************************************************************
              08251 ;*                                                                             *
              08252 ;*                                    BEEP                                     *
              08253 ;*                                                                             *
              08254 ;*                          Copy beeper sound pattern                          *
              08255 ;*                                                                             *
              08256 ;*******************************************************************************
              08257
              08258 ; DESCRIPTION
              08259 ;
              08260 ; Copies a 6-byte beeper sound pattern from beeper sound pattern table
              08261 ; BEEPPATTAB ($BF3E) to BEEPFRQIND ($D2)..BEEPFRQSTART ($D7), provided that no
              08262 ; beeper sound pattern with higher priority is currently playing. The beeper
              08263 ; sound pattern will then be automatically played in subroutine SOUND ($B2AB).
              08264 ; See subroutine SOUND ($B2AB) for more information on beeper sound patterns.
              08265 ;
              08266 ; NOTE: The bytes from table BEEPPATTAB ($BF3E) are copied in reverse order.
              08267 ;
              08268 ; INPUT
              08269 ;
              08270 ;   X = Offset to beeper sound pattern in table BEEPPATTAB ($BF3E). Used values
              08271 ;       are:
              08272 ;     $00 -> HYPERWARP TRANSIT
              08273 ;     $06 -> RED ALERT
              08274 ;     $0C -> ACKNOWLEDGE
              08275 ;     $12 -> DAMAGE REPORT
              08276 ;     $18 -> MESSAGE FROM STARBASE
              08277
B3A6 BD3EBF   08278 BEEP            LDA BEEPPATTAB,X        ; Return if beeper sound pattern of...
B3A9 C5D6     08279                 CMP BEEPPRIORITY        ; ...higher priority is playing
B3AB 900C     08280                 BCC SKIP194             ;
              08281
B3AD A005     08282                 LDY #5                  ; Copy 6-byte beeper sound pattern (in reverse order)
B3AF BD3EBF   08283 LOOP059         LDA BEEPPATTAB,X        ;
B3B2 99D200   08284                 STA BEEPFRQIND,Y        ;
B3B5 E8       08285                 INX                     ;
B3B6 88       08286                 DEY                     ;
B3B7 10F6     08287                 BPL LOOP059             ;
              08288
B3B9 60       08289 SKIP194         RTS                     ; Return
              08290
              08291 ;*******************************************************************************
              08292 ;*                                                                             *
              08293 ;*                                 INITIALIZE                                  *
              08294 ;*                                                                             *
              08295 ;*                          More game initialization                           *
              08296 ;*                                                                             *
              08297 ;*******************************************************************************
              08298
              08299 ; DESCRIPTION
              08300 ;
              08301 ; This subroutine executes the following initialization steps:
              08302 ;
              08303 ; (1)  Set up Display List
              08304 ;
              08305 ;      A Display List is created at DSPLST ($0280). It starts with 2 x 8 = 16
              08306 ;      blank video lines, followed by 90 GRAPHICS7 rows. After a deliberate gap
              08307 ;      in Display List instructions, which will be filled dynamically during the
              08308 ;      game by calls to subroutine MODDLST ($ADF1), it ends with a Display List
              08309 ;      wait-and-jump-back instruction to the start of the Display List at DSPLST
              08310 ;      ($0280).
              08311 ;
              08312 ;      NOTE: The PLAYFIELD color table PFCOLORTAB ($BFA9) is copied to zero-page
              08313 ;      table PF0COLOR ($F2) by loop jamming.
              08314 ;
              08315 ; (2)  Create lookup tables
              08316 ;
              08317 ;      The first lookup table MAPTO80 ($0DE9) maps a byte value of 0..255 to
              08318 ;      0..80. This table is used to map unsigned (absolute) position vector
              08319 ;      components (coordinates) to pixel (or PLAYER) row and column numbers.
              08320 ;
              08321 ;      NOTE: The PLAYFIELD is 160 pixels wide. Pixel column numbers relative the
              08322 ;      horizontal PLAYFIELD center are in -80..79, hence the range of this
              08323 ;      lookup table. Pixel row numbers relative the vertical PLAYFIELD center
              08324 ;      are in -50..49, thus they also fit in the range of this lookup table.
              08325 ;
              08326 ;      The second lookup table MAPTOBCD99 ($0EE9) maps a byte value of 0..255 to
              08327 ;      a BCD-encoded value in 00..99. This table is used to convert byte values
              08328 ;      into decimal 2-digit values displayed by the THETA (in "gradons"), PHI
              08329 ;      (in "gradons"), RANGE (in "centrons"), and VELOCITY (in "metrons per
              08330 ;      second") readouts of the Console Panel Display.
              08331 ;
              08332 ;      The third and fourth lookup tables accelerate drawing of PLAYFIELD space
              08333 ;      objects: In combination they contain the 16-bit start addresses of each
              08334 ;      of the 100 rows of PLAYFIELD memory. The low bytes of the 16-bit
              08335 ;      addresses are stored in table PFMEMROWLO ($0800). The high bytes are
              08336 ;      stored in table PFMEMROWHI ($0864).
              08337 ;
              08338 ;      NOTE: The address increment is 40 (40 bytes = 160 pixels in GRAPHICS7
              08339 ;      mode = 1 PLAYFIELD row of pixels).
              08340 ;
              08341 ;      NOTE: The PLAYFIELD consists of 90 GRAPHICS7 rows when the Control Panel
              08342 ;      Display is displayed at the bottom. When the Control Panel Display is not
              08343 ;      displayed, for example in demo mode, the PLAYFIELD contains additional
              08344 ;      GRAPHICS7 rows.
              08345 ;
              08346 ; (3)  Copy Control Panel Display and Galactic Chart Panel Display texts
              08347 ;
              08348 ;      The texts of the Control Panel Display and the Galactic Chart Panel
              08349 ;      Display are copied to their respective locations in memory by loop
              08350 ;      jamming.
              08351 ;
              08352 ; (4)  Initialize Zylon unit movement timer
              08353 ;
              08354 ;      The timer that triggers the movement of Zylon units in the Galactic Chart
              08355 ;      is initialized to a value of 99. See subroutine FLUSHGAMELOOP ($B4E4) for
              08356 ;      more information on Zylon unit movement.
              08357 ;
              08358 ; (5)  Create Galactic Chart
              08359 ;
              08360 ;      The Galactic Chart memory map GCMEMMAP ($08C9) is initialized. It
              08361 ;      represents 16 columns x 8 rows of sectors. Each sector contains one of
              08362 ;      the 4 sector types stored in table SECTORTYPETAB ($BBA6) (starbase, 4
              08363 ;      Zylon ships, 3 Zylon ships, and 2 or 1 Zylon ships), and empty sectors.
              08364 ;      Before distributing the sector types, the initial position of our
              08365 ;      starship is blocked on the Galactic Chart at sector row 4, sector column
              08366 ;      8, so that it will not be inadvertently occupied while other sector types
              08367 ;      are distributed. The number of each of the sector types to be distributed
              08368 ;      is the mission level plus 2. While Zylon units can be placed anywhere,
              08369 ;      starbases are placed neither at the borders of the Galactic Chart nor in
              08370 ;      a sector adjacent to an occupied sector.
              08371 ;
              08372 ;      After having initialized the Galactic Chart memory map, the top border of
              08373 ;      the Galactic Chart is drawn with characters from the custom character
              08374 ;      set.
              08375 ;
              08376 ;      Finally, the sector in which our starship is located and the arrival and
              08377 ;      departure hyperwarp marker column and row numbers are initialized.
              08378 ;
              08379 ; (6)  Apply a final tweak
              08380 ;
              08381 ;      The last entry of lookup table MAPTOBCD99 ($0EE9) is tweaked to a value
              08382 ;      of CCS.INF * 16 + CCS.SPC. It is used to display an infinity symbol by
              08383 ;      the RANGE readout of the Control Panel Display in subroutine SHOWCOORD
              08384 ;      ($B8A7).
              08385 ;
              08386 ; Code execution continues into subroutine DRAWGC ($B4B9), which draws the
              08387 ; content of the Galactic Chart with characters from the custom character set.
              08388
    =0068     08389 L.MEMPTR1       = $68                   ; 16-bit memory pointer
    =006A     08390 L.MEMPTR2       = $6A                   ; 16-bit memory pointer
    =006A     08391 L.SECTORTYPE    = $6A                   ; Saves sector type. Used values are:
              08392                                         ;   $CF -> Sector contains starbase
              08393                                         ;   $04 -> Sector contains 4 Zylon ships
              08394                                         ;   $03 -> Sector contains 3 Zylon ships
              08395                                         ;   $02 -> Sector contains 2 or 1 Zylon ships
    =006B     08396 L.SECTORCNT     = $6B                   ; Saves number of sectors of the current sector type
              08397
              08398 ;*** Initialize Display List and copy color table ******************************
B3BA A259     08399 INITIALIZE      LDX #89                 ; Set 89(+1) GRAPHICS7 rows from DSPLST+5 on
B3BC A90D     08400 LOOP060         LDA #$0D                ; Prep DL instruction $0D (one row of GRAPHICS7)
B3BE 9D8502   08401                 STA DSPLST+5,X          ; DSPLST+5,X := one row of GRAPHICS7
B3C1 E00A     08402                 CPX #10                 ;
B3C3 B005     08403                 BCS SKIP195             ;
B3C5 BDA9BF   08404                 LDA PFCOLORTAB,X        ; Copy PLAYFIELD color table to zero-page table
B3C8 95F2     08405                 STA PF0COLOR,X          ; (loop jamming)
B3CA CA       08406 SKIP195         DEX                     ;
B3CB 10EF     08407                 BPL LOOP060             ;
              08408
B3CD A970     08409                 LDA #$70                ; DSPLST     := BLK8
B3CF 8D8002   08410                 STA DSPLST              ; DSPLST+1   := BLK8
B3D2 8D8102   08411                 STA DSPLST+1            ;
B3D5 A941     08412                 LDA #$41                ; DSPLST+103 := WAITJMP @ DSPLST
B3D7 8DE702   08413                 STA DSPLST+103          ;
B3DA A980     08414                 LDA #<DSPLST            ;
B3DC 8DE802   08415                 STA DSPLST+104          ;
B3DF A902     08416                 LDA #>DSPLST            ;
B3E1 8DE902   08417                 STA DSPLST+105          ;
              08418
              08419 ;*** Calculate lookup tables ***************************************************
B3E4 A200     08420                 LDX #0                  ; Clear both 16-bit memory pointers
B3E6 8668     08421                 STX L.MEMPTR1           ;
B3E8 8669     08422                 STX L.MEMPTR1+1         ;
B3EA 866A     08423                 STX L.MEMPTR2           ;
B3EC 866B     08424                 STX L.MEMPTR2+1         ;
              08425
              08426 ;*** Calc MAPTO80 map (converts value of $00..$FF to value in 0..80) ***********
B3EE 18       08427 LOOP061         CLC                     ;
B3EF A568     08428                 LDA L.MEMPTR1           ;
B3F1 6951     08429                 ADC #81                 ;
B3F3 8568     08430                 STA L.MEMPTR1           ;
B3F5 A569     08431                 LDA L.MEMPTR1+1         ;
B3F7 9DE90D   08432                 STA MAPTO80,X           ;
B3FA 6900     08433                 ADC #0                  ;
B3FC 8569     08434                 STA L.MEMPTR1+1         ;
              08435
              08436 ;*** Calc MAPTOBCD99 map (converts value of $00..$FF to BCD-value in 00..99) ***
B3FE 18       08437                 CLC                     ;
B3FF A56A     08438                 LDA L.MEMPTR2           ;
B401 6964     08439                 ADC #100                ;
B403 856A     08440                 STA L.MEMPTR2           ;
B405 A56B     08441                 LDA L.MEMPTR2+1         ;
B407 9DE90E   08442                 STA MAPTOBCD99,X        ;
B40A F8       08443                 SED                     ;
B40B 6900     08444                 ADC #0                  ;
B40D D8       08445                 CLD                     ;
B40E 856B     08446                 STA L.MEMPTR2+1         ;
B410 E8       08447                 INX                     ;
B411 D0DB     08448                 BNE LOOP061             ;
              08449
              08450 ;*** Calculate PLAYFIELD memory row addresses, copy Panel Display texts ********
B413 A200     08451                 LDX #<PFMEM             ; Point L.MEMPTR1 to start of PLAYFIELD memory
B415 8668     08452                 STX L.MEMPTR1           ; (X = 0, because PFMEM is at $1000)
B417 A910     08453                 LDA #>PFMEM             ;
B419 8569     08454                 STA L.MEMPTR1+1         ;
              08455
B41B 18       08456 LOOP062         CLC                     ;
B41C A568     08457                 LDA L.MEMPTR1           ;
B41E 9D0008   08458                 STA PFMEMROWLO,X        ; Store 16-bit value of L.MEMPTR1 in PFMEMROWHI/LO
B421 6928     08459                 ADC #40                 ; Add 40 to L.MEMPTR
B423 8568     08460                 STA L.MEMPTR1           ; (40 bytes = 160 pixels = 1 PLAYFIELD row)
B425 A569     08461                 LDA L.MEMPTR1+1         ;
B427 9D6408   08462                 STA PFMEMROWHI,X        ;
B42A 6900     08463                 ADC #0                  ;
B42C 8569     08464                 STA L.MEMPTR1+1         ;
              08465
B42E BD42BB   08466                 LDA PANELTXTTAB,X       ; Copy Control and Galactic Chart Panel Display texts
B431 9D4909   08467                 STA PANELTXT,X          ; (loop jamming)
              08468
B434 E8       08469                 INX                     ;
B435 E064     08470                 CPX #100                ;
B437 90E2     08471                 BCC LOOP062             ; Loop 100 times
              08472
              08473 ;*** Set Zylon unit movement timer *********************************************
B439 CA       08474                 DEX                     ;
B43A 8678     08475                 STX ZYLONUNITTIM        ; Init Zylon unit movement timer to 99 game loops
              08476
              08477 ;*** Create memory map of the Galactic Chart ***********************************
B43C A203     08478                 LDX #3                  ; Loop over all 3(+1) sector types
B43E 8E1109   08479                 STX GCMEMMAP+4*16+8     ; Block our starship's initial position at center of
              08480                                         ; ...Galactic Chart (sector row 4, sector column 8)
              08481
B441 BDA6BB   08482 LOOP063         LDA SECTORTYPETAB,X     ; Prep sector type
B444 856A     08483                 STA L.SECTORTYPE        ;
              08484
B446 A462     08485                 LDY MISSIONLEVEL        ; Number sectors of current type := mission level + 2
B448 C8       08486                 INY                     ;
B449 C8       08487                 INY                     ;
B44A 846B     08488                 STY L.SECTORCNT         ;
              08489
B44C AD0AD2   08490 LOOP064         LDA RANDOM              ; Load random sector 0..127 from GC memory map
B44F 297F     08491                 AND #$7F                ;
B451 A8       08492                 TAY                     ;
B452 B9C908   08493                 LDA GCMEMMAP,Y          ;
B455 D0F5     08494                 BNE LOOP064             ; If sector already occupied, pick another
              08495
B457 A56A     08496                 LDA L.SECTORTYPE        ; Reload sector type
B459 1021     08497                 BPL SKIP196             ; Skip if sector not to be occupied by starbase
              08498
B45B C010     08499                 CPY #$10                ; Place starbase...
B45D 90ED     08500                 BCC LOOP064             ; ...not in first sector row of Galactic Chart
B45F C070     08501                 CPY #$70                ;
B461 B0E9     08502                 BCS LOOP064             ; ...not in last sector row of Galactic Chart
B463 98       08503                 TYA                     ;
B464 290F     08504                 AND #$0F                ;
B466 F0E4     08505                 BEQ LOOP064             ; ...not in first sector column of Galactic Chart
B468 C90F     08506                 CMP #15                 ;
B46A F0E0     08507                 BEQ LOOP064             ; ...not in last sector column of Galactic Chart
B46C B9C808   08508                 LDA GCMEMMAP-1,Y        ; ...not east  of an occupied sector
B46F 19CA08   08509                 ORA GCMEMMAP+1,Y        ; ...not west  of an occupied sector
B472 19D908   08510                 ORA GCMEMMAP+16,Y       ; ...not south of an occupied sector
B475 19B908   08511                 ORA GCMEMMAP-16,Y       ; ...not north of an occupied sector
B478 D0D2     08512                 BNE LOOP064             ;
              08513
B47A A56A     08514                 LDA L.SECTORTYPE        ; Reload sector type
              08515
B47C 99C908   08516 SKIP196         STA GCMEMMAP,Y          ; Store sector type in Galactic Chart memory map
B47F C66B     08517                 DEC L.SECTORCNT         ;
B481 10C9     08518                 BPL LOOP064             ; Next sector
B483 CA       08519                 DEX                     ;
B484 10BB     08520                 BPL LOOP063             ; Next sector type
              08521
              08522 ;*** Clear Galactic Chart and draw top border **********************************
B486 A2B4     08523                 LDX #180                ; Clear Galactic Chart PLAYFIELD
B488 A90A     08524 LOOP065         LDA #CCS.SPC            ;
B48A 9D340D   08525                 STA GCPFMEM-1,X         ;
B48D CA       08526                 DEX                     ;
B48E D0F8     08527                 BNE LOOP065             ;
              08528
B490 A20F     08529                 LDX #15                 ; Draw top border (15(+1) characters)
B492 A918     08530 LOOP066         LDA #CCS.BORDERS        ;
B494 9D370D   08531                 STA GCPFMEM+2,X         ;
B497 CA       08532                 DEX                     ;
B498 10F8     08533                 BPL LOOP066             ;
              08534
B49A A91A     08535                 LDA #CCS.CORNERSW       ; Draw NORTHEAST corner (1 character)
B49C 8D470D   08536                 STA GCPFMEM+18          ;
              08537
B49F A900     08538                 LDA #0                  ; Release starship's position at center of Galactic
B4A1 8D1109   08539                 STA GCMEMMAP+4*16+8     ; ...Chart (sector row 4, sector column 8)
              08540
              08541 ;*** Initialize current sector and hyperwarp marker column and row numbers *****
B4A4 A948     08542                 LDA #$48                ; Place our starship's current sector at
B4A6 8590     08543                 STA CURRSECTOR          ; ...sector row 4, sector column 8
B4A8 A943     08544                 LDA #$43                ; Init departure & arrival hyperwarp marker column
B4AA 858D     08545                 STA WARPDEPRCOLUMN      ;
B4AC 858F     08546                 STA WARPARRVCOLUMN      ;
B4AE A947     08547                 LDA #$47                ; Init departure & arrival hyperwarp marker row
B4B0 858E     08548                 STA WARPARRVROW         ;
B4B2 858C     08549                 STA WARPDEPRROW         ;
              08550
              08551 ;*** Tweak last entry of MAPTOBCD99 ********************************************
B4B4 A9EA     08552                 LDA #CCS.INF*16+CCS.SPC ; Last entry of MAPTOBCD99: 'INFINITY'+'SPACE' char
B4B6 8DE80F   08553                 STA MAPTOBCD99+255      ;
              08554
              08555 ;*******************************************************************************
              08556 ;*                                                                             *
              08557 ;*                                   DRAWGC                                    *
              08558 ;*                                                                             *
              08559 ;*                             Draw Galactic Chart                             *
              08560 ;*                                                                             *
              08561 ;*******************************************************************************
              08562
              08563 ; DESCRIPTION
              08564 ;
              08565 ; Draws the content of the Galactic Chart memory map in GCMEMMAP ($08C9) to the
              08566 ; Galactic Chart PLAYFIELD memory at GCPFMEM ($0D35).
              08567 ;
              08568 ; NOTE: CPU register X indexes the Galactic Chart memory map GCMEMMAP ($08C9)
              08569 ; (16 x 8 bytes). CPU register Y indexes the Galactic Chart PLAYFIELD memory
              08570 ; GCPFMEM ($0D35) (20 x 9 bytes).
              08571 ;
              08572 ; NOTE: Sectors with 1 or 2 Zylon ships display the same symbol in the Galactic
              08573 ; Chart.
              08574
    =006A     08575 L.GCMEMMAPIND   = $6A                   ; Saves Galactic Chart memory map index
              08576
B4B9 A000     08577 DRAWGC          LDY #0                  ; Clear Galactic Chart PLAYFIELD memory index
B4BB 846A     08578                 STY L.GCMEMMAPIND       ; Clear Galactic Chart memory map index
              08579
B4BD A66A     08580 LOOP067         LDX L.GCMEMMAPIND       ; Load sector of Galactic Chart memory map
B4BF BDC908   08581                 LDA GCMEMMAP,X          ;
B4C2 1002     08582                 BPL SKIP197             ; Skip if not a starbase sector
B4C4 A905     08583                 LDA #5                  ; Prep sector character index for starbase
              08584
B4C6 AA       08585 SKIP197         TAX                     ; Load sector character index
B4C7 BDD1BE   08586                 LDA SECTORCHARTAB,X     ; Load custom character set code from table...
B4CA 994B0D   08587                 STA GCPFMEM+22,Y        ; ...and store it in Galactic Chart PLAYFIELD memory
B4CD C8       08588                 INY                     ; Increment Galactic Chart PLAYFIELD memory index
B4CE E66A     08589                 INC L.GCMEMMAPIND       ; Increment Galactic Chart memory map index
B4D0 A56A     08590                 LDA L.GCMEMMAPIND       ;
B4D2 290F     08591                 AND #$0F                ;
B4D4 D0E7     08592                 BNE LOOP067             ; Next sector column until right border reached
              08593
B4D6 A919     08594                 LDA #CCS.BORDERW        ; Draw right border
B4D8 994B0D   08595                 STA GCPFMEM+22,Y        ;
              08596
B4DB C8       08597                 INY                     ; Adjust Galactic Chart PLAYFIELD memory index
B4DC C8       08598                 INY                     ;
B4DD C8       08599                 INY                     ;
B4DE C8       08600                 INY                     ;
B4DF C0A0     08601                 CPY #$A0                ;
B4E1 90DA     08602                 BCC LOOP067             ; Next sector until bottom-right sector reached
              08603
B4E3 60       08604                 RTS                     ; Return
              08605
              08606 ;*******************************************************************************
              08607 ;*                                                                             *
              08608 ;*                                FLUSHGAMELOOP                                *
              08609 ;*                                                                             *
              08610 ;*         Handle remaining tasks at the end of a game loop iteration          *
              08611 ;*                                                                             *
              08612 ;*******************************************************************************
              08613
              08614 ; DESCRIPTION
              08615 ;
              08616 ; This subroutine handles at the end of a game loop iteration the following
              08617 ; tasks:
              08618 ;
              08619 ; (1)  Increment counters COUNT256 ($76) and COUNT8 ($72).
              08620 ;
              08621 ; (2)  If our starship's energy has dropped below 1000 units then flash a {PINK}
              08622 ;      alert that changes to {DARK GREY BLUE} and back to {PINK} every 128 game
              08623 ;      loop iterations.
              08624 ;
              08625 ; (3)  Set the Shields color and the Control Panel background color every 8 game
              08626 ;      loop iterations:
              08627 ;
              08628 ;      o   If the Shields are up and OK then set the Shields color to {DARK
              08629 ;          GREEN} and the Control Panel background color to {DARK BLUE}.
              08630 ;
              08631 ;      o   If the Shields are up and damaged there is a probability of 78%
              08632 ;          (200:256) that the Shield color is not changed.
              08633 ;
              08634 ;      o   If the Shields are down, damaged, or destroyed then set the Shields
              08635 ;          color to {BLACK}.
              08636 ;
              08637 ;      o   If the Shields are destroyed then set the Control Panel background
              08638 ;          color to {ORANGE}.
              08639 ;
              08640 ; (4)  Decrement the lifetime of our starship's and Zylon photon torpedoes.
              08641 ;
              08642 ; (5)  Decrement the lifetime of an explosion. If the explosion lifetime is less
              08643 ;      than 112 game loop iterations, clear HITBADNESS ($8A) (thus the explosion
              08644 ;      cannot destroy our starship). If the explosion lifetime is less than 24
              08645 ;      (?) game loops decrement the number of explosion fragments. This makes
              08646 ;      explosion fragments disappear gradually toward the end of an explosion.
              08647 ;
              08648 ; (6)  Increment every 40 game loop iterations the stardate clock of the
              08649 ;      Galactic Chart Panel Display.
              08650 ;
              08651 ; (7)  Move Zylon units in the Galactic Chart.
              08652 ;
              08653 ;      Every 50 game loop iterations (or 100 game loop iterations when a
              08654 ;      starbase is surrounded by Zylon units) decrement the score.
              08655 ;
              08656 ; Code execution continues if the program is not in demo mode with the following
              08657 ; steps:
              08658 ;
              08659 ; (1)  Search the Galactic Chart for starbases surrounded by Zylon units.
              08660 ;      Destroy any such starbase: Replace it with a 2-Zylon sector and subtract
              08661 ;      18 points from the score. If the Subspace Radio was not destroyed, then
              08662 ;      flash the title phrase "STARBASE DESTROYED" and play the beeper sound
              08663 ;      pattern MESSAGE FROM STARBASE in subroutine BEEP ($B3A6).
              08664 ;
              08665 ; (2)  Every 8 game loop iterations the Zylon units decide, which starbase to
              08666 ;      hunt: First, 128 randomly picked sectors are searched for a starbase. If
              08667 ;      no starbase was found in this way, the sectors of the Galactic Chart are
              08668 ;      scanned systematically left-to-right, top-to-bottom. If a starbase was
              08669 ;      found then its sector, sector column, and sector row are saved, otherwise
              08670 ;      code execution returns.
              08671 ;
              08672 ; (3)  Now the Zylon units converge toward the sector of the hunted starbase:
              08673 ;      All sectors of the Galactic Chart are scanned. For any sector with a
              08674 ;      Zylon unit that was not moved yet (its sector does not have the temporary
              08675 ;      "already-moved" bit B5 set) its movement probability value is picked from
              08676 ;      table MOVEPROBTAB ($BFBB):
              08677 ;
              08678 ;      +---------------+-------------+----------------+
              08679 ;      |  Sector Type  |  Movement   |   Movement     |
              08680 ;      |               | Probability |  Probability   |
              08681 ;      |               |    Value    |                |
              08682 ;      +---------------+-------------+----------------+
              08683 ;      | Empty sector  |       0     |   0% (  0:256) |
              08684 ;      | 1 Zylon ship  |     255     | 100% (255:256) |
              08685 ;      | 2 Zylon ships |     255     | 100% (255:256) |
              08686 ;      | 3 Zylon ships |     192     |  75% (192:256) |
              08687 ;      | 4 Zylon ships |      32     |  13% ( 32:256) |
              08688 ;      +---------------+-------------+----------------+
              08689 ;
              08690 ;      If this value is less or equal than a random number in 0..255 then the
              08691 ;      Zylon unit is moved to another sector. A Zylon unit that currently
              08692 ;      occupies the sector of our starship is not moved.
              08693 ;
              08694 ;      BUG (at $B620): The instruction to check the marker bit B5 of the sector
              08695 ;      is CPY #$0A. This works, as sectors containing Zylon units that need to
              08696 ;      be moved have values of 2..4, see table SECTORTYPETAB ($BBA6). Suggested
              08697 ;      fix: Replace CPY #$0A with CPY #$20, which may make the code clearer.
              08698 ;
              08699 ; (4)  For every Zylon unit that is about to be moved, 9 distances ("block
              08700 ;      distances") between the Zylon unit and the starbase are calculated by
              08701 ;      tentatively moving the Zylon unit into each of its 8 adjacent sectors -
              08702 ;      and by moving it not at all. The sector offsets are taken from table
              08703 ;      COMPASSOFFTAB ($BFC0) which stores direction offsets in the following
              08704 ;      order: NORTH, NORTHWEST, WEST, SOUTHWEST, SOUTH, SOUTHEAST, EAST,
              08705 ;      NORTHEAST, CENTER. All 9 distances are stored in 9 consecutive bytes at
              08706 ;      NEWZYLONDIST ($96).
              08707 ;
              08708 ;      NOTE: The last calculated distance is the current distance between Zylon
              08709 ;      unit and starbase.
              08710 ;
              08711 ;      The Zylon unit moves to the first of the 8 adjacent sectors that matches
              08712 ;      the following conditions:
              08713 ;
              08714 ;      (1)  It is closer to the starbase than the Zylon unit's current sector.
              08715 ;
              08716 ;      (2)  It is located inside the Galactic Chart.
              08717 ;
              08718 ;      (3)  It is empty.
              08719 ;
              08720 ;      (4)  It is not the sector containing our starship.
              08721 ;
              08722 ;      If a suitable new sector was found then the Zylon unit is moved to this
              08723 ;      sector, which is marked with the "already-moved" marker bit B5 in the
              08724 ;      Galactic Chart memory map. This marker bit prevents a Zylon unit that has
              08725 ;      been already moved from being moved again. The old Zylon unit sector is
              08726 ;      cleared.
              08727 ;
              08728 ;      If no suitable new sector was found then the above distance calculations
              08729 ;      are repeated once again by adding 1 to the current distance between the
              08730 ;      Zylon unit and the starbase. This may provoke a Zylon unit to move that
              08731 ;      would not have moved in the previous set of distance calculations.
              08732 ;
              08733 ;      After having moved all Zylon units the sectors are stripped of the
              08734 ;      "already-moved" marker bit B5.
              08735 ;
              08736 ; (5)  If a starbase has been surrounded then the Zylon unit movement timer is
              08737 ;      reset to 99, buying our starship some time to destroy one of the
              08738 ;      surrounding Zylon units. If the Subspace Radio is not destroyed, then the
              08739 ;      message "STARBASE SURROUNDED" is flashed in the title line and the beeper
              08740 ;      sound pattern MESSAGE FROM STARBASE is played in subroutine BEEP ($B3A6).
              08741
    =006A     08742 L.ISDESTROYED   = $6A                   ; Flags the destruction of a starbase.
              08743                                         ; Used values are:
              08744                                         ;   $00 -> Starbase not destroyed
              08745                                         ;   $02 -> Starbase has been destroyed
    =006A     08746 L.NEWSECTOR     = $6A                   ; Sector to which the Zylon unit is tentatively moved
    =006B     08747 L.ABSDIFFCOL    = $6B                   ; Absolute difference between new Zylon and starbase
              08748                                         ;   column on Galactic Chart in PM pixels
    =006B     08749 L.LOOPCNT2      = $6B                   ; Loop counter. Used values are: 0..1.
    =006A     08750 L.DIRECTIONIND  = $6A                   ; Compass rose direction index.
              08751                                         ; Used values are: 0..7.
              08752
              08753 ;*** Increment counters and flash low-energy alert *****************************
B4E4 E676     08754 FLUSHGAMELOOP   INC COUNT256            ; Increment COUNT256 counter
              08755
B4E6 A290     08756                 LDX #$90                ; Prep DLI background color {DARK GREY BLUE}
B4E8 A576     08757                 LDA COUNT256            ;
B4EA 1009     08758                 BPL SKIP198             ; Skip if counter < 128.
              08759
B4EC AC5509   08760                 LDY ENERGYD1            ; When energy drops below 1000 units...
B4EF C080     08761                 CPY #CCS.COL2!CCS.0     ;
B4F1 D002     08762                 BNE SKIP198             ;
B4F3 A244     08763                 LDX #$44                ; ...prep new DLI background color {PINK}
              08764
B4F5 2903     08765 SKIP198         AND #$03                ; Increment COUNT8
B4F7 8572     08766                 STA COUNT8              ;
B4F9 D01F     08767                 BNE SKIP202             ; Skip setting colors but every 8 game loops
              08768
              08769 ;*** Set Shields and Control Panel background color ****************************
B4FB A47D     08770                 LDY DRAINSHIELDS        ; Skip if Shields are off
B4FD F017     08771                 BEQ SKIP201             ;
              08772
B4FF A0A0     08773                 LDY #$A0                ; Prep Shields color {DARK GREEN}
B501 2C9409   08774                 BIT GCSTATSHL           ; Skip if Shields are OK
B504 100B     08775                 BPL SKIP200             ;
B506 7007     08776                 BVS SKIP199             ; Skip if Shields are destroyed
B508 AD0AD2   08777                 LDA RANDOM              ; If Shields are damaged, Shields colors are...
B50B C9C8     08778                 CMP #200                ; ...unchanged with probability of 78% (200:256)
B50D 9007     08779                 BCC SKIP201             ;
              08780
B50F A000     08781 SKIP199         LDY #$00                ; Prep Shields color {BLACK}
B511 98       08782 SKIP200         TYA                     ;
B512 D002     08783                 BNE SKIP201             ;
              08784
B514 A226     08785                 LDX #$26                ; Prep Control Panel background color {ORANGE}
              08786
B516 8481     08787 SKIP201         STY SHIELDSCOLOR        ; Store Shields color
B518 86FB     08788                 STX BGRCOLORDLI         ; Store Control Panel background color
              08789
              08790 ;*** Decrement lifetime of our starship's and Zylon photon torpedoes ***********
B51A A202     08791 SKIP202         LDX #2                  ; Loop over PLAYER2..4
              08792
B51C BD8E0C   08793 LOOP068         LDA PL2SHAPTYPE,X       ; Next PLAYER if not PHOTON TORPEDO (shape type 0)
B51F D006     08794                 BNE SKIP203             ;
              08795
B521 B5EB     08796                 LDA PL2LIFE,X           ; Next PLAYER if this PLAYER not alive
B523 F002     08797                 BEQ SKIP203             ;
              08798
B525 D6EB     08799                 DEC PL2LIFE,X           ; Decrement photon torpedo PLAYER lifetime
              08800
B527 CA       08801 SKIP203         DEX                     ;
B528 10F2     08802                 BPL LOOP068             ; Next PLAYER
              08803
              08804 ;*** Decrement lifetime of explosion *******************************************
B52A A573     08805                 LDA EXPLLIFE            ; Skip if explosion lifetime expired
B52C F016     08806                 BEQ SKIP206             ;
              08807
B52E C673     08808                 DEC EXPLLIFE            ; Decrement explosion lifetime
B530 D004     08809                 BNE SKIP204             ; Skip if explosion lifetime still counting
              08810
B532 A211     08811                 LDX #NUMSPCOBJ.NORM     ; Explosion finished,...
B534 8679     08812                 STX MAXSPCOBJIND        ; ...restore normal number of space objects
              08813
B536 C970     08814 SKIP204         CMP #112                ; Skip if explosion lifetime >= 112 game loops
B538 B004     08815                 BCS SKIP205             ;
              08816
B53A A200     08817                 LDX #0                  ; HITBADNESS := NO HIT
B53C 868A     08818                 STX HITBADNESS          ;
              08819
B53E C918     08820 SKIP205         CMP #24                 ; Skip if explosion lifetime >= 24 game loops (?)
B540 B002     08821                 BCS SKIP206             ;
              08822
B542 C679     08823                 DEC MAXSPCOBJIND        ; Decrement number of explosion fragment space objs
              08824
              08825 ;*** Increment stardate clock **************************************************
B544 C674     08826 SKIP206         DEC CLOCKTIM            ; Decrement stardate clock timer
B546 1021     08827                 BPL SKIP209             ; Return if timer is still counting
              08828
B548 A928     08829                 LDA #40                 ; Reset stardate clock timer to 40 game loops
B54A 8574     08830                 STA CLOCKTIM            ;
              08831
B54C A204     08832                 LDX #4                  ; Increment stardate clock of Galactic Chart Panel
B54E FEA309   08833 LOOP069         INC GCSTARDAT,X         ;
B551 BDA309   08834                 LDA GCSTARDAT,X         ;
B554 C9DA     08835                 CMP #[CCS.COL3!ROM.9]+1 ;
B556 900D     08836                 BCC SKIP208             ;
B558 A9D0     08837                 LDA #[CCS.COL3!ROM.0]   ;
B55A 9DA309   08838                 STA GCSTARDAT,X         ;
B55D E003     08839                 CPX #3                  ;
B55F D001     08840                 BNE SKIP207             ;
B561 CA       08841                 DEX                     ;
B562 CA       08842 SKIP207         DEX                     ;
B563 10E9     08843                 BPL LOOP069             ;
              08844
              08845 ;*** Decrement Zylon unit movement timer ***************************************
B565 C678     08846 SKIP208         DEC ZYLONUNITTIM        ; Decrement Zylon unit movement timer
B567 3001     08847                 BMI SKIP210             ; If timer < 0 move Zylon units
              08848
B569 60       08849 SKIP209         RTS                     ; Return
              08850
              08851 ;*** Restore Zylon unit movement timer and decrement score *********************
B56A A931     08852 SKIP210         LDA #49                 ; Reset Zylon unit movement timer to 49
B56C 8578     08853                 STA ZYLONUNITTIM        ;
              08854
B56E A5CB     08855                 LDA SCORE               ; SCORE := SCORE - 1
B570 D002     08856                 BNE SKIP211             ;
B572 C6CC     08857                 DEC SCORE+1             ;
B574 C6CB     08858 SKIP211         DEC SCORE               ;
              08859
B576 A664     08860                 LDX ISDEMOMODE          ; Return if in demo mode
B578 D0EF     08861                 BNE SKIP209             ;
              08862
              08863 ;*** Is starbase surrounded? ***************************************************
B57A 866A     08864                 STX L.ISDESTROYED       ; Init L.ISDESTROYED with 0 (starbase not destroyed)
B57C BDC908   08865 LOOP070         LDA GCMEMMAP,X          ; Loop over all sectors, load sector type
B57F 1019     08866                 BPL SKIP212             ; Skip if not a starbase sector
              08867
B581 20F1B7   08868                 JSR ISSURROUNDED        ; Skip if starbase sector not completely surrounded
B584 F014     08869                 BEQ SKIP212             ;
              08870
              08871 ;*** Starbase is surrounded, destroy starbase **********************************
B586 A902     08872                 LDA #2                  ; Replace starbase sector with 2-Zylon sector
B588 9DC908   08873                 STA GCMEMMAP,X          ;
B58B 856A     08874                 STA L.ISDESTROYED       ; Flag destruction of starbase
              08875
B58D 38       08876                 SEC                     ; SCORE := SCORE - 18
B58E A5CB     08877                 LDA SCORE               ;
B590 E912     08878                 SBC #18                 ;
B592 85CB     08879                 STA SCORE               ;
B594 A5CC     08880                 LDA SCORE+1             ;
B596 E900     08881                 SBC #0                  ;
B598 85CC     08882                 STA SCORE+1             ;
              08883
B59A E8       08884 SKIP212         INX                     ;
B59B 10DF     08885                 BPL LOOP070             ; Next sector
              08886
              08887 ;*** Report starbase destruction ***********************************************
B59D A56A     08888                 LDA L.ISDESTROYED       ; Skip if no starbase has been destroyed
B59F F00F     08889                 BEQ SKIP213             ;
              08890
B5A1 2C9709   08891                 BIT GCSTATRAD           ; Skip notification if Subspace Radio destroyed
B5A4 700A     08892                 BVS SKIP213             ;
              08893
B5A6 A015     08894                 LDY #$15                ; Set title phrase "STARBASE DESTROYED"
B5A8 2023B2   08895                 JSR SETTITLE            ;
              08896
B5AB A218     08897                 LDX #$18                ; Play beeper sound pattern MESSAGE FROM STARBASE
B5AD 20A6B3   08898                 JSR BEEP                ;
              08899
              08900 ;*** Pick new starbase to be hunted by Zylon units *****************************
B5B0 C69F     08901 SKIP213         DEC HUNTTIM             ; Decrement hunting timer
B5B2 3007     08902                 BMI SKIP214             ; If timer < 0 decide which starbase to hunt
              08903
B5B4 A693     08904                 LDX HUNTSECTOR          ; Skip if Zylon units already picked starbase to hunt
B5B6 BDC908   08905                 LDA GCMEMMAP,X          ;
B5B9 301F     08906                 BMI SKIP215             ;
              08907
B5BB A907     08908 SKIP214         LDA #7                  ; Reset hunting timer
B5BD 859F     08909                 STA HUNTTIM             ;
              08910
B5BF A07F     08911                 LDY #127                ; Loop over 127(+1) randomly picked sectors
B5C1 AD0AD2   08912 LOOP071         LDA RANDOM              ;
B5C4 297F     08913                 AND #$7F                ;
B5C6 AA       08914                 TAX                     ;
B5C7 BDC908   08915                 LDA GCMEMMAP,X          ; Skip if starbase sector found
B5CA 300E     08916                 BMI SKIP215             ;
B5CC 88       08917                 DEY                     ;
B5CD 10F2     08918                 BPL LOOP071             ; Next sector
              08919
B5CF A27F     08920                 LDX #127                ; Loop over all sectors of the Galactic Chart
B5D1 BDC908   08921 LOOP072         LDA GCMEMMAP,X          ;
B5D4 3004     08922                 BMI SKIP215             ; Skip if starbase sector found
B5D6 CA       08923                 DEX                     ;
B5D7 10F8     08924                 BPL LOOP072             ; Next sector
              08925
B5D9 60       08926                 RTS                     ; Return (no starbase sector found)
              08927
              08928 ;*** Store coordinates of starbase to be hunted ********************************
B5DA 8693     08929 SKIP215         STX HUNTSECTOR          ; Store hunted starbase sector column and row
B5DC 8A       08930                 TXA                     ;
B5DD 290F     08931                 AND #$0F                ;
B5DF 8594     08932                 STA HUNTSECTCOLUMN      ;
B5E1 8A       08933                 TXA                     ;
B5E2 4A       08934                 LSR A                   ;
B5E3 4A       08935                 LSR A                   ;
B5E4 4A       08936                 LSR A                   ;
B5E5 4A       08937                 LSR A                   ;
B5E6 8595     08938                 STA HUNTSECTROW         ;
              08939
              08940 ;*** Move all Zylon units toward hunted starbase *******************************
B5E8 A2FF     08941                 LDX #$FF                ;
B5EA E8       08942 LOOP073         INX                     ; Loop over all sectors to move Zylon units
B5EB 1030     08943                 BPL SKIP218             ; Jump into loop body below
              08944
              08945 ;*** Strip marker bits from moved Zylon units **********************************
B5ED A200     08946                 LDX #0                  ;
B5EF BDC908   08947 LOOP074         LDA GCMEMMAP,X          ; Loop over all sectors
B5F2 29DF     08948                 AND #$DF                ;
B5F4 9DC908   08949                 STA GCMEMMAP,X          ; Strip marker bit B5 from moved Zylon units
B5F7 E8       08950                 INX                     ;
B5F8 10F5     08951                 BPL LOOP074             ; Next sector
              08952
              08953 ;*** Handle surrounded starbase ************************************************
B5FA 2C9709   08954                 BIT GCSTATRAD           ; Return if Subspace Radio is destroyed
B5FD 701D     08955                 BVS SKIP217             ;
              08956
B5FF A200     08957                 LDX #0                  ; Loop over all sectors
B601 BDC908   08958 LOOP075         LDA GCMEMMAP,X          ;
B604 1013     08959                 BPL SKIP216             ; Skip if not a starbase sector
B606 20F1B7   08960                 JSR ISSURROUNDED        ; Skip if starbase not surrounded
B609 F00E     08961                 BEQ SKIP216             ;
              08962
B60B A963     08963                 LDA #99                 ; Yes, starbase surrounded...
B60D 8578     08964                 STA ZYLONUNITTIM        ; ...set Zylon unit movement timer to 99
              08965
B60F A013     08966                 LDY #$13                ; Set title phrase "STARBASE SURROUNDED"
B611 2023B2   08967                 JSR SETTITLE            ;
              08968
B614 A218     08969                 LDX #$18                ; Play beeper sound pattern MESSAGE FROM STARBASE...
B616 4CA6B3   08970                 JMP BEEP                ; ...and return
              08971
B619 E8       08972 SKIP216         INX                     ;
B61A 10E5     08973                 BPL LOOP075             ; Next sector
              08974
B61C 60       08975 SKIP217         RTS                     ; Return
              08976
              08977 ;*** Move single Zylon unit ****************************************************
B61D BCC908   08978 SKIP218         LDY GCMEMMAP,X          ; X contains current sector
B620 C00A     08979                 CPY #$0A                ; Next sector if it has marker bit B5 set (!)
B622 B0C6     08980                 BCS LOOP073             ;
              08981
B624 AD0AD2   08982                 LDA RANDOM              ; Get random number
B627 D9BBBF   08983                 CMP MOVEPROBTAB,Y       ; Get movement probability
B62A B0BE     08984                 BCS LOOP073             ; Next sector if movement probability < random number
              08985
B62C E490     08986                 CPX CURRSECTOR          ; Next sector if this is our starship's sector
B62E F0BA     08987                 BEQ LOOP073             ;
              08988
              08989 ;*** Compute distance to starbase by moving Zylon unit into 9 directions *******
B630 A008     08990                 LDY #8                  ; Loop over 8(+1) possible directions
B632 18       08991 LOOP076         CLC                     ;
B633 8A       08992                 TXA                     ;
B634 79C0BF   08993                 ADC COMPASSOFFTAB,Y     ; Add direction offset to current sector
B637 856A     08994                 STA L.NEWSECTOR         ; Store new sector
              08995
B639 290F     08996                 AND #$0F                ; Calc distance ("block distance") between...
B63B 38       08997                 SEC                     ; ...starbase sector and tentative new Zylon sector
B63C E594     08998                 SBC HUNTSECTCOLUMN      ;
B63E B004     08999                 BCS SKIP219             ;
B640 49FF     09000                 EOR #$FF                ;
B642 6901     09001                 ADC #1                  ;
B644 856B     09002 SKIP219         STA L.ABSDIFFCOL        ;
B646 A56A     09003                 LDA L.NEWSECTOR         ;
B648 4A       09004                 LSR A                   ;
B649 4A       09005                 LSR A                   ;
B64A 4A       09006                 LSR A                   ;
B64B 4A       09007                 LSR A                   ;
B64C 38       09008                 SEC                     ;
B64D E595     09009                 SBC HUNTSECTROW         ;
B64F B004     09010                 BCS SKIP220             ;
B651 49FF     09011                 EOR #$FF                ;
B653 6901     09012                 ADC #1                  ;
B655 18       09013 SKIP220         CLC                     ;
B656 656B     09014                 ADC L.ABSDIFFCOL        ;
              09015
B658 999600   09016                 STA NEWZYLONDIST,Y      ; Store distance in distance array
B65B 88       09017                 DEY                     ;
B65C 10D4     09018                 BPL LOOP076             ; Next direction
              09019
              09020 ;*** Pick the shortest distance to starbase ************************************
B65E A901     09021                 LDA #1                  ; Loop over compass rose directions twice to...
B660 856B     09022                 STA L.LOOPCNT2          ; ...provoke movement regardless of truncation errors
              09023
B662 A007     09024 LOOP077         LDY #7                  ;
B664 B99600   09025 LOOP078         LDA NEWZYLONDIST,Y      ; Loop over all 7(+1) compass rose directions
B667 C59E     09026                 CMP OLDZYLONDIST        ;
B669 B024     09027                 BCS SKIP222             ; Next direction if new distance > current distance
              09028
B66B 18       09029                 CLC                     ; Calc new Galactic Chart sector for Zylon unit
B66C 8A       09030                 TXA                     ;
B66D 79C0BF   09031                 ADC COMPASSOFFTAB,Y     ;
B670 301D     09032                 BMI SKIP222             ; Next direction if new sector outside Galactic Chart
              09033
B672 846A     09034                 STY L.DIRECTIONIND      ; Save compass rose direction index
B674 A8       09035                 TAY                     ;
B675 B9C908   09036                 LDA GCMEMMAP,Y          ;
B678 D013     09037                 BNE SKIP221             ; Next direction if new sector not empty
              09038
B67A BDC908   09039                 LDA GCMEMMAP,X          ; Preload Zylon sector type to be moved
B67D C490     09040                 CPY CURRSECTOR          ;
B67F F00C     09041                 BEQ SKIP221             ; Next direction if sector is our starship's sector
              09042
B681 0920     09043                 ORA #$20                ; New sector for Zylon unit found!
B683 99C908   09044                 STA GCMEMMAP,Y          ; Temporarily mark that sector with marker bit B5
B686 A900     09045                 LDA #0                  ;
B688 9DC908   09046                 STA GCMEMMAP,X          ; Clear old Zylon unit sector
B68B F00B     09047                 BEQ SKIP223             ; Next sector (unconditional branch)
              09048
B68D A46A     09049 SKIP221         LDY L.DIRECTIONIND      ; Restore compass rose direction index
B68F 88       09050 SKIP222         DEY                     ; Next compass rose direction
B690 10D2     09051                 BPL LOOP078             ;
              09052
B692 E69E     09053                 INC OLDZYLONDIST        ; Increment center distance
B694 C66B     09054                 DEC L.LOOPCNT2          ;
B696 10CA     09055                 BPL LOOP077             ; Loop over all compass rose directions one more time
              09056
B698 4CEAB5   09057 SKIP223         JMP LOOP073             ; Next sector
              09058
              09059 ; *******************************************************************************
              09060 ; *                                                                             *
              09061 ; *                                   ROTATE                                    *
              09062 ; *                                                                             *
              09063 ; *        Rotate position vector component (coordinate) by fixed angle         *
              09064 ; *                                                                             *
              09065 ; *******************************************************************************
              09066
              09067 ; DESCRIPTION
              09068 ;
              09069 ; This subroutine rotates a position vector component (coordinate) of a space
              09070 ; object by a fixed angle around the center of the 3D coordinate system, the
              09071 ; location of our starship. This is used in the Front, Aft, and Long-Range Scan
              09072 ; views to rotate space objects in and out of the view. Although the code is
              09073 ; deceptively short, there is some interesting math involved, so a more detailed
              09074 ; discussion is in order.
              09075 ;
              09076 ; ROTATION MATHEMATICS
              09077 ;
              09078 ; The program uses a left-handed 3D coordinate system with the positive x-axis
              09079 ; pointing to the right, the positive y-axis pointing up, and the positive
              09080 ; z-axis pointing into flight direction.
              09081 ;
              09082 ; A rotation in this coordinate system around the y-axis (horizontal rotation)
              09083 ; can be expressed as
              09084 ;
              09085 ;     x' :=   cos(ry) * x + sin(ry) * z    (1a)
              09086 ;     z' := - sin(ry) * x + cos(ry) * z    (1b)
              09087 ;
              09088 ; where ry is the clockwise rotation angle around the y-axis, x and z are the
              09089 ; coordinates before this rotation, and the primed coordinates x' and z' the
              09090 ; coordinates after this rotation. The y-coordinate is not changed by this
              09091 ; rotation.
              09092 ;
              09093 ; A rotation in this coordinate system around the x-axis (vertical rotation) can
              09094 ; be expressed as
              09095 ;
              09096 ;     z' :=   cos(rx) * z + sin(rx) * y    (2a)
              09097 ;     y' := - sin(rx) * z + cos(rx) * y    (2b)
              09098 ;
              09099 ; where rx is the clockwise rotation angle around the x-axis, z and y are the
              09100 ; coordinates before this rotation, and the primed coordinates z' and y' the
              09101 ; coordinates after this rotation. The x-coordinate is not changed by this
              09102 ; rotation.
              09103 ;
              09104 ; SUBROUTINE IMPLEMENTATION OVERVIEW
              09105 ;
              09106 ; A single call of this subroutine is able to compute one of the four
              09107 ; expressions (1a)-(2b). To compute all four expressions to get the new set of
              09108 ; coordinates, this subroutine has to be called four times. This is done twice
              09109 ; in pairs in GAMELOOP ($A1F3) at $A391 and $A398, and at $A3AE and $A3B5,
              09110 ; respectively.
              09111 ;
              09112 ; The first pair of calls calculates the new x and z coordinates of a space
              09113 ; object due to a horizontal (left/right) rotation of our starship around the
              09114 ; y-axis following expressions (1a) and (1b).
              09115 ;
              09116 ; The second pair of calls calculates the new y and z coordinates of the same
              09117 ; space object due to a vertical (up/down) rotation of our starship around the
              09118 ; x-axis following expressions (2a) and (2b).
              09119 ;
              09120 ; If you look at the code, you may be wondering how this calculation is actually
              09121 ; executed, as there is neither a sin() nor a cos() function call. What you'll
              09122 ; actually find implemented are the following calculations:
              09123 ;
              09124 ;     Joystick left                        Joystick right
              09125 ;     ---------------------                ---------------------
              09126 ;     x :=  x      + z / 64    (3a)        x :=  x      - z / 64    (4a)
              09127 ;     z := -x / 64 + z         (3b)        z :=  x / 64 + z         (4b)
              09128 ;
              09129 ;     Joystick down                        Joystick up
              09130 ;     ---------------------                ---------------------
              09131 ;     y :=  y      + z / 64    (5a)        y :=  y      - z / 64    (6a)
              09132 ;     z := -y / 64 + z         (5b)        z :=  y / 64 + z         (6b)
              09133 ;
              09134 ; CORDIC ALGORITHM
              09135 ;
              09136 ; When you compare expressions (1a)-(2b) with (3a)-(6b), notice the similarity
              09137 ; between the expressions if you substitute
              09138 ;
              09139 ;     sin(ry) -> 1 / 64,
              09140 ;     cos(ry) -> 1,
              09141 ;     sin(rx) -> 1 / 64, and
              09142 ;     cos(rx) -> 1.
              09143 ;
              09144 ; From sin(ry) = 1 / 64 and sin(rx) = 1 / 64 you can derive that the rotation
              09145 ; angles ry and rx by which the space object is rotated per game loop iteration
              09146 ; have a constant value of 0.89 degrees, as arcsine(1 / 64) = 0.89 degrees.
              09147 ;
              09148 ; What about cos(ry) and cos(rx)? The substitution does not match our derived
              09149 ; angle exactly, because cos(0.89 degrees) = 0.99988 and is not exactly 1.
              09150 ; However, this value is so close to 1 that substituting cos(0.89 degrees) with
              09151 ; 1 is a very good approximation, simplifying calculations significantly.
              09152 ;
              09153 ; Another significant simplification results from the division by 64, because
              09154 ; the actual division operation can be replaced with a much faster bit shift
              09155 ; operation.
              09156 ;
              09157 ; This calculation-friendly way of computing rotations is known as the "CORDIC
              09158 ; (COordinate Rotation DIgital Computer)" algorithm.
              09159 ;
              09160 ; MINSKY ROTATION
              09161 ;
              09162 ; There is one more interesting mathematical subtlety: Did you notice that
              09163 ; expressions (1a)-(2b) use a new (primed) pair of variables to store the
              09164 ; resulting coordinates, whereas in the implemented expressions (3a)-(6b) the
              09165 ; value of the first coordinate of a coordinate pair is overwritten with its new
              09166 ; value and this value is used in the subsequent calculation of the second
              09167 ; coordinate? For example, when the joystick is pushed left, the first call of
              09168 ; this subroutine calculates the new value of x according to expression (3a),
              09169 ; overwriting the old value of x. During the second call to calculate z
              09170 ; according to expression (3b), the new value of x is used instead of the old
              09171 ; one. Is this to save the memory needed to temporarily store the old value of
              09172 ; x? But isn't this a bug? If so, why does the rotation calculation actually
              09173 ; work?
              09174 ;
              09175 ; Have a look at the expression pair (3a) and (3b) (the other expression pairs
              09176 ; (4a)-(6b) work in a similar fashion):
              09177 ;
              09178 ;     x :=  x      + z / 64
              09179 ;     z := -x / 64 + z
              09180 ;
              09181 ; With the substitution 1 / 64 -> e, we get
              09182 ;
              09183 ;     x :=  x     + e * z
              09184 ;     z := -e * x + z
              09185 ;
              09186 ; Note that x is calculated first and then used in the second expression. When
              09187 ; using primed coordinates for the resulting coordinates after calculating the
              09188 ; two expressions we get
              09189 ;
              09190 ;     x' := x + e * z
              09191 ;     z' := -e * x' + z = -e * (x + e * z) + z = -e * x + (1 - e^2) * z
              09192 ;
              09193 ; or in matrix form
              09194 ;
              09195 ;     |x'| := | 1       e   | * |x|
              09196 ;     |z'|    |-e  (1 - e^2)|   |z|
              09197 ;
              09198 ; Surprisingly, this turns out to be a rotation matrix, because its determinant
              09199 ; is (1 * (1 - e^2) - (e * -e)) = 1.
              09200 ;
              09201 ; (Incidentally, the column vectors of this matrix do not form a orthogonal
              09202 ; basis, as their scalar product is 1 * e + (-e * (1 - e^2)) = -e^2.
              09203 ; Orthogonality holds for e = 0 only.
              09204 ;
              09205 ; This kind of rotation calculation is described by Marvin Minsky in ["AIM 239
              09206 ; HAKMEM", Item 149, p. 73, MIT AI Lab, February 1972] and is called "Minsky
              09207 ; Rotation".
              09208 ;
              09209 ; SUBROUTINE IMPLEMENTATION DETAILS
              09210 ;
              09211 ; To better understand how the implementation of this subroutine works, have
              09212 ; again a look at expressions (3a)-(6b). If you rearrange the expressions a
              09213 ; little their structure is always of the form
              09214 ;
              09215 ;     TERM1 := TERM1 SIGN TERM2 / 64
              09216 ;
              09217 ;     or shorter
              09218 ;
              09219 ;     TERM1 := TERM1 SIGN TERM3
              09220 ;
              09221 ;     where
              09222 ;
              09223 ;     TERM3 := TERM2 / 64
              09224 ;     SIGN := + or -
              09225 ;
              09226 ; and where TERM1 and TERM2 are position vector components (coordinates). In
              09227 ; fact, this is all this subroutine actually does: It simply adds (or subtracts)
              09228 ; TERM2 divided by 64 to (from) TERM1.
              09229 ;
              09230 ; When calling this subroutine the correct indices for the appropriate position
              09231 ; vector components (coordinates) TERM1 and TERM2 are passed in the Y and X
              09232 ; registers, respectively.
              09233 ;
              09234 ; What about SIGN between TERM1 and TERM3? Have again a look at expressions
              09235 ; (3a)-(6b). To compute the two new coordinates after a rotation, the SIGN
              09236 ; toggles from plus to minus and vice versa. The SIGN is initialized by
              09237 ; JOYSTICKDELTA ($6D) before actually calling subroutine ROTATE ($B69B) and is
              09238 ; toggled in every subsequent call of this subroutine. The initial value of SIGN
              09239 ; should be positive (+) if the rotation is clockwise (the joystick is pushed
              09240 ; right or up) and negative if the rotation is counter-clockwise (the joystick
              09241 ; is pushed left or down), respectively. Because SIGN is always toggled you have
              09242 ; to pass the already toggled value with the first call.
              09243 ;
              09244 ; NOTE: Unclear still are three instructions starting at address $B6AD. They
              09245 ; seem to set the two least significant bits of TERM3 in a random fashion. Could
              09246 ; this be some quick hack to avoid messing with exact but potentially lengthy
              09247 ; two-complement's arithmetic here?
              09248 ;
              09249 ; INPUT
              09250 ;
              09251 ;   X = Position vector component index of TERM2. Used values are:
              09252 ;     $00..$30 -> z-component (z-coordinate) of position vector 0..48
              09253 ;     $31..$61 -> x-component (x-coordinate) of position vector 0..48
              09254 ;     $62..$92 -> y-component (y-coordinate) of position vector 0..48
              09255 ;
              09256 ;   Y = Position vector component index of TERM1. Used values are:
              09257 ;     $00..$30 -> z-component (z-coordinate) of position vector 0..48
              09258 ;     $31..$61 -> x-component (x-coordinate) of position vector 0..48
              09259 ;     $62..$92 -> y-component (y-coordinate) of position vector 0..48
              09260 ;
              09261 ;   JOYSTICKDELTA ($6D) = Initial value of SIGN. Used values are:
              09262 ;     $01 -> (= Positive) Rotate right or up
              09263 ;     $FF -> (= Negative) Rotate left or down
              09264
              09265                                         ; TERM3 is a 24-bit value, represented by 3 bytes as
              09266                                         ; $(sign)(high byte)(low byte)
    =006A     09267 L.TERM3LO       = $6A                   ; TERM3 (high byte), where TERM3 := TERM2 / 64
    =006B     09268 L.TERM3HI       = $6B                   ; TERM3 (low byte),  where TERM3 := TERM2 / 64
    =006C     09269 L.TERM3SIGN     = $6C                   ; TERM3 (sign),      where TERM3 := TERM2 / 64
              09270
B69B BDAD09   09271 ROTATE          LDA ZPOSSIGN,X          ;
B69E 4901     09272                 EOR #$01                ;
B6A0 F002     09273                 BEQ SKIP224             ; Skip if sign of TERM2 is positive
B6A2 A9FF     09274                 LDA #$FF                ;
              09275
B6A4 856B     09276 SKIP224         STA L.TERM3HI           ; If TERM2 pos. -> TERM3 := $0000xx (= TERM2 / 256)
B6A6 856C     09277                 STA L.TERM3SIGN         ; If TERM2 neg. -> TERM3 := $FFFFxx (= TERM2 / 256)
B6A8 BD400A   09278                 LDA ZPOSHI,X            ; where xx := TERM2 (high byte)
B6AB 856A     09279                 STA L.TERM3LO           ;
              09280
B6AD AD0AD2   09281                 LDA RANDOM              ; (?) Hack to avoid messing with two-complement's
B6B0 09BF     09282                 ORA #$BF                ; (?) arithmetic? Provides two least significant
B6B2 5DD30A   09283                 EOR ZPOSLO,X            ; (?) bits B1..0 in TERM3.
              09284
B6B5 0A       09285                 ASL A                   ; TERM3 := TERM3 * 4 (= TERM2 / 256 * 4 = TERM2 / 64)
B6B6 266A     09286                 ROL L.TERM3LO           ;
B6B8 266B     09287                 ROL L.TERM3HI           ;
B6BA 0A       09288                 ASL A                   ;
B6BB 266A     09289                 ROL L.TERM3LO           ;
B6BD 266B     09290                 ROL L.TERM3HI           ;
              09291
B6BF A56D     09292                 LDA JOYSTICKDELTA       ; Toggle SIGN for next call of ROTATE
B6C1 49FF     09293                 EOR #$FF                ;
B6C3 856D     09294                 STA JOYSTICKDELTA       ;
B6C5 301A     09295                 BMI SKIP225             ; If SIGN negative then subtract, else add TERM3
              09296
              09297 ;*** Addition ******************************************************************
B6C7 18       09298                 CLC                     ; TERM1 := TERM1 + TERM3
B6C8 B9D30A   09299                 LDA ZPOSLO,Y            ; (24-bit addition)
B6CB 656A     09300                 ADC L.TERM3LO           ;
B6CD 99D30A   09301                 STA ZPOSLO,Y            ;
              09302
B6D0 B9400A   09303                 LDA ZPOSHI,Y            ;
B6D3 656B     09304                 ADC L.TERM3HI           ;
B6D5 99400A   09305                 STA ZPOSHI,Y            ;
              09306
B6D8 B9AD09   09307                 LDA ZPOSSIGN,Y          ;
B6DB 656C     09308                 ADC L.TERM3SIGN         ;
B6DD 99AD09   09309                 STA ZPOSSIGN,Y          ;
B6E0 60       09310                 RTS                     ;
              09311
              09312 ;*** Subtraction ***************************************************************
B6E1 38       09313 SKIP225         SEC                     ; TERM1 := TERM1 - TERM3
B6E2 B9D30A   09314                 LDA ZPOSLO,Y            ; (24-bit subtraction)
B6E5 E56A     09315                 SBC L.TERM3LO           ;
B6E7 99D30A   09316                 STA ZPOSLO,Y            ;
              09317
B6EA B9400A   09318                 LDA ZPOSHI,Y            ;
B6ED E56B     09319                 SBC L.TERM3HI           ;
B6EF 99400A   09320                 STA ZPOSHI,Y            ;
              09321
B6F2 B9AD09   09322                 LDA ZPOSSIGN,Y          ;
B6F5 E56C     09323                 SBC L.TERM3SIGN         ;
B6F7 99AD09   09324                 STA ZPOSSIGN,Y          ;
B6FA 60       09325                 RTS                     ;
              09326
              09327 ;*******************************************************************************
              09328 ;*                                                                             *
              09329 ;*                                SCREENCOLUMN                                 *
              09330 ;*                                                                             *
              09331 ;*       Calculate pixel column number from centered pixel column number       *
              09332 ;*                                                                             *
              09333 ;*******************************************************************************
              09334
              09335 ; DESCRIPTION
              09336 ;
              09337 ; Converts a pixel column number relative to the horizontal screen center to a
              09338 ; pixel column number relative to the top-left corner of the screen and stores
              09339 ; the result in table PIXELCOLUMN ($0C2A). The passed relative pixel column
              09340 ; number is always positive. The sign is picked from the corresponding
              09341 ; x-component of the position vector (x-coordinate).
              09342 ;
              09343 ; If the passed relative pixel column number is offscreen horizontally the
              09344 ; calculation is skipped and code execution returns. If the position vector
              09345 ; corresponding to this pixel represents a PLAYFIELD space object (star,
              09346 ; explosion fragments) a new position vector is initialized before code
              09347 ; execution returns. If it represents a PLAYER space object the PLAYER is pushed
              09348 ; offscreen before code execution returns.
              09349 ;
              09350 ; NOTE: The horizontal screen center's pixel column number for PLAYFIELD space
              09351 ; objects has a value of 80 = 160 PLAYFIELD pixels / 2. For PLAYER space objects
              09352 ; it has a value of 125 Player/Missile (PM) pixels (from left to right: 128 PM
              09353 ; pixels to the horizontal screen center - 3 PM pixels relative offset of the
              09354 ; PLAYER shape's horizontal center to its left edge = 125 PM pixels).
              09355 ;
              09356 ; INPUT
              09357 ;
              09358 ;   A = Pixel column number relative to the horizontal screen center, always
              09359 ;       positive. Used values are:
              09360 ;     0..80 -> Regular values, pixel is onscreen
              09361 ;     $FF   -> Pixel is offscreen
              09362 ;
              09363 ;   X = Position vector index. Used values are:
              09364 ;     0..4  -> Position vector of a PLAYER space object
              09365 ;     5..48 -> Position vector of a PLAYFIELD space object
              09366
    =006D     09367 L.PIXELCOLUMN   = $6D                   ; Saves relative pixel column number
              09368
B6FB C950     09369 SCREENCOLUMN    CMP #80                 ; If pixel is offscreen (A > 79)...
B6FD B05B     09370                 BCS SKIP233             ; ...return via initializing a new position vector
              09371
B6FF 856D     09372                 STA L.PIXELCOLUMN       ; Save relative pixel column number
B701 A950     09373                 LDA #80                 ; If PLAYFIELD space object -> A := CENTERCOL = 80
B703 E005     09374                 CPX #NUMSPCOBJ.PL       ; If PLAYER space object    -> A := CENTERCOL = 125
B705 B002     09375                 BCS SKIP226             ;
B707 A97D     09376                 LDA #125                ;
              09377
B709 BCDE09   09378 SKIP226         LDY XPOSSIGN,X          ; Skip if x-coordinate positive
B70C D009     09379                 BNE SKIP227             ;
              09380
B70E 38       09381                 SEC                     ; Pixel in left screen half (x-coordinate negative)
B70F E66D     09382                 INC L.PIXELCOLUMN       ;
B711 E56D     09383                 SBC L.PIXELCOLUMN       ;
B713 9D2A0C   09384                 STA PIXELCOLUMN,X       ; Pixel column := CENTERCOL - (rel. pixel column + 1)
B716 60       09385                 RTS                     ; Return
              09386
B717 18       09387 SKIP227         CLC                     ; Pixel in right screen half (x-coordinate positive)
B718 656D     09388                 ADC L.PIXELCOLUMN       ;
B71A 9D2A0C   09389                 STA PIXELCOLUMN,X       ; Pixel column := CENTERCOL + relative pixel column
B71D 60       09390                 RTS                     ; Return
              09391
              09392 ;*******************************************************************************
              09393 ;*                                                                             *
              09394 ;*                                  SCREENROW                                  *
              09395 ;*                                                                             *
              09396 ;*          Calculate pixel row number from centered pixel row number          *
              09397 ;*                                                                             *
              09398 ;*******************************************************************************
              09399
              09400 ; Converts a pixel row number relative to the vertical screen center to a pixel
              09401 ; row number relative to the top-left corner of the screen and stores the result
              09402 ; in table PIXELROWNEW ($0BF9). The passed relative pixel row number is always
              09403 ; positive. The sign is picked from the corresponding y-component of the
              09404 ; position vector (y-coordinate).
              09405 ;
              09406 ; If the passed relative pixel row number is offscreen vertically the
              09407 ; calculation is skipped and code execution returns. If the position vector
              09408 ; corresponding to this pixel represents a PLAYFIELD space object (star,
              09409 ; explosion fragments) a new position vector is initialized in subroutine
              09410 ; INITPOSVEC ($B764) before code execution returns. If it represents a PLAYER
              09411 ; space object the PLAYER is pushed offscreen before code execution returns.
              09412 ;
              09413 ; NOTE: The vertical screen center's pixel row number for PLAYFIELD space
              09414 ; objects has a value of 50 = 100 PLAYFIELD pixels / 2. For PLAYER space objects
              09415 ; it has a value of 122 Player/Missile (PM) pixels (from top to bottom: 8 PM
              09416 ; pixels to start of Display List + 16 PM pixels to begin of PLAYFIELD + 100 PM
              09417 ; pixels to vertical screen center - 2 PM pixels (?) = 122 PM pixels).
              09418 ;
              09419 ; NOTE: If the position vector corresponding to the pixel represents a PLAYER
              09420 ; space object the passed pixel row number is doubled because 1 PLAYFIELD pixel
              09421 ; has the same height as 2 PM pixels at single-line resolution.
              09422 ;
              09423 ; When in Long-Range Scan view the z-coordinate takes the place of the
              09424 ; y-coordinate of the Front or Aft view. If the Long-Range Scan is damaged the
              09425 ; passed pixel row number is treated randomly as a negative or positive value
              09426 ; (mirror effect).
              09427 ;
              09428 ; INPUT
              09429 ;
              09430 ;   A = Pixel row number relative to the vertical screen center, always
              09431 ;       positive. Used values are:
              09432 ;     0..50 -> Regular values, pixel is onscreen
              09433 ;     $FF   -> Pixel is offscreen
              09434 ;
              09435 ;   X = Position vector index. Used values are:
              09436 ;     0..4  -> Position vector of a PLAYER space object
              09437 ;     5..48 -> Position vector of a PLAYFIELD space object
              09438
    =006D     09439 L.PIXELROW      = $6D                   ; Saves relative pixel row number
              09440
B71E C932     09441 SCREENROW       CMP #50                 ; If pixel is offscreen (A > 49)...
B720 B038     09442                 BCS SKIP233             ; ...return via initializing a new position vector
              09443
B722 856D     09444                 STA L.PIXELROW          ; Save relative pixel row number
B724 A932     09445                 LDA #50                 ; If PLAYFIELD space object -> A := CENTERROW = 50
B726 E005     09446                 CPX #NUMSPCOBJ.PL       ;
B728 B004     09447                 BCS SKIP228             ;
B72A 066D     09448                 ASL L.PIXELROW          ; If PLAYER space object -> Double pixel row number
B72C A97A     09449                 LDA #122                ; If PLAYER space object ->    A := CENTERROW = 122
              09450
B72E 24D0     09451 SKIP228         BIT SHIPVIEW            ; Skip if not in Long-Range Scan view
B730 5013     09452                 BVC SKIP230             ;
              09453
B732 2C9609   09454                 BIT GCSTATLRS           ; Skip if Long-Range Scan OK
B735 1007     09455                 BPL SKIP229             ;
              09456
B737 2C0AD2   09457                 BIT RANDOM              ; Long-Range Scan damaged...
B73A 500E     09458                 BVC SKIP231             ; ...branch randomly to pixel row number calculation
B73C 7015     09459                 BVS SKIP232             ; ...(mirror effect)
              09460
B73E BCAD09   09461 SKIP229         LDY ZPOSSIGN,X          ;
B741 D007     09462                 BNE SKIP231             ; Skip if z-coordinate pos. (Long-Range Scan view)
B743 F00E     09463                 BEQ SKIP232             ; Skip if z-coordinate neg. (Long-Range Scan view)
              09464
B745 BC0F0A   09465 SKIP230         LDY YPOSSIGN,X          ;
B748 F009     09466                 BEQ SKIP232             ; Skip if y-coordinate neg. (Front or Aft view)
              09467
B74A 38       09468 SKIP231         SEC                     ; Pixel in upper screen half (z or y coordinate pos.)
B74B E66D     09469                 INC L.PIXELROW          ;
B74D E56D     09470                 SBC L.PIXELROW          ;
B74F 9DF90B   09471                 STA PIXELROWNEW,X       ; Pixel row  := CENTERROW - (rel. pixel row + 1)
B752 60       09472                 RTS                     ; Return
              09473
B753 18       09474 SKIP232         CLC                     ; Pixel in lower screen half (y or z coordinate neg.)
B754 656D     09475                 ADC L.PIXELROW          ;
B756 9DF90B   09476                 STA PIXELROWNEW,X       ; Pixel row := CENTERROW + relative pixel row
B759 60       09477                 RTS                     ; Return
              09478
B75A E005     09479 SKIP233         CPX #NUMSPCOBJ.PL       ; Space object is offscreen. If it is a...
B75C B006     09480                 BCS INITPOSVEC          ; ...PLAYFIELD space object -> New position vector
B75E A9FB     09481                 LDA #251                ; ...PLAYER space object    -> Push PLAYER offscreen
B760 9DF90B   09482                 STA PIXELROWNEW,X       ;                              Why a value of 251 (?)
B763 60       09483 SKIP234         RTS                     ; Return
              09484
              09485 ;*******************************************************************************
              09486 ;*                                                                             *
              09487 ;*                                 INITPOSVEC                                  *
              09488 ;*                                                                             *
              09489 ;*                Initialize position vector of a space object                 *
              09490 ;*                                                                             *
              09491 ;*******************************************************************************
              09492
              09493 ; DESCRIPTION
              09494 ;
              09495 ; Initializes the position vector of a space object.
              09496 ;
              09497 ; This subroutine executes the following steps:
              09498 ;
              09499 ; (1)  Set the pixel row and column number to an offscreen value (= 99).
              09500 ;
              09501 ; (2)  If the position vector represents an explosion fragment space object then
              09502 ;      return code execution immediately. This avoids generating new explosion
              09503 ;      fragment space objects. They are separately initialized in subroutine
              09504 ;      COPYPOSVEC ($ACAF), which is called from subroutine INITEXPL ($AC6B).
              09505 ;
              09506 ; (3)  Assign default values (see below) to the position vector components
              09507 ;      (coordinates) depending on our starship's view.
              09508 ;
              09509 ; Code execution continues into subroutine RNDINVXY ($B7BE) where x and y
              09510 ; coordinates are inverted randomly.
              09511 ;
              09512 ; After passing through this and the next subroutine RNDINVXY ($B7BE) the
              09513 ; components of a position vector (coordinates) are assigned to one of the
              09514 ; following values depending on our starship's view:
              09515 ;
              09516 ; o   FRONT VIEW
              09517 ;
              09518 ;     +------------+---------------------------------------+
              09519 ;     | Coordinate |                 Values                |
              09520 ;     +------------+---------------------------------------+
              09521 ;     |     x      |  -4095..+4095 (-($0***)..+$0***) <KM> |
              09522 ;     |     y      |  -4095..+4095 (-($0***)..+$0***) <KM> |
              09523 ;     |     z      |  +3840..+4095 (          +$0F**) <KM> |
              09524 ;     +------------+---------------------------------------+
              09525 ;
              09526 ; o   AFT VIEW
              09527 ;
              09528 ;     +------------+---------------------------------------+
              09529 ;     | Coordinate |                 Values                |
              09530 ;     +------------+---------------------------------------+
              09531 ;     |     x      |  -3840..+3840 (-($0*00)..+$0*00) <KM> |
              09532 ;     |     y      |  -3840..+3840 (-($0*00)..+$0*00) <KM> |
              09533 ;     |     z      |  -3968.. -128 (-($0*80)        ) <KM> |
              09534 ;     +------------+---------------------------------------+
              09535 ;     Values of x, y, and z coordinates change in increments of 256.
              09536 ;     Second digit of z-coordinate is -MAX(RNDY,RNDX), where
              09537 ;     RNDY := RND($00..$0F), RNDX := RND($00..$0F).
              09538 ;
              09539 ; o   LONG-RANGE SCAN VIEW
              09540 ;
              09541 ;     +------------+---------------------------------------+
              09542 ;     | Coordinate |                 Values                |
              09543 ;     +------------+---------------------------------------+
              09544 ;     |     x      | -65535..+65535 (-($****)..$****) <KM> |
              09545 ;     |     y      |  -4095..+4095  (-($0***)..$0***) <KM> |
              09546 ;     |     z      | -65535..+65535 (-($****)..$****) <KM> |
              09547 ;     +------------+---------------------------------------+
              09548 ;
              09549 ; INPUT
              09550 ;
              09551 ;   X = Position vector index. Used values are: 0..48.
              09552
    =006A     09553 L.MAXRNDXY      = $6A                   ; Saves MAX(new y-coordinate (high byte), ...
              09554                                         ;  ...new x-coordinate (high byte))
              09555
B764 A963     09556 INITPOSVEC      LDA #99                 ; Init to offscreen pixel row and column numbers
B766 9DF90B   09557                 STA PIXELROWNEW,X       ;
B769 9D2A0C   09558                 STA PIXELCOLUMN,X       ;
              09559
B76C E011     09560                 CPX #NUMSPCOBJ.NORM     ; Return if pos vector is explosion frag space obj
B76E B0F3     09561                 BCS SKIP234             ; This avoids creating new explosion frag space objs
              09562
B770 AD0AD2   09563                 LDA RANDOM              ; RNDY := RND($00..$0F)
B773 290F     09564                 AND #$0F                ;
B775 856A     09565                 STA L.MAXRNDXY          ; Save RNDY
B777 9DA20A   09566                 STA YPOSHI,X            ; y-coordinate (high byte) := RNDY
              09567
B77A AD0AD2   09568                 LDA RANDOM              ; RNDX := RND($00..$0F)
B77D 290F     09569                 AND #$0F                ;
B77F C56A     09570                 CMP L.MAXRNDXY          ;
B781 9002     09571                 BCC SKIP235             ;
B783 856A     09572                 STA L.MAXRNDXY          ; Save MAX(RNDY,RNDX)
B785 9D710A   09573 SKIP235         STA XPOSHI,X            ; x-coordinate (high byte) := RNDX
              09574
B788 A90F     09575                 LDA #$0F                ; z-coordinate (high byte) := $0F
B78A 9D400A   09576                 STA ZPOSHI,X            ;
              09577
B78D A5D0     09578                 LDA SHIPVIEW            ; z-coordinate (sign) := 1 or 0 (Front or Aft view)
B78F 4901     09579                 EOR #$01                ;
B791 2901     09580                 AND #$01                ;
B793 9DAD09   09581                 STA ZPOSSIGN,X          ;
B796 D011     09582                 BNE SKIP236             ; Skip if in Front or Long-Range Scan view
              09583
              09584                                         ; Aft view only:
B798 9D040B   09585                 STA XPOSLO,X            ; x-coordinate (low byte) := 0
B79B 9D350B   09586                 STA YPOSLO,X            ; y-coordinate (low byte) := 0
B79E 38       09587                 SEC                     ; z-coordinate (high byte) := -MAX(RNDY,RNDX)
B79F E56A     09588                 SBC L.MAXRNDXY          ;
B7A1 9D400A   09589                 STA ZPOSHI,X            ;
B7A4 A980     09590                 LDA #$80                ; z-coordinate (low byte) := $80
B7A6 9DD30A   09591                 STA ZPOSLO,X            ;
              09592
B7A9 24D0     09593 SKIP236         BIT SHIPVIEW            ; If not in Long-Range Scan view skip to RNDINVXY
B7AB 5011     09594                 BVC RNDINVXY            ;
              09595
              09596                                         ; Long-Range Scan view only:
B7AD AD0AD2   09597                 LDA RANDOM              ; x-coordinate (high byte) := RND($00..$FF)
B7B0 9D710A   09598                 STA XPOSHI,X            ;
B7B3 AD0AD2   09599                 LDA RANDOM              ; z-coordinate (high byte) := RND($00..$FF)
B7B6 9D400A   09600                 STA ZPOSHI,X            ;
B7B9 2901     09601                 AND #$01                ; Invert z-coordinate randomly
B7BB 9DAD09   09602                 STA ZPOSSIGN,X          ;
              09603
              09604 ;*******************************************************************************
              09605 ;*                                                                             *
              09606 ;*                                  RNDINVXY                                   *
              09607 ;*                                                                             *
              09608 ;*         Randomly invert the x and y components of a position vector         *
              09609 ;*                                                                             *
              09610 ;*******************************************************************************
              09611
              09612 ; DESCRIPTION
              09613 ;
              09614 ; Randomly inverts the x and y components of a position vector (x and y
              09615 ; coordinates). See also subroutine INITPOSVEC ($B764).
              09616 ;
              09617 ; INPUT
              09618 ;
              09619 ;   X = Position vector index. Used values are: 0..48.
              09620
B7BE AD0AD2   09621 RNDINVXY        LDA RANDOM              ; Set sign of y-coordinate randomly
B7C1 2901     09622                 AND #$01                ;
B7C3 9D0F0A   09623                 STA YPOSSIGN,X          ;
B7C6 D00F     09624                 BNE SKIP237             ; Skip if sign positive
              09625
B7C8 38       09626                 SEC                     ; Sign negative -> Calc negative y-coordinate
B7C9 FD350B   09627                 SBC YPOSLO,X            ; (calculate two's-complement of 16-bit value)
B7CC 9D350B   09628                 STA YPOSLO,X            ;
B7CF A900     09629                 LDA #0                  ;
B7D1 FDA20A   09630                 SBC YPOSHI,X            ;
B7D4 9DA20A   09631                 STA YPOSHI,X            ;
              09632
B7D7 AD0AD2   09633 SKIP237         LDA RANDOM              ; Set sign of x-coordinate randomly
B7DA 2901     09634                 AND #$01                ;
B7DC 9DDE09   09635                 STA XPOSSIGN,X          ;
B7DF D00F     09636                 BNE SKIP238             ; Skip if sign positive
              09637
B7E1 38       09638                 SEC                     ; Sign negative -> Calc negative x-coordinate
B7E2 FD040B   09639                 SBC XPOSLO,X            ; (calculate two's-complement of 16-bit value)
B7E5 9D040B   09640                 STA XPOSLO,X            ;
B7E8 A900     09641                 LDA #0                  ;
B7EA FD710A   09642                 SBC XPOSHI,X            ;
B7ED 9D710A   09643                 STA XPOSHI,X            ;
B7F0 60       09644 SKIP238         RTS                     ; Return
              09645
              09646 ;*******************************************************************************
              09647 ;*                                                                             *
              09648 ;*                                ISSURROUNDED                                 *
              09649 ;*                                                                             *
              09650 ;*               Check if a sector is surrounded by Zylon units                *
              09651 ;*                                                                             *
              09652 ;*******************************************************************************
              09653
              09654 ; DESCRIPTION
              09655 ;
              09656 ; Checks if a sector of the Galactic Chart is surrounded by Zylon units in the
              09657 ; adjacent NORTH, EAST, SOUTH, and WEST sectors.
              09658 ;
              09659 ; INPUT
              09660 ;
              09661 ;   X = Sector of Galactic Chart. Used values are: $00..$7F with, for example,
              09662 ;     $00 -> NORTHWEST corner sector
              09663 ;     $0F -> NORTHEAST corner sector
              09664 ;     $70 -> SOUTHWEST corner sector
              09665 ;     $7F -> SOUTHWEST corner sector
              09666 ;
              09667 ; OUTPUT
              09668 ;
              09669 ;   A = Returns if the sector is surrounded by Zylon units in the adjacent
              09670 ;       NORTH, EAST, SOUTH, and WEST sectors.
              09671 ;       0 -> Sector is not surrounded
              09672 ;     > 0 -> Sector is surrounded
              09673
B7F1 BDC808   09674 ISSURROUNDED    LDA GCMEMMAP-1,X        ; Check WEST sector
B7F4 F00D     09675                 BEQ SKIP239             ;
B7F6 BDCA08   09676                 LDA GCMEMMAP+1,X        ; Check EAST sector
B7F9 F008     09677                 BEQ SKIP239             ;
B7FB BDB908   09678                 LDA GCMEMMAP-16,X       ; Check NORTH sector
B7FE F003     09679                 BEQ SKIP239             ;
B800 BDD908   09680                 LDA GCMEMMAP+16,X       ; Check SOUTH sector
B803 60       09681 SKIP239         RTS                     ; Return
              09682
              09683 ;*******************************************************************************
              09684 ;*                                                                             *
              09685 ;*                                  UPDPANEL                                   *
              09686 ;*                                                                             *
              09687 ;*                        Update Control Panel Display                         *
              09688 ;*                                                                             *
              09689 ;*******************************************************************************
              09690
              09691 ; DESCRIPTION
              09692 ;
              09693 ; This subroutine executes the following steps:
              09694 ;
              09695 ; (1)  Accelerate or decelerate our starship, update the VELOCITY readout
              09696 ;
              09697 ;      If the new velocity value is different from the current one either
              09698 ;      increment or decrement the current velocity value toward the new one.
              09699 ;
              09700 ;      If the Engines are damaged or destroyed (and hyperwarp is not engaged)
              09701 ;      then store a random value (less or equal than the current velocity) as
              09702 ;      the current velocity.
              09703 ;
              09704 ;      Display the updated velocity by the VELOCITY readout of the Control Panel
              09705 ;      Display.
              09706 ;
              09707 ; (2)  Update THETA, PHI, and RANGE readouts
              09708 ;
              09709 ;      If the Attack Computer is working then display the x, y, and z
              09710 ;      coordinates of the currently tracked space object as THETA, PHI, and
              09711 ;      RANGE readout values of the Control Panel Display.
              09712 ;
              09713 ; (3)  Calculate overall energy consumption
              09714 ;
              09715 ;      Add the overall energy consumption per game loop iteration to the energy
              09716 ;      counter. This value is given in energy subunits (256 energy subunits = 1
              09717 ;      energy unit displayed by the 4-digit ENERGY readout of the Console Panel
              09718 ;      Display). It is the total of the following items:
              09719 ;
              09720 ;      (1)  8 energy subunits if the Shields are up
              09721 ;
              09722 ;      (2)  2 energy subunits if the Attack Computer is on
              09723 ;
              09724 ;      (3)  1 energy subunit of the life support system
              09725 ;
              09726 ;      (4)  Our starship's Engines energy drain rate (depending on its velocity)
              09727 ;
              09728 ;      If there is a carryover of the energy counter then decrement the ENERGY
              09729 ;      readout of the Control Panel Display by one energy unit after code
              09730 ;      execution has continued into subroutine DECENERGY ($B86F).
              09731
              09732 ;*** Accelerate or decelerate our starship *************************************
B804 A670     09733 UPDPANEL        LDX VELOCITYLO          ; Skip if new velocity = current velocity
B806 E471     09734                 CPX NEWVELOCITY         ;
B808 F008     09735                 BEQ SKIP241             ;
              09736
B80A 9004     09737                 BCC SKIP240             ; In/decrement current velocity toward new velocity
B80C C670     09738                 DEC VELOCITYLO          ;
B80E B012     09739                 BCS SKIP242             ;
B810 E670     09740 SKIP240         INC VELOCITYLO          ;
              09741
B812 A5C0     09742 SKIP241         LDA WARPSTATE           ; Skip if hyperwarp engaged
B814 D00C     09743                 BNE SKIP242             ;
              09744
B816 2C9309   09745                 BIT GCSTATENG           ; Skip if Engines are OK
B819 1007     09746                 BPL SKIP242             ;
              09747
B81B A571     09748                 LDA NEWVELOCITY         ; Store RND(0..current velocity) to current velocity
B81D 2D0AD2   09749                 AND RANDOM              ;
B820 8570     09750                 STA VELOCITYLO          ;
              09751
B822 A001     09752 SKIP242         LDY #VELOCD1-PANELTXT-1 ; Update digits of VELOCITY readout
B824 20CDB8   09753                 JSR SHOWDIGITS          ;
              09754
              09755 ;*** Display coordinates of tracked space object of Control Panel Display ******
B827 2C9509   09756                 BIT GCSTATCOM           ; Skip if Attack Computer damaged or destroyed
B82A 3030     09757                 BMI SKIP243             ;
              09758
B82C A931     09759                 LDA #$31                ; Update THETA readout (x-coordinate)
B82E A017     09760                 LDY #THETAC1-PANELTXT   ;
B830 20A7B8   09761                 JSR SHOWCOORD           ;
              09762
B833 A962     09763                 LDA #$62                ; Update PHI readout (y-coordinate)
B835 A01D     09764                 LDY #PHIC1-PANELTXT     ;
B837 20A7B8   09765                 JSR SHOWCOORD           ;
              09766
B83A A900     09767                 LDA #$00                ; Update RANGE readout (z-coordinate)
B83C A023     09768                 LDY #RANGEC1-PANELTXT   ;
B83E 20A7B8   09769                 JSR SHOWCOORD           ;
              09770
B841 AD6E09   09771                 LDA RANGEC1+2           ; Hack to clear RANGE digit 3 when in hyperwarp:
B844 8D6F09   09772                 STA RANGEC1+3           ; Copy RANGE digit 2 to digit 3
B847 C90A     09773                 CMP #CCS.9+1            ; Skip if digit character > '9' (= 'infinity' char)
B849 B011     09774                 BCS SKIP243             ;
              09775
B84B AE5C09   09776                 LDX TRACKDIGIT          ; Get z-coordinate (low byte) of tracked space object
B84E BDD30A   09777                 LDA ZPOSLO,X            ;
B851 4A       09778                 LSR A                   ; ...divide it by 16...
B852 4A       09779                 LSR A                   ;
B853 4A       09780                 LSR A                   ;
B854 4A       09781                 LSR A                   ;
B855 AA       09782                 TAX                     ;
B856 BDE90E   09783                 LDA MAPTOBCD99,X        ; ...map value of $00..$0F to BCD value 0..9
B859 8D6F09   09784                 STA RANGEC1+3           ; ...and store it to RANGE digit 3
              09785
              09786 ;*** Calculate overall energy consumption **************************************
B85C 18       09787 SKIP243         CLC                     ;
B85D A57F     09788                 LDA ENERGYCNT           ; Load energy counter
B85F 657D     09789                 ADC DRAINSHIELDS        ; Add energy drain rate of Shields
B861 6580     09790                 ADC DRAINENGINES        ; Add energy drain rate of our starship's Engines
B863 657E     09791                 ADC DRAINATTCOMP        ; Add energy drain rate of Attack Computer
B865 6901     09792                 ADC #$01                ; Add 1 energy subunit of life support system
B867 C57F     09793                 CMP ENERGYCNT           ;
B869 857F     09794                 STA ENERGYCNT           ;
B86B B039     09795                 BCS SKIP246             ; Return if no energy counter carryover
              09796
B86D A203     09797                 LDX #3                  ; Will decrement third energy digit
              09798
              09799 ;*******************************************************************************
              09800 ;*                                                                             *
              09801 ;*                                  DECENERGY                                  *
              09802 ;*                                                                             *
              09803 ;*                               Decrease energy                               *
              09804 ;*                                                                             *
              09805 ;*******************************************************************************
              09806
              09807 ; DESCRIPTION
              09808 ;
              09809 ; When not in demo mode, subtract energy from the 4-digit ENERGY readout of the
              09810 ; Control Panel Display. If crossing a 100-energy-unit boundary during
              09811 ; subtraction the score is decremented by one unit. If the energy is zero the
              09812 ; game is over.
              09813 ;
              09814 ; INPUT
              09815 ;
              09816 ;   X = ENERGY readout digit to be decremented. Used values are:
              09817 ;     1 -> Subtract 100 units from ENERGY readout
              09818 ;     2 -> Subtract  10 units from ENERGY readout
              09819 ;     3 -> Subtract   1 unit  from ENERGY readout
              09820
              09821 ;*** Display ENERGY readout ****************************************************
B86F 2464     09822 DECENERGY       BIT ISDEMOMODE          ; Return if in demo mode
B871 7033     09823                 BVS SKIP246             ;
              09824
B873 DE5509   09825                 DEC ENERGYD1,X          ; Decrement energy digit character
B876 BD5509   09826                 LDA ENERGYD1,X          ;
B879 C980     09827                 CMP #CCS.COL2!CCS.0     ;
B87B B029     09828                 BCS SKIP246             ; Return if digit character >= '0'
B87D A989     09829                 LDA #CCS.COL2!CCS.9     ;
B87F 9D5509   09830                 STA ENERGYD1,X          ; Store digit character '9'
              09831
              09832 ;*** Decrement score when crossing a 100-energy-unit boundary while subtracting
B882 E002     09833                 CPX #2                  ; Skip if no crossing of 100-energy-unit boundary
B884 D008     09834                 BNE SKIP245             ;
              09835
B886 A5CB     09836                 LDA SCORE               ; SCORE := SCORE - 1
B888 D002     09837                 BNE SKIP244             ;
B88A C6CC     09838                 DEC SCORE+1             ;
B88C C6CB     09839 SKIP244         DEC SCORE               ;
              09840
B88E CA       09841 SKIP245         DEX                     ;
B88F 10DE     09842                 BPL DECENERGY           ; Next digit
              09843
              09844 ;*** Energy is zero, game over *************************************************
B891 A20A     09845                 LDX #CCS.SPC            ; Clear 4-digit ENERGY readout
B893 8A       09846                 TXA                     ;
B894 A003     09847                 LDY #3                  ;
B896 995509   09848 LOOP079         STA ENERGYD1,Y          ;
B899 88       09849                 DEY                     ;
B89A 10FA     09850                 BPL LOOP079             ;
              09851
B89C 2045B0   09852                 JSR SETVIEW             ; Set Front view
              09853
B89F A031     09854                 LDY #$31                ; Set title phrase "MISSION ABORTED ZERO ENERGY"
B8A1 A204     09855                 LDX #$04                ; Set mission bonus offset
B8A3 200AB1   09856                 JSR GAMEOVER            ; Game over
              09857
B8A6 60       09858 SKIP246         RTS                     ; Return
              09859
              09860 ;*******************************************************************************
              09861 ;*                                                                             *
              09862 ;*                                  SHOWCOORD                                  *
              09863 ;*                                                                             *
              09864 ;*  Display a position vector component (coordinate) in Control Panel Display  *
              09865 ;*                                                                             *
              09866 ;*******************************************************************************
              09867
              09868 ; DESCRIPTION
              09869 ;
              09870 ; Displays a position vector component (coordinate) by one of the THETA, PHI, or
              09871 ; RANGE readouts of the Control Panel Display.
              09872 ;
              09873 ; Write the sign to the Control Panel Display, then map the high byte of the
              09874 ; respective coordinate (x -> THETA, y -> PHI, z -> RANGE) to a BCD-value in
              09875 ; 00..99. Code execution continues into subroutine SHOWDIGITS ($B8CD) where the
              09876 ; digits are actually stored in the Control Panel Display.
              09877 ;
              09878 ; NOTE: If the digits of either the THETA or PHI readout are to be displayed and
              09879 ; the x or y position vector component (high byte) is $FF then tweak the value
              09880 ; to $FE. This avoids accessing table MAPTOBCD99 ($0EE9) with an index of $FF
              09881 ; that would return the special value $EA. This value represents the CCS.INF
              09882 ; ($0E) and CCS.SPC ($0A) characters (see comments in subroutine INITIALIZE
              09883 ; ($B3BA)) that are displayed by the RANGE readout only.
              09884 ;
              09885 ; INPUT
              09886 ;
              09887 ;   A = Position vector component (coordinate) offset. Used values are:
              09888 ;     $00 -> z-coordinate
              09889 ;     $31 -> x-coordinate
              09890 ;     $62 -> y-coordinate
              09891 ;
              09892 ;   Y = Offset into the Control Panel Display memory map. Used values are:
              09893 ;     $17 -> First character (sign) of THETA readout (x-coordinate of tracked
              09894 ;            space object)
              09895 ;     $1D -> First character (sign) of PHI readout   (y-coordinate of tracked
              09896 ;            space object)
              09897 ;     $23 -> First character (sign) of RANGE readout (z-coordinate of tracked
              09898 ;            space object)
              09899
    =006A     09900 L.SIGNCHAR      = $6A                   ; Saves sign character
              09901
B8A7 18       09902 SHOWCOORD       CLC                     ; Add index of tracked space object...
B8A8 6D5C09   09903                 ADC TRACKDIGIT          ; ...to position vector component offset
B8AB AA       09904                 TAX                     ; Save position vector component index
              09905
              09906 ;*** Display sign in Control Panel Display *************************************
B8AC A910     09907                 LDA #CCS.PLUS           ; Save '+' (CCS.PLUS) to sign character
B8AE 856A     09908                 STA L.SIGNCHAR          ;
              09909
B8B0 BDAD09   09910                 LDA ZPOSSIGN,X          ; Prep sign of coordinate
B8B3 4A       09911                 LSR A                   ;
B8B4 BD400A   09912                 LDA ZPOSHI,X            ; Prep coordinate (high byte)
B8B7 B004     09913                 BCS SKIP247             ; Skip if sign is positive
              09914
B8B9 49FF     09915                 EOR #$FF                ; Invert coordinate (high byte)
B8BB C66A     09916                 DEC L.SIGNCHAR          ; Change saved sign character to '-' (CCS.MINUS)
              09917
B8BD AA       09918 SKIP247         TAX                     ; Save coordinate (high byte)
B8BE A56A     09919                 LDA L.SIGNCHAR          ; Store sign character in Control Panel Display
B8C0 994909   09920                 STA PANELTXT,Y          ;
              09921
              09922 ;*** Get RANGE digits **********************************************************
B8C3 98       09923                 TYA                     ; Skip if RANGE is to be displayed
B8C4 2910     09924                 AND #$10                ;
B8C6 F005     09925                 BEQ SHOWDIGITS          ;
              09926
B8C8 E0FF     09927                 CPX #$FF                ; If coordinate (high byte) = $FF decrement value
B8CA D001     09928                 BNE SHOWDIGITS          ; This avoids output of CCS.INFINITY in...
B8CC CA       09929                 DEX                     ; ...THETA and PHI readouts
              09930
              09931 ;*******************************************************************************
              09932 ;*                                                                             *
              09933 ;*                                 SHOWDIGITS                                  *
              09934 ;*                                                                             *
              09935 ;*          Display a value by a readout of the Control Panel Display          *
              09936 ;*                                                                             *
              09937 ;*******************************************************************************
              09938
              09939 ; DESCRIPTION
              09940 ;
              09941 ; Converts a binary value in $00..$FF to a BCD-value in 0..99 and displays it as
              09942 ; a 2-digit number in the Control Panel Display.
              09943 ;
              09944 ; INPUT
              09945 ;
              09946 ;   X = Value to be displayed as a 2-digit BCD-value. Used values are: $00..$FF.
              09947 ;
              09948 ;   Y = Offset into the Control Panel Display memory map relative to the first
              09949 ;       character of the Control Panel Display (the 'V' of the VELOCITY
              09950 ;       readout). Used values are:
              09951 ;     $01 -> Character before first digit of VELOCITY readout
              09952 ;     $17 -> First character (sign) of THETA readout (x-coordinate of tracked
              09953 ;            space object)
              09954 ;     $1D -> First character (sign) of PHI readout   (y-coordinate of tracked
              09955 ;            space object)
              09956 ;     $23 -> First character (sign) of RANGE readout (z-coordinate of tracked
              09957 ;            space object)
              09958
B8CD BDE90E   09959 SHOWDIGITS      LDA MAPTOBCD99,X        ; Map binary value to BCD-value
B8D0 AA       09960                 TAX                     ;
B8D1 290F     09961                 AND #$0F                ;
B8D3 994B09   09962                 STA PANELTXT+2,Y        ; Store 'ones' digit in Control Panel Display
B8D6 8A       09963                 TXA                     ;
B8D7 4A       09964                 LSR A                   ;
B8D8 4A       09965                 LSR A                   ;
B8D9 4A       09966                 LSR A                   ;
B8DA 4A       09967                 LSR A                   ;
B8DB 994A09   09968                 STA PANELTXT+1,Y        ; Store 'tens' digit in Control Panel Display
B8DE 60       09969                 RTS                     ; Return
              09970
              09971 ;*******************************************************************************
              09972 ;*                                                                             *
              09973 ;*                G A M E   D A T A   ( P A R T   2   O F   2 )                *
              09974 ;*                                                                             *
              09975 ;*******************************************************************************
              09976
              09977 ;*** Color register offsets of PLAYER0..4 **************************************
B8DF 00       09978 PLCOLOROFFTAB   .BYTE 0                               ; PLAYER0
B8E0 01       09979                 .BYTE 1                               ; PLAYER1
B8E1 02       09980                 .BYTE 2                               ; PLAYER2
B8E2 03       09981                 .BYTE 3                               ; PLAYER3
B8E3 07       09982                 .BYTE 7                               ; PLAYER4
              09983
              09984 ;*** Shape table 1 (PLAYER2..4) ************************************************
B8E4 00       09985 PLSHAP1TAB      .BYTE $00                             ; ........
B8E5 18       09986                 .BYTE $18                             ; ...##...
B8E6 3C       09987                 .BYTE $3C                             ; ..####..
B8E7 7E       09988                 .BYTE $7E                             ; .######.
B8E8 7E       09989                 .BYTE $7E                             ; .######.
B8E9 76       09990                 .BYTE $76                             ; .###.##.
B8EA F7       09991                 .BYTE $F7                             ; ####.###
B8EB DF       09992                 .BYTE $DF                             ; ##.#####
B8EC DF       09993                 .BYTE $DF                             ; ##.#####
B8ED FF       09994                 .BYTE $FF                             ; ########
B8EE FF       09995                 .BYTE $FF                             ; ########
B8EF F7       09996                 .BYTE $F7                             ; ####.###
B8F0 76       09997                 .BYTE $76                             ; .###.##.
B8F1 7E       09998                 .BYTE $7E                             ; .######.
B8F2 7E       09999                 .BYTE $7E                             ; .######.
B8F3 3C       10000                 .BYTE $3C                             ; ..####..
B8F4 18       10001                 .BYTE $18                             ; ...##...
B8F5 10       10002                 .BYTE $10                             ; ...#....
B8F6 38       10003                 .BYTE $38                             ; ..###...
B8F7 7C       10004                 .BYTE $7C                             ; .#####..
B8F8 7C       10005                 .BYTE $7C                             ; .#####..
B8F9 FE       10006                 .BYTE $FE                             ; #######.
B8FA DE       10007                 .BYTE $DE                             ; ##.####.
B8FB DA       10008                 .BYTE $DA                             ; ##.##.#.
B8FC FA       10009                 .BYTE $FA                             ; #####.#.
B8FD EE       10010                 .BYTE $EE                             ; ###.###.
B8FE EE       10011                 .BYTE $EE                             ; ###.###.
B8FF 7C       10012                 .BYTE $7C                             ; .#####..
B900 7C       10013                 .BYTE $7C                             ; .#####..
B901 38       10014                 .BYTE $38                             ; ..###...
B902 10       10015                 .BYTE $10                             ; ...#....
B903 18       10016                 .BYTE $18                             ; ...##...
B904 3C       10017                 .BYTE $3C                             ; ..####..
B905 3C       10018                 .BYTE $3C                             ; ..####..
B906 7E       10019                 .BYTE $7E                             ; .######.
B907 6E       10020                 .BYTE $6E                             ; .##.###.
B908 7A       10021                 .BYTE $7A                             ; .####.#.
B909 7E       10022                 .BYTE $7E                             ; .######.
B90A 76       10023                 .BYTE $76                             ; .###.##.
B90B 7E       10024                 .BYTE $7E                             ; .######.
B90C 3C       10025                 .BYTE $3C                             ; ..####..
B90D 3C       10026                 .BYTE $3C                             ; ..####..
B90E 18       10027                 .BYTE $18                             ; ...##...
B90F 10       10028                 .BYTE $10                             ; ...#....
B910 38       10029                 .BYTE $38                             ; ..###...
B911 38       10030                 .BYTE $38                             ; ..###...
B912 7C       10031                 .BYTE $7C                             ; .#####..
B913 74       10032                 .BYTE $74                             ; .###.#..
B914 7C       10033                 .BYTE $7C                             ; .#####..
B915 6C       10034                 .BYTE $6C                             ; .##.##..
B916 38       10035                 .BYTE $38                             ; ..###...
B917 38       10036                 .BYTE $38                             ; ..###...
B918 10       10037                 .BYTE $10                             ; ...#....
B919 10       10038                 .BYTE $10                             ; ...#....
B91A 18       10039                 .BYTE $18                             ; ...##...
B91B 3C       10040                 .BYTE $3C                             ; ..####..
B91C 2C       10041                 .BYTE $2C                             ; ..#.##..
B91D 3C       10042                 .BYTE $3C                             ; ..####..
B91E 3C       10043                 .BYTE $3C                             ; ..####..
B91F 18       10044                 .BYTE $18                             ; ...##...
B920 08       10045                 .BYTE $08                             ; ....#...
B921 10       10046                 .BYTE $10                             ; ...#....
B922 38       10047                 .BYTE $38                             ; ..###...
B923 38       10048                 .BYTE $38                             ; ..###...
B924 28       10049                 .BYTE $28                             ; ..#.#...
B925 38       10050                 .BYTE $38                             ; ..###...
B926 10       10051                 .BYTE $10                             ; ...#....
B927 3C       10052                 .BYTE $3C                             ; ..####..
B928 3C       10053                 .BYTE $3C                             ; ..####..
B929 24       10054                 .BYTE $24                             ; ..#..#..
B92A 3C       10055                 .BYTE $3C                             ; ..####..
B92B 7E       10056                 .BYTE $7E                             ; .######.
B92C 7E       10057                 .BYTE $7E                             ; .######.
B92D 7E       10058                 .BYTE $7E                             ; .######.
B92E 5A       10059                 .BYTE $5A                             ; .#.##.#.
B92F FF       10060                 .BYTE $FF                             ; ########
B930 FF       10061                 .BYTE $FF                             ; ########
B931 42       10062                 .BYTE $42                             ; .#....#.
B932 42       10063                 .BYTE $42                             ; .#....#.
B933 42       10064                 .BYTE $42                             ; .#....#.
B934 42       10065                 .BYTE $42                             ; .#....#.
B935 42       10066                 .BYTE $42                             ; .#....#.
B936 42       10067                 .BYTE $42                             ; .#....#.
B937 1C       10068                 .BYTE $1C                             ; ...###..
B938 1C       10069                 .BYTE $1C                             ; ...###..
B939 14       10070                 .BYTE $14                             ; ...#.#..
B93A 3E       10071                 .BYTE $3E                             ; ..#####.
B93B 3E       10072                 .BYTE $3E                             ; ..#####.
B93C 3E       10073                 .BYTE $3E                             ; ..#####.
B93D 2A       10074                 .BYTE $2A                             ; ..#.#.#.
B93E 7F       10075                 .BYTE $7F                             ; .#######
B93F 7F       10076                 .BYTE $7F                             ; .#######
B940 22       10077                 .BYTE $22                             ; ..#...#.
B941 22       10078                 .BYTE $22                             ; ..#...#.
B942 22       10079                 .BYTE $22                             ; ..#...#.
B943 22       10080                 .BYTE $22                             ; ..#...#.
B944 22       10081                 .BYTE $22                             ; ..#...#.
B945 18       10082                 .BYTE $18                             ; ...##...
B946 18       10083                 .BYTE $18                             ; ...##...
B947 3C       10084                 .BYTE $3C                             ; ..####..
B948 3C       10085                 .BYTE $3C                             ; ..####..
B949 3C       10086                 .BYTE $3C                             ; ..####..
B94A 3C       10087                 .BYTE $3C                             ; ..####..
B94B 7E       10088                 .BYTE $7E                             ; .######.
B94C 24       10089                 .BYTE $24                             ; ..#..#..
B94D 24       10090                 .BYTE $24                             ; ..#..#..
B94E 24       10091                 .BYTE $24                             ; ..#..#..
B94F 24       10092                 .BYTE $24                             ; ..#..#..
B950 10       10093                 .BYTE $10                             ; ...#....
B951 10       10094                 .BYTE $10                             ; ...#....
B952 38       10095                 .BYTE $38                             ; ..###...
B953 38       10096                 .BYTE $38                             ; ..###...
B954 38       10097                 .BYTE $38                             ; ..###...
B955 7C       10098                 .BYTE $7C                             ; .#####..
B956 28       10099                 .BYTE $28                             ; ..#.#...
B957 28       10100                 .BYTE $28                             ; ..#.#...
B958 28       10101                 .BYTE $28                             ; ..#.#...
B959 18       10102                 .BYTE $18                             ; ...##...
B95A 18       10103                 .BYTE $18                             ; ...##...
B95B 3C       10104                 .BYTE $3C                             ; ..####..
B95C 18       10105                 .BYTE $18                             ; ...##...
B95D 18       10106                 .BYTE $18                             ; ...##...
B95E 10       10107                 .BYTE $10                             ; ...#....
B95F 10       10108                 .BYTE $10                             ; ...#....
B960 38       10109                 .BYTE $38                             ; ..###...
B961 10       10110                 .BYTE $10                             ; ...#....
B962 18       10111                 .BYTE $18                             ; ...##...
B963 7E       10112                 .BYTE $7E                             ; .######.
B964 FF       10113                 .BYTE $FF                             ; ########
B965 FF       10114                 .BYTE $FF                             ; ########
B966 FF       10115                 .BYTE $FF                             ; ########
B967 FF       10116                 .BYTE $FF                             ; ########
B968 FF       10117                 .BYTE $FF                             ; ########
B969 E7       10118                 .BYTE $E7                             ; ###..###
B96A E7       10119                 .BYTE $E7                             ; ###..###
B96B FF       10120                 .BYTE $FF                             ; ########
B96C FF       10121                 .BYTE $FF                             ; ########
B96D FF       10122                 .BYTE $FF                             ; ########
B96E FF       10123                 .BYTE $FF                             ; ########
B96F FF       10124                 .BYTE $FF                             ; ########
B970 7E       10125                 .BYTE $7E                             ; .######.
B971 7E       10126                 .BYTE $7E                             ; .######.
B972 00       10127                 .BYTE $00                             ; ........
B973 18       10128                 .BYTE $18                             ; ...##...
B974 3C       10129                 .BYTE $3C                             ; ..####..
B975 7E       10130                 .BYTE $7E                             ; .######.
B976 FF       10131                 .BYTE $FF                             ; ########
B977 FF       10132                 .BYTE $FF                             ; ########
B978 FF       10133                 .BYTE $FF                             ; ########
B979 E7       10134                 .BYTE $E7                             ; ###..###
B97A 66       10135                 .BYTE $66                             ; .##..##.
B97B FF       10136                 .BYTE $FF                             ; ########
B97C FF       10137                 .BYTE $FF                             ; ########
B97D FF       10138                 .BYTE $FF                             ; ########
B97E FF       10139                 .BYTE $FF                             ; ########
B97F 7E       10140                 .BYTE $7E                             ; .######.
B980 7E       10141                 .BYTE $7E                             ; .######.
B981 00       10142                 .BYTE $00                             ; ........
B982 18       10143                 .BYTE $18                             ; ...##...
B983 3C       10144                 .BYTE $3C                             ; ..####..
B984 7E       10145                 .BYTE $7E                             ; .######.
B985 FF       10146                 .BYTE $FF                             ; ########
B986 FF       10147                 .BYTE $FF                             ; ########
B987 E7       10148                 .BYTE $E7                             ; ###..###
B988 66       10149                 .BYTE $66                             ; .##..##.
B989 FF       10150                 .BYTE $FF                             ; ########
B98A FF       10151                 .BYTE $FF                             ; ########
B98B FF       10152                 .BYTE $FF                             ; ########
B98C FF       10153                 .BYTE $FF                             ; ########
B98D 3C       10154                 .BYTE $3C                             ; ..####..
B98E 18       10155                 .BYTE $18                             ; ...##...
B98F 3C       10156                 .BYTE $3C                             ; ..####..
B990 FF       10157                 .BYTE $FF                             ; ########
B991 FF       10158                 .BYTE $FF                             ; ########
B992 E7       10159                 .BYTE $E7                             ; ###..###
B993 66       10160                 .BYTE $66                             ; .##..##.
B994 FF       10161                 .BYTE $FF                             ; ########
B995 FF       10162                 .BYTE $FF                             ; ########
B996 7E       10163                 .BYTE $7E                             ; .######.
B997 3C       10164                 .BYTE $3C                             ; ..####..
B998 00       10165                 .BYTE $00                             ; ........
B999 18       10166                 .BYTE $18                             ; ...##...
B99A 3C       10167                 .BYTE $3C                             ; ..####..
B99B FF       10168                 .BYTE $FF                             ; ########
B99C FF       10169                 .BYTE $FF                             ; ########
B99D FF       10170                 .BYTE $FF                             ; ########
B99E 3C       10171                 .BYTE $3C                             ; ..####..
B99F 18       10172                 .BYTE $18                             ; ...##...
B9A0 18       10173                 .BYTE $18                             ; ...##...
B9A1 3C       10174                 .BYTE $3C                             ; ..####..
B9A2 FF       10175                 .BYTE $FF                             ; ########
B9A3 3C       10176                 .BYTE $3C                             ; ..####..
B9A4 18       10177                 .BYTE $18                             ; ...##...
B9A5 28       10178                 .BYTE $28                             ; ..#.#...
B9A6 28       10179                 .BYTE $28                             ; ..#.#...
B9A7 28       10180                 .BYTE $28                             ; ..#.#...
B9A8 28       10181                 .BYTE $28                             ; ..#.#...
B9A9 EE       10182                 .BYTE $EE                             ; ###.###.
B9AA 00       10183                 .BYTE $00                             ; ........
B9AB 00       10184                 .BYTE $00                             ; ........
B9AC EE       10185                 .BYTE $EE                             ; ###.###.
B9AD 28       10186                 .BYTE $28                             ; ..#.#...
B9AE 28       10187                 .BYTE $28                             ; ..#.#...
B9AF 28       10188                 .BYTE $28                             ; ..#.#...
B9B0 28       10189                 .BYTE $28                             ; ..#.#...
              10190
              10191 ;*** Shape table 2 (PLAYER0..1) ************************************************
B9B1 00       10192 PLSHAP2TAB      .BYTE $00                             ; ........
B9B2 81       10193                 .BYTE $81                             ; #......#
B9B3 81       10194                 .BYTE $81                             ; #......#
B9B4 81       10195                 .BYTE $81                             ; #......#
B9B5 81       10196                 .BYTE $81                             ; #......#
B9B6 BD       10197                 .BYTE $BD                             ; #.####.#
B9B7 FF       10198                 .BYTE $FF                             ; ########
B9B8 FF       10199                 .BYTE $FF                             ; ########
B9B9 BD       10200                 .BYTE $BD                             ; #.####.#
B9BA 81       10201                 .BYTE $81                             ; #......#
B9BB 81       10202                 .BYTE $81                             ; #......#
B9BC 81       10203                 .BYTE $81                             ; #......#
B9BD 81       10204                 .BYTE $81                             ; #......#
B9BE 82       10205                 .BYTE $82                             ; #.....#.
B9BF 82       10206                 .BYTE $82                             ; #.....#.
B9C0 BA       10207                 .BYTE $BA                             ; #.###.#.
B9C1 FE       10208                 .BYTE $FE                             ; #######.
B9C2 FE       10209                 .BYTE $FE                             ; #######.
B9C3 BA       10210                 .BYTE $BA                             ; #.###.#.
B9C4 82       10211                 .BYTE $82                             ; #.....#.
B9C5 82       10212                 .BYTE $82                             ; #.....#.
B9C6 42       10213                 .BYTE $42                             ; .#....#.
B9C7 5A       10214                 .BYTE $5A                             ; .#.##.#.
B9C8 7E       10215                 .BYTE $7E                             ; .######.
B9C9 7E       10216                 .BYTE $7E                             ; .######.
B9CA 5A       10217                 .BYTE $5A                             ; .#.##.#.
B9CB 42       10218                 .BYTE $42                             ; .#....#.
B9CC 44       10219                 .BYTE $44                             ; .#...#..
B9CD 54       10220                 .BYTE $54                             ; .#.#.#..
B9CE 7C       10221                 .BYTE $7C                             ; .#####..
B9CF 7C       10222                 .BYTE $7C                             ; .#####..
B9D0 54       10223                 .BYTE $54                             ; .#.#.#..
B9D1 44       10224                 .BYTE $44                             ; .#...#..
B9D2 24       10225                 .BYTE $24                             ; ..#..#..
B9D3 3C       10226                 .BYTE $3C                             ; ..####..
B9D4 3C       10227                 .BYTE $3C                             ; ..####..
B9D5 24       10228                 .BYTE $24                             ; ..#..#..
B9D6 28       10229                 .BYTE $28                             ; ..#.#...
B9D7 38       10230                 .BYTE $38                             ; ..###...
B9D8 38       10231                 .BYTE $38                             ; ..###...
B9D9 28       10232                 .BYTE $28                             ; ..#.#...
B9DA 18       10233                 .BYTE $18                             ; ...##...
B9DB 18       10234                 .BYTE $18                             ; ...##...
B9DC 10       10235                 .BYTE $10                             ; ...#....
B9DD 10       10236                 .BYTE $10                             ; ...#....
B9DE E0       10237                 .BYTE $E0                             ; ###.....
B9DF F8       10238                 .BYTE $F8                             ; #####...
B9E0 F8       10239                 .BYTE $F8                             ; #####...
B9E1 FE       10240                 .BYTE $FE                             ; #######.
B9E2 57       10241                 .BYTE $57                             ; .#.#.###
B9E3 FE       10242                 .BYTE $FE                             ; #######.
B9E4 F8       10243                 .BYTE $F8                             ; #####...
B9E5 F8       10244                 .BYTE $F8                             ; #####...
B9E6 C0       10245                 .BYTE $C0                             ; ##......
B9E7 C0       10246                 .BYTE $C0                             ; ##......
B9E8 F0       10247                 .BYTE $F0                             ; ####....
B9E9 C0       10248                 .BYTE $C0                             ; ##......
B9EA F0       10249                 .BYTE $F0                             ; ####....
B9EB F0       10250                 .BYTE $F0                             ; ####....
B9EC FC       10251                 .BYTE $FC                             ; ######..
B9ED BE       10252                 .BYTE $BE                             ; #.#####.
B9EE FC       10253                 .BYTE $FC                             ; ######..
B9EF F0       10254                 .BYTE $F0                             ; ####....
B9F0 80       10255                 .BYTE $80                             ; #.......
B9F1 80       10256                 .BYTE $80                             ; #.......
B9F2 C0       10257                 .BYTE $C0                             ; ##......
B9F3 C0       10258                 .BYTE $C0                             ; ##......
B9F4 F0       10259                 .BYTE $F0                             ; ####....
B9F5 BC       10260                 .BYTE $BC                             ; #.####..
B9F6 F0       10261                 .BYTE $F0                             ; ####....
B9F7 C0       10262                 .BYTE $C0                             ; ##......
B9F8 07       10263                 .BYTE $07                             ; .....###
B9F9 1F       10264                 .BYTE $1F                             ; ...#####
B9FA 1F       10265                 .BYTE $1F                             ; ...#####
B9FB 7F       10266                 .BYTE $7F                             ; .#######
B9FC EA       10267                 .BYTE $EA                             ; ###.#.#.
B9FD 7F       10268                 .BYTE $7F                             ; .#######
B9FE 1F       10269                 .BYTE $1F                             ; ...#####
B9FF 1F       10270                 .BYTE $1F                             ; ...#####
BA00 03       10271                 .BYTE $03                             ; ......##
BA01 03       10272                 .BYTE $03                             ; ......##
BA02 0F       10273                 .BYTE $0F                             ; ....####
BA03 03       10274                 .BYTE $03                             ; ......##
BA04 0F       10275                 .BYTE $0F                             ; ....####
BA05 0F       10276                 .BYTE $0F                             ; ....####
BA06 3F       10277                 .BYTE $3F                             ; ..######
BA07 7D       10278                 .BYTE $7D                             ; .#####.#
BA08 3F       10279                 .BYTE $3F                             ; ..######
BA09 0F       10280                 .BYTE $0F                             ; ....####
BA0A 01       10281                 .BYTE $01                             ; .......#
BA0B 01       10282                 .BYTE $01                             ; .......#
BA0C 03       10283                 .BYTE $03                             ; ......##
BA0D 03       10284                 .BYTE $03                             ; ......##
BA0E 0F       10285                 .BYTE $0F                             ; ....####
BA0F 3D       10286                 .BYTE $3D                             ; ..####.#
BA10 0F       10287                 .BYTE $0F                             ; ....####
BA11 03       10288                 .BYTE $03                             ; ......##
BA12 18       10289                 .BYTE $18                             ; ...##...
BA13 3C       10290                 .BYTE $3C                             ; ..####..
BA14 7E       10291                 .BYTE $7E                             ; .######.
BA15 7E       10292                 .BYTE $7E                             ; .######.
BA16 DB       10293                 .BYTE $DB                             ; ##.##.##
BA17 C3       10294                 .BYTE $C3                             ; ##....##
BA18 81       10295                 .BYTE $81                             ; #......#
BA19 81       10296                 .BYTE $81                             ; #......#
BA1A 81       10297                 .BYTE $81                             ; #......#
BA1B 10       10298                 .BYTE $10                             ; ...#....
BA1C 38       10299                 .BYTE $38                             ; ..###...
BA1D 7C       10300                 .BYTE $7C                             ; .#####..
BA1E 7C       10301                 .BYTE $7C                             ; .#####..
BA1F D6       10302                 .BYTE $D6                             ; ##.#.##.
BA20 C6       10303                 .BYTE $C6                             ; ##...##.
BA21 82       10304                 .BYTE $82                             ; #.....#.
BA22 82       10305                 .BYTE $82                             ; #.....#.
BA23 18       10306                 .BYTE $18                             ; ...##...
BA24 3C       10307                 .BYTE $3C                             ; ..####..
BA25 3C       10308                 .BYTE $3C                             ; ..####..
BA26 66       10309                 .BYTE $66                             ; .##..##.
BA27 66       10310                 .BYTE $66                             ; .##..##.
BA28 42       10311                 .BYTE $42                             ; .#....#.
BA29 42       10312                 .BYTE $42                             ; .#....#.
BA2A 10       10313                 .BYTE $10                             ; ...#....
BA2B 38       10314                 .BYTE $38                             ; ..###...
BA2C 38       10315                 .BYTE $38                             ; ..###...
BA2D 6C       10316                 .BYTE $6C                             ; .##.##..
BA2E 44       10317                 .BYTE $44                             ; .#...#..
BA2F 44       10318                 .BYTE $44                             ; .#...#..
BA30 18       10319                 .BYTE $18                             ; ...##...
BA31 3C       10320                 .BYTE $3C                             ; ..####..
BA32 24       10321                 .BYTE $24                             ; ..#..#..
BA33 24       10322                 .BYTE $24                             ; ..#..#..
BA34 10       10323                 .BYTE $10                             ; ...#....
BA35 38       10324                 .BYTE $38                             ; ..###...
BA36 28       10325                 .BYTE $28                             ; ..#.#...
BA37 18       10326                 .BYTE $18                             ; ...##...
BA38 3C       10327                 .BYTE $3C                             ; ..####..
BA39 7E       10328                 .BYTE $7E                             ; .######.
BA3A FF       10329                 .BYTE $FF                             ; ########
BA3B 18       10330                 .BYTE $18                             ; ...##...
BA3C 18       10331                 .BYTE $18                             ; ...##...
BA3D FF       10332                 .BYTE $FF                             ; ########
BA3E 7E       10333                 .BYTE $7E                             ; .######.
BA3F 3C       10334                 .BYTE $3C                             ; ..####..
BA40 18       10335                 .BYTE $18                             ; ...##...
BA41 10       10336                 .BYTE $10                             ; ...#....
BA42 38       10337                 .BYTE $38                             ; ..###...
BA43 7C       10338                 .BYTE $7C                             ; .#####..
BA44 FE       10339                 .BYTE $FE                             ; #######.
BA45 38       10340                 .BYTE $38                             ; ..###...
BA46 38       10341                 .BYTE $38                             ; ..###...
BA47 FE       10342                 .BYTE $FE                             ; #######.
BA48 7C       10343                 .BYTE $7C                             ; .#####..
BA49 38       10344                 .BYTE $38                             ; ..###...
BA4A 10       10345                 .BYTE $10                             ; ...#....
BA4B 18       10346                 .BYTE $18                             ; ...##...
BA4C 3C       10347                 .BYTE $3C                             ; ..####..
BA4D 7E       10348                 .BYTE $7E                             ; .######.
BA4E 18       10349                 .BYTE $18                             ; ...##...
BA4F 7E       10350                 .BYTE $7E                             ; .######.
BA50 3C       10351                 .BYTE $3C                             ; ..####..
BA51 18       10352                 .BYTE $18                             ; ...##...
BA52 10       10353                 .BYTE $10                             ; ...#....
BA53 38       10354                 .BYTE $38                             ; ..###...
BA54 7C       10355                 .BYTE $7C                             ; .#####..
BA55 10       10356                 .BYTE $10                             ; ...#....
BA56 7C       10357                 .BYTE $7C                             ; .#####..
BA57 38       10358                 .BYTE $38                             ; ..###...
BA58 10       10359                 .BYTE $10                             ; ...#....
BA59 18       10360                 .BYTE $18                             ; ...##...
BA5A 3C       10361                 .BYTE $3C                             ; ..####..
BA5B 18       10362                 .BYTE $18                             ; ...##...
BA5C 3C       10363                 .BYTE $3C                             ; ..####..
BA5D 18       10364                 .BYTE $18                             ; ...##...
BA5E 10       10365                 .BYTE $10                             ; ...#....
BA5F 38       10366                 .BYTE $38                             ; ..###...
BA60 38       10367                 .BYTE $38                             ; ..###...
BA61 10       10368                 .BYTE $10                             ; ...#....
              10369
              10370 ;*** Display List fragments ****************************************************
              10371 ;
              10372 ; LOCAL VARIABLES
    =1000     10373 PFMEM.C0R0      = PFMEM+0*40                          ; Start address of PLAYFIELD row 0
    =10C8     10374 PFMEM.C0R5      = PFMEM+5*40                          ; Start address of PLAYFIELD row 5
    =12A8     10375 PFMEM.C0R17     = PFMEM+17*40                         ; Start address of PLAYFIELD row 17
              10376
              10377 ;*** Display List fragment for Control Panel Display (bottom text window) ******
BA62 8D       10378 DLSTFRAG        .BYTE $8D                             ; GR7 + DLI
BA63 00       10379                 .BYTE $00                             ; BLK1
BA64 464909   10380                 .BYTE $46,<PANELTXT,>PANELTXT         ; GR1 @ PANELTXT
BA67 20       10381                 .BYTE $20                             ; BLK3
BA68 06       10382                 .BYTE $06                             ; GR1
BA69 00       10383                 .BYTE $00                             ; BLK1
              10384
              10385 ;*** Display List fragment for Galactic Chart view *****************************
BA6A 012EA1   10386 DLSTFRAGGC      .BYTE $01,<DLSTGC,>DLSTGC             ; JMP @ DLSTGC
              10387
              10388 ;*** Display List fragment for Long-Range Scan view ****************************
BA6D 00       10389 DLSTFRAGLRS     .BYTE $00                             ; BLK1
BA6E 00       10390                 .BYTE $00                             ; BLK1
BA6F 46F8A0   10391                 .BYTE $46,<LRSHEADER,>LRSHEADER       ; GR1 @ LRSHEADER
BA72 4DC810   10392                 .BYTE $4D,<PFMEM.C0R5,>PFMEM.C0R5     ; GR7 @ PFMEM.C0R5
              10393
              10394 ;*** Display List fragment for Aft view ****************************************
BA75 00       10395 DLSTFRAGAFT     .BYTE $00                             ; BLK1
BA76 00       10396                 .BYTE $00                             ; BLK1
BA77 4609A1   10397                 .BYTE $46,<AFTHEADER,>AFTHEADER       ; GR1 @ AFTHEADER
BA7A 4DC810   10398                 .BYTE $4D,<PFMEM.C0R5,>PFMEM.C0R5     ; GR7 @ PFMEM.C0R5
              10399
              10400 ;*** Display List fragment for Front view and Title text line ******************
BA7D 4D0010   10401 DLSTFRAGFRONT   .BYTE $4D,<PFMEM.C0R0,>PFMEM.C0R0     ; GR7 @ PFMEM.C0R0
BA80 0D       10402                 .BYTE $0D                             ; GR7
BA81 0D       10403                 .BYTE $0D                             ; GR7
BA82 0D       10404                 .BYTE $0D                             ; GR7
BA83 0D       10405                 .BYTE $0D                             ; GR7
BA84 0D       10406                 .BYTE $0D                             ; GR7
BA85 30       10407                 .BYTE $30                             ; BLK4
BA86 461F0D   10408                 .BYTE $46,<TITLETXT,>TITLETXT         ; GR1 @ TITLETXT
BA89 4DA812   10409                 .BYTE $4D,<PFMEM.C0R17,>PFMEM.C0R17   ; GR7 @ PFMEM.C0R17
              10410
              10411 ;*** Display List fragment offsets relative to DLSTFRAG ************************
BA8C 1B       10412 DLSTFRAGOFFTAB  .BYTE DLSTFRAGFRONT-DLSTFRAG          ; Front view
BA8D 13       10413                 .BYTE DLSTFRAGAFT-DLSTFRAG            ; Aft view
BA8E 0B       10414                 .BYTE DLSTFRAGLRS-DLSTFRAG            ; Long-Range Scan view
BA8F 08       10415                 .BYTE DLSTFRAGGC-DLSTFRAG             ; Galactic Chart view
              10416
              10417 ;*** 1-byte bit patterns for 4 pixels of same color for PLAYFIELD space objects
BA90 FF       10418 FOURCOLORPIXEL  .BYTE $FF                             ; COLOR3
BA91 FF       10419                 .BYTE $FF                             ; COLOR3
BA92 FF       10420                 .BYTE $FF                             ; COLOR3
BA93 FF       10421                 .BYTE $FF                             ; COLOR3
BA94 AA       10422                 .BYTE $AA                             ; COLOR2
BA95 FF       10423                 .BYTE $FF                             ; COLOR3
BA96 AA       10424                 .BYTE $AA                             ; COLOR2
BA97 FF       10425                 .BYTE $FF                             ; COLOR3
BA98 AA       10426                 .BYTE $AA                             ; COLOR2
BA99 AA       10427                 .BYTE $AA                             ; COLOR2
BA9A AA       10428                 .BYTE $AA                             ; COLOR2
BA9B FF       10429                 .BYTE $FF                             ; COLOR3
BA9C AA       10430                 .BYTE $AA                             ; COLOR2
BA9D AA       10431                 .BYTE $AA                             ; COLOR2
BA9E AA       10432                 .BYTE $AA                             ; COLOR2
BA9F AA       10433                 .BYTE $AA                             ; COLOR2
BAA0 AA       10434                 .BYTE $AA                             ; COLOR2
BAA1 AA       10435                 .BYTE $AA                             ; COLOR2
BAA2 AA       10436                 .BYTE $AA                             ; COLOR2
BAA3 55       10437                 .BYTE $55                             ; COLOR1
BAA4 55       10438                 .BYTE $55                             ; COLOR1
BAA5 AA       10439                 .BYTE $AA                             ; COLOR2
BAA6 55       10440                 .BYTE $55                             ; COLOR1
BAA7 AA       10441                 .BYTE $AA                             ; COLOR2
BAA8 55       10442                 .BYTE $55                             ; COLOR1
BAA9 55       10443                 .BYTE $55                             ; COLOR1
BAAA 55       10444                 .BYTE $55                             ; COLOR1
BAAB AA       10445                 .BYTE $AA                             ; COLOR2
BAAC 55       10446                 .BYTE $55                             ; COLOR1
BAAD 55       10447                 .BYTE $55                             ; COLOR1
BAAE 55       10448                 .BYTE $55                             ; COLOR1
BAAF 55       10449                 .BYTE $55                             ; COLOR1
              10450
              10451 ;*** Masks to filter 1 pixel (2 bits) from 4 pixels (1 byte of PLAYFIELD memory)
BAB0 C0       10452 PIXELMASKTAB    .BYTE $C0                             ; ##......
BAB1 30       10453                 .BYTE $30                             ; ..##....
BAB2 0C       10454                 .BYTE $0C                             ; ....##..
BAB3 03       10455                 .BYTE $03                             ; ......##
              10456
              10457 ;*** Velocity table ************************************************************
BAB4 00       10458 VELOCITYTAB     .BYTE 0                               ; Speed 0 =   0 <KM/H>
BAB5 01       10459                 .BYTE 1                               ; Speed 1 =   1 <KM/H>
BAB6 02       10460                 .BYTE 2                               ; Speed 2 =   2 <KM/H>
BAB7 04       10461                 .BYTE 4                               ; Speed 3 =   4 <KM/H>
BAB8 08       10462                 .BYTE 8                               ; Speed 4 =   8 <KM/H>
BAB9 10       10463                 .BYTE 16                              ; Speed 5 =  16 <KM/H>
BABA 20       10464                 .BYTE 32                              ; Speed 6 =  32 <KM/H>
BABB 40       10465                 .BYTE 64                              ; Speed 7 =  64 <KM/H>
BABC 60       10466                 .BYTE 96                              ; Speed 8 =  96 <KM/H>
BABD 70       10467                 .BYTE 112                             ; Speed 9 = 112 <KM/H>
              10468
              10469 ;*** Keyboard code lookup table ************************************************
BABE F2       10470 KEYTAB          .BYTE $F2                             ; '0'   - Speed 0
BABF DF       10471                 .BYTE $DF                             ; '1'   - Speed 1
BAC0 DE       10472                 .BYTE $DE                             ; '2'   - Speed 2
BAC1 DA       10473                 .BYTE $DA                             ; '3'   - Speed 3
BAC2 D8       10474                 .BYTE $D8                             ; '4'   - Speed 4
BAC3 DD       10475                 .BYTE $DD                             ; '5'   - Speed 5
BAC4 DB       10476                 .BYTE $DB                             ; '6'   - Speed 6
BAC5 F3       10477                 .BYTE $F3                             ; '7'   - Speed 7
BAC6 F5       10478                 .BYTE $F5                             ; '8'   - Speed 8
BAC7 F0       10479                 .BYTE $F0                             ; '9'   - Speed 9
BAC8 F8       10480                 .BYTE $F8                             ; 'F'   - Front view
BAC9 FF       10481                 .BYTE $FF                             ; 'A'   - Aft view
BACA C0       10482                 .BYTE $C0                             ; 'L'   - Long-Range Scan view
BACB FD       10483                 .BYTE $FD                             ; 'G'   - Galactic Chart view
BACC ED       10484                 .BYTE $ED                             ; 'T'   - Tracking on/off
BACD FE       10485                 .BYTE $FE                             ; 'S'   - Shields on/off
BACE D2       10486                 .BYTE $D2                             ; 'C'   - Attack Computer on/off
BACF F9       10487                 .BYTE $F9                             ; 'H'   - Hyperwarp
BAD0 E5       10488                 .BYTE $E5                             ; 'M'   - Manual Target Selector
BAD1 CA       10489                 .BYTE $CA                             ; 'P'   - Pause
BAD2 E7       10490                 .BYTE $E7                             ; 'INV' - Abort Mission
              10491
              10492 ;*** Engines energy drain rates per game loop iteration in energy subunits *****
BAD3 00       10493 DRAINRATETAB    .BYTE 0                               ;
BAD4 04       10494                 .BYTE 4                               ;
BAD5 06       10495                 .BYTE 6                               ;
BAD6 08       10496                 .BYTE 8                               ;
BAD7 0A       10497                 .BYTE 10                              ;
BAD8 0C       10498                 .BYTE 12                              ;
BAD9 0E       10499                 .BYTE 14                              ;
BADA 1E       10500                 .BYTE 30                              ;
BADB 2D       10501                 .BYTE 45                              ;
BADC 3C       10502                 .BYTE 60                              ;
              10503
              10504 ;*** Hyperwarp energy depending on distance ************************************
BADD 0A       10505 WARPENERGYTAB   .BYTE 10                              ; =  100 energy units
BADE 0D       10506                 .BYTE 13                              ; =  130 energy units
BADF 10       10507                 .BYTE 16                              ; =  160 energy units
BAE0 14       10508                 .BYTE 20                              ; =  200 energy units
BAE1 17       10509                 .BYTE 23                              ; =  230 energy units
BAE2 32       10510                 .BYTE 50                              ; =  500 energy units
BAE3 46       10511                 .BYTE 70                              ; =  700 energy units
BAE4 50       10512                 .BYTE 80                              ; =  800 energy units
BAE5 5A       10513                 .BYTE 90                              ; =  900 energy units
BAE6 78       10514                 .BYTE 120                             ; = 1200 energy units
BAE7 7D       10515                 .BYTE 125                             ; = 1250 energy units
BAE8 82       10516                 .BYTE 130                             ; = 1300 energy units
BAE9 87       10517                 .BYTE 135                             ; = 1350 energy units
BAEA 8C       10518                 .BYTE 140                             ; = 1400 energy units
BAEB 9B       10519                 .BYTE 155                             ; = 1550 energy units
BAEC AA       10520                 .BYTE 170                             ; = 1700 energy units
BAED B8       10521                 .BYTE 184                             ; = 1840 energy units
BAEE C8       10522                 .BYTE 200                             ; = 2000 energy units
BAEF D0       10523                 .BYTE 208                             ; = 2080 energy units
BAF0 D8       10524                 .BYTE 216                             ; = 2160 energy units
BAF1 DF       10525                 .BYTE 223                             ; = 2230 energy units
BAF2 E8       10526                 .BYTE 232                             ; = 2320 energy units
BAF3 F1       10527                 .BYTE 241                             ; = 2410 energy units
BAF4 FA       10528                 .BYTE 250                             ; = 2500 energy units
              10529
              10530 ;*** Joystick increments *******************************************************
BAF5 00       10531 STICKINCTAB     .BYTE 0                               ; Centered
BAF6 01       10532                 .BYTE 1                               ; Right or up
BAF7 FF       10533                 .BYTE -1                              ; Left or down
BAF8 00       10534                 .BYTE 0                               ; Centered
              10535
              10536 ;*** 3-byte elements to draw cross hairs and Attack Computer Display ***********
              10537 ;   Byte 1 : Pixel column number of line start
              10538 ;   Byte 2 : Pixel row number of line start
              10539 ;   Byte 3 : B7 = 0 -> Draw line to the right
              10540 ;            B7 = 1 -> Draw line down
              10541 ;            B6..0  -> Length of line in pixels. Possible values are: 0..127.
              10542 ;
              10543 ;                   #
              10544 ;                   #                              4
              10545 ;                   #                      ##############################
              10546 ;                   #1                     #             #              #
              10547 ;                   #                      #             #11            #
              10548 ;                   #                      #             #              #
              10549 ;                   #                      #5            #    8         #6
              10550 ;                                          #      ###############       #
              10551 ;                                          #      #             #       #
              10552 ;         15                  16           #   7  #             #   10  #
              10553 ; ###############       ###############    ########             #########
              10554 ;                                          #      #12           #       #
              10555 ;                                          #      #             #13     #
              10556 ;                                          #      ###############       #
              10557 ;                   #                      #         9   #              #
              10558 ;                   #                      #             #              #
              10559 ;                   #                      #             #14            #
              10560 ;                   #                      #       3     #              #
              10561 ;                   #2                     ##############################
              10562 ;                   #
              10563 ;                   #
              10564 ;
              10565 ;         Front/Aft Cross Hairs                Attack Computer Display
              10566 ;
              10567 ; LOCAL VARIABLES
    =0080     10568 DOWN            = $80
    =0000     10569 RIGHT           = $00
              10570
BAF9 502887   10571 DRAWLINESTAB    .BYTE 80,40,DOWN!7                    ; Line 1
BAFC 503687   10572                 .BYTE 80,54,DOWN!7                    ; Line 2
              10573
BAFF 77461E   10574                 .BYTE 119,70,RIGHT!30                 ; Line 3
BB02 77561E   10575                 .BYTE 119,86,RIGHT!30                 ; Line 4
BB05 774691   10576                 .BYTE 119,70,DOWN!17                  ; Line 5
BB08 944691   10577                 .BYTE 148,70,DOWN!17                  ; Line 6
BB0B 784E06   10578                 .BYTE 120,78,RIGHT!6                  ; Line 7
BB0E 7E4B0F   10579                 .BYTE 126,75,RIGHT!15                 ; Line 8
BB11 7E510F   10580                 .BYTE 126,81,RIGHT!15                 ; Line 9
BB14 8D4E07   10581                 .BYTE 141,78,RIGHT!7                  ; Line 10
BB17 854784   10582                 .BYTE 133,71,DOWN!4                   ; Line 11
BB1A 7E4C85   10583                 .BYTE 126,76,DOWN!5                   ; Line 12
BB1D 8C4C85   10584                 .BYTE 140,76,DOWN!5                   ; Line 13
BB20 855284   10585                 .BYTE 133,82,DOWN!4                   ; Line 14
              10586
BB23 3E320F   10587                 .BYTE 62,50,RIGHT!15                  ; Line 15
BB26 54320F   10588                 .BYTE 84,50,RIGHT!15                  ; Line 16
BB29 FE       10589                 .BYTE $FE                             ; End marker
              10590
              10591 ;*** 3-byte elements to draw our starship's shape in Long-Range Scan view ******
              10592 ;
              10593 ;   Line  17 18 19 20 21
              10594 ;               ##
              10595 ;               ##
              10596 ;            ## ## ##
              10597 ;         ## ## ## ## ##
              10598 ;         ##    ##    ##
              10599
BB2A 4E3582   10600                 .BYTE 78,53,DOWN!2                    ; Line 17
BB2D 4F3482   10601                 .BYTE 79,52,DOWN!2                    ; Line 18
BB30 503285   10602                 .BYTE 80,50,DOWN!5                    ; Line 19
BB33 513482   10603                 .BYTE 81,52,DOWN!2                    ; Line 20
BB36 523582   10604                 .BYTE 82,53,DOWN!2                    ; Line 21
BB39 FE       10605                 .BYTE $FE                             ; End marker
              10606
              10607 ;*** Initial x and y coordinates of a star during hyperwarp ********************
              10608 ; The following two tables are used to determine the initial x and y coordinates
              10609 ; (high byte) of a star during hyperwarp. An index in 0..3 picks both the x and
              10610 ; y coordinate, thus 4 pairs of coordinates are possible:
              10611 ;
              10612 ; Y           +-------+----------------------------+----------------------------+
              10613 ; ^           | Index |        x-coordinate        |        y-coordinate        |
              10614 ; |           +-------+----------------------------+----------------------------+
              10615 ; |.32.       |   0   | +1024..+1279 (+$04**) <KM> |  +512..+767  (+$02**) <KM> |
              10616 ; |...1       |   1   | +1024..+1279 (+$04**) <KM> |  +768..+1023 (+$03**) <KM> |
              10617 ; |...0       |   2   |  +768..+1023 (+$03**) <KM> | +1024..+1279 (+$04**) <KM> |
              10618 ; |....       |   3   |  +512..+767  (+$02**) <KM> | +1024..+1279 (+$04**) <KM> |
              10619 ; 0----->X    +-------+----------------------------+----------------------------+
              10620
              10621 ;*** Initial x-coordinate (high byte) of star in hyperwarp *********************
BB3A 04       10622 WARPSTARXTAB    .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB3B 04       10623                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB3C 03       10624                 .BYTE $03                             ;  +768..+1023 (+$03**) <KM>
BB3D 02       10625                 .BYTE $02                             ;  +512..+767  (+$02**) <KM>
              10626
              10627 ;*** Initial y-coordinate (high byte) of star in hyperwarp *********************
BB3E 02       10628 WARPSTARYTAB    .BYTE $02                             ;  +512..+767  (+$02**) <KM>
BB3F 03       10629                 .BYTE $03                             ;  +768..+1023 (+$03**) <KM>
BB40 04       10630                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB41 04       10631                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
              10632
              10633 ;*** Text of Control Panel Display (encoded in custom character set) ***********
              10634 ; Row 1: "V:00 K:00 E:9999 T:0"
              10635 ; Row 2: " O:-00 O:-00 R:-000 "
              10636
BB42 12       10637 PANELTXTTAB     .BYTE CCS.V
BB43 0B       10638                 .BYTE CCS.COLON
BB44 00       10639                 .BYTE CCS.0
BB45 00       10640                 .BYTE CCS.0
BB46 0A       10641                 .BYTE CCS.SPC
BB47 55       10642                 .BYTE CCS.COL1!CCS.K
BB48 4B       10643                 .BYTE CCS.COL1!CCS.COLON
BB49 40       10644                 .BYTE CCS.COL1!CCS.0
BB4A 40       10645                 .BYTE CCS.COL1!CCS.0
BB4B 0A       10646                 .BYTE CCS.SPC
BB4C 8D       10647                 .BYTE CCS.COL2!CCS.E
BB4D 8B       10648                 .BYTE CCS.COL2!CCS.COLON
BB4E 89       10649                 .BYTE CCS.COL2!CCS.9
BB4F 89       10650                 .BYTE CCS.COL2!CCS.9
BB50 89       10651                 .BYTE CCS.COL2!CCS.9
BB51 89       10652                 .BYTE CCS.COL2!CCS.9
BB52 0A       10653                 .BYTE CCS.SPC
BB53 16       10654                 .BYTE CCS.T
BB54 0B       10655                 .BYTE CCS.COLON
BB55 00       10656                 .BYTE CCS.0
              10657
BB56 0A       10658                 .BYTE CCS.SPC
BB57 14       10659                 .BYTE CCS.THETA
BB58 0B       10660                 .BYTE CCS.COLON
BB59 0F       10661                 .BYTE CCS.MINUS
BB5A 00       10662                 .BYTE CCS.0
BB5B 00       10663                 .BYTE CCS.0
BB5C 0A       10664                 .BYTE CCS.SPC
BB5D 51       10665                 .BYTE CCS.COL1!CCS.PHI
BB5E 4B       10666                 .BYTE CCS.COL1!CCS.COLON
BB5F 0F       10667                 .BYTE CCS.MINUS
BB60 00       10668                 .BYTE CCS.0
BB61 00       10669                 .BYTE CCS.0
BB62 0A       10670                 .BYTE CCS.SPC
BB63 93       10671                 .BYTE CCS.COL2!CCS.R
BB64 8B       10672                 .BYTE CCS.COL2!CCS.COLON
BB65 0F       10673                 .BYTE CCS.MINUS
BB66 00       10674                 .BYTE CCS.0
BB67 00       10675                 .BYTE CCS.0
BB68 00       10676                 .BYTE CCS.0
BB69 0A       10677                 .BYTE CCS.SPC
              10678
              10679 ;*** Text of Galactic Chart Panel Display **************************************
              10680 ; Row 1: "WARP ENERGY:   0    "
              10681 ; Row 2: "TARGETS:  DC:PESCLR "
              10682 ; Row 3: "STAR DATE:00.00     "
              10683
BB6A 37       10684                 .BYTE ROM.W
BB6B 21       10685                 .BYTE ROM.A
BB6C 32       10686                 .BYTE ROM.R
BB6D 30       10687                 .BYTE ROM.P
BB6E 00       10688                 .BYTE ROM.SPC
BB6F 25       10689                 .BYTE ROM.E
BB70 2E       10690                 .BYTE ROM.N
BB71 25       10691                 .BYTE ROM.E
BB72 32       10692                 .BYTE ROM.R
BB73 27       10693                 .BYTE ROM.G
BB74 39       10694                 .BYTE ROM.Y
BB75 1A       10695                 .BYTE ROM.COLON
BB76 00       10696                 .BYTE ROM.SPC
BB77 00       10697                 .BYTE ROM.SPC
BB78 00       10698                 .BYTE ROM.SPC
BB79 10       10699                 .BYTE ROM.0
BB7A 00       10700                 .BYTE ROM.SPC
BB7B 00       10701                 .BYTE ROM.SPC
BB7C 00       10702                 .BYTE ROM.SPC
BB7D 00       10703                 .BYTE ROM.SPC
              10704
BB7E B4       10705                 .BYTE CCS.COL2!ROM.T
BB7F A1       10706                 .BYTE CCS.COL2!ROM.A
BB80 B2       10707                 .BYTE CCS.COL2!ROM.R
BB81 A7       10708                 .BYTE CCS.COL2!ROM.G
BB82 A5       10709                 .BYTE CCS.COL2!ROM.E
BB83 B4       10710                 .BYTE CCS.COL2!ROM.T
BB84 B3       10711                 .BYTE CCS.COL2!ROM.S
BB85 9A       10712                 .BYTE CCS.COL2!ROM.COLON
BB86 00       10713                 .BYTE ROM.SPC
BB87 00       10714                 .BYTE ROM.SPC
BB88 24       10715                 .BYTE ROM.D
BB89 23       10716                 .BYTE ROM.C
BB8A 1A       10717                 .BYTE ROM.COLON
BB8B 30       10718                 .BYTE ROM.P
BB8C 25       10719                 .BYTE ROM.E
BB8D 33       10720                 .BYTE ROM.S
BB8E 23       10721                 .BYTE ROM.C
BB8F 2C       10722                 .BYTE ROM.L
BB90 32       10723                 .BYTE ROM.R
BB91 00       10724                 .BYTE ROM.SPC
              10725
BB92 F3       10726                 .BYTE CCS.COL3!ROM.S
BB93 F4       10727                 .BYTE CCS.COL3!ROM.T
BB94 E1       10728                 .BYTE CCS.COL3!ROM.A
BB95 F2       10729                 .BYTE CCS.COL3!ROM.R
BB96 00       10730                 .BYTE ROM.SPC
BB97 E4       10731                 .BYTE CCS.COL3!ROM.D
BB98 E1       10732                 .BYTE CCS.COL3!ROM.A
BB99 F4       10733                 .BYTE CCS.COL3!ROM.T
BB9A E5       10734                 .BYTE CCS.COL3!ROM.E
BB9B DA       10735                 .BYTE CCS.COL3!ROM.COLON
BB9C D0       10736                 .BYTE CCS.COL3!ROM.0
BB9D D0       10737                 .BYTE CCS.COL3!ROM.0
BB9E CE       10738                 .BYTE CCS.COL3!ROM.DOT
BB9F D0       10739                 .BYTE CCS.COL3!ROM.0
BBA0 D0       10740                 .BYTE CCS.COL3!ROM.0
BBA1 00       10741                 .BYTE ROM.SPC
BBA2 00       10742                 .BYTE ROM.SPC
BBA3 00       10743                 .BYTE ROM.SPC
BBA4 00       10744                 .BYTE ROM.SPC
BBA5 00       10745                 .BYTE ROM.SPC
              10746
              10747 ;*** Galactic Chart sector type table ******************************************
BBA6 CF       10748 SECTORTYPETAB   .BYTE $CF                             ; Starbase
BBA7 04       10749                 .BYTE $04                             ; 4 Zylon ships
BBA8 03       10750                 .BYTE $03                             ; 3 Zylon ships
BBA9 02       10751                 .BYTE $02                             ; 1 or 2 Zylon ships
              10752
              10753 ;*** Phrase table **************************************************************
              10754 ; Phrases consist of phrase tokens. These are bytes that encode words, segments
              10755 ; (multiple words that fit into a single line of text), and how they are displayed.
              10756 ;
              10757 ; LOCAL VARIABLES
    =0040     10758 EOP             = $40                                 ; End of phrase
    =0080     10759 EOS             = $80                                 ; End of segment
    =00C0     10760 LONG            = $C0                                 ; Display title phrase for a long time
              10761
              10762                                                       ; Title Phrase Offset, Text
BBAA 00       10763 PHRASETAB       .BYTE $00                             ; (unused)
BBAB 050642   10764                 .BYTE $05,$06,$02!EOP                 ; $01  "ATTACK COMPUTER ON"
BBAE 050643   10765                 .BYTE $05,$06,$03!EOP                 ; $04  "ATTACK COMPUTER OFF"
BBB1 0442     10766                 .BYTE $04,$02!EOP                     ; $07  "SHIELDS ON"
BBB3 0443     10767                 .BYTE $04,$03!EOP                     ; $09  "SHIELDS OFF"
BBB5 060742   10768                 .BYTE $06,$07,$02!EOP                 ; $0B  "COMPUTER TRACKING ON"
BBB8 0743     10769                 .BYTE $07,$03!EOP                     ; $0E  "TRACKING OFF"
BBBA 48       10770                 .BYTE $08!EOP                         ; $10  "WHATS WRONG?"
BBBB 094A     10771                 .BYTE $09,$0A!EOP                     ; $11  "HYPERWARP ENGAGED"
BBBD 0BCD     10772                 .BYTE $0B,$0D!LONG                    ; $13  "STARBASE SURROUNDED"
BBBF 0BCC     10773                 .BYTE $0B,$0C!LONG                    ; $15  "STARBASE DESTROYED"
BBC1 094E     10774                 .BYTE $09,$0E!EOP                     ; $17  "HYPERWARP ABORTED"
BBC3 094F     10775                 .BYTE $09,$0F!EOP                     ; $19  "HYPERWARP COMPLETE"
BBC5 D0       10776                 .BYTE $10!LONG                        ; $1B  "HYPERSPACE"
BBC6 1192     10777                 .BYTE $11,$12!EOS                     ; $1C  "ORBIT ESTABLISHED"
BBC8 56       10778                 .BYTE $16!EOP                         ; $1E  "STANDBY"
BBC9 134E     10779                 .BYTE $13,$0E!EOP                     ; $1F  "DOCKING ABORTED"
BBCB 154F     10780                 .BYTE $15,$0F!EOP                     ; $21  "TRANSFER COMPLETE"
BBCD B8       10781                 .BYTE $38!EOS                         ; $23  " "
BBCE 97       10782                 .BYTE $17!EOS                         ; $24  "STAR FLEET TO"
BBCF 99       10783                 .BYTE $19!EOS                         ; $25  "ALL UNITS"
BBD0 98       10784                 .BYTE $18!EOS                         ; $26  "STAR CRUISER 7"
BBD1 8C       10785                 .BYTE $0C!EOS                         ; $27  "DESTROYED"
BBD2 9D       10786                 .BYTE $1D!EOS                         ; $28  "BY ZYLON FIRE"
BBD3 1E9F     10787                 .BYTE $1E,$1F!EOS                     ; $29  "POSTHUMOUS RANK IS:"
BBD5 FD       10788                 .BYTE $FD                             ; $2B  "<PLACEHOLDER FOR RANK>"
BBD6 25FC     10789                 .BYTE $25,$FC                         ; $2C  "CLASS <PLACEHOLDER FOR CLASS>"
BBD8 78       10790                 .BYTE $38!EOP                         ; $2E  " "
BBD9 9B       10791                 .BYTE $1B!EOS                         ; $2F  "STAR RAIDERS"
BBDA 60       10792                 .BYTE $20!EOP                         ; $30  "COPYRIGHT ATARI 1979"
BBDB B8       10793                 .BYTE $38!EOS                         ; $31  " "
BBDC 97       10794                 .BYTE $17!EOS                         ; $32  "STAR FLEET TO"
BBDD 98       10795                 .BYTE $18!EOS                         ; $33  "STAR CRUISER 7"
BBDE 1A8E     10796                 .BYTE $1A,$0E!EOS                     ; $34  "MISSION ABORTED"
BBE0 1C94     10797                 .BYTE $1C,$14!EOS                     ; $36  "ZERO ENERGY"
BBE2 249F     10798                 .BYTE $24,$1F!EOS                     ; $38  "NEW RANK IS"
BBE4 FD       10799                 .BYTE $FD                             ; $3A  "<PLACEHOLDER FOR RANK>"
BBE5 25FC     10800                 .BYTE $25,$FC                         ; $3B  "CLASS <PLACEHOLDER FOR CLASS>"
BBE7 A7       10801                 .BYTE $27!EOS                         ; $3D  "REPORT TO BASE"
BBE8 68       10802                 .BYTE $28!EOP                         ; $3E  "FOR TRAINING"
BBE9 B8       10803                 .BYTE $38!EOS                         ; $3F  " "
BBEA 97       10804                 .BYTE $17!EOS                         ; $40  "STAR FLEET TO"
BBEB 98       10805                 .BYTE $18!EOS                         ; $41  "STAR CRUISER 7"
BBEC 1A8F     10806                 .BYTE $1A,$0F!EOS                     ; $42  "MISSION COMPLETE"
BBEE 249F     10807                 .BYTE $24,$1F!EOS                     ; $44  "NEW RANK IS:"
BBF0 FD       10808                 .BYTE $FD                             ; $46  "<PLACEHOLDER FOR RANK>"
BBF1 25FC     10809                 .BYTE $25,$FC                         ; $47  "CLASS <PLACEHOLDER FOR CLASS>"
BBF3 66       10810                 .BYTE $26!EOP                         ; $49  "CONGRATULATIONS"
BBF4 2C5A     10811                 .BYTE $2C,$1A!EOP                     ; $4A  "NOVICE MISSION"
BBF6 2E5A     10812                 .BYTE $2E,$1A!EOP                     ; $4C  "PILOT MISSION"
BBF8 315A     10813                 .BYTE $31,$1A!EOP                     ; $4E  "WARRIOR MISSION"
BBFA 335A     10814                 .BYTE $33,$1A!EOP                     ; $50  "COMMANDER MISSION"
BBFC B8       10815                 .BYTE $38!EOS                         ; $52  " "
BBFD 3476     10816                 .BYTE $34,$36!EOP                     ; $53  "DAMAGE CONTROL"
BBFF 37B5     10817                 .BYTE $37,$35!EOS                     ; $55  "PHOTONS DAMAGED"
BC01 78       10818                 .BYTE $38!EOP                         ; $57  " "
BC02 378C     10819                 .BYTE $37,$0C!EOS                     ; $58  "PHOTONS DESTROYED"
BC04 78       10820                 .BYTE $38!EOP                         ; $5A  " "
BC05 23B5     10821                 .BYTE $23,$35!EOS                     ; $5B  "ENGINES DAMAGED"
BC07 78       10822                 .BYTE $38!EOP                         ; $5D  " "
BC08 238C     10823                 .BYTE $23,$0C!EOS                     ; $5E  "ENGINES DESTROYED"
BC0A 78       10824                 .BYTE $38!EOP                         ; $60  " "
BC0B 04B5     10825                 .BYTE $04,$35!EOS                     ; $61  "SHIELDS DAMAGED"
BC0D 78       10826                 .BYTE $38!EOP                         ; $63  " "
BC0E 048C     10827                 .BYTE $04,$0C!EOS                     ; $64  "SHIELDS DESTROYED"
BC10 78       10828                 .BYTE $38!EOP                         ; $66  " "
BC11 06B5     10829                 .BYTE $06,$35!EOS                     ; $67  "COMPUTER DAMAGED"
BC13 78       10830                 .BYTE $38!EOP                         ; $69  " "
BC14 068C     10831                 .BYTE $06,$0C!EOS                     ; $6A  "COMPUTER DESTROYED"
BC16 78       10832                 .BYTE $38!EOP                         ; $6C  " "
BC17 A2       10833                 .BYTE $22!EOS                         ; $6D  "SECTOR SCAN"
BC18 75       10834                 .BYTE $35!EOP                         ; $6E  "DAMAGED"
BC19 A2       10835                 .BYTE $22!EOS                         ; $6F  "SECTOR SCAN"
BC1A 4C       10836                 .BYTE $0C!EOP                         ; $70  "DESTROYED"
BC1B A1       10837                 .BYTE $21!EOS                         ; $71  "SUB-SPACE RADIO"
BC1C 75       10838                 .BYTE $35!EOP                         ; $72  "DAMAGED"
BC1D A1       10839                 .BYTE $21!EOS                         ; $73  "SUB-SPACE RADIO"
BC1E 4C       10840                 .BYTE $0C!EOP                         ; $74  "DESTROYED"
BC1F C1       10841                 .BYTE $01!LONG                        ; $75  "RED ALERT"
BC20 B8       10842                 .BYTE $38!EOS                         ; $76  " "
BC21 97       10843                 .BYTE $17!EOS                         ; $77  "STAR FLEET TO"
BC22 98       10844                 .BYTE $18!EOS                         ; $78  "STAR CRUISER 7"
BC23 1A8E     10845                 .BYTE $1A,$0E!EOS                     ; $79  "MISSION ABORTED"
BC25 249F     10846                 .BYTE $24,$1F!EOS                     ; $7B  "NEW RANK IS:"
BC27 FD       10847                 .BYTE $FD                             ; $7D  "<PLACEHOLDER FOR RANK>"
BC28 25FC     10848                 .BYTE $25,$FC                         ; $7E  "CLASS <PLACEHOLDER FOR CLASS>"
BC2A 66       10849                 .BYTE $26!EOP                         ; $80  "CONGRATULATIONS"
              10850
              10851 ;*** Word table ****************************************************************
              10852 ; Bit B7 of the first byte of a word is the end-of-word marker of the preceding
              10853 ; word
              10854 ;
              10855 ; LOCAL VARIABLES
    =0080     10856 EOW             = $80                                 ; End of word
              10857
BC2B A0202020 10858 WORDTAB         .BYTE EOW!$20,"    RED ALERT"         ; Word $01
BC2F 20524544
BC33 20414C45
BC37 5254
BC39 CF4E     10859                 .BYTE EOW!'O,"N"                      ; Word $02
BC3B CF4646   10860                 .BYTE EOW!'O,"FF"                     ; Word $03
BC3E D3484945 10861                 .BYTE EOW!'S,"HIELDS"                 ; Word $04
BC42 4C4453
BC45 C1545441 10862                 .BYTE EOW!'A,"TTACK"                  ; Word $05
BC49 434B
BC4B C34F4D50 10863                 .BYTE EOW!'C,"OMPUTER"                ; Word $06
BC4F 55544552
BC53 D4524143 10864                 .BYTE EOW!'T,"RACKING"                ; Word $07
BC57 4B494E47
BC5B D7484154 10865                 .BYTE EOW!'W,"HATS WRONG?"            ; Word $08
BC5F 53205752
BC63 4F4E473F
BC67 C8595045 10866                 .BYTE EOW!'H,"YPERWARP"               ; Word $09
BC6B 52574152
BC6F 50
BC70 C54E4741 10867                 .BYTE EOW!'E,"NGAGED"                 ; Word $0A
BC74 474544
BC77 D3544152 10868                 .BYTE EOW!'S,"TARBASE"                ; Word $0B
BC7B 42415345
BC7F C4455354 10869                 .BYTE EOW!'D,"ESTROYED"               ; Word $0C
BC83 524F5945
BC87 44
BC88 D3555252 10870                 .BYTE EOW!'S,"URROUNDED"              ; Word $0D
BC8C 4F554E44
BC90 4544
BC92 C1424F52 10871                 .BYTE EOW!'A,"BORTED"                 ; Word $0E
BC96 544544
BC99 C34F4D50 10872                 .BYTE EOW!'C,"OMPLETE"                ; Word $0F
BC9D 4C455445
BCA1 C8595045 10873                 .BYTE EOW!'H,"YPERSPACE"              ; Word $10
BCA5 52535041
BCA9 4345
BCAB CF524249 10874                 .BYTE EOW!'O,"RBIT"                   ; Word $11
BCAF 54
BCB0 C5535441 10875                 .BYTE EOW!'E,"STABLISHED"             ; Word $12
BCB4 424C4953
BCB8 484544
BCBB C44F434B 10876                 .BYTE EOW!'D,"OCKING"                 ; Word $13
BCBF 494E47
BCC2 C54E4552 10877                 .BYTE EOW!'E,"NERGY"                  ; Word $14
BCC6 4759
BCC8 D452414E 10878                 .BYTE EOW!'T,"RANSFER"                ; Word $15
BCCC 53464552
BCD0 D354414E 10879                 .BYTE EOW!'S,"TANDBY"                 ; Word $16
BCD4 444259
BCD7 D3544152 10880                 .BYTE EOW!'S,"TAR FLEET TO"           ; Word $17
BCDB 20464C45
BCDF 45542054
BCE3 4F
BCE4 D3544152 10881                 .BYTE EOW!'S,"TAR CRUISER 7"          ; Word $18
BCE8 20435255
BCEC 49534552
BCF0 2037
BCF2 C14C4C20 10882                 .BYTE EOW!'A,"LL UNITS"               ; Word $19
BCF6 554E4954
BCFA 53
BCFB CD495353 10883                 .BYTE EOW!'M,"ISSION"                 ; Word $1A
BCFF 494F4E
BD02 A0202020 10884                 .BYTE EOW!$20,"   STAR RAIDERS"       ; Word $1B
BD06 53544152
BD0A 20524149
BD0E 44455253
BD12 DA45524F 10885                 .BYTE EOW!'Z,"ERO"                    ; Word $1C
BD16 C259205A 10886                 .BYTE EOW!'B,"Y ZYLON FIRE"           ; Word $1D
BD1A 594C4F4E
BD1E 20464952
BD22 45
BD23 D04F5354 10887                 .BYTE EOW!'P,"OSTHUMOUS"              ; Word $1E
BD27 48554D4F
BD2B 5553
BD2D D2414E4B 10888                 .BYTE EOW!'R,"ANK IS:"                ; Word $1F
BD31 2049533A
BD35 C34F5059 10889                 .BYTE EOW!'C,"OPYRIGHT ATARI 1979"    ; Word $20
BD39 52494748
BD3D 54204154
BD41 41524920
BD45 31393739
BD49 D355422D 10890                 .BYTE EOW!'S,"UB-SPACE RADIO"         ; Word $21
BD4D 53504143
BD51 45205241
BD55 44494F
BD58 D3454354 10891                 .BYTE EOW!'S,"ECTOR SCAN"             ; Word $22
BD5C 4F522053
BD60 43414E
BD63 C54E4749 10892                 .BYTE EOW!'E,"NGINES"                 ; Word $23
BD67 4E4553
BD6A CE4557   10893                 .BYTE EOW!'N,"EW"                     ; Word $24
BD6D C34C4153 10894                 .BYTE EOW!'C,"LASS"                   ; Word $25
BD71 53
BD72 C34F4E47 10895                 .BYTE EOW!'C,"ONGRATULATIONS"         ; Word $26
BD76 52415455
BD7A 4C415449
BD7E 4F4E53
BD81 D245504F 10896                 .BYTE EOW!'R,"EPORT TO BASE"          ; Word $27
BD85 52542054
BD89 4F204241
BD8D 5345
BD8F C64F5220 10897                 .BYTE EOW!'F,"OR TRAINING"            ; Word $28
BD93 54524149
BD97 4E494E47
BD9B C7414C41 10898                 .BYTE EOW!'G,"ALACTIC COOK"           ; Word $29
BD9F 43544943
BDA3 20434F4F
BDA7 4B
BDA8 C7415242 10899                 .BYTE EOW!'G,"ARBAGE SCOW CAPTAIN"    ; Word $2A
BDAC 41474520
BDB0 53434F57
BDB4 20434150
BDB8 5441494E
BDBC D24F4F4B 10900                 .BYTE EOW!'R,"OOKIE"                  ; Word $2B
BDC0 4945
BDC2 CE4F5649 10901                 .BYTE EOW!'N,"OVICE"                  ; Word $2C
BDC6 4345
BDC8 C54E5349 10902                 .BYTE EOW!'E,"NSIGN"                  ; Word $2D
BDCC 474E
BDCE D0494C4F 10903                 .BYTE EOW!'P,"ILOT"                   ; Word $2E
BDD2 54
BDD3 C14345   10904                 .BYTE EOW!'A,"CE"                     ; Word $2F
BDD6 CC494555 10905                 .BYTE EOW!'L,"IEUTENANT"              ; Word $30
BDDA 54454E41
BDDE 4E54
BDE0 D7415252 10906                 .BYTE EOW!'W,"ARRIOR"                 ; Word $31
BDE4 494F52
BDE7 C3415054 10907                 .BYTE EOW!'C,"APTAIN"                 ; Word $32
BDEB 41494E
BDEE C34F4D4D 10908                 .BYTE EOW!'C,"OMMANDER"               ; Word $33
BDF2 414E4445
BDF6 52
BDF7 C4414D41 10909                 .BYTE EOW!'D,"AMAGE"                  ; Word $34
BDFB 4745
BDFD C4414D41 10910                 .BYTE EOW!'D,"AMAGED"                 ; Word $35
BE01 474544
BE04 C34F4E54 10911                 .BYTE EOW!'C,"ONTROL"                 ; Word $36
BE08 524F4C
BE0B D0484F54 10912                 .BYTE EOW!'P,"HOTONS"                 ; Word $37
BE0F 4F4E53
BE12 A0       10913                 .BYTE EOW!$20                         ; Word $38
BE13 D3544152 10914                 .BYTE EOW!'S,"TAR COMMANDER"          ; Word $39
BE17 20434F4D
BE1B 4D414E44
BE1F 4552
BE21 80       10915                 .BYTE EOW!$00                         ;
              10916
              10917 ;*** View modes ****************************************************************
BE22 00       10918 VIEWMODETAB     .BYTE $00                             ; Front view
BE23 01       10919                 .BYTE $01                             ; Aft view
BE24 40       10920                 .BYTE $40                             ; Long-Range Scan view
BE25 80       10921                 .BYTE $80                             ; Galactic Chart view
              10922
              10923 ;*** Title phrase offsets of "TRACKING OFF", "SHIELDS OFF", "COMPUTER OFF" *****
BE26 0E       10924 MSGOFFTAB       .BYTE $0E                             ; "TRACKING OFF"
BE27 09       10925                 .BYTE $09                             ; "SHIELDS OFF"
BE28 04       10926                 .BYTE $04                             ; "COMPUTER OFF"
              10927
              10928 ;*** Masks to test if Tracking Computer, Shields, or Attack Computer are on ****
BE29 FF       10929 MSGBITTAB       .BYTE $FF                             ; Mask Tracking Computer
BE2A 08       10930                 .BYTE $08                             ; Mask Shields
BE2B 02       10931                 .BYTE $02                             ; Mask Attack Computer
              10932
              10933 ;*** Title phrase offsets of "COMPUTER TRACKING ON", "SHIELDS ON", "COMPUTER ON"
BE2C 0B       10934 MSGONTAB        .BYTE $0B                             ; "COMPUTER TRACKING ON"
BE2D 07       10935                 .BYTE $07                             ; "SHIELDS ON"
BE2E 01       10936                 .BYTE $01                             ; "COMPUTER ON"
              10937
              10938 ;*** The following two tables encode the PLAYER shapes *************************
              10939 ;
              10940 ; PHOTON TORPEDO (shape type 0, data in shape table PLSHAP1TAB)
              10941 ; Numbers at top indicate the shape table offset of the first and last shape row
              10942 ;
              10943 ; $01..$10  $11..$1E  $1F..$2A  $2B..$34  $35..$3C  $3D..$42  $75..$76  $7A..$7B
              10944 ; ...##...  ...#....  ...##...  ...#....  ...#....  ...#....  ...##...  ...#....
              10945 ; ..####..  ..###...  ..####..  ..###...  ...##...  ..###...  ...##...  ...#....
              10946 ; .######.  .#####..  ..####..  ..###...  ..####..  ..###...
              10947 ; .######.  .#####..  .######.  .#####..  ..#.##..  ..#.#...
              10948 ; .###.##.  #######.  .##.###.  .###.#..  ..####..  ..###...
              10949 ; ####.###  ##.####.  .####.#.  .#####..  ..####..  ...#....
              10950 ; ##.#####  ##.##.#.  .######.  .##.##..  ...##...
              10951 ; ##.#####  #####.#.  .###.##.  ..###...  ....#...
              10952 ; ########  ###.###.  .######.  ..###...
              10953 ; ########  ###.###.  ..####..  ...#....
              10954 ; ####.###  .#####..  ..####..
              10955 ; .###.##.  .#####..  ...##...
              10956 ; .######.  ..###...
              10957 ; .######.  ...#....
              10958 ; ..####..
              10959 ; ...##...
              10960 ;
              10961 ; ZYLON FIGHTER (shape type 1, data in shape table PLSHAP2TAB)
              10962 ; Numbers at top indicate the shape table offset of the first and last shape row
              10963 ;
              10964 ; $01..$0C  $0D..$14  $15..$1A  $1B..$20  $21..$24  $25..$28  $29..$2A  $2B..$2C
              10965 ; #......#  #.....#.  .#....#.  .#...#..  ..#..#..  ..#.#...  ...##...  ...#....
              10966 ; #......#  #.....#.  .#.##.#.  .#.#.#..  ..####..  ..###...  ...##...  ...#....
              10967 ; #......#  #.###.#.  .######.  .#####..  ..####..  ..###...
              10968 ; #......#  #######.  .######.  .#####..  ..#..#..  ..#.#...
              10969 ; #.####.#  #######.  .#.##.#.  .#.#.#..
              10970 ; ########  #.###.#.  .#....#.  .#...#..
              10971 ; ########  #.....#.
              10972 ; #.####.#  #.....#.
              10973 ; #......#
              10974 ; #......#
              10975 ; #......#
              10976 ; #......#
              10977 ;
              10978 ; STARBASE RIGHT (shape type 2, data in shape table PLSHAP2TAB)
              10979 ; Numbers at top indicate the shape table offset of the first and last shape row
              10980 ;
              10981 ; $2D..$36  $38..$40  $41..$46  $36..$38  $36       $00       $00       $00
              10982 ; ###.....  ##......  ##......  ##......  ##......  ........  ........  ........
              10983 ; #####...  ####....  ##......  ####....
              10984 ; #####...  ####....  ####....  ##......
              10985 ; #######.  ######..  #.####..
              10986 ;  #.#.###  #.#####.  ####....
              10987 ; #######.  ######..  ##......
              10988 ; #####...  ####....
              10989 ; #####...  #.......
              10990 ; ##......  #.......
              10991 ; ##......
              10992 ;
              10993 ; STARBASE CENTER (shape type 3, data in shape table PLSHAP1TAB)
              10994 ; Numbers at top indicate the shape table offset of the first and last shape row
              10995 ;
              10996 ; $7E..$8D  $8E..$9C  $9D..$A9  $AA..$B3  $B4..$BB  $BC..$C0  $7B..$7D  $7A..$7B
              10997 ; ...##...  ........  ........  ...##...  ........  ...##...  ...#....  ...#....
              10998 ; .######.  ...##...  ...##...  ..####..  ...##...  ..####..  ..###...  ...#....
              10999 ; ########  ..####..  ..####..  ########  ..####..  ########  ...#....
              11000 ; ########  .######.  .######.  ########  ########  ..####..
              11001 ; ########  ########  ########  ###..###  ########  ...##...
              11002 ; ########  ########  ########  .##..##.  ########
              11003 ; ########  ########  ###..###  ########  ..####..
              11004 ; ###..###  ###..###  .##..##.  ########  ...##...
              11005 ; ###..###  .##..##.  ########  .######.
              11006 ; ########  ########  ########  ..####..
              11007 ; ########  ########  ########
              11008 ; ########  ########  ########
              11009 ; ########  ########  ..####..
              11010 ; ########  .######.
              11011 ; .######.  .######.
              11012 ; .######.
              11013 ;
              11014 ; STARBASE LEFT (shape type 4, data in shape table PLSHAP2TAB)
              11015 ; Numbers at top indicate the shape table offset of the first and last shape row
              11016 ;
              11017 ; $47..$50  $52..$5A  $5B..$60  $50..$52  $50       $00       $00       $00
              11018 ; .....###  ......##  ......##  ......##  ......##  ........  ........  ........
              11019 ; ...#####  ....####  ......##  ....####
              11020 ; ...#####  ....####  ....####  ......##
              11021 ; .#######  ..######  ..####.#
              11022 ; ###.#.#.  .#####.#  ....####
              11023 ; .#######  ..######  ......##
              11024 ; ...#####  ....####
              11025 ; ...#####  .......#
              11026 ; ......##  .......#
              11027 ; ......##
              11028 ;
              11029 ; TRANSFER VESSEL (shape type 5, data in shape table PLSHAP1TAB)
              11030 ; Numbers at top indicate the shape table offset of the first and last shape row
              11031 ;
              11032 ; $43..$52  $53..$60  $61..$6B  $6C..$74  $75..$79  $7A..$7D  $75..$76  $7A..$7B
              11033 ; ..####..  ...###..  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11034 ; ..####..  ...###..  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11035 ; ..#..#..  ...#.#..  ..####..  ..###...  ..####..  ..###...
              11036 ; ..####..  ..#####.  ..####..  ..###...  ...##...  ...#....
              11037 ; .######.  ..#####.  ..####..  ..###...  ...##...
              11038 ; .######.  ..#####.  ..####..  .#####..
              11039 ; .######.  ..#.#.#.  .######.  ..#.#...
              11040 ; .#.##.#.  .#######  ..#..#..  ..#.#...
              11041 ; ########  .#######  ..#..#..  ..#.#...
              11042 ; ########  ..#...#.  ..#..#..
              11043 ; .#....#.  ..#...#.  ..#..#..
              11044 ; .#....#.  ..#...#.
              11045 ; .#....#.  ..#...#.
              11046 ; .#....#.  ..#...#.
              11047 ; .#....#.
              11048 ; .#....#.
              11049 ;
              11050 ; METEOR (shape type 6, data in shape table PLSHAP1TAB)
              11051 ; Numbers at top indicate the shape table offset of the first and last shape row
              11052 ;
              11053 ; $01..$10  $11..$1E  $1F..$2A  $2B..$34  $35..$3C  $3D..$42  $75..$76  $7A..$7B
              11054 ; ...##...  ...#....  ...##...  ...#....  ...#....  ...#....  ...##...  ...#....
              11055 ; ..####..  ..###...  ..####..  ..###...  ...##...  ..###...  ...##...  ...#....
              11056 ; .######.  .#####..  ..####..  ..###...  ..####..  ..###...
              11057 ; .######.  .#####..  .######.  .#####..  ..#.##..  ..#.#...
              11058 ; .###.##.  #######.  .##.###.  .###.#..  ..####..  ..###...
              11059 ; ####.###  ##.####.  .####.#.  .#####..  ..####..  ...#....
              11060 ; ##.#####  ##.##.#.  .######.  .##.##..  ...##...
              11061 ; ##.#####  #####.#.  .###.##.  ..###...  ....#...
              11062 ; ########  ###.###.  .######.  ..###...
              11063 ; ########  ###.###.  ..####..  ...#....
              11064 ; ####.###  .#####..  ..####..
              11065 ; .###.##.  .#####..  ...##...
              11066 ; .######.  ..###...
              11067 ; .######.  ...#....
              11068 ; ..####..
              11069 ; ...##...
              11070 ;
              11071 ; ZYLON CRUISER (shape type 7, data in shape table PLSHAP2TAB)
              11072 ; Numbers at top indicate the shape table offset of the first and last shape row
              11073 ;
              11074 ; $61..$69  $6A..$71  $72..$78  $79..$7E  $7F..$82  $83..$85  $29..$2A  $2B..$2C
              11075 ; ...##...  ...#....  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11076 ; ..####..  ..###...  ..####..  ..###...  ..####..  ..###...  ...##...  ...#....
              11077 ; .######.  .#####..  ..####..  ..###...  ..#..#..  ..#.#...
              11078 ; .######.  .#####..  .##..##.  .##.##..  ..#..#..
              11079 ; ##.##.##  ##.#.##.  .##..##.  .#...#..
              11080 ; ##....##  ##...##.  .#....#.  .#...#..
              11081 ; #......#  #.....#.  .#....#.
              11082 ; #......#  #.....#.
              11083 ; #......#
              11084 ;
              11085 ; ZYLON BASESTAR (shape type 8, data in shape table PLSHAP2TAB)
              11086 ; Numbers at top indicate the shape table offset of the first and last shape row
              11087 ;
              11088 ; $86..$8F  $90..$99  $9A..$A0  $A1..$A7  $A8..$AC  $AD..$B0  $29..$2A  $2B..$2C
              11089 ; ...##...  ...#....  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11090 ; ..####..  ..###...  ..####..  ..###...  ..####..  ..###...  ...##...  ...#....
              11091 ; .######.  .#####..  .######.  .#####..  ...##...  ..###...
              11092 ; ########  #######.  ...##...  ...#....  ..####..  ...#....
              11093 ; ...##...  ..###...  .######.  .#####..  ...##...
              11094 ; ...##...  ..###...  ..####..  ..###...
              11095 ; ########  #######.  ...##...  ...#....
              11096 ; .######.  .#####..
              11097 ; ..####..  ..###...
              11098 ; ...##...  ...#....
              11099 ;
              11100 ; HYPERWARP TARGET MARKER (shape type 9, data in shape table PLSHAP1TAB)
              11101 ; Numbers at top indicate the shape table offset of the first and last shape row
              11102 ;
              11103 ; $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $75..$76  $C1..$CC
              11104 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ...##...  ..#.#...
              11105 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ...##...  ..#.#...
              11106 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11107 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11108 ; ###.###.  ###.###.  ###.###.  ###.###.  ###.###.  ###.###.            ###.###.
              11109 ; ........  ........  ........  ........  ........  ........            ........
              11110 ; ........  ........  ........  ........  ........  ........            ........
              11111 ; ###.###.  ###.###.  ###.###.  ###.###.  ###.###.  ###.###.            ###.###.
              11112 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11113 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11114 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11115 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11116
              11117 ;*** Shape type 0..9 offset table (10 shape cell offsets of shape type...) *****
BE2F 01111F2B 11118 PLSHAPOFFTAB    .BYTE $01,$11,$1F,$2B,$35,$3D,$75,$7A ; ...0 into PLSHAP1TAB
BE33 353D757A
BE37 010D151B 11119                 .BYTE $01,$0D,$15,$1B,$21,$25,$29,$2B ; ...1 into PLSHAP2TAB
BE3B 2125292B
BE3F 2D384136 11120                 .BYTE $2D,$38,$41,$36,$36,$00,$00,$00 ; ...2 into PLSHAP2TAB
BE43 36000000
BE47 7E8E9DAA 11121                 .BYTE $7E,$8E,$9D,$AA,$B4,$BC,$7B,$7A ; ...3 into PLSHAP1TAB
BE4B B4BC7B7A
BE4F 47525B50 11122                 .BYTE $47,$52,$5B,$50,$50,$00,$00,$00 ; ...4 into PLSHAP2TAB
BE53 50000000
BE57 4353616C 11123                 .BYTE $43,$53,$61,$6C,$75,$7A,$75,$7A ; ...5 into PLSHAP1TAB
BE5B 757A757A
BE5F 01111F2B 11124                 .BYTE $01,$11,$1F,$2B,$35,$3D,$75,$7A ; ...6 into PLSHAP1TAB
BE63 353D757A
BE67 616A7279 11125                 .BYTE $61,$6A,$72,$79,$7F,$83,$29,$2B ; ...7 into PLSHAP2TAB
BE6B 7F83292B
BE6F 86909AA1 11126                 .BYTE $86,$90,$9A,$A1,$A8,$AD,$29,$2B ; ...8 into PLSHAP2TAB
BE73 A8AD292B
BE77 C1C1C1C1 11127                 .BYTE $C1,$C1,$C1,$C1,$C1,$C1,$75,$C1 ; ...9 into PLSHAP1TAB
BE7B C1C175C1
              11128
              11129 ;*** Shape type 0..9 height table (10 shape cell heights of shape type...) *****
BE7F 0F0D0B09 11130 PLSHPHEIGHTTAB  .BYTE $0F,$0D,$0B,$09,$07,$05,$01,$01 ; ...0
BE83 07050101
BE87 0B070505 11131                 .BYTE $0B,$07,$05,$05,$03,$03,$01,$01 ; ...1
BE8B 03030101
BE8F 09080502 11132                 .BYTE $09,$08,$05,$02,$00,$00,$00,$00 ; ...2
BE93 00000000
BE97 0F0E0C09 11133                 .BYTE $0F,$0E,$0C,$09,$07,$04,$02,$01 ; ...3
BE9B 07040201
BE9F 09080502 11134                 .BYTE $09,$08,$05,$02,$00,$00,$00,$00 ; ...4
BEA3 00000000
BEA7 0F0D0A08 11135                 .BYTE $0F,$0D,$0A,$08,$04,$03,$01,$01 ; ...5
BEAB 04030101
BEAF 0F0D0B09 11136                 .BYTE $0F,$0D,$0B,$09,$07,$05,$01,$01 ; ...6
BEB3 07050101
BEB7 08070605 11137                 .BYTE $08,$07,$06,$05,$03,$02,$01,$01 ; ...7
BEBB 03020101
BEBF 09090606 11138                 .BYTE $09,$09,$06,$06,$04,$03,$01,$01 ; ...8
BEC3 04030101
BEC7 0B0B0B0B 11139                 .BYTE $0B,$0B,$0B,$0B,$0B,$0B,$01,$0B ; ...9
BECB 0B0B010B
              11140
              11141 ;*** Keyboard codes to switch to Front or Aft view when Tracking Computer is on
BECF F8       11142 TRACKKEYSTAB    .BYTE $F8                             ; 'F' - Front view
BED0 FF       11143                 .BYTE $FF                             ; 'A' - Aft view
              11144
              11145 ;*** Galactic Chart sector character codes (encoded in custom character set) ***
BED1 0C       11146 SECTORCHARTAB   .BYTE CCS.BORDERSW                    ; Empty sector
BED2 1E       11147                 .BYTE CCS.2ZYLONS                     ; Sector contains 1 Zylon ship
BED3 1E       11148                 .BYTE CCS.2ZYLONS                     ; Sector contains 2 Zylon ships
BED4 1D       11149                 .BYTE CCS.3ZYLONS                     ; Sector contains 3 Zylon ships
BED5 1C       11150                 .BYTE CCS.4ZYLONS                     ; Sector contains 4 Zylon ships
BED6 1B       11151                 .BYTE CCS.STARBASE                    ; Sector contains starbase
              11152
              11153 ;*** Mask to limit veer-off velocity of Hyperwarp Target Marker in hyperwarp ***
BED7 9F       11154 VEERMASKTAB     .BYTE NEG!31                          ;  -31..+31  <KM/H> (unused)
BED8 BF       11155                 .BYTE NEG!63                          ;  -63..+63  <KM/H> PILOT mission
BED9 DF       11156                 .BYTE NEG!95                          ;  -95..+95  <KM/H> WARRIOR mission
BEDA FF       11157                 .BYTE NEG!127                         ; -127..+127 <KM/H> COMMANDER mission
              11158
              11159 ;*** Horizontal PLAYER offsets for PLAYER0..1 (STARBASE LEFT, STARBASE RIGHT) **
BEDB F8       11160 PLSTARBAOFFTAB  .BYTE -8                              ; -8 Player/Missile pixels
BEDC 08       11161                 .BYTE 8                               ; +8 Player/Missile pixels
              11162
              11163 ;*** Mission bonus table *******************************************************
BEDD 50       11164 BONUSTAB        .BYTE 80                              ; Mission complete   NOVICE mission
BEDE 4C       11165                 .BYTE 76                              ; Mission complete   PILOT mission
BEDF 3C       11166                 .BYTE 60                              ; Mission complete   WARRIOR mission
BEE0 6F       11167                 .BYTE 111                             ; Mission complete   COMMANDER mission
              11168
BEE1 3C       11169                 .BYTE 60                              ; Mission aborted    NOVICE mission
BEE2 3C       11170                 .BYTE 60                              ; Mission aborted    PILOT mission
BEE3 32       11171                 .BYTE 50                              ; Mission aborted    WARRIOR mission
BEE4 64       11172                 .BYTE 100                             ; Mission aborted    COMMANDER mission
              11173
BEE5 28       11174                 .BYTE 40                              ; Starship destroyed NOVICE mission
BEE6 32       11175                 .BYTE 50                              ; Starship destroyed PILOT mission
BEE7 28       11176                 .BYTE 40                              ; Starship destroyed WARRIOR mission
BEE8 5A       11177                 .BYTE 90                              ; Starship destroyed COMMANDER mission
              11178
              11179 ;*** Title phrase offsets of scored class rank *********************************
BEE9 A9       11180 RANKTAB         .BYTE $29!EOS                         ; "GALACTIC COOK"
BEEA AA       11181                 .BYTE $2A!EOS                         ; "GARBAGE SCOW CAPTAIN"
BEEB AA       11182                 .BYTE $2A!EOS                         ; "GARBAGE SCOW CAPTAIN"
BEEC AB       11183                 .BYTE $2B!EOS                         ; "ROOKIE"
BEED AB       11184                 .BYTE $2B!EOS                         ; "ROOKIE"
BEEE AC       11185                 .BYTE $2C!EOS                         ; "NOVICE"
BEEF AC       11186                 .BYTE $2C!EOS                         ; "NOVICE"
BEF0 AD       11187                 .BYTE $2D!EOS                         ; "ENSIGN"
BEF1 AD       11188                 .BYTE $2D!EOS                         ; "ENSIGN"
BEF2 AE       11189                 .BYTE $2E!EOS                         ; "PILOT"
BEF3 AE       11190                 .BYTE $2E!EOS                         ; "PILOT"
BEF4 AF       11191                 .BYTE $2F!EOS                         ; "ACE"
BEF5 B0       11192                 .BYTE $30!EOS                         ; "LIEUTENANT"
BEF6 B1       11193                 .BYTE $31!EOS                         ; "WARRIOR"
BEF7 B2       11194                 .BYTE $32!EOS                         ; "CAPTAIN"
BEF8 B3       11195                 .BYTE $33!EOS                         ; "COMMANDER"
BEF9 B3       11196                 .BYTE $33!EOS                         ; "COMMANDER"
BEFA B9       11197                 .BYTE $39!EOS                         ; "STAR COMMANDER"
BEFB B9       11198                 .BYTE $39!EOS                         ; "STAR COMMANDER"
              11199
              11200 ;*** Scored class number table *************************************************
BEFC 95       11201 CLASSTAB        .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFD 95       11202                 .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFE 95       11203                 .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFF 94       11204                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF00 94       11205                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF01 94       11206                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF02 94       11207                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF03 93       11208                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF04 93       11209                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF05 93       11210                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF06 92       11211                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF07 92       11212                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF08 92       11213                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF09 91       11214                 .BYTE CCS.COL2!ROM.1                  ; Class 1
BF0A 91       11215                 .BYTE CCS.COL2!ROM.1                  ; Class 1
BF0B 91       11216                 .BYTE CCS.COL2!ROM.1                  ; Class 1
              11217
              11218 ;*** Title phrase offsets of mission level *************************************
BF0C 4A       11219 MISSIONPHRTAB   .BYTE $4A                             ; "NOVICE MISSION"
BF0D 4C       11220                 .BYTE $4C                             ; "PILOT MISSION"
BF0E 4E       11221                 .BYTE $4E                             ; "WARRIOR MISSION"
BF0F 50       11222                 .BYTE $50                             ; "COMMANDER MISSION"
              11223
              11224 ;*** Damage probability of subsystems depending on mission level ***************
BF10 00       11225 DAMAGEPROBTAB   .BYTE 0                               ;  0% (  0:256) NOVICE mission
BF11 50       11226                 .BYTE 80                              ; 31% ( 80:256) PILOT mission
BF12 B4       11227                 .BYTE 180                             ; 70% (180:256) WARRIOR mission
BF13 FE       11228                 .BYTE 254                             ; 99% (254:256) COMMANDER mission
              11229
              11230 ;*** Title phrase offsets of damaged subsystems ********************************
BF14 55       11231 DAMAGEPHRTAB    .BYTE $55                             ; "PHOTON TORPEDOS DAMAGED"
BF15 5B       11232                 .BYTE $5B                             ; "ENGINES DAMAGED"
BF16 61       11233                 .BYTE $61                             ; "SHIELDS DAMAGED"
BF17 67       11234                 .BYTE $67                             ; "COMPUTER DAMAGED"
BF18 6D       11235                 .BYTE $6D                             ; "LONG RANGE SCAN DAMAGED"
BF19 71       11236                 .BYTE $71                             ; "SUB-SPACE RADIO DAMAGED"
              11237
              11238 ;*** Title phrase offsets of destroyed subsystems ******************************
BF1A 58       11239 DESTROYPHRTAB   .BYTE $58                             ; "PHOTON TORPEDOS DESTROYED"
BF1B 5E       11240                 .BYTE $5E                             ; "ENGINES DESTROYED"
BF1C 64       11241                 .BYTE $64                             ; "SHIELDS DESTROYED"
BF1D 6A       11242                 .BYTE $6A                             ; "COMPUTER DESTROYED"
BF1E 6F       11243                 .BYTE $6F                             ; "LONG RANGE SCAN DESTROYED"
BF1F 73       11244                 .BYTE $73                             ; "SUB-SPACE RADIO DESTROYED"
              11245
              11246 ;*** 3 x 10-byte noise sound patterns (bytes 0..7 stored in reverse order) *****
              11247 ;
              11248 ; (9) AUDCTL        ($D208) POKEY: Audio control
              11249 ; (8) AUDF3         ($D204) POKEY: Audio channel 3 frequency
              11250 ; (7) NOISETORPTIM  ($DA)   Timer for PHOTON TORPEDO LAUNCHED noise sound patterns
              11251 ; (6) NOISEEXPLTIM  ($DB)   Timer for SHIELD and ZYLON EXPLOSION noise sound patterns
              11252 ; (5) NOISEAUDC2    ($DC)   Audio channel 1/2 control shadow register
              11253 ; (4) NOISEAUDC3    ($DD)   Audio channel 3   control shadow register
              11254 ; (3) NOISEAUDF1    ($DE)   Audio channel 1 frequency shadow register
              11255 ; (2) NOISEAUDF2    ($DF)   Audio channel 2 frequency shadow register
              11256 ; (1) NOISEFRQINC   ($E0)   Audio channel 1/2 frequency increment
              11257 ; (0) NOISELIFE     ($E1)   Noise sound pattern lifetime
              11258 ;
              11259 ;                     (0),(1),(2),(3),(4),(5),(6),(7),(8),(9)
BF20 18FF0200 11260 NOISEPATTAB     .BYTE $18,$FF,$02,$00,$8A,$A0,$00,$08,$50,$00; PHOTON TORPEDO LAUNCHED
BF24 8AA00008
BF28 5000
BF2A 40400103 11261                 .BYTE $40,$40,$01,$03,$88,$AF,$08,$00,$50,$04; SHIELD EXPLOSION
BF2E 88AF0800
BF32 5004
BF34 30400103 11262                 .BYTE $30,$40,$01,$03,$84,$A8,$04,$00,$50,$04; ZYLON EXPLOSION
BF38 84A80400
BF3C 5004
              11263
              11264 ;*** 5 x 6-byte beeper sound patterns (bytes 0..5 stored in reverse order) *****
              11265 ;
              11266 ; (5) BEEPFRQIND    ($D2) Running index into frequency table BEEPFRQTAB ($BF5C)
              11267 ; (4) BEEPREPEAT    ($D3) Number of times the beeper sound pattern sequence is repeated - 1
              11268 ; (3) BEEPTONELIFE  ($D4) Lifetime of tone in TICKs - 1
              11269 ; (2) BEEPPAUSELIFE ($D5) Lifetime of pause in TICKs - 1 ($FF -> No pause)
              11270 ; (1) BEEPPRIORITY  ($D6) Beeper sound pattern priority. A playing beeper sound pattern is
              11271 ;                         stopped if a beeper sound pattern of higher priority is about to be
              11272 ;                         played. A value of 0 indicates that no beeper sound pattern is
              11273 ;                         playing at the moment.
              11274 ; (0) BEEPFRQSTART  ($D7) Index to first byte of the beeper sound pattern frequency in table
              11275 ;                         BEEPFRQTAB ($BF5C)
              11276 ;
              11277 ; Frequency-over-TICKs diagrams for all beeper sound patterns:
              11278 ;
              11279 ; HYPERWARP TRANSIT
              11280 ;
              11281 ;      FRQ
              11282 ;       |
              11283 ;   $18 |-4--
              11284 ;       |
              11285 ;   $00 |    -3-
              11286 ;       +-------> TICKS
              11287 ;        <13 x >
              11288 ;
              11289 ; RED ALERT
              11290 ;
              11291 ;      FRQ
              11292 ;       |
              11293 ;   $60 |                 --------17-------
              11294 ;       |
              11295 ;   $40 |--------17-------
              11296 ;       |
              11297 ;       +----------------------------------> TICKS
              11298 ;        <-------------- 8 x ------------->
              11299 ;
              11300 ; ACKNOWLEDGE
              11301 ;
              11302 ;      FRQ
              11303 ;       |
              11304 ;   $10 |-3-   -3-   -3-
              11305 ;       |
              11306 ;   $00 |   -3-   -3-   -3-
              11307 ;       +------------------> TICKS
              11308 ;        <------ 1 x ----->
              11309 ;
              11310 ; DAMAGE REPORT (not to scale)
              11311 ;
              11312 ;      FRQ
              11313 ;       |
              11314 ;   $40 |------------33-------------
              11315 ;       |
              11316 ;   $20 |                           ------------33-------------
              11317 ;       |
              11318 ;       +------------------------------------------------------> TICKS
              11319 ;        <------------------------ 3 x ----------------------->
              11320 ;
              11321 ; MESSAGE FROM STARBASE (not to scale)
              11322 ;
              11323 ;      FRQ
              11324 ;       |
              11325 ;   $51 |                                  -----33-----
              11326 ;   $48 |-----33-----
              11327 ;   $40 |                 -----33-----
              11328 ;       |
              11329 ;   $00 |            --9--            --9--            --9--
              11330 ;       +----------------------------------------------------> TICKS
              11331 ;        <---------------------- 1 x ---------------------->
              11332 ;
              11333 ;                     (0),(1),(2),(3),(4),(5)
BF3E 02020203 11334 BEEPPATTAB      .BYTE $02,$02,$02,$03,$0C,$02         ; HYPERWARP TRANSIT
BF42 0C02
BF44 0403FF10 11335                 .BYTE $04,$03,$FF,$10,$07,$04         ; RED ALERT
BF48 0704
BF4A 07040202 11336                 .BYTE $07,$04,$02,$02,$00,$07         ; ACKNOWLEDGE
BF4E 0007
BF50 0B05FF20 11337                 .BYTE $0B,$05,$FF,$20,$02,$0B         ; DAMAGE REPORT
BF54 020B
BF56 0E060820 11338                 .BYTE $0E,$06,$08,$20,$00,$0E         ; MESSAGE FROM STARBASE
BF5A 000E
              11339
              11340 ;*** Beeper sound pattern frequency table **************************************
BF5C 10FF     11341 BEEPFRQTAB      .BYTE $10,$FF                         ; (unused) (!)
BF5E 18FF     11342                 .BYTE $18,$FF                         ; HYPERWARP TRANSIT
BF60 4060FF   11343                 .BYTE $40,$60,$FF                     ; RED ALERT
BF63 101010FF 11344                 .BYTE $10,$10,$10,$FF                 ; ACKNOWLEDGE
BF67 4020FF   11345                 .BYTE $40,$20,$FF                     ; DAMAGE REPORT
BF6A 484051FF 11346                 .BYTE $48,$40,$51,$FF                 ; MESSAGE FROM STARBASE
              11347
              11348 ;*** Shape of blip in Attack Computer Display **********************************
BF6E 84       11349 BLIPSHAPTAB     .BYTE $84                             ; #....#..
BF6F B4       11350                 .BYTE $B4                             ; #.##.#..
BF70 FC       11351                 .BYTE $FC                             ; ######..
BF71 B4       11352                 .BYTE $B4                             ; #.##.#..
BF72 84       11353                 .BYTE $84                             ; #....#..
              11354
              11355 ;*** Initial x-coordinate (high byte) of our starship's photon torpedo *********
BF73 FF       11356 BARRELXTAB      .BYTE $FF                             ; Left barrel  = -256 (-$FF00) <KM>
BF74 01       11357                 .BYTE $01                             ; Right barrel = +256 (+$0100) <KM>
              11358
              11359 ;*** Maximum photon torpedo hit z-coordinate (high byte) ***********************
BF75 0C       11360 HITMAXZTAB      .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF76 0C       11361                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF77 0C       11362                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF78 0C       11363                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF79 0E       11364                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7A 0E       11365                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7B 0E       11366                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7C 20       11367                 .BYTE $20                             ; < 8448 ($20**) <KM>
              11368
              11369 ;*** Minimum photon torpedo hit z-coordinate (high byte) ***********************
BF7D 00       11370 HITMINZTAB      .BYTE $00                             ; >=    0 ($00**) <KM>
BF7E 00       11371                 .BYTE $00                             ; >=    0 ($00**) <KM>
BF7F 00       11372                 .BYTE $00                             ; >=    0 ($00**) <KM>
BF80 02       11373                 .BYTE $02                             ; >=  512 ($02**) <KM>
BF81 04       11374                 .BYTE $04                             ; >= 1024 ($04**) <KM>
BF82 06       11375                 .BYTE $06                             ; >= 1536 ($06**) <KM>
BF83 08       11376                 .BYTE $08                             ; >= 2048 ($08**) <KM>
BF84 0C       11377                 .BYTE $0C                             ; >= 3072 ($0C**) <KM>
              11378
              11379 ;*** Velocity of homing Zylon photon torpedo ***********************************
BF85 81       11380 ZYLONHOMVELTAB  .BYTE NEG!1                           ;  -1 <KM/H> NOVICE mission
BF86 84       11381                 .BYTE NEG!4                           ;  -4 <KM/H> PILOT mission
BF87 88       11382                 .BYTE NEG!8                           ;  -8 <KM/H> WARRIOR mission
BF88 94       11383                 .BYTE NEG!20                          ; -20 <KM/H> COMMANDER mission
              11384
              11385 ;*** Zylon shape type table ****************************************************
BF89 80       11386 ZYLONSHAPTAB    .BYTE SHAP.ZBASESTAR                  ; ZYLON BASESTAR
BF8A 10       11387                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8B 10       11388                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8C 10       11389                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8D 70       11390                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF8E 70       11391                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF8F 70       11392                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF90 10       11393                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
              11394
              11395 ;*** Zylon flight pattern table ************************************************
BF91 04       11396 ZYLONFLPATTAB   .BYTE 4                               ; Flight pattern 4
BF92 04       11397                 .BYTE 4                               ; Flight pattern 4
BF93 00       11398                 .BYTE 0                               ; Attack Flight Pattern 0
BF94 00       11399                 .BYTE 0                               ; Attack Flight Pattern 0
BF95 00       11400                 .BYTE 0                               ; Attack Flight Pattern 0
BF96 01       11401                 .BYTE 1                               ; Flight pattern 1
BF97 00       11402                 .BYTE 0                               ; Attack Flight Pattern 0
BF98 00       11403                 .BYTE 0                               ; Attack Flight Pattern 0
              11404
              11405 ;*** Zylon velocity table ******************************************************
BF99 3E       11406 ZYLONVELTAB     .BYTE 62                              ; +62 <KM/H>
BF9A 1E       11407                 .BYTE 30                              ; +30 <KM/H>
BF9B 10       11408                 .BYTE 16                              ; +16 <KM/H>
BF9C 08       11409                 .BYTE 8                               ;  +8 <KM/H>
BF9D 04       11410                 .BYTE 4                               ;  +4 <KM/H>
BF9E 02       11411                 .BYTE 2                               ;  +2 <KM/H>
BF9F 01       11412                 .BYTE 1                               ;  +1 <KM/H>
BFA0 00       11413                 .BYTE 0                               ;   0 <KM/H>
BFA1 00       11414                 .BYTE 0                               ;   0 <KM/H>
BFA2 81       11415                 .BYTE NEG!1                           ;  -1 <KM/H>
BFA3 82       11416                 .BYTE NEG!2                           ;  -2 <KM/H>
BFA4 84       11417                 .BYTE NEG!4                           ;  -4 <KM/H>
BFA5 88       11418                 .BYTE NEG!8                           ;  -8 <KM/H>
BFA6 90       11419                 .BYTE NEG!16                          ; -16 <KM/H>
BFA7 9E       11420                 .BYTE NEG!30                          ; -30 <KM/H>
BFA8 BE       11421                 .BYTE NEG!62                          ; -62 <KM/H>
              11422
              11423 ;*** PLAYFIELD colors (including PLAYFIELD colors during DLI) ******************
BFA9 A6       11424 PFCOLORTAB      .BYTE $A6                             ; PF0COLOR    = {GREEN}
BFAA AA       11425                 .BYTE $AA                             ; PF1COLOR    = {LIGHT GREEN}
BFAB AF       11426                 .BYTE $AF                             ; PF2COLOR    = {VERY LIGHT GREEN}
BFAC 00       11427                 .BYTE $00                             ; PF3COLOR    = {BLACK}
BFAD 00       11428                 .BYTE $00                             ; BGRCOLOR    = {BLACK}
BFAE B8       11429                 .BYTE $B8                             ; PF0COLORDLI = {LIGHT MINT}
BFAF 5A       11430                 .BYTE $5A                             ; PF1COLORDLI = {MEDIUM PINK}
BFB0 FC       11431                 .BYTE $FC                             ; PF2COLORDLI = {LIGHT ORANGE}
BFB1 5E       11432                 .BYTE $5E                             ; PF3COLORDLI = {LIGHT PINK}
BFB2 90       11433                 .BYTE $90                             ; BGRCOLORDLI = {DARK BLUE}
              11434
              11435 ;*** Vicinity mask table. Confines coordinates of space objects in sector ******
BFB3 FF       11436 VICINITYMASKTAB .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFB4 FF       11437                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFB5 3F       11438                 .BYTE $3F                             ; <= 16383 ($3F**) <KM>
BFB6 0F       11439                 .BYTE $0F                             ; <=  4095 ($0F**) <KM>
BFB7 3F       11440                 .BYTE $3F                             ; <= 16383 ($3F**) <KM>
BFB8 7F       11441                 .BYTE $7F                             ; <= 32767 ($7F**) <KM>
BFB9 FF       11442                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFBA FF       11443                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
              11444
              11445 ;*** Movement probability of sector types in Galactic Chart ********************
BFBB 00       11446 MOVEPROBTAB     .BYTE 0                               ; Empty sector    0% (  0:256)
BFBC FF       11447                 .BYTE 255                             ; 1 Zylon ship  100% (255:256)
BFBD FF       11448                 .BYTE 255                             ; 2 Zylon ships 100% (255:256)
BFBE C0       11449                 .BYTE 192                             ; 3 Zylon ships  75% (192:256)
BFBF 20       11450                 .BYTE 32                              ; 4 Zylon ships  13% ( 32:256)
              11451
              11452 ;*** Galactic Chart sector offset to adjacent sector ***************************
BFC0 F0       11453 COMPASSOFFTAB   .BYTE -16                             ; NORTH
BFC1 EF       11454                 .BYTE -17                             ; NORTHWEST
BFC2 FF       11455                 .BYTE -1                              ; WEST
BFC3 0F       11456                 .BYTE 15                              ; SOUTHWEST
BFC4 10       11457                 .BYTE 16                              ; SOUTH
BFC5 11       11458                 .BYTE 17                              ; SOUTHEAST
BFC6 01       11459                 .BYTE 1                               ; EAST
BFC7 F1       11460                 .BYTE -15                             ; NORTHEAST
BFC8 00       11461                 .BYTE 0                               ; CENTER
              11462
              11463 ;*** Homing velocities of photon torpedoes 0..1 depending on distance to target
BFC9 00       11464 HOMVELTAB       .BYTE 0                               ;  +0 <KM/H>
BFCA 08       11465                 .BYTE 8                               ;  +8 <KM/H>
BFCB 10       11466                 .BYTE 16                              ; +16 <KM/H>
BFCC 18       11467                 .BYTE 24                              ; +24 <KM/H>
BFCD 28       11468                 .BYTE 40                              ; +40 <KM/H>
BFCE 30       11469                 .BYTE 48                              ; +48 <KM/H>
BFCF 38       11470                 .BYTE 56                              ; +56 <KM/H>
BFD0 40       11471                 .BYTE 64                              ; +64 <KM/H>
              11472
              11473 ;*** PLAYER shape color table (bits B7..4 of color/brightness) *****************
BFD1 50       11474 PLSHAPCOLORTAB  .BYTE $50                             ; PHOTON TORPEDO          = {PURPLE}
BFD2 00       11475                 .BYTE $00                             ; ZYLON FIGHTER           = {GRAY}
BFD3 20       11476                 .BYTE $20                             ; STARBASE RIGHT          = {ORANGE}
BFD4 20       11477                 .BYTE $20                             ; STARBASE CENTER         = {ORANGE}
BFD5 20       11478                 .BYTE $20                             ; STARBASE LEFT           = {ORANGE}
BFD6 00       11479                 .BYTE $00                             ; TRANSFER VESSEL         = {GRAY}
BFD7 A0       11480                 .BYTE $A0                             ; METEOR                  = {GREEN}
BFD8 00       11481                 .BYTE $00                             ; ZYLON CRUISER           = {GRAY}
BFD9 00       11482                 .BYTE $00                             ; ZYLON BASESTAR          = {GRAY}
BFDA 9F       11483                 .BYTE $9F                             ; HYPERWARP TARGET MARKER = {SKY BLUE}
              11484
              11485 ;*** PLAYER shape brightness table (bits B3..0 of color/brightness) ************
BFDB 0E       11486 PLSHAPBRITTAB   .BYTE $0E                             ; ##############..
BFDC 0E       11487                 .BYTE $0E                             ; ##############..
BFDD 0E       11488                 .BYTE $0E                             ; ##############..
BFDE 0C       11489                 .BYTE $0C                             ; ############....
BFDF 0C       11490                 .BYTE $0C                             ; ############....
BFE0 0C       11491                 .BYTE $0C                             ; ############....
BFE1 0A       11492                 .BYTE $0A                             ; ##########......
BFE2 0A       11493                 .BYTE $0A                             ; ##########......
BFE3 0A       11494                 .BYTE $0A                             ; ##########......
BFE4 08       11495                 .BYTE $08                             ; ########........
BFE5 08       11496                 .BYTE $08                             ; ########........
BFE6 08       11497                 .BYTE $08                             ; ########........
BFE7 06       11498                 .BYTE $06                             ; ######..........
BFE8 06       11499                 .BYTE $06                             ; ######..........
BFE9 04       11500                 .BYTE $04                             ; ####............
BFEA 04       11501                 .BYTE $04                             ; ####............
              11502
              11503 ;*** PHOTON TORPEDO LAUNCHED noise bit and volume (stored in reverse order) ****
BFEB 8A       11504 NOISETORPVOLTAB .BYTE $8A                             ; ##########.....
BFEC 8F       11505                 .BYTE $8F                             ; ###############
BFED 8D       11506                 .BYTE $8D                             ; #############..
BFEE 8B       11507                 .BYTE $8B                             ; ###########....
BFEF 89       11508                 .BYTE $89                             ; #########......
BFF0 87       11509                 .BYTE $87                             ; #######........
BFF1 85       11510                 .BYTE $85                             ; ######.........
BFF2 83       11511                 .BYTE $83                             ; ###............
              11512
              11513 ;*** PHOTON TORPEDO LAUNCHED noise frequency table (stored in reverse order) ***
BFF3 00       11514 NOISETORPFRQTAB .BYTE $00                             ;
BFF4 04       11515                 .BYTE $04                             ;
BFF5 01       11516                 .BYTE $01                             ;
BFF6 04       11517                 .BYTE $04                             ;
BFF7 01       11518                 .BYTE $01                             ;
BFF8 04       11519                 .BYTE $04                             ;
BFF9 01       11520                 .BYTE $01                             ;
BFFA 04       11521                 .BYTE $04                             ;
              11522
BFFB 07       11523                 .BYTE $07                             ; (unused)
              11524
BFFC 00       11525                 .BYTE $00                             ; Always 0 for cartridges
BFFD 80       11526                 .BYTE $80                             ; On SYSTEM RESET jump to INITCOLD via
BFFE 4AA1     11527                 .WORD INITCOLD                        ; Cartridge Initialization Address

SYMBOLS (SORTED BY NAME): 898

 A980  ABORTWARP
 A109  AFTHEADER
=0092  ARRVSECTOR
=D203  AUDC2
=D205  AUDC3
=D207  AUDC4
=D208  AUDCTL
=D200  AUDF1
=D202  AUDF2
=D204  AUDF3
=D206  AUDF4
=0087  BARRELNR
 BF73  BARRELXTAB
 B3A6  BEEP
=00D2  BEEPFRQIND
=00D7  BEEPFRQSTART
 BF5C  BEEPFRQTAB
=00D8  BEEPLIFE
 BF3E  BEEPPATTAB
=00D5  BEEPPAUSELIFE
=00D6  BEEPPRIORITY
=00D3  BEEPREPEAT
=00D9  BEEPTOGGLE
=00D4  BEEPTONELIFE
=00F6  BGRCOLOR
=00FB  BGRCOLORDLI
=00A0  BLIPCOLUMN
=00A2  BLIPCYCLECNT
=00A1  BLIPROW
 BF6E  BLIPSHAPTAB
 BEDD  BONUSTAB
 B1A7  CALCWARP
=0000  CCS.0
=0001 ?CCS.1
=0002 ?CCS.2
=001E  CCS.2ZYLONS
=0003 ?CCS.3
=001D  CCS.3ZYLONS
=0004 ?CCS.4
=001C  CCS.4ZYLONS
=0005 ?CCS.5
=0006 ?CCS.6
=0007 ?CCS.7
=0008 ?CCS.8
=0009  CCS.9
=0018  CCS.BORDERS
=000C  CCS.BORDERSW
=0019  CCS.BORDERW
=0017 ?CCS.C
=0040  CCS.COL1
=0080  CCS.COL2
=00C0  CCS.COL3
=000B  CCS.COLON
=001A  CCS.CORNERSW
=000D  CCS.E
=000E  CCS.INF
=0015  CCS.K
=000F  CCS.MINUS
=0011  CCS.PHI
=0010  CCS.PLUS
=0013  CCS.R
=000A  CCS.SPC
=001B  CCS.STARBASE
=0016  CCS.T
=0014  CCS.THETA
=0012  CCS.V
 A000  CHARSET
=D409  CHBASE
 BEFC  CLASSTAB
 A98D  CLEANUPWARP
=0074  CLOCKTIM
 AE0F  CLRMEM
 AE0D  CLRPLAYFIELD
 AF3D  COLLISION
=D016  COLPF0
=D012  COLPM0
 BFC0  COMPASSOFFTAB
=D01F  CONSOL
 ACAF  COPYPOSVEC
 ACC1  COPYPOSXY
=0076  COUNT256
=0072  COUNT8
=00A7  CTRLDZYLON
=0090  CURRSECTOR
 AEE1  DAMAGE
 BF14  DAMAGEPHRTAB
 BF10  DAMAGEPROBTAB
 B86F  DECENERGY
 BF1A  DESTROYPHRTAB
=00A4  DIRLEN
=006A  DIVIDEND
=D402  DLIST
 BA62  DLSTFRAG
 BA75  DLSTFRAGAFT
 BA7D  DLSTFRAGFRONT
 BA6A  DLSTFRAGGC
 BA6D  DLSTFRAGLRS
 BA8C  DLSTFRAGOFFTAB
 A12E  DLSTGC
 A718  DLSTHNDLR
=D400  DMACTL
 ACE6  DOCKING
=0075  DOCKSTATE
=0080  DOWN
=007E  DRAINATTCOMP
=0080  DRAINENGINES
 BAD3  DRAINRATETAB
=007D  DRAINSHIELDS
 B4B9  DRAWGC
 A782  DRAWLINE
 A784  DRAWLINE2
 A76F  DRAWLINES
 BAF9  DRAWLINESTAB
=0280  DSPLST
 A987  ENDWARP
=007F  ENERGYCNT
=0955  ENERGYD1
=0040  EOP
=0080  EOS
=0080  EOW
=0073  EXPLLIFE
=0063  FKEYCODE
 B4E4  FLUSHGAMELOOP
 BA90  FOURCOLORPIXEL
 A1F3  GAMELOOP
 B10A  GAMEOVER
 B121  GAMEOVER2
 A11A  GCHEADER
=08C9  GCMEMMAP
=0D35  GCPFMEM
=09A3  GCSTARDAT
=0995  GCSTATCOM
=0993  GCSTATENG
=0996  GCSTATLRS
=0992  GCSTATPHO
=0997  GCSTATRAD
=0994  GCSTATSHL
=098D  GCTRGCNT
=0971  GCTXT
=097D  GCWARPD1
=D01D  GRACTL
=008A  HITBADNESS
=D01E  HITCLR
 BF75  HITMAXZTAB
 BF7D  HITMINZTAB
 AECA  HOMINGVEL
 BFC9  HOMVELTAB
=D004  HPOSM0
=D005  HPOSM1
=D006  HPOSM2
=D007  HPOSM3
=D000  HPOSP0
=D001  HPOSP1
=D002  HPOSP2
=D003  HPOSP3
=0094  HUNTSECTCOLUMN
=0093  HUNTSECTOR
=0095  HUNTSECTROW
=009F  HUNTTIM
 A89B  HYPERWARP
=0066  IDLECNTHI
=0077  IDLECNTLO
 A14A  INITCOLD
 A15C  INITDEMO
 AC6B  INITEXPL
 B3BA  INITIALIZE
 B764  INITPOSVEC
 A15A  INITSELECT
 A15E  INITSTART
 A9B4  INITTRAIL
=D20E  IRQEN
 A751  IRQHNDLR
=00B8  ISBACKATTACK0
=00B9 ?ISBACKATTACK1
=0064  ISDEMOMODE
=00A3  ISINLOCKON
=007B  ISSTARBASESECT
 B7F1  ISSURROUNDED
=007C  ISTRACKCOMPON
=0086  ISTRACKING
=0067  ISVBISYNC
=006D  JOYSTICKDELTA
=00C8  JOYSTICKX
=00C9  JOYSTICKY
 A47D  JUMP001
 A4A4  JUMP002
 A579  JUMP003
 A74B  JUMP004
=D209  KBCODE
 AFFE  KEYBOARD
=00CA  KEYCODE
 BABE  KEYTAB
=0950  KILLCNTD1
=006B  L.ABSDIFFCOL
=006B  L.BITPAT
=006B  L.COLORMASK
=006B  L.COLUMNPOS
=006A  L.CTRLDZYLON
=006A  L.DIFFC
=006A  L.DIRECTIONIND
=006E  L.DIRSAV
=0068  L.DIVISOR
=006A  L.FOURCOLORPIX
=006A  L.GCMEMMAPIND
=006A  L.HEIGHTCNT
=006A  L.ISDESTROYED
=006A  L.KEYCODE
=006E  L.LOOPCNT
=006B  L.LOOPCNT2
=006A  L.MAXRNDXY
=0068  L.MEMPTR1
=006A  L.MEMPTR2
=006A  L.NEWSECTOR
=006A  L.NUMBYTES
=006A  L.PIXELBYTEOFF
=006D  L.PIXELCOLUMN
=006D  L.PIXELROW
=006B  L.PLHIT
=006D  L.QUOTIENT
=0068  L.RANGE
=006A  L.RANGEINDEX
=006B  L.SECTORCNT
=006A  L.SECTORTYPE
=006C  L.SHIFTSHAPE
=006A  L.SIGNCHAR
=006B  L.TERM3HI
=006A  L.TERM3LO
=006C  L.TERM3SIGN
=006C  L.TOKEN
=006E  L.TRAILCNT
=006A  L.VECCOMPIND
=006B  L.VELOCITYHI
=006A  L.VELSIGN
=006C  L.VIEWDIR
=006A  L.WARPARRVCOL
=006A  L.WORD
=006E  L.ZPOSOFF
=0088  LOCKONLIFE
=00C0  LONG
 A165  LOOP001
 A201  LOOP002
 A227  LOOP003
 A26A  LOOP004
 A277  LOOP005
 A284  LOOP006
 A291  LOOP007
 A29E  LOOP008
 A2BA  LOOP009
 A2E0  LOOP010
 A306  LOOP011
 A327  LOOP012
 A343  LOOP013
 A389  LOOP014
 A3A6  LOOP015
 A3BD  LOOP016
 A3E4  LOOP017
 A3EB  LOOP018
 A422  LOOP019
 A428  LOOP020
 A453  LOOP021
 A4C0  LOOP022
 A4E7  LOOP023
 A4FC  LOOP024
 A593  LOOP025
 A6F6  LOOP026
 A730  LOOP027
 A765  LOOP028
 A78E  LOOP029
 A7CF  LOOP030
 A83A  LOOP031
 A83C  LOOP032
 A947  LOOP033
 A9E5  LOOP034
 AA52  LOOP035
 AAB5  LOOP036
 ABB3  LOOP037
 ABCA  LOOP038
 ABFC  LOOP039
 AC73  LOOP040
 ADCA  LOOP041
 ADD7  LOOP042
 ADF4  LOOP043
 ADFB  LOOP044
 AE1A  LOOP045
 AEB3  LOOP046
 AEE7  LOOP047
 AF3F  LOOP048
 AFD5  LOOP049
 AFEC  LOOP050
 B011  LOOP051
 B056  LOOP052
 B1FE  LOOP053
 B200  LOOP054
 B234  LOOP055
 B276  LOOP056
 B286  LOOP057
 B2C1  LOOP058
 B3AF  LOOP059
 B3BC  LOOP060
 B3EE  LOOP061
 B41B  LOOP062
 B441  LOOP063
 B44C  LOOP064
 B488  LOOP065
 B492  LOOP066
 B4BD  LOOP067
 B51C  LOOP068
 B54E  LOOP069
 B57C  LOOP070
 B5C1  LOOP071
 B5D1  LOOP072
 B5EA  LOOP073
 B5EF  LOOP074
 B601  LOOP075
 B632  LOOP076
 B662  LOOP077
 B664  LOOP078
 B896  LOOP079
 A0F8  LRSHEADER
=D008  M0PL
=D009  M1PL
=D00A  M2PL
=D00B  M3PL
 AA79  MANEUVER
=0DE9  MAPTO80
=0EE9  MAPTOBCD99
=0079  MAXSPCOBJIND
=0068  MEMPTR
=00AA  MILESTTIM0
=00AB ?MILESTTIM1
=00AE ?MILESTVELINDX0
=00AF ?MILESTVELINDX1
=00B0 ?MILESTVELINDY0
=00B1 ?MILESTVELINDY1
=00AC  MILESTVELINDZ0
=00AD ?MILESTVELINDZ1
=0062  MISSIONLEVEL
 BF0C  MISSIONPHRTAB
 ADF1  MODDLST
 BFBB  MOVEPROBTAB
 BE29  MSGBITTAB
 BE26  MSGOFFTAB
 BE2C  MSGONTAB
=0080  NEG
=0065  NEWTITLEPHR
=0071  NEWVELOCITY
=0096  NEWZYLONDIST
=D40E  NMIEN
 AEA8  NOISE
=00DC  NOISEAUDC2
=00DD  NOISEAUDC3
=00DE  NOISEAUDF1
=00DF  NOISEAUDF2
=00DB  NOISEEXPLTIM
=00E0  NOISEFRQINC
=00E3  NOISEHITLIFE
=00E1  NOISELIFE
 BF20  NOISEPATTAB
 BFF3  NOISETORPFRQTAB
=00DA  NOISETORPTIM
 BFEB  NOISETORPVOLTAB
=00E2  NOISEZYLONTIM
=0031  NUMSPCOBJ.ALL
=0011  NUMSPCOBJ.NORM
=0005  NUMSPCOBJ.PL
=000C  NUMSPCOBJ.STARS
=007A  OLDMAXSPCOBJIND
=0084  OLDTRIG0
=009E  OLDZYLONDIST
=D00F  P3PL
=D302  PACTL
=0949  PANELTXT
 BB42  PANELTXTTAB
=00A6  PENCOLUMN
=00A5  PENROW
=00F2  PF0COLOR
=00F7  PF0COLORDLI
=00F3 ?PF1COLOR
=00F8 ?PF1COLORDLI
=00F4  PF2COLOR
=00F9 ?PF2COLORDLI
=00F5 ?PF3COLOR
=00FA ?PF3COLORDLI
 BFA9  PFCOLORTAB
=1000  PFMEM
=1000  PFMEM.C0R0
=12A8  PFMEM.C0R17
=10C8  PFMEM.C0R5
=1B36  PFMEM.C120R71
=1BFE  PFMEM.C120R76
=1C9E  PFMEM.C120R80
=1D40  PFMEM.C128R84
=1D68  PFMEM.C128R85
=1D42  PFMEM.C136R84
=1D6A  PFMEM.C136R85
=1C04  PFMEM.C144R76
=1CA4  PFMEM.C144R80
=17BB  PFMEM.C76R49
=17E3  PFMEM.C76R50
=17BC  PFMEM.C80R49
=17E4  PFMEM.C80R50
=0864  PFMEMROWHI
=0800  PFMEMROWLO
=0966  PHIC1
 BBAA  PHRASETAB
=0CEE  PIXELBYTE
=0C8C  PIXELBYTEOFF
=0C2A  PIXELCOLUMN
 BAB0  PIXELMASKTAB
=0C5B  PIXELROW
=0BF9  PIXELROWNEW
=0CBD  PIXELSAVE
=00EE  PL0COLOR
=0C2A  PL0COLUMN
=0400  PL0DATA
=0CBD  PL0HEIGHT
=0CEE  PL0HEIGHTNEW
=00E9  PL0LIFE
=0C5B  PL0ROW
=0BF9  PL0ROWNEW
=00E4  PL0SHAPOFF
=0C8C  PL0SHAPTYPE
=0B97 ?PL0XVEL
=0BC8 ?PL0YVEL
=0A40  PL0ZPOSHI
=0B66 ?PL0ZVEL
=00EF ?PL1COLOR
=0C2B  PL1COLUMN
=0500  PL1DATA
=0CBE  PL1HEIGHT
=0CEF  PL1HEIGHTNEW
=00EA  PL1LIFE
=0C5C  PL1ROW
=0BFA  PL1ROWNEW
=00E5  PL1SHAPOFF
=0C8D  PL1SHAPTYPE
=0B98 ?PL1XVEL
=0BC9 ?PL1YVEL
=0B67 ?PL1ZVEL
=00F0 ?PL2COLOR
=0C2C  PL2COLUMN
=0600  PL2DATA
=0CBF  PL2HEIGHT
=0CF0  PL2HEIGHTNEW
=00EB  PL2LIFE
=0C5D  PL2ROW
=0BFB  PL2ROWNEW
=00E6  PL2SHAPOFF
=0C8E  PL2SHAPTYPE
=0A73  PL2XPOSHI
=0B06 ?PL2XPOSLO
=09E0 ?PL2XPOSSIGN
=0B99  PL2XVEL
=0AA4  PL2YPOSHI
=0B37 ?PL2YPOSLO
=0A11  PL2YPOSSIGN
=0BCA  PL2YVEL
=0A42  PL2ZPOSHI
=0AD5  PL2ZPOSLO
=09AF  PL2ZPOSSIGN
=0B68  PL2ZVEL
=00F1 ?PL3COLOR
=0C2D  PL3COLUMN
=0700  PL3DATA
=0CC0  PL3HEIGHT
=0CF1  PL3HEIGHTNEW
=0082  PL3HIT
=00EC  PL3LIFE
=0C5E  PL3ROW
=0BFC  PL3ROWNEW
=00E7  PL3SHAPOFF
=0C8F  PL3SHAPTYPE
=0A74  PL3XPOSHI
=0B07  PL3XPOSLO
=09E1  PL3XPOSSIGN
=0B9A  PL3XVEL
=0AA5  PL3YPOSHI
=0B38  PL3YPOSLO
=0A12  PL3YPOSSIGN
=0BCB  PL3YVEL
=0A43  PL3ZPOSHI
=0AD6  PL3ZPOSLO
=09B0  PL3ZPOSSIGN
=0B69  PL3ZVEL
=0C2E  PL4COLUMN
=0300  PL4DATA
=0CC1  PL4HEIGHT
=0CF2  PL4HEIGHTNEW
=0083  PL4HIT
=00ED  PL4LIFE
=0C5F  PL4ROW
=0BFD  PL4ROWNEW
=00E8  PL4SHAPOFF
=0C90  PL4SHAPTYPE
=0A75  PL4XPOSHI
=0B08 ?PL4XPOSLO
=09E2  PL4XPOSSIGN
=0B9B  PL4XVEL
=0AA6  PL4YPOSHI
=0B39 ?PL4YPOSLO
=0A13  PL4YPOSSIGN
=0BCC  PL4YVEL
=0A44  PL4ZPOSHI
=0AD7 ?PL4ZPOSLO
=09B1  PL4ZPOSSIGN
=0B6A  PL4ZVEL
 B8DF  PLCOLOROFFTAB
 B8E4  PLSHAP1TAB
 B9B1  PLSHAP2TAB
 BFDB  PLSHAPBRITTAB
 BFD1  PLSHAPCOLORTAB
 BE2F  PLSHAPOFFTAB
 BE7F  PLSHPHEIGHTTAB
 BEDB  PLSTARBAOFFTAB
=0089  PLTRACKED
=D407  PMBASE
=D300  PORTA
=D01B  PRIOR
 AA21  PROJECTION
=D20A  RANDOM
=096C  RANGEC1
 BEE9  RANKTAB
=008B  REDALERTLIFE
=0000  RIGHT
 B7BE  RNDINVXY
=0010  ROM.0
=0011  ROM.1
=0012  ROM.2
=0013  ROM.3
=0014  ROM.4
=0015  ROM.5
=0019  ROM.9
=0021  ROM.A
=0023  ROM.C
=001A  ROM.COLON
=0024  ROM.D
=000E  ROM.DOT
=0025  ROM.E
=0027  ROM.G
=002C  ROM.L
=002E  ROM.N
=0030  ROM.P
=0032  ROM.R
=0033  ROM.S
=0000  ROM.SPC
=0034  ROM.T
=0037  ROM.W
=0039  ROM.Y
=E000  ROMCHARSET
 B69B  ROTATE
=00CB  SCORE
=00CE  SCOREDCLASSIND
=00CD  SCOREDRANKIND
 B6FB  SCREENCOLUMN
 B71E  SCREENROW
 BED1  SECTORCHARTAB
 BBA6  SECTORTYPETAB
 B162  SELECTWARP
 B223  SETTITLE
 B045  SETVIEW
=0090  SHAP.HYPERWARP
=0060  SHAP.METEOR
=0030  SHAP.STARBASEC
=0020  SHAP.STARBASEL
=0040  SHAP.STARBASER
=0000 ?SHAP.TORPEDO
=0050  SHAP.TRANSVSSL
=0080  SHAP.ZBASESTAR
=0070  SHAP.ZCRUISER
=0010  SHAP.ZFIGHTER
=0081  SHIELDSCOLOR
=00D0  SHIPVIEW
 B8A7  SHOWCOORD
 B8CD  SHOWDIGITS
=D20F  SKCTL
 A172  SKIP001
 A21F  SKIP002
 A250  SKIP003
 A262  SKIP004
 A2C2  SKIP005
 A2E8  SKIP006
 A30E  SKIP007
 A39E  SKIP008
 A3BB  SKIP009
 A3C6  SKIP010
 A3DF  SKIP011
 A3EA  SKIP012
 A3FE  SKIP013
 A43C  SKIP014
 A43F  SKIP015
 A473  SKIP016
 A49A  SKIP017
 A4A7  SKIP018
 A4AD  SKIP019
 A4CA  SKIP020
 A4DB  SKIP021
 A4E5  SKIP022
 A4ED  SKIP023
 A503  SKIP024
 A52A  SKIP025
 A52E  SKIP026
 A53E  SKIP027
 A548  SKIP028
 A569  SKIP029
 A58D  SKIP030
 A5A3  SKIP031
 A5A5  SKIP032
 A5AB  SKIP033
 A5D0  SKIP034
 A600  SKIP035
 A60C  SKIP036
 A61B  SKIP037
 A635  SKIP038
 A687  SKIP039
 A69B  SKIP040
 A6B7  SKIP041
 A6C2  SKIP042
 A6E9  SKIP043
 A6EA  SKIP044
 A6F2  SKIP045
 A715  SKIP046
 A728  SKIP047
 A77A  SKIP048
 A781  SKIP049
 A7B8  SKIP050
 A7BA  SKIP051
 A7E1  SKIP052
 A7E9  SKIP053
 A7EC  SKIP054
 A804  SKIP055
 A80A  SKIP056
 A821  SKIP057
 A827  SKIP058
 A830  SKIP059
 A850  SKIP060
 A85F  SKIP061
 A898  SKIP062
 A8AC  SKIP063
 A8E8  SKIP064
 A8EC  SKIP065
 A900  SKIP066
 A901  SKIP067
 A915  SKIP068
 A91E  SKIP069
 A96F  SKIP070
 A97F  SKIP071
 A9A6  SKIP072
 AA1A  SKIP073
 AA20  SKIP074
 AA40  SKIP075
 AA66  SKIP076
 AA6F  SKIP077
 AA78  SKIP078
 AA90  SKIP079
 AAB3  SKIP080
 AAC8  SKIP081
 AACF  SKIP082
 AAD5  SKIP083
 AADD  SKIP084
 AAE0  SKIP085
 AAF4  SKIP086
 AB00  SKIP087
 AB03  SKIP088
 AB09  SKIP089
 AB11  SKIP090
 AB36  SKIP091
 AB37  SKIP092
 AB66  SKIP093
 AB84  SKIP094
 AB98  SKIP095
 AB9C  SKIP096
 ABAE  SKIP097
 ABBA  SKIP098
 ABC4  SKIP099
 ABDD  SKIP100
 ABE1  SKIP101
 ABE5  SKIP102
 ABE9  SKIP103
 ABEB  SKIP104
 ABFA  SKIP105
 AC08  SKIP106
 AC0A  SKIP107
 AC31  SKIP108
 AC32  SKIP109
 AC4F  SKIP110
 ACE5  SKIP111
 ACF3  SKIP112
 AD12  SKIP113
 AD26  SKIP114
 AD35  SKIP115
 AD61  SKIP116
 AD6C  SKIP117
 AD70  SKIP118
 AD71  SKIP119
 AD82  SKIP120
 ADB8  SKIP121
 ADB9  SKIP122
 AE03  SKIP123
 AE40  SKIP124
 AE41  SKIP125
 AE56  SKIP126
 AE58  SKIP127
 AE66  SKIP128
 AEB1  SKIP129
 AEC9  SKIP130
 AED2  SKIP131
 AEDA  SKIP132
 AF10  SKIP133
 AF19  SKIP134
 AF1E  SKIP135
 AF32  SKIP136
 AF3C  SKIP137
 AF43  SKIP138
 AF58  SKIP139
 AF64  SKIP140
 AF6F  SKIP141
 AF94  SKIP142
 AFC6  SKIP143
 AFE7  SKIP144
 AFF3  SKIP145
 AFFD  SKIP146
 B020  SKIP147
 B02B  SKIP148
 B036  SKIP149
 B040  SKIP150
 B041  SKIP151
 B060  SKIP152
 B073  SKIP153
 B082  SKIP154
 B096  SKIP155
 B099  SKIP156
 B0E6  SKIP157
 B0ED  SKIP158
 B0FB  SKIP159
 B0FC  SKIP160
 B106  SKIP161
 B14A  SKIP162
 B15A  SKIP163
 B15D  SKIP164
 B161  SKIP165
 B16A  SKIP166
 B16B  SKIP167
 B173  SKIP168
 B1BE  SKIP169
 B1C8  SKIP170
 B1D3  SKIP171
 B1E0  SKIP172
 B212  SKIP173
 B21E  SKIP174
 B21F  SKIP175
 B22E  SKIP176
 B23A  SKIP177
 B249  SKIP178
 B25F  SKIP179
 B268  SKIP180
 B27C  SKIP181
 B2A2  SKIP182
 B2A8  SKIP183
 B2E1  SKIP184
 B2E6  SKIP185
 B2F3  SKIP186
 B32B  SKIP187
 B337  SKIP188
 B349  SKIP189
 B357  SKIP190
 B369  SKIP191
 B397  SKIP192
 B39F  SKIP193
 B3B9  SKIP194
 B3CA  SKIP195
 B47C  SKIP196
 B4C6  SKIP197
 B4F5  SKIP198
 B50F  SKIP199
 B511  SKIP200
 B516  SKIP201
 B51A  SKIP202
 B527  SKIP203
 B536  SKIP204
 B53E  SKIP205
 B544  SKIP206
 B562  SKIP207
 B565  SKIP208
 B569  SKIP209
 B56A  SKIP210
 B574  SKIP211
 B59A  SKIP212
 B5B0  SKIP213
 B5BB  SKIP214
 B5DA  SKIP215
 B619  SKIP216
 B61C  SKIP217
 B61D  SKIP218
 B644  SKIP219
 B655  SKIP220
 B68D  SKIP221
 B68F  SKIP222
 B698  SKIP223
 B6A4  SKIP224
 B6E1  SKIP225
 B709  SKIP226
 B717  SKIP227
 B72E  SKIP228
 B73E  SKIP229
 B745  SKIP230
 B74A  SKIP231
 B753  SKIP232
 B75A  SKIP233
 B763  SKIP234
 B785  SKIP235
 B7A9  SKIP236
 B7D7  SKIP237
 B7F0  SKIP238
 B803  SKIP239
 B810  SKIP240
 B812  SKIP241
 B822  SKIP242
 B85C  SKIP243
 B88C  SKIP244
 B88E  SKIP245
 B8A6  SKIP246
 B8BD  SKIP247
 B2AB  SOUND
 BAF5  STICKINCTAB
=D209  STIMER
=0960  THETAC1
=00CF  TITLELIFE
=00D1  TITLEPHR
=0D1F  TITLETXT
=00BE  TORPEDODELAY
=095A  TRACKC1
=095C  TRACKDIGIT
 BECF  TRACKKEYSTAB
=00C2  TRAILDELAY
=00C3  TRAILIND
=D010  TRIG0
 AE29  TRIGGER
 A7BF  UPDATTCOMP
 B804  UPDPANEL
 B07B  UPDSCREEN
 B216  UPDTITLE
 A6D1  VBIHNDLR
=D40B  VCOUNT
=0200  VDSLST
=00C6  VEERMASK
 BED7  VEERMASKTAB
=094B  VELOCD1
=00C1  VELOCITYHI
=0070  VELOCITYLO
 BAB4  VELOCITYTAB
=00C7  VICINITYMASK
 BFB3  VICINITYMASKTAB
 BE22  VIEWMODETAB
=0216  VIMIRQ
=0222  VVBLKI
=008F  WARPARRVCOLUMN
=008E  WARPARRVROW
=008D  WARPDEPRCOLUMN
=008C  WARPDEPRROW
=0091  WARPENERGY
 BADD  WARPENERGYTAB
 BB3A  WARPSTARXTAB
 BB3E  WARPSTARYTAB
=00C0  WARPSTATE
=00C4  WARPTEMPCOLUMN
=00C5  WARPTEMPROW
 BC2B  WORDTAB
=D40A  WSYNC
=0A71  XPOSHI
=0B04  XPOSLO
=09DE  XPOSSIGN
=0B97  XVEL
=0AA2  YPOSHI
=0B35  YPOSLO
=0A0F  YPOSSIGN
=0BC8  YVEL
=0A40  ZPOSHI
=0AD3  ZPOSLO
=09AD  ZPOSSIGN
=0B66  ZVEL
=00BF  ZYLONATTACKER
=00A8  ZYLONFLPAT0
=00A9 ?ZYLONFLPAT1
 BF91  ZYLONFLPATTAB
 BF85  ZYLONHOMVELTAB
 BF89  ZYLONSHAPTAB
=00BA  ZYLONTIMX0
=00BB ?ZYLONTIMX1
=00BC ?ZYLONTIMY0
=00BD ?ZYLONTIMY1
=0078  ZYLONUNITTIM
=00B4  ZYLONVELINDX0
=00B5 ?ZYLONVELINDX1
=00B6 ?ZYLONVELINDY0
=00B7 ?ZYLONVELINDY1
=00B2  ZYLONVELINDZ0
=00B3 ?ZYLONVELINDZ1
 BF99  ZYLONVELTAB

SYMBOLS (SORTED BY VALUE): 898

=0000  CCS.0
=0000  RIGHT
=0000  ROM.SPC
=0000 ?SHAP.TORPEDO
=0001 ?CCS.1
=0002 ?CCS.2
=0003 ?CCS.3
=0004 ?CCS.4
=0005 ?CCS.5
=0005  NUMSPCOBJ.PL
=0006 ?CCS.6
=0007 ?CCS.7
=0008 ?CCS.8
=0009  CCS.9
=000A  CCS.SPC
=000B  CCS.COLON
=000C  CCS.BORDERSW
=000C  NUMSPCOBJ.STARS
=000D  CCS.E
=000E  CCS.INF
=000E  ROM.DOT
=000F  CCS.MINUS
=0010  CCS.PLUS
=0010  ROM.0
=0010  SHAP.ZFIGHTER
=0011  CCS.PHI
=0011  NUMSPCOBJ.NORM
=0011  ROM.1
=0012  CCS.V
=0012  ROM.2
=0013  CCS.R
=0013  ROM.3
=0014  CCS.THETA
=0014  ROM.4
=0015  CCS.K
=0015  ROM.5
=0016  CCS.T
=0017 ?CCS.C
=0018  CCS.BORDERS
=0019  CCS.BORDERW
=0019  ROM.9
=001A  CCS.CORNERSW
=001A  ROM.COLON
=001B  CCS.STARBASE
=001C  CCS.4ZYLONS
=001D  CCS.3ZYLONS
=001E  CCS.2ZYLONS
=0020  SHAP.STARBASEL
=0021  ROM.A
=0023  ROM.C
=0024  ROM.D
=0025  ROM.E
=0027  ROM.G
=002C  ROM.L
=002E  ROM.N
=0030  ROM.P
=0030  SHAP.STARBASEC
=0031  NUMSPCOBJ.ALL
=0032  ROM.R
=0033  ROM.S
=0034  ROM.T
=0037  ROM.W
=0039  ROM.Y
=0040  CCS.COL1
=0040  EOP
=0040  SHAP.STARBASER
=0050  SHAP.TRANSVSSL
=0060  SHAP.METEOR
=0062  MISSIONLEVEL
=0063  FKEYCODE
=0064  ISDEMOMODE
=0065  NEWTITLEPHR
=0066  IDLECNTHI
=0067  ISVBISYNC
=0068  L.DIVISOR
=0068  L.MEMPTR1
=0068  L.RANGE
=0068  MEMPTR
=006A  DIVIDEND
=006A  L.CTRLDZYLON
=006A  L.DIFFC
=006A  L.DIRECTIONIND
=006A  L.FOURCOLORPIX
=006A  L.GCMEMMAPIND
=006A  L.HEIGHTCNT
=006A  L.ISDESTROYED
=006A  L.KEYCODE
=006A  L.MAXRNDXY
=006A  L.MEMPTR2
=006A  L.NEWSECTOR
=006A  L.NUMBYTES
=006A  L.PIXELBYTEOFF
=006A  L.RANGEINDEX
=006A  L.SECTORTYPE
=006A  L.SIGNCHAR
=006A  L.TERM3LO
=006A  L.VECCOMPIND
=006A  L.VELSIGN
=006A  L.WARPARRVCOL
=006A  L.WORD
=006B  L.ABSDIFFCOL
=006B  L.BITPAT
=006B  L.COLORMASK
=006B  L.COLUMNPOS
=006B  L.LOOPCNT2
=006B  L.PLHIT
=006B  L.SECTORCNT
=006B  L.TERM3HI
=006B  L.VELOCITYHI
=006C  L.SHIFTSHAPE
=006C  L.TERM3SIGN
=006C  L.TOKEN
=006C  L.VIEWDIR
=006D  JOYSTICKDELTA
=006D  L.PIXELCOLUMN
=006D  L.PIXELROW
=006D  L.QUOTIENT
=006E  L.DIRSAV
=006E  L.LOOPCNT
=006E  L.TRAILCNT
=006E  L.ZPOSOFF
=0070  SHAP.ZCRUISER
=0070  VELOCITYLO
=0071  NEWVELOCITY
=0072  COUNT8
=0073  EXPLLIFE
=0074  CLOCKTIM
=0075  DOCKSTATE
=0076  COUNT256
=0077  IDLECNTLO
=0078  ZYLONUNITTIM
=0079  MAXSPCOBJIND
=007A  OLDMAXSPCOBJIND
=007B  ISSTARBASESECT
=007C  ISTRACKCOMPON
=007D  DRAINSHIELDS
=007E  DRAINATTCOMP
=007F  ENERGYCNT
=0080  CCS.COL2
=0080  DOWN
=0080  DRAINENGINES
=0080  EOS
=0080  EOW
=0080  NEG
=0080  SHAP.ZBASESTAR
=0081  SHIELDSCOLOR
=0082  PL3HIT
=0083  PL4HIT
=0084  OLDTRIG0
=0086  ISTRACKING
=0087  BARRELNR
=0088  LOCKONLIFE
=0089  PLTRACKED
=008A  HITBADNESS
=008B  REDALERTLIFE
=008C  WARPDEPRROW
=008D  WARPDEPRCOLUMN
=008E  WARPARRVROW
=008F  WARPARRVCOLUMN
=0090  CURRSECTOR
=0090  SHAP.HYPERWARP
=0091  WARPENERGY
=0092  ARRVSECTOR
=0093  HUNTSECTOR
=0094  HUNTSECTCOLUMN
=0095  HUNTSECTROW
=0096  NEWZYLONDIST
=009E  OLDZYLONDIST
=009F  HUNTTIM
=00A0  BLIPCOLUMN
=00A1  BLIPROW
=00A2  BLIPCYCLECNT
=00A3  ISINLOCKON
=00A4  DIRLEN
=00A5  PENROW
=00A6  PENCOLUMN
=00A7  CTRLDZYLON
=00A8  ZYLONFLPAT0
=00A9 ?ZYLONFLPAT1
=00AA  MILESTTIM0
=00AB ?MILESTTIM1
=00AC  MILESTVELINDZ0
=00AD ?MILESTVELINDZ1
=00AE ?MILESTVELINDX0
=00AF ?MILESTVELINDX1
=00B0 ?MILESTVELINDY0
=00B1 ?MILESTVELINDY1
=00B2  ZYLONVELINDZ0
=00B3 ?ZYLONVELINDZ1
=00B4  ZYLONVELINDX0
=00B5 ?ZYLONVELINDX1
=00B6 ?ZYLONVELINDY0
=00B7 ?ZYLONVELINDY1
=00B8  ISBACKATTACK0
=00B9 ?ISBACKATTACK1
=00BA  ZYLONTIMX0
=00BB ?ZYLONTIMX1
=00BC ?ZYLONTIMY0
=00BD ?ZYLONTIMY1
=00BE  TORPEDODELAY
=00BF  ZYLONATTACKER
=00C0  CCS.COL3
=00C0  LONG
=00C0  WARPSTATE
=00C1  VELOCITYHI
=00C2  TRAILDELAY
=00C3  TRAILIND
=00C4  WARPTEMPCOLUMN
=00C5  WARPTEMPROW
=00C6  VEERMASK
=00C7  VICINITYMASK
=00C8  JOYSTICKX
=00C9  JOYSTICKY
=00CA  KEYCODE
=00CB  SCORE
=00CD  SCOREDRANKIND
=00CE  SCOREDCLASSIND
=00CF  TITLELIFE
=00D0  SHIPVIEW
=00D1  TITLEPHR
=00D2  BEEPFRQIND
=00D3  BEEPREPEAT
=00D4  BEEPTONELIFE
=00D5  BEEPPAUSELIFE
=00D6  BEEPPRIORITY
=00D7  BEEPFRQSTART
=00D8  BEEPLIFE
=00D9  BEEPTOGGLE
=00DA  NOISETORPTIM
=00DB  NOISEEXPLTIM
=00DC  NOISEAUDC2
=00DD  NOISEAUDC3
=00DE  NOISEAUDF1
=00DF  NOISEAUDF2
=00E0  NOISEFRQINC
=00E1  NOISELIFE
=00E2  NOISEZYLONTIM
=00E3  NOISEHITLIFE
=00E4  PL0SHAPOFF
=00E5  PL1SHAPOFF
=00E6  PL2SHAPOFF
=00E7  PL3SHAPOFF
=00E8  PL4SHAPOFF
=00E9  PL0LIFE
=00EA  PL1LIFE
=00EB  PL2LIFE
=00EC  PL3LIFE
=00ED  PL4LIFE
=00EE  PL0COLOR
=00EF ?PL1COLOR
=00F0 ?PL2COLOR
=00F1 ?PL3COLOR
=00F2  PF0COLOR
=00F3 ?PF1COLOR
=00F4  PF2COLOR
=00F5 ?PF3COLOR
=00F6  BGRCOLOR
=00F7  PF0COLORDLI
=00F8 ?PF1COLORDLI
=00F9 ?PF2COLORDLI
=00FA ?PF3COLORDLI
=00FB  BGRCOLORDLI
=0200  VDSLST
=0216  VIMIRQ
=0222  VVBLKI
=0280  DSPLST
=0300  PL4DATA
=0400  PL0DATA
=0500  PL1DATA
=0600  PL2DATA
=0700  PL3DATA
=0800  PFMEMROWLO
=0864  PFMEMROWHI
=08C9  GCMEMMAP
=0949  PANELTXT
=094B  VELOCD1
=0950  KILLCNTD1
=0955  ENERGYD1
=095A  TRACKC1
=095C  TRACKDIGIT
=0960  THETAC1
=0966  PHIC1
=096C  RANGEC1
=0971  GCTXT
=097D  GCWARPD1
=098D  GCTRGCNT
=0992  GCSTATPHO
=0993  GCSTATENG
=0994  GCSTATSHL
=0995  GCSTATCOM
=0996  GCSTATLRS
=0997  GCSTATRAD
=09A3  GCSTARDAT
=09AD  ZPOSSIGN
=09AF  PL2ZPOSSIGN
=09B0  PL3ZPOSSIGN
=09B1  PL4ZPOSSIGN
=09DE  XPOSSIGN
=09E0 ?PL2XPOSSIGN
=09E1  PL3XPOSSIGN
=09E2  PL4XPOSSIGN
=0A0F  YPOSSIGN
=0A11  PL2YPOSSIGN
=0A12  PL3YPOSSIGN
=0A13  PL4YPOSSIGN
=0A40  PL0ZPOSHI
=0A40  ZPOSHI
=0A42  PL2ZPOSHI
=0A43  PL3ZPOSHI
=0A44  PL4ZPOSHI
=0A71  XPOSHI
=0A73  PL2XPOSHI
=0A74  PL3XPOSHI
=0A75  PL4XPOSHI
=0AA2  YPOSHI
=0AA4  PL2YPOSHI
=0AA5  PL3YPOSHI
=0AA6  PL4YPOSHI
=0AD3  ZPOSLO
=0AD5  PL2ZPOSLO
=0AD6  PL3ZPOSLO
=0AD7 ?PL4ZPOSLO
=0B04  XPOSLO
=0B06 ?PL2XPOSLO
=0B07  PL3XPOSLO
=0B08 ?PL4XPOSLO
=0B35  YPOSLO
=0B37 ?PL2YPOSLO
=0B38  PL3YPOSLO
=0B39 ?PL4YPOSLO
=0B66 ?PL0ZVEL
=0B66  ZVEL
=0B67 ?PL1ZVEL
=0B68  PL2ZVEL
=0B69  PL3ZVEL
=0B6A  PL4ZVEL
=0B97 ?PL0XVEL
=0B97  XVEL
=0B98 ?PL1XVEL
=0B99  PL2XVEL
=0B9A  PL3XVEL
=0B9B  PL4XVEL
=0BC8 ?PL0YVEL
=0BC8  YVEL
=0BC9 ?PL1YVEL
=0BCA  PL2YVEL
=0BCB  PL3YVEL
=0BCC  PL4YVEL
=0BF9  PIXELROWNEW
=0BF9  PL0ROWNEW
=0BFA  PL1ROWNEW
=0BFB  PL2ROWNEW
=0BFC  PL3ROWNEW
=0BFD  PL4ROWNEW
=0C2A  PIXELCOLUMN
=0C2A  PL0COLUMN
=0C2B  PL1COLUMN
=0C2C  PL2COLUMN
=0C2D  PL3COLUMN
=0C2E  PL4COLUMN
=0C5B  PIXELROW
=0C5B  PL0ROW
=0C5C  PL1ROW
=0C5D  PL2ROW
=0C5E  PL3ROW
=0C5F  PL4ROW
=0C8C  PIXELBYTEOFF
=0C8C  PL0SHAPTYPE
=0C8D  PL1SHAPTYPE
=0C8E  PL2SHAPTYPE
=0C8F  PL3SHAPTYPE
=0C90  PL4SHAPTYPE
=0CBD  PIXELSAVE
=0CBD  PL0HEIGHT
=0CBE  PL1HEIGHT
=0CBF  PL2HEIGHT
=0CC0  PL3HEIGHT
=0CC1  PL4HEIGHT
=0CEE  PIXELBYTE
=0CEE  PL0HEIGHTNEW
=0CEF  PL1HEIGHTNEW
=0CF0  PL2HEIGHTNEW
=0CF1  PL3HEIGHTNEW
=0CF2  PL4HEIGHTNEW
=0D1F  TITLETXT
=0D35  GCPFMEM
=0DE9  MAPTO80
=0EE9  MAPTOBCD99
=1000  PFMEM
=1000  PFMEM.C0R0
=10C8  PFMEM.C0R5
=12A8  PFMEM.C0R17
=17BB  PFMEM.C76R49
=17BC  PFMEM.C80R49
=17E3  PFMEM.C76R50
=17E4  PFMEM.C80R50
=1B36  PFMEM.C120R71
=1BFE  PFMEM.C120R76
=1C04  PFMEM.C144R76
=1C9E  PFMEM.C120R80
=1CA4  PFMEM.C144R80
=1D40  PFMEM.C128R84
=1D42  PFMEM.C136R84
=1D68  PFMEM.C128R85
=1D6A  PFMEM.C136R85
 A000  CHARSET
 A0F8  LRSHEADER
 A109  AFTHEADER
 A11A  GCHEADER
 A12E  DLSTGC
 A14A  INITCOLD
 A15A  INITSELECT
 A15C  INITDEMO
 A15E  INITSTART
 A165  LOOP001
 A172  SKIP001
 A1F3  GAMELOOP
 A201  LOOP002
 A21F  SKIP002
 A227  LOOP003
 A250  SKIP003
 A262  SKIP004
 A26A  LOOP004
 A277  LOOP005
 A284  LOOP006
 A291  LOOP007
 A29E  LOOP008
 A2BA  LOOP009
 A2C2  SKIP005
 A2E0  LOOP010
 A2E8  SKIP006
 A306  LOOP011
 A30E  SKIP007
 A327  LOOP012
 A343  LOOP013
 A389  LOOP014
 A39E  SKIP008
 A3A6  LOOP015
 A3BB  SKIP009
 A3BD  LOOP016
 A3C6  SKIP010
 A3DF  SKIP011
 A3E4  LOOP017
 A3EA  SKIP012
 A3EB  LOOP018
 A3FE  SKIP013
 A422  LOOP019
 A428  LOOP020
 A43C  SKIP014
 A43F  SKIP015
 A453  LOOP021
 A473  SKIP016
 A47D  JUMP001
 A49A  SKIP017
 A4A4  JUMP002
 A4A7  SKIP018
 A4AD  SKIP019
 A4C0  LOOP022
 A4CA  SKIP020
 A4DB  SKIP021
 A4E5  SKIP022
 A4E7  LOOP023
 A4ED  SKIP023
 A4FC  LOOP024
 A503  SKIP024
 A52A  SKIP025
 A52E  SKIP026
 A53E  SKIP027
 A548  SKIP028
 A569  SKIP029
 A579  JUMP003
 A58D  SKIP030
 A593  LOOP025
 A5A3  SKIP031
 A5A5  SKIP032
 A5AB  SKIP033
 A5D0  SKIP034
 A600  SKIP035
 A60C  SKIP036
 A61B  SKIP037
 A635  SKIP038
 A687  SKIP039
 A69B  SKIP040
 A6B7  SKIP041
 A6C2  SKIP042
 A6D1  VBIHNDLR
 A6E9  SKIP043
 A6EA  SKIP044
 A6F2  SKIP045
 A6F6  LOOP026
 A715  SKIP046
 A718  DLSTHNDLR
 A728  SKIP047
 A730  LOOP027
 A74B  JUMP004
 A751  IRQHNDLR
 A765  LOOP028
 A76F  DRAWLINES
 A77A  SKIP048
 A781  SKIP049
 A782  DRAWLINE
 A784  DRAWLINE2
 A78E  LOOP029
 A7B8  SKIP050
 A7BA  SKIP051
 A7BF  UPDATTCOMP
 A7CF  LOOP030
 A7E1  SKIP052
 A7E9  SKIP053
 A7EC  SKIP054
 A804  SKIP055
 A80A  SKIP056
 A821  SKIP057
 A827  SKIP058
 A830  SKIP059
 A83A  LOOP031
 A83C  LOOP032
 A850  SKIP060
 A85F  SKIP061
 A898  SKIP062
 A89B  HYPERWARP
 A8AC  SKIP063
 A8E8  SKIP064
 A8EC  SKIP065
 A900  SKIP066
 A901  SKIP067
 A915  SKIP068
 A91E  SKIP069
 A947  LOOP033
 A96F  SKIP070
 A97F  SKIP071
 A980  ABORTWARP
 A987  ENDWARP
 A98D  CLEANUPWARP
 A9A6  SKIP072
 A9B4  INITTRAIL
 A9E5  LOOP034
 AA1A  SKIP073
 AA20  SKIP074
 AA21  PROJECTION
 AA40  SKIP075
 AA52  LOOP035
 AA66  SKIP076
 AA6F  SKIP077
 AA78  SKIP078
 AA79  MANEUVER
 AA90  SKIP079
 AAB3  SKIP080
 AAB5  LOOP036
 AAC8  SKIP081
 AACF  SKIP082
 AAD5  SKIP083
 AADD  SKIP084
 AAE0  SKIP085
 AAF4  SKIP086
 AB00  SKIP087
 AB03  SKIP088
 AB09  SKIP089
 AB11  SKIP090
 AB36  SKIP091
 AB37  SKIP092
 AB66  SKIP093
 AB84  SKIP094
 AB98  SKIP095
 AB9C  SKIP096
 ABAE  SKIP097
 ABB3  LOOP037
 ABBA  SKIP098
 ABC4  SKIP099
 ABCA  LOOP038
 ABDD  SKIP100
 ABE1  SKIP101
 ABE5  SKIP102
 ABE9  SKIP103
 ABEB  SKIP104
 ABFA  SKIP105
 ABFC  LOOP039
 AC08  SKIP106
 AC0A  SKIP107
 AC31  SKIP108
 AC32  SKIP109
 AC4F  SKIP110
 AC6B  INITEXPL
 AC73  LOOP040
 ACAF  COPYPOSVEC
 ACC1  COPYPOSXY
 ACE5  SKIP111
 ACE6  DOCKING
 ACF3  SKIP112
 AD12  SKIP113
 AD26  SKIP114
 AD35  SKIP115
 AD61  SKIP116
 AD6C  SKIP117
 AD70  SKIP118
 AD71  SKIP119
 AD82  SKIP120
 ADB8  SKIP121
 ADB9  SKIP122
 ADCA  LOOP041
 ADD7  LOOP042
 ADF1  MODDLST
 ADF4  LOOP043
 ADFB  LOOP044
 AE03  SKIP123
 AE0D  CLRPLAYFIELD
 AE0F  CLRMEM
 AE1A  LOOP045
 AE29  TRIGGER
 AE40  SKIP124
 AE41  SKIP125
 AE56  SKIP126
 AE58  SKIP127
 AE66  SKIP128
 AEA8  NOISE
 AEB1  SKIP129
 AEB3  LOOP046
 AEC9  SKIP130
 AECA  HOMINGVEL
 AED2  SKIP131
 AEDA  SKIP132
 AEE1  DAMAGE
 AEE7  LOOP047
 AF10  SKIP133
 AF19  SKIP134
 AF1E  SKIP135
 AF32  SKIP136
 AF3C  SKIP137
 AF3D  COLLISION
 AF3F  LOOP048
 AF43  SKIP138
 AF58  SKIP139
 AF64  SKIP140
 AF6F  SKIP141
 AF94  SKIP142
 AFC6  SKIP143
 AFD5  LOOP049
 AFE7  SKIP144
 AFEC  LOOP050
 AFF3  SKIP145
 AFFD  SKIP146
 AFFE  KEYBOARD
 B011  LOOP051
 B020  SKIP147
 B02B  SKIP148
 B036  SKIP149
 B040  SKIP150
 B041  SKIP151
 B045  SETVIEW
 B056  LOOP052
 B060  SKIP152
 B073  SKIP153
 B07B  UPDSCREEN
 B082  SKIP154
 B096  SKIP155
 B099  SKIP156
 B0E6  SKIP157
 B0ED  SKIP158
 B0FB  SKIP159
 B0FC  SKIP160
 B106  SKIP161
 B10A  GAMEOVER
 B121  GAMEOVER2
 B14A  SKIP162
 B15A  SKIP163
 B15D  SKIP164
 B161  SKIP165
 B162  SELECTWARP
 B16A  SKIP166
 B16B  SKIP167
 B173  SKIP168
 B1A7  CALCWARP
 B1BE  SKIP169
 B1C8  SKIP170
 B1D3  SKIP171
 B1E0  SKIP172
 B1FE  LOOP053
 B200  LOOP054
 B212  SKIP173
 B216  UPDTITLE
 B21E  SKIP174
 B21F  SKIP175
 B223  SETTITLE
 B22E  SKIP176
 B234  LOOP055
 B23A  SKIP177
 B249  SKIP178
 B25F  SKIP179
 B268  SKIP180
 B276  LOOP056
 B27C  SKIP181
 B286  LOOP057
 B2A2  SKIP182
 B2A8  SKIP183
 B2AB  SOUND
 B2C1  LOOP058
 B2E1  SKIP184
 B2E6  SKIP185
 B2F3  SKIP186
 B32B  SKIP187
 B337  SKIP188
 B349  SKIP189
 B357  SKIP190
 B369  SKIP191
 B397  SKIP192
 B39F  SKIP193
 B3A6  BEEP
 B3AF  LOOP059
 B3B9  SKIP194
 B3BA  INITIALIZE
 B3BC  LOOP060
 B3CA  SKIP195
 B3EE  LOOP061
 B41B  LOOP062
 B441  LOOP063
 B44C  LOOP064
 B47C  SKIP196
 B488  LOOP065
 B492  LOOP066
 B4B9  DRAWGC
 B4BD  LOOP067
 B4C6  SKIP197
 B4E4  FLUSHGAMELOOP
 B4F5  SKIP198
 B50F  SKIP199
 B511  SKIP200
 B516  SKIP201
 B51A  SKIP202
 B51C  LOOP068
 B527  SKIP203
 B536  SKIP204
 B53E  SKIP205
 B544  SKIP206
 B54E  LOOP069
 B562  SKIP207
 B565  SKIP208
 B569  SKIP209
 B56A  SKIP210
 B574  SKIP211
 B57C  LOOP070
 B59A  SKIP212
 B5B0  SKIP213
 B5BB  SKIP214
 B5C1  LOOP071
 B5D1  LOOP072
 B5DA  SKIP215
 B5EA  LOOP073
 B5EF  LOOP074
 B601  LOOP075
 B619  SKIP216
 B61C  SKIP217
 B61D  SKIP218
 B632  LOOP076
 B644  SKIP219
 B655  SKIP220
 B662  LOOP077
 B664  LOOP078
 B68D  SKIP221
 B68F  SKIP222
 B698  SKIP223
 B69B  ROTATE
 B6A4  SKIP224
 B6E1  SKIP225
 B6FB  SCREENCOLUMN
 B709  SKIP226
 B717  SKIP227
 B71E  SCREENROW
 B72E  SKIP228
 B73E  SKIP229
 B745  SKIP230
 B74A  SKIP231
 B753  SKIP232
 B75A  SKIP233
 B763  SKIP234
 B764  INITPOSVEC
 B785  SKIP235
 B7A9  SKIP236
 B7BE  RNDINVXY
 B7D7  SKIP237
 B7F0  SKIP238
 B7F1  ISSURROUNDED
 B803  SKIP239
 B804  UPDPANEL
 B810  SKIP240
 B812  SKIP241
 B822  SKIP242
 B85C  SKIP243
 B86F  DECENERGY
 B88C  SKIP244
 B88E  SKIP245
 B896  LOOP079
 B8A6  SKIP246
 B8A7  SHOWCOORD
 B8BD  SKIP247
 B8CD  SHOWDIGITS
 B8DF  PLCOLOROFFTAB
 B8E4  PLSHAP1TAB
 B9B1  PLSHAP2TAB
 BA62  DLSTFRAG
 BA6A  DLSTFRAGGC
 BA6D  DLSTFRAGLRS
 BA75  DLSTFRAGAFT
 BA7D  DLSTFRAGFRONT
 BA8C  DLSTFRAGOFFTAB
 BA90  FOURCOLORPIXEL
 BAB0  PIXELMASKTAB
 BAB4  VELOCITYTAB
 BABE  KEYTAB
 BAD3  DRAINRATETAB
 BADD  WARPENERGYTAB
 BAF5  STICKINCTAB
 BAF9  DRAWLINESTAB
 BB3A  WARPSTARXTAB
 BB3E  WARPSTARYTAB
 BB42  PANELTXTTAB
 BBA6  SECTORTYPETAB
 BBAA  PHRASETAB
 BC2B  WORDTAB
 BE22  VIEWMODETAB
 BE26  MSGOFFTAB
 BE29  MSGBITTAB
 BE2C  MSGONTAB
 BE2F  PLSHAPOFFTAB
 BE7F  PLSHPHEIGHTTAB
 BECF  TRACKKEYSTAB
 BED1  SECTORCHARTAB
 BED7  VEERMASKTAB
 BEDB  PLSTARBAOFFTAB
 BEDD  BONUSTAB
 BEE9  RANKTAB
 BEFC  CLASSTAB
 BF0C  MISSIONPHRTAB
 BF10  DAMAGEPROBTAB
 BF14  DAMAGEPHRTAB
 BF1A  DESTROYPHRTAB
 BF20  NOISEPATTAB
 BF3E  BEEPPATTAB
 BF5C  BEEPFRQTAB
 BF6E  BLIPSHAPTAB
 BF73  BARRELXTAB
 BF75  HITMAXZTAB
 BF7D  HITMINZTAB
 BF85  ZYLONHOMVELTAB
 BF89  ZYLONSHAPTAB
 BF91  ZYLONFLPATTAB
 BF99  ZYLONVELTAB
 BFA9  PFCOLORTAB
 BFB3  VICINITYMASKTAB
 BFBB  MOVEPROBTAB
 BFC0  COMPASSOFFTAB
 BFC9  HOMVELTAB
 BFD1  PLSHAPCOLORTAB
 BFDB  PLSHAPBRITTAB
 BFEB  NOISETORPVOLTAB
 BFF3  NOISETORPFRQTAB
=D000  HPOSP0
=D001  HPOSP1
=D002  HPOSP2
=D003  HPOSP3
=D004  HPOSM0
=D005  HPOSM1
=D006  HPOSM2
=D007  HPOSM3
=D008  M0PL
=D009  M1PL
=D00A  M2PL
=D00B  M3PL
=D00F  P3PL
=D010  TRIG0
=D012  COLPM0
=D016  COLPF0
=D01B  PRIOR
=D01D  GRACTL
=D01E  HITCLR
=D01F  CONSOL
=D200  AUDF1
=D202  AUDF2
=D203  AUDC2
=D204  AUDF3
=D205  AUDC3
=D206  AUDF4
=D207  AUDC4
=D208  AUDCTL
=D209  KBCODE
=D209  STIMER
=D20A  RANDOM
=D20E  IRQEN
=D20F  SKCTL
=D300  PORTA
=D302  PACTL
=D400  DMACTL
=D402  DLIST
=D407  PMBASE
=D409  CHBASE
=D40A  WSYNC
=D40B  VCOUNT
=D40E  NMIEN
=E000  ROMCHARSET

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txt
StarRaiders.source.txt 824.0 kB 2 01-Apr-2016 18:32 Roland B. Wassenberg StarRaiders.source.txt
« This page (revision-5) was last changed on 01-Apr-2016 18:35 by Roland B. Wassenberg