Star Raiders source code by Lorenz Wiest
Back to current versionRestore this version

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 ;*                                 22-SEP-2015                                 *
              00016 ;*                                                                             *
              00017 ;*                STAR RAIDERS was created by Douglas Neubauer                 *
              00018 ;*                  STAR RAIDERS was published by Atari Inc.                   *
              00019 ;*                                                                             *
              00020 ;*******************************************************************************
              00021
              00022 ; I wrote this document out of my own curiosity. When STAR RAIDERS was released
              00023 ; in 1979 it became the killer app for the Atari 8-bit Home Computer System.
              00024 ; Since then I have always been wondering what made it tick and how its (at that
              00025 ; time) spectacular 3D graphics worked, especially the rotating star field.
              00026 ; Impressed by "The Atari BASIC Source Book" I decided to reverse-engineer the
              00027 ; STAR RAIDERS 8KB ROM cartridge to recreate a fully documented assembly
              00028 ; language source code file. I had no access to the original source code, so the
              00029 ; only way to succeed was a combination of educated guesses, trial-and-error,
              00030 ; and patience. Eventually, I made it.
              00031 ;
              00032 ; Essential in preparing this document were three programs I wrote:
              00033 ;
              00034 ; (1) A 6502-cross-assembler based on the syntax of the MAC/65 assembler for the
              00035 ;     Atari 8-bit Home Computer System to create the binary file that I verified
              00036 ;     against the binary of the original ROM cartridge.
              00037 ;
              00038 ; (2) A text formatter to layout the source code file with its copious comment
              00039 ;     sections. This was a big time saver, because as the documentation grew the
              00040 ;     source code had to be reformatted over and over again.
              00041 ;
              00042 ; (3) A symbol checker to verify that the ubiquitous symbol-value pairs in the
              00043 ;     documentation match the corresponding symbol values produced by the
              00044 ;     assembler.
              00045 ;
              00046 ; This assembly language source code file is compatible with the MAC/65
              00047 ; assembler for the Atari 8-bit Home Computer System. I was able to assemble it
              00048 ; on an emulated Atari running MAC/65, producing the identical binary of the ROM
              00049 ; cartridge. 
              00050 ;
              00051 ; Your feedback is welcome! Send feedback to lo.wiest(at)web.de.
              00052 ;
              00053 ; Enjoy! -- Lorenz
              00054
              00055 ;*******************************************************************************
              00056 ;*                                                                             *
              00057 ;*                               N O T A T I O N                               *
              00058 ;*                                                                             *
              00059 ;*******************************************************************************
              00060
              00061 ; BITS AND BYTES
              00062 ;
              00063 ; o   A "byte" consists of 8 bits. They are numbered B7..0. Bit B0 is the least
              00064 ;     significant bit.
              00065 ;
              00066 ; o   A "word" consists of 16 bits. They are numbered B15..B0. Bit B0 is the
              00067 ;     least significant bit. A word is stored in low-order then high-order byte
              00068 ;     order.
              00069 ;
              00070 ; o   The high-order byte ("high byte") of a word consists of bits B15..8 of the
              00071 ;     word.
              00072 ;
              00073 ; o   The low-order byte ("low byte") of a word consists of bits B7..0 of the
              00074 ;     word.
              00075 ;
              00076 ; NUMBERS
              00077 ;
              00078 ; o   The dollar sign ($) prefixes hexadecimal numbers.
              00079 ;     Example: $101 is the decimal number 257.
              00080 ;
              00081 ; o   The percent sign (%) prefixes binary numbers.
              00082 ;     Example: %101 is the decimal number 5.
              00083 ;
              00084 ; o   The asterisk (*) is a wildcard character for a single hexadecimal or
              00085 ;     binary digit.
              00086 ;     Example: $0*00 is a placeholder for the numbers $0000, $0100, ..., $0F00.
              00087 ;
              00088 ; o   The lowercase R (r) is a wildcard character for a single random
              00089 ;     hexadecimal or binary digit. The random digit r is chosen by a random
              00090 ;     number generator.
              00091 ;     Example: %00r0 is a placeholder for the numbers %0000 or %0010.
              00092 ;
              00093 ; OPERATORS
              00094 ;
              00095 ; o   The exclamation mark (!) is the binary OR operator.
              00096 ;     Example: $01!$02 is $03.
              00097 ;
              00098 ; o   The less-than sign (<) indicates bits B7..0 of a word.
              00099 ;     Example: <$1234 is $34.
              00100 ;
              00101 ; o   The greater-than sign (>) indicates bits B15..8 of a word.
              00102 ;     Example: >$1234 is $12.
              00103 ;
              00104 ; o   A pair of brackets ([]) groups mathematical expressions.
              00105 ;     Example: [3-1]*4 is 8.
              00106 ;
              00107 ; ASSEMBLY LANGUAGE
              00108 ;
              00109 ; o   The uppercase A (A) indicates the accumulator register of the 6502 CPU.
              00110 ;
              00111 ; o   The uppercase X (X) indicates the X register of the 6502 CPU.
              00112 ;
              00113 ; o   The uppercase Y (Y) indicates the Y register of the 6502 CPU.
              00114 ;
              00115 ; o   The prefix uppercase L and dot (L.) indicates a local variable, a memory
              00116 ;     location used temporarily in a subroutine.
              00117 ;
              00118 ; PSEUDO-FUNCTIONS
              00119 ;
              00120 ; o   The function ABS(<num>) returns the absolute value of <num>.
              00121 ;     Example: ABS(3) returns 3.
              00122 ;     Example: ABS(-3) returns 3.
              00123 ;
              00124 ; o   The function RND(<num1>..<num2>) returns a random integer in
              00125 ;     <num1>..<num2>.
              00126 ;     Example: RND(3..5) returns a random number out of 3, 4, or 5.
              00127 ;
              00128 ; o   The function MAX(<num1>, <num2>) returns the larger number of <num1> and
              00129 ;     <num2>.
              00130 ;     Example: MAX(2, 4) returns 4.
              00131 ;
              00132 ; VECTORS
              00133 ;
              00134 ; o   The lowercase X (x) indicates the x-axis of the 3D coordinate system.
              00135 ;
              00136 ; o   The lowercase Y (y) indicates the y-axis of the 3D coordinate system.
              00137 ;
              00138 ; o   The lowercase Z (z) indicates the z-axis of the 3D coordinate system.
              00139 ;
              00140 ; o   Components of a position vector (called "coordinates") have the arbitrary
              00141 ;     unit <KM> ("kilometers").
              00142 ;
              00143 ; o   Components of a velocity vector have the arbitrary unit <KM/H>
              00144 ;     ("kilometers per hour").
              00145 ;
              00146 ; o   A positive component of a position vector (coordinate) in hexadecimal
              00147 ;     notation is written in the form +$<hexNum> <KM>. <hexNum> is an unsigned
              00148 ;     integer value.
              00149 ;     Example: The starbase is +$1000 (or 4096) <KM> ahead of our starship.
              00150 ;
              00151 ; o   A negative component of a position vector (coordinate) in hexadecimal
              00152 ;     notation is written in the form -($<hexNum>) <KM>. <hexNum> is an unsigned
              00153 ;     integer value. To calculate the actual bit pattern of this coordinate
              00154 ;     value compute the two's-complement of <hexNum>. See also "ON POSITION
              00155 ;     VECTORS".
              00156 ;     Example: The starbase is -($1000) (or -4096) <KM> behind our starship.
              00157 ;
              00158 ; o   An absolute component of a position vector (coordinate) in hexadecimal
              00159 ;     notation is written in the form $<hexNum> <KM>. <hexNum> is an unsigned
              00160 ;     integer value.
              00161 ;     Example: The Zylon fighter fires when it is closer than $1000 (or 4096)
              00162 ;              <KM>. 
              00163 ;
              00164 ; DISPLAY LIST
              00165 ;
              00166 ; o   The following notation is used for Display List instructions:
              00167 ;
              00168 ;     BLK<n>           = Display <n> blank video lines (<n> in 1..8)
              00169 ;     GR1              = Display one GRAPHICS 1 row of 20 text characters
              00170 ;     GR2              = Display one GRAPHICS 2 row of 20 text characters
              00171 ;     GR7              = Display one GRAPHICS 7 row of 160 pixels
              00172 ;     DLI              = Trigger a Display List Interrupt
              00173 ;     ... @ <addr>     = Point to screen memory at address <addr>
              00174 ;     JMP @ <addr>     = Jump to next Display List instruction at address <addr>
              00175 ;     WAITJMP @ <addr> = Wait for vertical blank phase, then jump to next
              00176 ;                        Display List instruction at address <addr>
              00177 ;
              00178 ; MISCELLANEOUS
              00179 ;
              00180 ; o   Probabilities are written in the form <percentage>% (<number of values out
              00181 ;     of the possible values>:<number of possible values>).
              00182 ;     Example: The probability to throw the number 3 with a die is 16% (1:6).
              00183 ;
              00184 ; o   A "game loop iteration" (or "game loop") is a single execution of the game
              00185 ;     loop, the main program of the game.
              00186 ;
              00187 ; o   A "TICK" is the time span it takes to update the TV screen (1/60 s on an
              00188 ;     NTSC TV system, 1/50 s on a PAL TV system).
              00189 ;
              00190 ; o   A pair of braces ({}) encloses color names.
              00191 ;     Example: {BLACK}
              00192 ;
              00193 ; o   A pair of parentheses enclosing a question mark ((?)) indicates code that
              00194 ;     is not well understood.
              00195 ;
              00196 ; o   A pair of parentheses enclosing an exclamation mark ((!)) indicates a
              00197 ;     potential bug.
              00198
              00199 ;*******************************************************************************
              00200 ;*                                                                             *
              00201 ;*                               O V E R V I E W                               *
              00202 ;*                                                                             *
              00203 ;*******************************************************************************
              00204
              00205 ; ON POSITION VECTORS
              00206 ;
              00207 ; The program uses a 3D coordinate system with the position of our starship at
              00208 ; its center and the following coordinate axes:
              00209 ;
              00210 ; o   The x-axis points to the right.
              00211 ; o   The y-axis points up.
              00212 ; o   The z-axis points in flight direction.
              00213 ;
              00214 ; By the way, this is called a "left-handed" coordinate system.
              00215 ;
              00216 ; The locations of all space objects (Zylon ships, meteors, photon torpedoes,
              00217 ; starbase, transfer vessel, Hyperwarp Target Marker, stars, and explosion
              00218 ; fragments) are described by a "position vector".
              00219 ;
              00220 ; A "position vector" is composed of an x, y, and z component. The values of the
              00221 ; position vector components are called the x, y, and z "coordinates". They have
              00222 ; the arbitrary unit <KM>.
              00223 ;
              00224 ; Each coordinate is a signed 17-bit integer number, which fits into 3 bytes:
              00225 ;
              00226 ;     Sign     Mantissa
              00227 ;          B16 B15...B8 B7....B0
              00228 ;            | |      | |      |
              00229 ;     0000000* ******** ********
              00230 ;
              00231 ; o   B16 contains the sign bit. Used values are:
              00232 ;       1 -> Positive sign
              00233 ;       0 -> Negative sign
              00234 ; o   B15..0 contain the coordinate value (or "mantissa") as a two's-complement
              00235 ;     integer number.
              00236 ;
              00237 ; The range of a position vector component is -65536..+65535 <KM>.
              00238 ;
              00239 ; Examples:
              00240 ;
              00241 ;     00000001 11111111 11111111 = +65535 <KM>
              00242 ;     00000001 00010000 00000000 =  +4096 <KM>
              00243 ;     00000001 00001111 11111111 =  +4095 <KM>
              00244 ;     00000001 00000001 00000000 =   +256 <KM>
              00245 ;     00000001 00000000 11111111 =   +255 <KM>
              00246 ;     00000001 00000000 00010000 =    +16 <KM>
              00247 ;     00000001 00000000 00001111 =    +15 <KM>
              00248 ;     00000001 00000000 00000001 =     +1 <KM>
              00249 ;     00000001 00000000 00000000 =     +0 <KM>
              00250 ;
              00251 ;     00000000 11111111 11111111 =     -1 <KM>
              00252 ;     00000000 11111111 11111110 =     -2 <KM>
              00253 ;     00000000 11111111 11110001 =    -15 <KM>
              00254 ;     00000000 11111111 11110000 =    -16 <KM>
              00255 ;     00000000 11111111 00000001 =   -255 <KM>
              00256 ;     00000000 11111111 00000000 =   -256 <KM>
              00257 ;     00000000 11110000 00000001 =  -4095 <KM>
              00258 ;     00000000 11110000 00000000 =  -4096 <KM>
              00259 ;     00000000 00000000 00000000 = -65536 <KM>
              00260 ;
              00261 ; The position vector for each space object is stored in 9 tables:
              00262 ;
              00263 ; o   XPOSSIGN ($09DE..$0A0E), XPOSHI ($0A71..$0AA1), and XPOSLO ($0B04..$0B34)
              00264 ; o   YPOSSIGN ($0A0F..$0A3F), YPOSHI ($0AA2..$0AD2), and YPOSLO ($0B35..$0B65)
              00265 ; o   ZPOSSIGN ($09AD..$09DD), ZPOSHI ($0A40..$0A70), and ZPOSLO ($0AD3..$0B03)
              00266 ;
              00267 ; There are up to 49 space objects used in the program simultaneously, thus each
              00268 ; table is 49 bytes long.
              00269 ;
              00270 ; o   Position vectors 0..4 belong to space objects represented by PLAYERs
              00271 ;     (Zylon ships, meteors, photon torpedoes, starbase, transfer vessel, and
              00272 ;     Hyperwarp Target Marker).
              00273 ; o   Position vectors 5..48 belong to space objects represented by PLAYFIELD
              00274 ;     pixels. Position vectors 5..16 are used for stars, position vectors 17..48
              00275 ;     are used for explosion fragments and star trails.
              00276 ;
              00277 ; INFO: The x and y coordinates of space objects are converted and displayed by
              00278 ; the THETA and PHI readouts of the Control Panel Display in "gradons". The
              00279 ; z-coordinate is converted and displayed by the RANGE readout in "centrons".
              00280 ; The conversion takes place in subroutine SHOWDIGITS ($B8CD) where the high
              00281 ; byte of a coordinate (with values $00..$FF) is transformed with lookup table
              00282 ; MAPTOBCD99 ($0EE9) into a BCD value of 00..99 in "gradons" or "centrons".
              00283 ;
              00284 ;
              00285 ; ON VELOCITY VECTORS
              00286 ;
              00287 ; The velocities of all space objects are described by a "velocity vector". The
              00288 ; velocity vector is relative to our starship.
              00289 ;
              00290 ; A "velocity vector" is composed of an x, y, and z component. The values of the
              00291 ; velocity vector components are called the x, y, and z "velocities". They have
              00292 ; the arbitrary unit <KM/H>.
              00293 ;
              00294 ; Each velocity vector component is a 8-bit integer number, which fits into 1
              00295 ; byte:
              00296 ;
              00297 ;     B7 Sign
              00298 ;     |
              00299 ;     |B6...B0 Mantissa
              00300 ;     ||     |
              00301 ;     ********
              00302 ;
              00303 ; o   B7 contains the sign bit. Used values are:
              00304 ;     0 -> Positive sign, movement along the positive coordinate axis
              00305 ;          (x-velocity: right, y-velocity: up, z-velocity: in flight direction)
              00306 ;     1 -> Negative sign, movement along the negative coordinate axis
              00307 ;          (x-velocity: left, y-velocity: down, z-velocity: in reverse flight
              00308 ;          direction)
              00309 ; o   B6..B0 contain the velocity value (or "mantissa"). It is an unsigned
              00310 ;     number.
              00311 ;
              00312 ; The range of a velocity vector component is -127..+127 <KM/H>.
              00313 ;
              00314 ; Examples:
              00315 ;
              00316 ;     01111111 = +127 <KM/H>
              00317 ;     00010000 =  +16 <KM/H>
              00318 ;     00001111 =  +15 <KM/H>
              00319 ;     00000001 =   +1 <KM/H>
              00320 ;     00000000 =   +0 <KM/H>
              00321 ;
              00322 ;     10000000 =   -0 <KM/H>
              00323 ;     10000001 =   -1 <KM/H>
              00324 ;     10001111 =  +15 <KM/H>
              00325 ;     10010000 =  +16 <KM/H>
              00326 ;     11111111 = -127 <KM/H>
              00327 ;
              00328 ; The velocity vector for each space object stored in 3 tables:
              00329 ;
              00330 ; o   XVEL ($0B97..$0BC7)
              00331 ; o   YVEL ($0BC8..$0BF8)
              00332 ; o   ZVEL ($0B66..$0B96)
              00333 ;
              00334 ; There are up to 49 space objects used in the program simultaneously, thus each
              00335 ; table is 49 bytes long.
              00336 ;
              00337 ; o   Velocity vectors 0..4 belong to space objects represented by PLAYERs
              00338 ;     (Zylon ships, meteors, photon torpedoes, starbase, transfer vessel, and
              00339 ;     Hyperwarp Target Marker).
              00340 ; o   Velocity vectors 5..48 belong to space objects represented by PLAYFIELD
              00341 ;     pixels. Velocity vectors 5..16 are used for stars, velocity vectors 17..48
              00342 ;     are used for explosion fragments and star trails.
              00343 ;
              00344 ; INFO: The velocity of our starship is converted and displayed by the VELOCITY
              00345 ; readout of the Control Panel Display in "metrons per second" units. The
              00346 ; conversion takes place in subroutine SHOWDIGITS ($B8CD) where our starship's
              00347 ; velocity VELOCITYL ($70) (with values $00..$FF) is transformed with lookup
              00348 ; table MAPTOBCD99 ($0EE9) into a BCD value of 00..99 in "metrons per second".  
              00349
              00350 ;*******************************************************************************
              00351 ;*                                                                             *
              00352 ;*                             M E M O R Y   M A P                             *
              00353 ;*                                                                             *
              00354 ;*******************************************************************************
              00355 ;
              00356 ; The following variables are not changed by a SYSTEM RESET:
              00357 ;
              00358 ; $62      MISSIONLEVEL
              00359 ;
              00360 ;          Mission level. Used values are:
              00361 ;            $00 -> NOVICE mission
              00362 ;            $01 -> PILOT mission
              00363 ;            $02 -> WARRIOR mission
              00364 ;            $03 -> COMMANDER mission
              00365 ;
              00366 ; $63      FKEYCODE
              00367 ;
              00368 ;          Function key code. Used values are:
              00369 ;            $00 -> No function key pressed
              00370 ;            $01 -> START function key pressed
              00371 ;            $02 -> SELECT function key pressed
              00372 ;
              00373 ; $64      ISDEMOMODE
              00374 ;
              00375 ;          Indicates whether the program is in game or demo mode. Used values
              00376 ;          are:
              00377 ;            $00 -> Game mode
              00378 ;            $FF -> Demo mode
              00379 ;
              00380 ; $65      NEWTITLEPHR
              00381 ;
              00382 ;          New title phrase offset for the text in the title line. The new title
              00383 ;          phrase is not immediately displayed in the title line but only after
              00384 ;          the display time of the currently displayed title phrase has expired.
              00385 ;          Thus, setting a value to NEWTITLEPHR ($65) "enqueues" the display of
              00386 ;          new title phrase. Used values are:
              00387 ;            $00..$7B -> Title phrase offset into PHRASETAB ($BBAA)
              00388 ;            $FF      -> Hide title line
              00389 ;
              00390 ;          See also TITLEPHR ($D1).
              00391 ;
              00392 ; $66      IDLECNTHI
              00393 ;
              00394 ;          Idle counter (high byte). Forms a 16-bit counter together with
              00395 ;          IDLECNTLO ($77), which is incremented during the execution of the
              00396 ;          Vertical Blank Interrupt handler VBIHNDLR ($A6D1). IDLECNTHI ($66) is
              00397 ;          reset to 0 when the joystick trigger or a keyboard key has been
              00398 ;          pressed, or to 1..3 when a function key has been pressed. When
              00399 ;          IDLECNTHI ($66) reaches a value of 128 (after about 10 min idle time)
              00400 ;          the program enters demo mode.
              00401 ;
              00402 ; The following variables are set to 0 after a SYSTEM RESET:
              00403 ;
              00404 ; $67      ISVBISYNC
              00405 ;
              00406 ;          Indicates whether the Vertical Blank Interrupt handler VBIHNDLR
              00407 ;          ($A6D1) is executed. Used to synchronize the execution of a new game
              00408 ;          loop iteration in GAMELOOP ($A1F3) with the vertical blank phase.
              00409 ;          Used values are:
              00410 ;            $00 -> Halt execution at start of game loop and wait for VBI
              00411 ;            $FF -> Continue execution of game loop
              00412 ;
              00413 ; $68..$69 MEMPTR
              00414 ;
              00415 ;          A 16-bit memory pointer.
              00416 ;
              00417 ;          Also used as a local variable.
              00418 ;
              00419 ; $6A..$6B DIVIDEND
              00420 ;
              00421 ;          A 16-bit dividend value passed in GAMELOOP ($A1F3) to subroutine
              00422 ;          PROJECTION ($AA21) to calculate a division.
              00423 ;
              00424 ;          Also used as a local variable.
              00425 ;
              00426 ; $6C      Used as a local variable.
              00427 ;
              00428 ; $6D      JOYSTICKDELTA
              00429 ;
              00430 ;          Used to pass joystick directions from GAMELOOP ($A1F3) to subroutine
              00431 ;          ROTATE ($B69B). Used values are:
              00432 ;            $01 -> Joystick pressed right or up
              00433 ;            $00 -> Joystick centered
              00434 ;            $FF -> Joystick pressed left or down
              00435 ;
              00436 ;          Also used as a local variable.
              00437 ;
              00438 ; $6E      Used as a local variable.
              00439 ;
              00440 ; $70      VELOCITYLO
              00441 ;
              00442 ;          Our starship's current velocity (low byte) in <KM/H>. Forms a 16-bit
              00443 ;          value together with VELOCITYHI ($C1). In subroutine UPDPANEL ($B804),
              00444 ;          VELOCITYLO ($70) is mapped to a BCD-value in 00..99 and displayed by
              00445 ;          the VELOCITY readout of the Control Panel Display. See also
              00446 ;          NEWVELOCITY ($71).
              00447 ;
              00448 ; $71      NEWVELOCITY
              00449 ;
              00450 ;          Our starship's new velocity (low byte) in <KM/H>. It is set by
              00451 ;          pressing one of the speed keys '0'..'9'. A pressed speed key is
              00452 ;          mapped to the new velocity value with VELOCITYTAB ($BAB4).
              00453 ;
              00454 ; $72      COUNT8
              00455 ;
              00456 ;          Wrap-around counter. Counts from 0..7, then starts over at 0. It is
              00457 ;          incremented every game loop iteration.
              00458 ;
              00459 ; $73      EXPLLIFE
              00460 ;
              00461 ;          Explosion lifetime. It is decremented every game loop iteration. Used
              00462 ;          values are:
              00463 ;              $00 -> Explosion is over
              00464 ;            < $18 -> Number of explosion fragment space objects is decremented
              00465 ;            < $70 -> HITBADNESS ($8A) is reset
              00466 ;              $80 -> Initial value at start of explosion
              00467 ;
              00468 ; $74      CLOCKTIM
              00469 ;
              00470 ;          Star date clock delay timer. Counts down from 40 to 0. It is
              00471 ;          decremented every game loop iteration. When the timer falls below 0
              00472 ;          the last digit of the star date of the Galactic Chart Panel Display
              00473 ;          is increased and the timer is reset to a value of 40. 
              00474 ;
              00475 ; $75      DOCKSTATE
              00476 ;
              00477 ;          State of docking operation. Used values are:
              00478 ;            $00 -> NOT DOCKED
              00479 ;            $01 -> TRANSFER COMPLETE
              00480 ;            $81 -> RETURN TRANSFER VESSEL
              00481 ;            $FF -> ORBIT ESTABLISHED
              00482 ;
              00483 ; $76      COUNT256
              00484 ;
              00485 ;          Wrap-around counter. Counts from 0..255, then starts over at 0. It is
              00486 ;          incremented every game loop iteration.
              00487 ;
              00488 ; $77      IDLECNTLO
              00489 ;
              00490 ;          Idle counter (low byte). Forms a 16-bit counter together with
              00491 ;          IDLECNTHI ($66), which is incremented during the execution of the
              00492 ;          Vertical Blank Interrupt handler VBIHNDLR ($A6D1).
              00493 ;
              00494 ;          NOTE: This variable is never properly initialized except at initial
              00495 ;          cartridge startup (cold start).
              00496 ;
              00497 ; $78      ZYLONUNITTIM
              00498 ;
              00499 ;          Zylon unit movement timer. Triggers movement of Zylon units on the
              00500 ;          Galactic Chart. At the start of the game, the timer is initialized to
              00501 ;          a value of 100. It is decremented every 40 game loop iterations. When
              00502 ;          the timer falls below 0 the Zylon units move on the Galactic Chart
              00503 ;          and the timer value is reset to 49. If a starbase is surrounded the
              00504 ;          timer is reset to 99 to buy you some extra time to destroy one of the
              00505 ;          surrounding Zylon units.
              00506 ;
              00507 ; $79      MAXSPCOBJIND
              00508 ;
              00509 ;          Maximum index of used space objects in the current game loop
              00510 ;          iteration. Frequently used values are:
              00511 ;            $10 -> During regular cruise (5 PLAYER space objects + 12 PLAYFIELD
              00512 ;                   space objects (stars))
              00513 ;            $30 -> During explosion or hyperwarp (5 PLAYER space objects + 12
              00514 ;                   PLAYFIELD space objects (stars) + 32 PLAYFIELD space objects
              00515 ;                   (explosion fragments or stars of star trails))
              00516 ;
              00517 ; $7A      SAVMAXSPCOBJIND
              00518 ;
              00519 ;          Maximum index of used space objects in the previous 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 ; $7B      ISSTARBASESECT
              00528 ;
              00529 ;          Indicates whether a starbase is in this sector. Used values are:
              00530 ;            $00 -> Sector contains no starbase
              00531 ;            $FF -> Sector contains starbase
              00532 ;
              00533 ; $7C      ISTRACKCOMPON
              00534 ;
              00535 ;          Indicates whether the Tracking Computer is on or off. Used values
              00536 ;          are:
              00537 ;            $00 -> Tracking Computer is off
              00538 ;            $FF -> Tracking Computer is on
              00539 ;
              00540 ; $7D      ISSHIELDSON
              00541 ;
              00542 ;          Indicates whether the Shields are on or off. Used values are:
              00543 ;            $00 -> Shields are off
              00544 ;            $08 -> Shields are on
              00545 ;
              00546 ;          If the Shields are on then the value of ISSHIELDSON ($7D) also
              00547 ;          indicates the number of energy subunits consumed per game loop
              00548 ;          iteration. See also subroutine UPDPANEL ($B804).
              00549 ;
              00550 ; $7E      ISATTCOMPON
              00551 ;
              00552 ;          Indicates whether the Attack Computer is on or off. Used values are:
              00553 ;            $00 -> Attack Computer off
              00554 ;            $02 -> Attack Computer on
              00555 ;
              00556 ;          If the Attack Computer is on then the value of ISATTCOMPON ($7E) also
              00557 ;          indicates the number of energy subunits consumed per game loop
              00558 ;          iteration. See also subroutine UPDPANEL ($B804).
              00559 ;
              00560 ; $7F      ENERGYCNT
              00561 ;
              00562 ;          Running counter of consumed energy subunits (256 energy subunits = 1
              00563 ;          energy unit displayed by the 4-digit ENERGY readout of the Control
              00564 ;          Panel Display). Forms an invisible fractional or "decimals" part of
              00565 ;          the 4-digit ENERGY readout of the Control Panel Display. See also
              00566 ;          subroutine UPDPANEL ($B804).
              00567 ;
              00568 ; $80      DRAINRATE
              00569 ;
              00570 ;          Energy drain rate of our starship's Engines per game loop iteration
              00571 ;          in energy subunits (256 energy subunits = 1 energy unit displayed by
              00572 ;          the 4-digit ENERGY readout of the Control Panel Display). Values are
              00573 ;          picked from table DRAINRATETAB ($BAD3). See also subroutine UPDPANEL
              00574 ;          ($B804).
              00575 ;
              00576 ; $81      SHIELDSCOLOR
              00577 ;
              00578 ;          Shields color. Used values are: 
              00579 ;            $00 -> {BLACK} (Shields are off)
              00580 ;            $A0 -> {DARK GREEN} (Shields are on)
              00581 ;
              00582 ; $82      PL3HIT
              00583 ;
              00584 ;          Collision register of PLAYER3 (usually our starship's photon torpedo
              00585 ;          0) with other PLAYERs. Used values are:
              00586 ;              $00 -> No collision
              00587 ;            > $00 -> PLAYER3 has collided with another PLAYER space object. See
              00588 ;                     subroutine COLLISION ($AF3D) for details which PLAYER has
              00589 ;                     been hit by PLAYER3.
              00590 ;
              00591 ; $83      PL4HIT
              00592 ;
              00593 ;          Collision register of PLAYER4 (usually our starship's photon torpedo
              00594 ;          1) with other PLAYERs. Used values are:
              00595 ;              $00 -> No collision
              00596 ;            > $00 -> PLAYER4 has collided with another PLAYER space object. See
              00597 ;                     subroutine COLLISION ($AF3D) for details which PLAYER has
              00598 ;                     been hit by PLAYER4.
              00599 ;
              00600 ; $84      OLDTRIG0
              00601 ;
              00602 ;          Joystick trigger state. Used values are:
              00603 ;            $00 -> Joystick trigger was pressed
              00604 ;            $01 -> Joystick trigger was not pressed
              00605 ;            $AA -> Joystick trigger was "virtually" pressed (will launch
              00606 ;                   another of our starship's photon torpedoes, see subroutine
              00607 ;                   TRIGGER ($AE29).
              00608 ;
              00609 ; $86      ISTRACKING
              00610 ;
              00611 ;          Indicates whether one of our starship's photon torpedoes is currently
              00612 ;          tracking (homing in on) the target space object. Used values are:
              00613 ;              $00 -> No target space object tracked. Our starship's photon
              00614 ;                     torpedoes will fly just straight ahead.
              00615 ;            > $00 -> Tracking a target space object. Our starship's photon
              00616 ;                     torpedoes will home in on the tracked space object.
              00617 ;
              00618 ; $87      BARRELNR
              00619 ;
              00620 ;          Barrel from which our starship's next photon torpedo will be
              00621 ;          launched. Used values are:
              00622 ;            $00 -> Left barrel
              00623 ;            $01 -> Right barrel
              00624 ;
              00625 ; $88      LOCKONLIFE
              00626 ;
              00627 ;          Lifetime of target lock-on. A target remains in lock-on while
              00628 ;          LOCKONLIFE ($88) counts down from 12 to 0. It is decremented every
              00629 ;          game loop iteration.
              00630 ;
              00631 ; $89      PLTRACKED
              00632 ;
              00633 ;          Index of currently tracked PLAYER. It is copied in subroutine TRIGGER
              00634 ;          ($AE29) from TRACKDIGIT ($095C). Used values are:
              00635 ;            $00 -> Track Zylon ship 0
              00636 ;            $01 -> Track Zylon ship 1
              00637 ;            $02 -> Track starbase during docking operations
              00638 ;            $03 -> Track Hyperwarp Target Marker during hyperwarp
              00639 ;
              00640 ; $8A      HITBADNESS
              00641 ;
              00642 ;          Severeness of a Zylon photon torpedo hit. Used values are:
              00643 ;            $00 -> NO HIT
              00644 ;            $7F -> SHIELDS HIT
              00645 ;            $FF -> STARSHIP DESTROYED
              00646 ;
              00647 ; $8B      REDALERTLIFE
              00648 ;
              00649 ;          Lifetime of red alert. It decreases from 255 to 0. It is decremented
              00650 ;          every game loop iteration.
              00651 ;
              00652 ; $8C      WARPDEPRROW
              00653 ;
              00654 ;          Departure hyperwarp marker row number on the Galactic Chart. It is
              00655 ;          given in Player/Missile pixels relative to the top Galactic Chart
              00656 ;          border. It is initialized to a value of $47 (vertical center of
              00657 ;          Galactic Chart). Divide this value by 16 to get the departure sector
              00658 ;          row number. Used values are: $00..$7F.
              00659 ;
              00660 ; $8D      WARPDEPRCOLUMN
              00661 ;
              00662 ;          Departure hyperwarp marker column number on the Galactic Chart. It is
              00663 ;          given in Player/Missile pixels relative to the left Galactic Chart
              00664 ;          border and initialized to a value of $43 (horizontal center of
              00665 ;          Galactic Chart). Divide this value by 8 to get the departure sector
              00666 ;          column number. Used values are: $00..$7F.
              00667 ;
              00668 ; $8E      WARPARRVROW
              00669 ;
              00670 ;          Arrival hyperwarp marker row number on the Galactic Chart in
              00671 ;          Player/Missile pixels relative to top Galactic Chart border. It is
              00672 ;          initialized to a value of $47 (vertical center of Galactic Chart).
              00673 ;          Divide this value by 16 to get the arrival sector row number. Used
              00674 ;          values are: $00..$7F. 
              00675 ;
              00676 ; $8F      WARPARRVCOLUMN
              00677 ;
              00678 ;          Arrival hyperwarp marker column number on the Galactic Chart in
              00679 ;          Player/Missile pixels relative to left Galactic Chart border. It is
              00680 ;          initialized to a value of $43 (horizontal center of Galactic Chart).
              00681 ;          Divide this value by 8 to get the arrival sector column number. Used
              00682 ;          values are: $00..$7F. 
              00683 ;
              00684 ; $90      CURRSECTOR
              00685 ;
              00686 ;          Galactic Chart sector of the current location of our starship. At the
              00687 ;          start of the game it is initialized to a value of $48. Used values
              00688 ;          are: $00..$7F with, for example,
              00689 ;            $00 -> NORTHWEST corner sector
              00690 ;            $0F -> NORTHEAST corner sector
              00691 ;            $70 -> SOUTHWEST corner sector
              00692 ;            $7F -> SOUTHWEST corner sector
              00693 ;
              00694 ;          See also ARRVSECTOR ($92). 
              00695 ;
              00696 ; $91      WARPENERGY
              00697 ;
              00698 ;          Energy required to hyperwarp between the departure and arrival
              00699 ;          hyperwarp marker locations on the Galactic Chart divided by 10.
              00700 ;          Values are picked from table WARPENERGYTAB ($BADD). Multiply this
              00701 ;          value by 10 to get the actual value in energy units displayed by the
              00702 ;          Galactic Chart Panel Display.
              00703 ;
              00704 ; $92      ARRVSECTOR
              00705 ;
              00706 ;          Galactic Chart arrival sector of our starship after hyperwarp. Used
              00707 ;          values are: $00..$7F with, for example,
              00708 ;            $00 -> NORTHWEST corner sector
              00709 ;            $0F -> NORTHEAST corner sector
              00710 ;            $70 -> SOUTHWEST corner sector
              00711 ;            $7F -> SOUTHWEST corner sector
              00712 ;
              00713 ;          See also CURRSECTOR ($90). 
              00714 ;
              00715 ; $93      HUNTSECTOR
              00716 ;
              00717 ;          Galactic Chart sector of the starbase toward which the Zylon units
              00718 ;          are currently moving. Used values are: $00..$7F with, for example,
              00719 ;            $00 -> NORTHWEST corner sector
              00720 ;            $0F -> NORTHEAST corner sector
              00721 ;            $70 -> SOUTHWEST corner sector
              00722 ;            $7F -> SOUTHWEST corner sector
              00723 ;
              00724 ; $94      HUNTSECTCOLUMN
              00725 ;
              00726 ;          Galactic Chart sector column number of the starbase toward which the
              00727 ;          Zylon units are currently moving. Used values are: 0..15.
              00728 ;
              00729 ; $95      HUNTSECTROW
              00730 ;
              00731 ;          Galactic Chart sector row number of the starbase toward which the
              00732 ;          Zylon units are currently moving. Used values are: 0..7.
              00733 ;
              00734 ; $96..$9E NEWZYLONDIST
              00735 ;
              00736 ;          Table of distances between a Zylon unit and the hunted starbase when
              00737 ;          the Zylon unit is tentatively moved in one of the 9 possible
              00738 ;          directions NORTH, NORTHWEST, WEST, SOUTHWEST, SOUTH, SOUTHEAST, EAST,
              00739 ;          NORTHEAST, CENTER. Used to decide into which sector the Zylon unit
              00740 ;          should move.
              00741 ;
              00742 ; $9E      OLDZYLONDIST
              00743 ;
              00744 ;          Current distance between the Zylon unit and the hunted starbase.
              00745 ;
              00746 ; $9F      HUNTTIM
              00747 ;
              00748 ;          This timer counts down from 7. It is decremented every game loop
              00749 ;          iteration. When the timer falls below 0 the Zylon units re-decide
              00750 ;          toward which starbase to move.
              00751 ;
              00752 ; $A0      BLIPCOLUMN
              00753 ;
              00754 ;          Top-left screen pixel column number of blip shape displayed in the
              00755 ;          Attack Computer Display. Used in subroutine UPDATTCOMP ($A7BF). Used
              00756 ;          values are: 120..142.
              00757 ;
              00758 ; $A1      BLIPROW
              00759 ;
              00760 ;          Top-left screen pixel row number of blip shape displayed in the
              00761 ;          Attack Computer Display. Used in subroutine UPDATTCOMP ($A7BF). Used
              00762 ;          values are: 71..81.
              00763 ;
              00764 ; $A2      BLIPCYCLECNT
              00765 ;
              00766 ;          Blip cycle counter. It controls drawing the blip shape in the Attack
              00767 ;          Computer Display. This value is incremented every game loop
              00768 ;          iteration. Used in subroutine UPDATTCOMP ($A7BF). Used values are:
              00769 ;            $00..$04 -> Draw 0..4th row of blip shape
              00770 ;            $05..$09 -> Do not draw blip shape (delay)
              00771 ;            $0A      -> Recalculate blip shape position, erase Attack Computer
              00772 ;                        Display
              00773 ;
              00774 ; $A3      ISINLOCKON
              00775 ;
              00776 ;          Indicates whether the tracked space object is currently in full
              00777 ;          lock-on (horizontally and vertically centered as well as in range) in
              00778 ;          the Attack Computer Display. If so, all lock-on markers show up on
              00779 ;          the Attack Computer Display and our starship's launched photon
              00780 ;          torpedoes will home in on the tracked space object. Used values are:
              00781 ;            $00 -> Not in lock-on
              00782 ;            $A0 -> In lock-on
              00783 ;
              00784 ; $A4      DIRLEN
              00785 ;
              00786 ;          Used to pass the direction and length of a single line to be drawn in
              00787 ;          the PLAYFIELD. Used in subroutines DRAWLINES ($A76F), DRAWLINE
              00788 ;          ($A782), and UPDATTCOMP ($A7BF). Used values are:
              00789 ;            Bit B7 = 0 -> Draw left
              00790 ;            Bit B7 = 1 -> Draw down
              00791 ;            Bits B6..0 -> Length of line in pixels.
              00792 ;
              00793 ;          See also PENROW ($A5) and PENCOLUMN ($A6).
              00794 ;
              00795 ; $A5      PENROW
              00796 ;
              00797 ;          Used to pass the start screen pixel row number of the line to be
              00798 ;          drawn in the PLAYFIELD. Used in subroutines DRAWLINES ($A76F),
              00799 ;          DRAWLINE ($A782), and UPDATTCOMP ($A7BF).
              00800 ;
              00801 ; $A6      PENCOLUMN
              00802 ;
              00803 ;          Used to pass the start screen pixel column number of the line to be
              00804 ;          drawn in the PLAYFIELD. Used in subroutines DRAWLINES ($A76F),
              00805 ;          DRAWLINE ($A782), and UPDATTCOMP ($A7BF).
              00806 ;
              00807 ; $A7      CTRLDZYLON
              00808 ;
              00809 ;          Index of Zylon ship currently controlled by the program. Used in
              00810 ;          subroutine MANEUVER ($AA79). The value is toggled every other game
              00811 ;          loop iteration. Used values are:
              00812 ;            $00 -> Control Zylon ship 0.
              00813 ;            $01 -> Control Zylon ship 1.
              00814 ;
              00815 ; $A8      ZYLONFLPAT0
              00816 ;
              00817 ;          Flight pattern of Zylon ship 0. Used in subroutine MANEUVER ($AA79).
              00818 ;          Used values are:
              00819 ;            $00 -> Attack flight pattern "0"
              00820 ;            $01 -> Flight pattern "1"
              00821 ;            $04 -> Flight pattern "4"
              00822 ;
              00823 ; $A9      ZYLONFLPAT1
              00824 ;
              00825 ;          Flight pattern of Zylon ship 1. Compare ZYLONFLPAT0 ($A8).
              00826 ;
              00827 ; $AA      MILESTTIM0
              00828 ;
              00829 ;          Timer of the milestone velocity indices of Zylon ship 0. Used in
              00830 ;          subroutine MANEUVER ($AA79).
              00831 ;
              00832 ;          When Zylon ship 0 is active, this value is decremented every game
              00833 ;          loop iteration. If it falls below 0 then the milestone velocity
              00834 ;          indices of Zylon ship 0 are recalculated. When Zylon ship 0 is
              00835 ;          controlled by the computer for the first time, the timer is set to an
              00836 ;          initial value of 1, later to an initial value of 120.
              00837 ;
              00838 ; $AB      MILESTTIM1
              00839 ;
              00840 ;          Timer of the milestone velocity index vector of Zylon ship 1. Compare
              00841 ;          MILESTTIM0 ($AA).
              00842 ;
              00843 ; $AC      MILESTVELINDZ0
              00844 ;
              00845 ;          Milestone z-velocity index of Zylon ship 0. Used in subroutine
              00846 ;          MANEUVER ($AA79). The current z-velocity index of Zylon ship 0
              00847 ;          ZYLONVELINDZ0 ($B2) is compared with this index and gradually
              00848 ;          adjusted to it. Used values are: 0..15.
              00849 ;
              00850 ; $AD      MILESTVELINDZ1
              00851 ;
              00852 ;          Milestone z-velocity index of Zylon ship 1. Compare MILESTVELINDZ0
              00853 ;          ($AC).
              00854 ;
              00855 ; $AE      MILESTVELINDX0
              00856 ;
              00857 ;          Milestone x-velocity index of Zylon ship 0. Used in subroutine
              00858 ;          MANEUVER ($AA79). The current x-velocity index of Zylon ship 0
              00859 ;          ZYLONVELINDX0 ($B4) is compared with this index and gradually
              00860 ;          adjusted to it. Used values are: 0..15.
              00861 ;
              00862 ; $AF      MILESTVELINDX1
              00863 ;
              00864 ;          Milestone x-velocity index of Zylon ship 1. Compare MILESTVELINDX0
              00865 ;          ($AE).
              00866 ;
              00867 ; $B0      MILESTVELINDY0
              00868 ;
              00869 ;          Milestone y-velocity index of Zylon ship 0. Used in subroutine
              00870 ;          MANEUVER ($AA79). The current y-velocity index of Zylon ship 0
              00871 ;          ZYLONVELINDY0 ($B6) is compared with this index and gradually
              00872 ;          adjusted to it. Used values are: 0..15.
              00873 ;
              00874 ; $B1      MILESTVELINDY1
              00875 ;
              00876 ;          Milestone y-velocity index of Zylon ship 1. Compare MILESTVELINDY0
              00877 ;          ($B0).
              00878 ;
              00879 ; $B2      ZYLONVELINDZ0
              00880 ;
              00881 ;          Current z-velocity index of Zylon ship 0. Used in subroutine MANEUVER
              00882 ;          ($AA79). It indexes velocity values in ZYLONVELTAB ($BF99). Used
              00883 ;          values are: 0..15.
              00884 ;
              00885 ; $B3      ZYLONVELINDZ1
              00886 ;
              00887 ;          Current z-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00888 ;          ($B2).
              00889 ;
              00890 ; $B4      ZYLONVELINDX0
              00891 ;
              00892 ;          Current x-velocity index of Zylon ship 0. Compare ZYLONVELINDZ0
              00893 ;          ($B2).
              00894 ;
              00895 ; $B5      ZYLONVELINDX1
              00896 ;
              00897 ;          Current x-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00898 ;          ($B2).
              00899 ;
              00900 ; $B6      ZYLONVELINDY0
              00901 ;
              00902 ;          Current y-velocity index of Zylon ship 0. Compare ZYLONVELINDZ0
              00903 ;          ($B2).
              00904 ;
              00905 ; $B7      ZYLONVELINDY1
              00906 ;
              00907 ;          Current y-velocity index of Zylon ship 1. Compare ZYLONVELINDZ0
              00908 ;          ($B2).
              00909 ;
              00910 ; $B8      ISBACKATTACK0
              00911 ;
              00912 ;          Indicates whether Zylon ship 0 will attack our starship from the
              00913 ;          back. Used in subroutine MANEUVER ($AA79). Used values are:
              00914 ;            $00 -> Zylon ship 0 attacks from the front of our starship
              00915 ;            $01 -> Zylon ship 0 attacks from the front and back of our starship
              00916 ;
              00917 ; $B9      ISBACKATTACK1
              00918 ;
              00919 ;          Indicates whether Zylon ship 1 will attack our starship from the
              00920 ;          back. Compare ISBACKATTACK0 ($B8).
              00921 ;
              00922 ; $BA      ZYLONTIMX0
              00923 ;
              00924 ;          Delay timer of the x-velocity index of Zylon ship 0. Used in
              00925 ;          subroutine MANEUVER ($AA79). It is decremented every game loop
              00926 ;          iteration. When the timer value falls below 0 the current velocity
              00927 ;          index ZYLONVELINDX0 ($B4) is adjusted depending on the current
              00928 ;          joystick position. The new timer value is set depending on the
              00929 ;          resulting new x-velocity index. Used values are: 0, 2, 4, ..., 14.
              00930 ;
              00931 ; $BB      ZYLONTIMX1
              00932 ;
              00933 ;          Delay timer of x-velocity index of Zylon ship 1. Compare ZYLONTIMX0
              00934 ;          ($BA).
              00935 ;
              00936 ; $BC      ZYLONTIMY0
              00937 ;
              00938 ;          Delay timer of y-velocity index of Zylon ship 0. Compare ZYLONTIMX0
              00939 ;          ($BA).
              00940 ;
              00941 ; $BD      ZYLONTIMY1
              00942 ;
              00943 ;          Delay timer of y-velocity index of Zylon ship 1. Compare ZYLONTIMX0
              00944 ;          ($BA).
              00945 ;
              00946 ; $BE      TORPEDODELAY
              00947 ;
              00948 ;          After a Zylon photon torpedo has hit our starship this timer is
              00949 ;          initialized to a value of 2. It is decremented every game loop
              00950 ;          iteration and so delays the launch of the next Zylon photon torpedo
              00951 ;          for 2 game loop iterations.
              00952 ;
              00953 ; $BF      ZYLONATTACKER
              00954 ;
              00955 ;          PLAYER index of the Zylon ship that launched the Zylon photon
              00956 ;          torpedo. It is used in GAMELOOP ($A1F3) to override the current
              00957 ;          tracking computer settings in order to track this Zylon ship first.
              00958 ;          Used values are:
              00959 ;            $00 -> Zylon photon torpedo was launched by Zylon ship 0
              00960 ;            $01 -> Zylon photon torpedo was launched by Zylon ship 1
              00961 ;
              00962 ; $C0      WARPSTATE
              00963 ;
              00964 ;          Hyperwarp state. Used values are:
              00965 ;            $00 -> Hyperwarp not engaged
              00966 ;            $7F -> Hyperwarp engaged
              00967 ;            $FF -> In hyperspace
              00968 ;
              00969 ; $C1      VELOCITYHI
              00970 ;
              00971 ;          Our starship's velocity (high byte) in <KM/H>. Used values are:
              00972 ;            $00 -> Not in hyperspace (regular cruise or accelerating to
              00973 ;                   hyperspace velocity)
              00974 ;            $01 -> Hyperspace velocity
              00975 ;
              00976 ;          See also VELOCITYLO ($70). 
              00977 ;
              00978 ; $C2      TRAILDELAY
              00979 ;
              00980 ;          Timer to delay the creation of the next star trail. This value is
              00981 ;          decremented from 3 to 0 every game loop iteration during the
              00982 ;          hyperwarp STAR TRAIL PHASE in subroutine INITTRAIL ($A9B4).
              00983 ;
              00984 ; $C3      TRAILIND
              00985 ;
              00986 ;          Position vector index of the star trail's first star. Used in
              00987 ;          subroutine INITTRAIL ($A9B4) to initialize a star trail, which is
              00988 ;          then displayed during the hyperwarp STAR TRAIL PHASE. Used values
              00989 ;          are: 17..48 in wrap-around fashion.
              00990 ;
              00991 ; $C4      WARPTEMPCOLUMN
              00992 ;
              00993 ;          Temporary arrival column number of our starship on the Galactic Chart
              00994 ;          at the begin of hyperspace. It is given in Player/Missile pixels
              00995 ;          relative to the left Galactic Chart border. Divide this value by 8 to
              00996 ;          get the sector column number. Used values are: $00..$7F. See also
              00997 ;          WARPARRVCOLUMN ($8F).
              00998 ;
              00999 ; $C5      WARPTEMPROW
              01000 ;
              01001 ;          Temporary arrival row number of our starship on the Galactic Chart at
              01002 ;          the begin of hyperspace. It is given in Player/Missile pixels
              01003 ;          relative to top Galactic Chart border. Divide this value by 16 to get
              01004 ;          the sector row number.  Used values are: $00..$7F. See also
              01005 ;          WARPARRVROW ($8E).
              01006 ;
              01007 ; $C6      VEERMASK
              01008 ;
              01009 ;          Limits the veer-off velocity of the Hyperwarp Target Marker during
              01010 ;          the hyperwarp ACCELERATION PHASE in subroutine HYPERWARP ($A89B).
              01011 ;          Values are picked from table VEERMASKTAB ($BED7).
              01012 ;
              01013 ;          Also used as a local variable.
              01014 ;
              01015 ; $C7      VICINITYMASK
              01016 ;
              01017 ;          Mask to confine space objects' position vector components
              01018 ;          (coordinates) in a sector into a certain interval around our starship
              01019 ;          after its arrival from hyperspace. Values are picked from table
              01020 ;          VICINITYMASKTAB ($BFB3).
              01021 ;
              01022 ; $C8      JOYSTICKX
              01023 ;
              01024 ;          Horizontal joystick direction. Values are picked from table
              01025 ;          STICKINCTAB ($BAF5). Used values are:
              01026 ;            $01 -> Right
              01027 ;            $00 -> Centered
              01028 ;            $FF -> Left
              01029 ;
              01030 ; $C9      JOYSTICKY
              01031 ;
              01032 ;          Vertical joystick direction. Values are picked from table STICKINCTAB
              01033 ;          ($BAF5). Used values are:
              01034 ;            $01 -> Up
              01035 ;            $00 -> Centered 
              01036 ;            $FF -> Down
              01037 ;
              01038 ; $CA      KEYCODE
              01039 ;
              01040 ;          Hardware keyboard code of the pressed key on the keyboard. Shift and
              01041 ;          Control key bits B7..6 are always set.
              01042 ;
              01043 ; $CB..$CC SCORE
              01044 ;
              01045 ;          Internal 16-bit score of the game in low byte-high byte order
              01046 ;
              01047 ; $CD      SCOREDRANKIND
              01048 ;
              01049 ;          Scored Rank Index. It is translated with table RANKTAB ($BEE9) to a
              01050 ;          title phrase offset pointing to the rank string. Used values are: 
              01051 ;            $00 -> GALACTIC COOK
              01052 ;            $01 -> GARBAGE SCOW CAPTAIN
              01053 ;            $02 -> GARBAGE SCOW CAPTAIN
              01054 ;            $03 -> ROOKIE
              01055 ;            $04 -> ROOKIE
              01056 ;            $05 -> NOVICE
              01057 ;            $06 -> NOVICE
              01058 ;            $07 -> ENSIGN
              01059 ;            $08 -> ENSIGN
              01060 ;            $09 -> PILOT
              01061 ;            $0A -> PILOT
              01062 ;            $0B -> ACE
              01063 ;            $0C -> LIEUTENANT
              01064 ;            $0D -> WARRIOR
              01065 ;            $0E -> CAPTAIN
              01066 ;            $0F -> COMMANDER
              01067 ;            $10 -> COMMANDER
              01068 ;            $11 -> STAR COMMANDER
              01069 ;            $12 -> STAR COMMANDER
              01070 ;
              01071 ; $CE      SCOREDCLASSIND
              01072 ;
              01073 ;          Scored Class Index. It is translated into a class number with table
              01074 ;          CLASSTAB ($BEFC). Used values are:
              01075 ;            $00 -> Class 5
              01076 ;            $01 -> Class 5
              01077 ;            $02 -> Class 5
              01078 ;            $03 -> Class 4
              01079 ;            $04 -> Class 4
              01080 ;            $05 -> Class 4
              01081 ;            $06 -> Class 4
              01082 ;            $07 -> Class 3
              01083 ;            $08 -> Class 3
              01084 ;            $09 -> Class 3
              01085 ;            $0A -> Class 2
              01086 ;            $0B -> Class 2
              01087 ;            $0C -> Class 2
              01088 ;            $0D -> Class 1
              01089 ;            $0E -> Class 1
              01090 ;            $0F -> Class 1
              01091 ;
              01092 ; $CF      TITLELIFE
              01093 ;
              01094 ;          Lifetime of title line. It is decremented every game loop iteration.
              01095 ;          Used initial values are:
              01096 ;            $3C -> When displaying regular title phrases
              01097 ;            $FE -> When displaying "STARBASE SURROUNDED", "STARBASE DESTOYED",
              01098 ;                   and "RED ALERT" messages
              01099 ;            $FF -> Hide title line
              01100 ;
              01101 ; $D0      SHIPVIEW
              01102 ;
              01103 ;          Current view of our starship. Values are picked from table
              01104 ;          VIEWMODETAB ($BE22). Used values are:
              01105 ;            $00 -> Front view
              01106 ;            $01 -> Aft view
              01107 ;            $40 -> Long-Range Scan view
              01108 ;            $80 -> Galactic Chart view
              01109 ;
              01110 ; $D1      TITLEPHR
              01111 ;
              01112 ;          Title phrase offset for text phrase in title line. Used values are:
              01113 ;            $00..$7B -> Title phrase offset into PHRASETAB ($BBAA)
              01114 ;            $FF      -> Hide title line
              01115 ;
              01116 ;          See also NEWTITLEPHR ($65). 
              01117 ;
              01118 ; $D2      BEEPFRQIND
              01119 ;
              01120 ;          Beeper sound pattern: Running index into frequency table BEEPFRQTAB
              01121 ;          ($BF5C). See also BEEPFRQSTART ($D7). See also subroutines BEEP
              01122 ;          ($B3A6) and SOUND ($B2AB).
              01123 ;
              01124 ; $D3      BEEPREPEAT
              01125 ;
              01126 ;          Beeper sound pattern: Number of times the beeper sound pattern is
              01127 ;          repeated - 1. See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01128 ;
              01129 ; $D4      BEEPTONELIFE
              01130 ;
              01131 ;          Beeper sound pattern: Lifetime of tone in TICKs - 1. See also
              01132 ;          subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01133 ;
              01134 ; $D5      BEEPPAUSELIFE
              01135 ;
              01136 ;          Beeper sound pattern: Lifetime of pause in TICKs - 1. Used values
              01137 ;          are: 
              01138 ;            < $FF -> Number of TICKs - 1 to play
              01139 ;              $FF -> Skip playing pause
              01140 ;
              01141 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01142 ;
              01143 ; $D6      BEEPPRIORITY
              01144 ;
              01145 ;          Beeper sound pattern: Pattern priority. Each beeper sound pattern has
              01146 ;          a priority. When a pattern of higher priority is about to be played
              01147 ;          the pattern that is currently playing is stopped. Used values are:
              01148 ;              $00 -> No pattern playing at the moment
              01149 ;            > $00 -> Pattern priority
              01150 ;
              01151 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01152 ;
              01153 ; $D7      BEEPFRQSTART
              01154 ;
              01155 ;          Beeper sound pattern: Index to first byte of the pattern frequency in
              01156 ;          table BEEPFRQTAB ($BF5C). See also BEEPFRQIND ($D2). See also
              01157 ;          subroutines BEEP ($B3A6) and SOUND ($B2AB).
              01158 ;
              01159 ; $D8      BEEPLIFE
              01160 ;
              01161 ;          Beeper sound pattern: Lifetime of the current tone or pause in TICKs.
              01162 ;          It is decremented every TICK. See also subroutines BEEP ($B3A6) and
              01163 ;          SOUND ($B2AB). 
              01164 ;
              01165 ; $D9      BEEPTOGGLE
              01166 ;
              01167 ;          Beeper sound pattern: Indicates that either a tone or a pause is
              01168 ;          currently played. Used values are:
              01169 ;            $00 -> Tone
              01170 ;            $01 -> Pause
              01171 ;
              01172 ;          See also subroutines BEEP ($B3A6) and SOUND ($B2AB).    
              01173 ;
              01174 ; $DA      NOISETORPTIM
              01175 ;
              01176 ;          Noise sound pattern: Timer for PHOTON TORPEDO LAUNCHED noise sound
              01177 ;          pattern. It is decremented every TICK. See also subroutines NOISE
              01178 ;          ($AEA8) and SOUND ($B2AB).
              01179 ;
              01180 ; $DB      NOISEEXPLTIM
              01181 ;
              01182 ;          Noise sound pattern: Timer for SHIP EXPLOSION and ZYLON EXPLOSION
              01183 ;          noise sound pattern. It is decremented every TICK. See also
              01184 ;          subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01185 ;
              01186 ; $DC      NOISEAUDC2
              01187 ;
              01188 ;          Noise sound pattern: Audio channel 1/2 control shadow register. See
              01189 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01190 ;
              01191 ; $DD      NOISEAUDC3
              01192 ;
              01193 ;          Noise sound pattern: Audio channel 3 control shadow register. See
              01194 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01195 ;
              01196 ; $DE      NOISEAUDF1
              01197 ;
              01198 ;          Noise sound pattern: Audio channel 1 frequency shadow register. See
              01199 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01200 ;
              01201 ; $DF      NOISEAUDF2
              01202 ;
              01203 ;          Noise sound pattern: Audio channel 2 frequency shadow register. See
              01204 ;          also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01205 ;
              01206 ; $E0      NOISEFRQINC
              01207 ;
              01208 ;          Noise sound pattern: Audio channel 1/2 frequency increment. See also
              01209 ;          subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01210 ;
              01211 ; $E1      NOISELIFE
              01212 ;
              01213 ;          Noise sound pattern: Noise sound pattern lifetime. It is decremented
              01214 ;          every TICK. See also subroutines NOISE ($AEA8) and SOUND ($B2AB).
              01215 ;
              01216 ; $E2      NOISEZYLONTIM
              01217 ;
              01218 ;          Timer to trigger the ZYLON EXPLOSION noise sound pattern. It is set
              01219 ;          in subroutine COLLISION ($AF3D) when an impact of one of our
              01220 ;          starship's photon torpedoes into a target is imminent. The timer is
              01221 ;          decremented every TICK during the execution of the Vertical Blank
              01222 ;          Interrupt handler VBIHNDLR ($A6D1). When the timer value reaches 0
              01223 ;          the ZYLON EXPLOSION noise sound pattern is played in subroutine SOUND
              01224 ;          ($B2AB). 
              01225 ;
              01226 ; $E3      NOISEHITLIFE
              01227 ;
              01228 ;          Lifetime of special explosion noise when our starship was hit by a
              01229 ;          Zylon photon torpedo. It is set in routine GAMELOOP ($A1F3) to a
              01230 ;          value of 64 TICKs. It is decremented every TICK during the execution
              01231 ;          of the Vertical Blank Interrupt handler VBIHNDLR ($A6D1).
              01232 ;
              01233 ; $E4      PL0SHAPOFF
              01234 ;
              01235 ;          PLAYER0 offset into shape table PLSHAP2TAB ($B9B1)
              01236 ;
              01237 ; $E5      PL1SHAPOFF
              01238 ;
              01239 ;          PLAYER1 offset into shape table PLSHAP2TAB ($B9B1)
              01240 ;
              01241 ; $E6      PL2SHAPOFF
              01242 ;
              01243 ;          PLAYER2 offset into shape table PLSHAP1TAB ($B8E4)
              01244 ;
              01245 ; $E7      PL3SHAPOFF
              01246 ;
              01247 ;          PLAYER3 offset into shape table PLSHAP1TAB ($B8E4)
              01248 ;
              01249 ; $E8      PL4SHAPOFF
              01250 ;
              01251 ;          PLAYER4 offset into shape table PLSHAP1TAB ($B8E4)
              01252 ;
              01253 ; $E9      PL0LIFE
              01254 ;
              01255 ;          Lifetime of the space object represented by PLAYER0 (usually Zylon
              01256 ;          ship 0). Any value other than $FF is decremented with every game loop
              01257 ;          iteration. Used values are:
              01258 ;            $00      -> Space object not alive (= not in use)
              01259 ;            $01..$FE -> Values during lifetime countdown
              01260 ;            $FF      -> Infinite lifetime (not counted down)
              01261 ;
              01262 ; $EA      PL1LIFE
              01263 ;
              01264 ;          Lifetime of a space object represented by PLAYER1 (usually Zylon ship
              01265 ;          1). Compare PL0LIFE ($E9).
              01266 ;
              01267 ; $EB      PL2LIFE
              01268 ;
              01269 ;          Lifetime of a space object represented by PLAYER2 (usually the Zylon
              01270 ;          photon torpedo). Compare PL0LIFE ($E9).
              01271 ;
              01272 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01273 ;          decremented from an initial value of $FF.
              01274 ;
              01275 ; $EC      PL3LIFE
              01276 ;
              01277 ;          Lifetime of a space object represented by PLAYER3 (usually our
              01278 ;          starship's photon torpedo 0). Compare PL2LIFE ($EB).
              01279 ;
              01280 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01281 ;          decremented from an initial value of $FF.
              01282 ;
              01283 ; $ED      PL4LIFE
              01284 ;
              01285 ;          Lifetime of a space object represented by PLAYER4 (usually our
              01286 ;          starship's photon torpedo 1). Compare PL2LIFE ($EB).
              01287 ;
              01288 ;          If this PLAYER represents a photon torpedo, its lifetime is
              01289 ;          decremented from an initial value of $FF.
              01290 ;
              01291 ; $EE      PL0COLOR
              01292 ;
              01293 ;          Color of PLAYER0
              01294 ;
              01295 ; $EF      PL1COLOR
              01296 ;
              01297 ;          Color of PLAYER1
              01298 ;
              01299 ; $F0      PL2COLOR
              01300 ;
              01301 ;          Color of PLAYER2
              01302 ;
              01303 ; $F1      PL3COLOR
              01304 ;
              01305 ;          Color of PLAYER3
              01306 ;
              01307 ; $F2      PF0COLOR
              01308 ;
              01309 ;          Color of PLAYFIELD0
              01310 ;
              01311 ; $F3      PF1COLOR
              01312 ;
              01313 ;          Color of PLAYFIELD1
              01314 ;
              01315 ; $F4      PF2COLOR
              01316 ;
              01317 ;          Color of PLAYFIELD2
              01318 ;
              01319 ; $F5      PF3COLOR
              01320 ;
              01321 ;          Color of PLAYFIELD3
              01322 ;
              01323 ; $F6      BGRCOLOR
              01324 ;
              01325 ;          Color of BACKGROUND
              01326 ;
              01327 ; $F7      PF0COLORDLI
              01328 ;
              01329 ;          Color of PLAYFIELD0 after DLI
              01330 ;
              01331 ; $F8      PF1COLORDLI
              01332 ;
              01333 ;          Color of PLAYFIELD1 after DLI
              01334 ;
              01335 ; $F9      PF2COLORDLI
              01336 ;
              01337 ;          Color of PLAYFIELD2 after DLI
              01338 ;
              01339 ; $FA      PF3COLORDLI
              01340 ;
              01341 ;          Color of PLAYFIELD3 after DLI
              01342 ;
              01343 ; $FB      BGRCOLORDLI
              01344 ;
              01345 ;          Color of BACKGROUND after DLI
              01346 ;
              01347 ; $0280..$02E9 DSPLST
              01348 ;
              01349 ;              Display List
              01350 ;
              01351 ; $0300..$03FF PL4DATA
              01352 ;
              01353 ;              PLAYER4 data area
              01354 ;
              01355 ; $0400..$04FF PL0DATA
              01356 ;
              01357 ;              PLAYER0 data area
              01358 ;
              01359 ; $0500..$05FF PL1DATA
              01360 ;
              01361 ;              PLAYER1 data area
              01362 ;
              01363 ; $0600..$06FF PL2DATA
              01364 ;
              01365 ;              PLAYER2 data area
              01366 ;
              01367 ; $0700..$07FF PL3DATA
              01368 ;
              01369 ;              PLAYER3 data area
              01370 ;
              01371 ; $0800..$0863 PFMEMROWLO
              01372 ;
              01373 ;              Lookup table of start addresses (low byte) for each row of
              01374 ;              PLAYFIELD memory, which is located at PFMEM ($1000). The table
              01375 ;              contains 100 bytes for 100 rows (of which only 99 are shown by
              01376 ;              the Display List, the PLAYFIELD is 160 x 99 pixels). The
              01377 ;              addresses grow in increments of 40 (40 bytes = 160 pixels in
              01378 ;              GRAPHICS7 mode = 1 PLAYFIELD row of pixels). See also PFMEMROWHI
              01379 ;              ($0864).
              01380 ;
              01381 ; $0864..$08C7 PFMEMROWHI
              01382 ;
              01383 ;              Lookup table of start addresses (high byte) of each row of
              01384 ;              PLAYFIELD memory. See also PFMEMROWLO ($0800).
              01385 ;
              01386 ; $08C9..$0948 GCMEMMAP
              01387 ;
              01388 ;              Galactic Chart memory map (16 columns x 8 rows = 128 bytes)
              01389 ;
              01390 ; $0949..$0970 PANELTXT
              01391 ;
              01392 ;              Memory of Control Panel Display (bottom text window) in Front
              01393 ;              view, Aft view, and Long-Range Scan view (20 characters x 2 rows
              01394 ;              = 40 bytes).
              01395 ;
              01396 ; $094A        VELOCD1
              01397 ;
              01398 ;              First digit (of 2) of the VELOCITY readout in Control Panel
              01399 ;              Display memory.
              01400 ;
              01401 ; $0950        KILLCNTD1
              01402 ;
              01403 ;              First digit (of 2) of the KILL COUNTER readout in Control Panel
              01404 ;              Display memory.
              01405 ;
              01406 ; $0955        ENERGYD1
              01407 ;
              01408 ;              First digit (of 4) of the ENERGY readout in Control Panel Display
              01409 ;              memory.
              01410 ;
              01411 ; $095A        TRACKC1
              01412 ;
              01413 ;              Character of the TRACKING readout 'T' or 'C' in Control Panel
              01414 ;              Display memory.
              01415 ;
              01416 ; $095C        TRACKDIGIT
              01417 ;
              01418 ;              Digit of the TRACKING readout in Control Panel Display memory. It
              01419 ;              is used to store the index of the currently tracked space object.
              01420 ;              Used values are:
              01421 ;                $00 -> Track Zylon ship 0
              01422 ;                $01 -> Track Zylon ship 1
              01423 ;                $02 -> Track starbase
              01424 ;                $03 -> Track Hyperwarp Target Marker
              01425 ;
              01426 ; $0960        THETAC1
              01427 ;
              01428 ;              First character of the THETA readout in Control Panel Display
              01429 ;              memory.
              01430 ;
              01431 ; $0966        PHIC1
              01432 ;
              01433 ;              First character of the PHI readout in Control Panel Display
              01434 ;              memory.
              01435 ;
              01436 ; $096C        RANGEC1
              01437 ;
              01438 ;              First character of the RANGE readout in Control Panel Display
              01439 ;              memory.
              01440 ;
              01441 ; $0971..$09AC GCTXT
              01442 ;
              01443 ;              Memory of Galactic Chart Panel Display (bottom text window) of
              01444 ;              Galactic Chart view (20 characters x 3 rows = 60 bytes).
              01445 ;
              01446 ; $097D        GCWARPD1
              01447 ;
              01448 ;              First digit (of 4) of the HYPERWARP ENERGY readout in Galactic
              01449 ;              Chart Panel Display memory.
              01450 ;
              01451 ; $098D        GCTRGCNT
              01452 ;
              01453 ;              First target counter digit (of 2) in Galactic Chart Panel Display
              01454 ;              memory.
              01455 ;
              01456 ; $0992        GCSTATPHO
              01457 ;
              01458 ;              Photon Torpedo status letter in Galactic Chart Panel Display
              01459 ;              memory. Used values are:
              01460 ;                %00****** -> OK
              01461 ;                %10****** -> Destroyed
              01462 ;                %11****** -> Damaged
              01463 ;
              01464 ; $0993        GCSTATENG
              01465 ;
              01466 ;              Engines status letter in Galactic Chart Panel Display memory.
              01467 ;              Used values are:
              01468 ;                %00****** -> OK
              01469 ;                %10****** -> Destroyed
              01470 ;                %11****** -> Damaged
              01471 ;
              01472 ; $0994        GCSTATSHL
              01473 ;
              01474 ;              Shields status letter in Galactic Chart Panel Display memory.
              01475 ;              Used values are:
              01476 ;                %00****** -> OK
              01477 ;                %10****** -> Destroyed
              01478 ;                %11****** -> Damaged
              01479 ;
              01480 ; $0995        GCSTATCOM
              01481 ;
              01482 ;              Attack Computer status letter in Galactic Chart Panel Display
              01483 ;              memory. Used values are:
              01484 ;                %00****** -> OK
              01485 ;                %10****** -> Destroyed
              01486 ;                %11****** -> Damaged
              01487 ;
              01488 ; $0996        GCSTATLRS
              01489 ;
              01490 ;              Long-Range Scan status letter in Galactic Chart Panel Display
              01491 ;              memory. Used values are:
              01492 ;                %00****** -> OK
              01493 ;                %10****** -> Destroyed
              01494 ;                %11****** -> Damaged
              01495 ;
              01496 ; $0997        GCSTATRAD
              01497 ;
              01498 ;              Subspace Radio status letter in Galactic Chart Panel Display
              01499 ;              memory. Used values are:
              01500 ;                %00****** -> OK
              01501 ;                %10****** -> Destroyed
              01502 ;                %11****** -> Damaged
              01503 ;
              01504 ; $09A3        GCSTARDAT
              01505 ;
              01506 ;              First (of 5) digits of the star date clock in the Galactic Chart
              01507 ;              Panel Display memory.
              01508 ;
              01509 ; $09AD..$09DD ZPOSSIGN
              01510 ;
              01511 ;              Table containing the sign bit (B16) of position vector
              01512 ;              z-components (z-coordinate) (49 bytes). Bytes 0..4 belong to
              01513 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01514 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01515 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01516 ;              are:
              01517 ;                $00 -> Negative sign (behind our starship)
              01518 ;                $01 -> Positive sign (in front of our starship)
              01519 ;
              01520 ;              See also "ON POSITION VECTORS".
              01521 ;
              01522 ; $09AD        PL0ZPOSSIGN
              01523 ;
              01524 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01525 ;              PLAYER0. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01526 ;              VECTORS".
              01527 ;
              01528 ; $09AE        PL1ZPOSSIGN
              01529 ;
              01530 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01531 ;              PLAYER1. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01532 ;              VECTORS".
              01533 ;
              01534 ; $09AF        PL2ZPOSSIGN
              01535 ;
              01536 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01537 ;              PLAYER2. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01538 ;              VECTORS".
              01539 ;
              01540 ; $09B0        PL3ZPOSSIGN
              01541 ;
              01542 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01543 ;              PLAYER3. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01544 ;              VECTORS".
              01545 ;
              01546 ; $09B1        PL4ZPOSSIGN
              01547 ;
              01548 ;              Sign bit (B16) of position vector z-component (z-coordinate) of
              01549 ;              PLAYER4. Compare ZPOSSIGN ($09AD). See also "ON POSITION
              01550 ;              VECTORS".
              01551 ;
              01552 ; $09DE..$0A0E XPOSSIGN
              01553 ;
              01554 ;              Table containing the sign bit (B16) of position vector
              01555 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01556 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01557 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01558 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01559 ;              are:
              01560 ;                $00 -> Negative sign (left)
              01561 ;                $01 -> Positive sign (right)
              01562 ;
              01563 ;              See also "ON POSITION VECTORS".
              01564 ;
              01565 ; $09DE        PL0XPOSSIGN
              01566 ;
              01567 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01568 ;              PLAYER0. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01569 ;              VECTORS".
              01570 ;
              01571 ; $09DF        PL1XPOSSIGN
              01572 ;
              01573 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01574 ;              PLAYER1. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01575 ;              VECTORS".
              01576 ;
              01577 ; $09E0        PL2XPOSSIGN
              01578 ;
              01579 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01580 ;              PLAYER2. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01581 ;              VECTORS".
              01582 ;
              01583 ; $09E1        PL3XPOSSIGN
              01584 ;
              01585 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01586 ;              PLAYER3. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01587 ;              VECTORS".
              01588 ;
              01589 ; $09E2        PL4XPOSSIGN
              01590 ;
              01591 ;              Sign bit (B16) of position vector x-component (x-coordinate) of
              01592 ;              PLAYER4. Compare XPOSSIGN ($09DE). See also "ON POSITION
              01593 ;              VECTORS".
              01594 ;
              01595 ; $0A0F..$0A3F YPOSSIGN
              01596 ;
              01597 ;              Table containing the sign bit (B16) of position vector
              01598 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01599 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01600 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01601 ;              PLAYFIELD space objects (stars, explosion fragments). Used values
              01602 ;              are:
              01603 ;                $00 -> Negative sign (down)
              01604 ;                $01 -> Positive sign (up)
              01605 ;
              01606 ;              See also "ON POSITION VECTORS".
              01607 ;
              01608 ; $0A0F        PL0YPOSSIGN
              01609 ;
              01610 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01611 ;              PLAYER0. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01612 ;              VECTORS".
              01613 ;
              01614 ; $0A10        PL1YPOSSIGN
              01615 ;
              01616 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01617 ;              PLAYER1. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01618 ;              VECTORS".
              01619 ;
              01620 ; $0A11        PL2YPOSSIGN
              01621 ;
              01622 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01623 ;              PLAYER2. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01624 ;              VECTORS".
              01625 ;
              01626 ; $0A12        PL3YPOSSIGN
              01627 ;
              01628 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01629 ;              PLAYER3. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01630 ;              VECTORS".
              01631 ;
              01632 ; $0A13        PL4YPOSSIGN
              01633 ;
              01634 ;              Sign bit (B16) of position vector y-component (y-coordinate) of
              01635 ;              PLAYER4. Compare YPOSSIGN ($0A0F). See also "ON POSITION
              01636 ;              VECTORS".
              01637 ;
              01638 ; $0A40..$0A70 ZPOSHI
              01639 ;
              01640 ;              Table containing the high byte (B15..8) of position vector
              01641 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01642 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01643 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01644 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01645 ;              "ON POSITION VECTORS".
              01646 ;
              01647 ; $0A40        PL0ZPOSHI
              01648 ;
              01649 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01650 ;              of PLAYER0. Compare ZPOSHI ($0A40). See also "ON POSITION
              01651 ;              VECTORS".
              01652 ;
              01653 ; $0A41        PL1ZPOSHI
              01654 ;
              01655 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01656 ;              of PLAYER1. Compare ZPOSHI ($0A40). See also "ON POSITION
              01657 ;              VECTORS".
              01658 ;
              01659 ; $0A42        PL2ZPOSHI
              01660 ;
              01661 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01662 ;              of PLAYER2. Compare ZPOSHI ($0A40). See also "ON POSITION
              01663 ;              VECTORS".
              01664 ;
              01665 ; $0A43        PL3ZPOSHI
              01666 ;
              01667 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01668 ;              of PLAYER3. Compare ZPOSHI ($0A40). See also "ON POSITION
              01669 ;              VECTORS".
              01670 ;
              01671 ; $0A44        PL4ZPOSHI
              01672 ;
              01673 ;              High byte (B15..8) of position vector z-component (z-coordinate)
              01674 ;              of PLAYER4. Compare ZPOSHI ($0A40). See also "ON POSITION
              01675 ;              VECTORS".
              01676 ;
              01677 ; $0A71..$0AA1 XPOSHI
              01678 ;
              01679 ;              Table containing the high byte (B15..8) of position vector
              01680 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01681 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01682 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01683 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01684 ;              "ON POSITION VECTORS".
              01685 ;
              01686 ; $0A71        PL0XPOSHI
              01687 ;
              01688 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01689 ;              of PLAYER0. Compare XPOSHI ($0A71). See also "ON POSITION
              01690 ;              VECTORS".
              01691 ;
              01692 ; $0A72        PL1XPOSHI
              01693 ;
              01694 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01695 ;              of PLAYER1. Compare XPOSHI ($0A71). See also "ON POSITION
              01696 ;              VECTORS".
              01697 ;
              01698 ; $0A73        PL2XPOSHI
              01699 ;
              01700 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01701 ;              of PLAYER2. Compare XPOSHI ($0A71). See also "ON POSITION
              01702 ;              VECTORS".
              01703 ;
              01704 ; $0A74        PL3XPOSHI
              01705 ;
              01706 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01707 ;              of PLAYER3. Compare XPOSHI ($0A71). See also "ON POSITION
              01708 ;              VECTORS".
              01709 ;
              01710 ; $0A75        PL4XPOSHI
              01711 ;
              01712 ;              High byte (B15..8) of position vector x-component (x-coordinate)
              01713 ;              of PLAYER4. Compare XPOSHI ($0A71). See also "ON POSITION
              01714 ;              VECTORS".
              01715 ;
              01716 ; $0AA2..$0AD2 YPOSHI
              01717 ;
              01718 ;              Table containing the high byte (B15..8) of position vector
              01719 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01720 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01721 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01722 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01723 ;              "ON POSITION VECTORS".
              01724 ;
              01725 ; $0AA2        PL0YPOSHI
              01726 ;
              01727 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01728 ;              of PLAYER0. Compare YPOSHI ($0AA2). See also "ON POSITION
              01729 ;              VECTORS".
              01730 ;
              01731 ; $0AA3        PL1YPOSHI
              01732 ;
              01733 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01734 ;              of PLAYER1. Compare YPOSHI ($0AA2). See also "ON POSITION
              01735 ;              VECTORS".
              01736 ;
              01737 ; $0AA4        PL2YPOSHI
              01738 ;
              01739 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01740 ;              of PLAYER2. Compare YPOSHI ($0AA2). See also "ON POSITION
              01741 ;              VECTORS".
              01742 ;
              01743 ; $0AA5        PL3YPOSHI
              01744 ;
              01745 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01746 ;              of PLAYER3. Compare YPOSHI ($0AA2). See also "ON POSITION
              01747 ;              VECTORS".
              01748 ;
              01749 ; $0AA6        PL4YPOSHI
              01750 ;
              01751 ;              High byte (B15..8) of position vector y-component (y-coordinate)
              01752 ;              of PLAYER4. Compare YPOSHI ($0AA2). See also "ON POSITION
              01753 ;              VECTORS".
              01754 ;
              01755 ; $0AD3..$0B03 ZPOSLO
              01756 ;
              01757 ;              Table containing the low byte (B7..0) of position vector
              01758 ;              z-components (z-coordinate) (49 bytes). Bytes 0..4 belong to
              01759 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01760 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01761 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01762 ;              "ON POSITION VECTORS".
              01763 ;
              01764 ; $0AD3        PL0ZPOSLO
              01765 ;
              01766 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01767 ;              PLAYER0. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01768 ;
              01769 ; $0AD4        PL1ZPOSLO
              01770 ;
              01771 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01772 ;              PLAYER1. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01773 ;
              01774 ; $0AD5        PL2ZPOSLO
              01775 ;
              01776 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01777 ;              PLAYER2. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01778 ;
              01779 ; $0AD6        PL3ZPOSLO
              01780 ;
              01781 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01782 ;              PLAYER3. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01783 ;
              01784 ; $0AD7        PL4ZPOSLO
              01785 ;
              01786 ;              Low byte (B7..0) of position vector z-component (z-coordinate) of
              01787 ;              PLAYER4. Compare ZPOSLO ($0AD3). See also "ON POSITION VECTORS".
              01788 ;
              01789 ; $0B04..$0B34 XPOSLO
              01790 ;
              01791 ;              Table containing the low byte (B7..0) of position vector
              01792 ;              x-components (x-coordinate) (49 bytes). Bytes 0..4 belong to
              01793 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01794 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01795 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01796 ;              "ON POSITION VECTORS".
              01797 ;
              01798 ; $0B04        PL0XPOSLO
              01799 ;
              01800 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01801 ;              PLAYER0. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01802 ;
              01803 ; $0B05        PL1XPOSLO
              01804 ;
              01805 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01806 ;              PLAYER1. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01807 ;
              01808 ; $0B06        PL2XPOSLO
              01809 ;
              01810 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01811 ;              PLAYER2. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01812 ;
              01813 ; $0B07        PL3XPOSLO
              01814 ;
              01815 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01816 ;              PLAYER3. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01817 ;
              01818 ; $0B08        PL4XPOSLO
              01819 ;
              01820 ;              Low byte (B7..0) of position vector x-component (x-coordinate) of
              01821 ;              PLAYER4. Compare XPOSLO ($0B04). See also "ON POSITION VECTORS".
              01822 ;
              01823 ; $0B35..$0B65 YPOSLO
              01824 ;
              01825 ;              Table containing the low byte (B7..0) of position vector
              01826 ;              y-components (y-coordinate) (49 bytes). Bytes 0..4 belong to
              01827 ;              position vectors of PLAYER space objects (Zylon ships, photon
              01828 ;              torpedoes, etc.). Bytes 5..48 belong to position vectors of
              01829 ;              PLAYFIELD space objects (stars, explosion fragments). See also
              01830 ;              "ON POSITION VECTORS".
              01831 ;
              01832 ; $0B35        PL0YPOSLO
              01833 ;
              01834 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01835 ;              PLAYER0. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS". 
              01836 ;
              01837 ; $0B36        PL1YPOSLO
              01838 ;
              01839 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01840 ;              PLAYER1. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01841 ;
              01842 ; $0B37        PL2YPOSLO
              01843 ;
              01844 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01845 ;              PLAYER2. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01846 ;
              01847 ; $0B38        PL3YPOSLO
              01848 ;
              01849 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01850 ;              PLAYER3. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01851 ;
              01852 ; $0B39        PL4YPOSLO
              01853 ;
              01854 ;              Low byte (B7..0) of position vector y-component (y-coordinate) of
              01855 ;              PLAYER4. Compare YPOSLO ($0B35). See also "ON POSITION VECTORS".
              01856 ;
              01857 ; $0B66..$0B96 ZVEL
              01858 ;
              01859 ;              Table containing velocity vector z-components (z-velocities) (49
              01860 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01861 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01862 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01863 ;              fragments). Each z-velocity is stored in the binary format
              01864 ;              %sxxxxxxx where
              01865 ;                %s = 0   -> Positive sign (moving in flight direction)
              01866 ;                %s = 1   -> Negative sign (moving in reverse flight direction)
              01867 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01868 ;
              01869 ;              See also "ON VELOCITY VECTORS".
              01870 ;
              01871 ; $0B66        PL0ZVEL
              01872 ;
              01873 ;              Velocity vector z-component (z-velocity) of PLAYER0. Compare ZVEL
              01874 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01875 ;
              01876 ; $0B67        PL1ZVEL
              01877 ;
              01878 ;              Velocity vector z-component (z-velocity) of PLAYER1. Compare ZVEL
              01879 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01880 ;
              01881 ; $0B68        PL2ZVEL
              01882 ;
              01883 ;              Velocity vector z-component (z-velocity) of PLAYER2. Compare ZVEL
              01884 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01885 ;
              01886 ; $0B69        PL3ZVEL
              01887 ;
              01888 ;              Velocity vector z-component (z-velocity) of PLAYER3. Compare ZVEL
              01889 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01890 ;
              01891 ; $0B6A        PL4ZVEL
              01892 ;
              01893 ;              Velocity vector z-component (z-velocity) of PLAYER4. Compare ZVEL
              01894 ;              ($0B66). See also "ON VELOCITY VECTORS".
              01895 ;
              01896 ; $0B97..$0BC7 XVEL
              01897 ;
              01898 ;              Table containing velocity vector x-components (x-velocities) (49
              01899 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01900 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01901 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01902 ;              fragments). Each x-velocity is stored in the binary format
              01903 ;              %sxxxxxxx where
              01904 ;                %s = 0   -> Positive sign (moving to the right)
              01905 ;                %s = 1   -> Negative sign (moving to the left)
              01906 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01907 ;
              01908 ;              See also "ON VELOCITY VECTORS".
              01909 ;
              01910 ; $0B97        PL0XVEL
              01911 ;
              01912 ;              Velocity vector x-component (x-velocity) of PLAYER0. Compare XVEL
              01913 ;              ($0B97). See also "ON VELOCITY VECTORS". 
              01914 ;
              01915 ; $0B98        PL1XVEL
              01916 ;
              01917 ;              Velocity vector x-component (x-velocity) of PLAYER1. Compare XVEL
              01918 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01919 ;
              01920 ; $0B99        PL2XVEL
              01921 ;
              01922 ;              Velocity vector x-component (x-velocity) of PLAYER2. Compare XVEL
              01923 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01924 ;
              01925 ; $0B9A        PL3XVEL
              01926 ;
              01927 ;              Velocity vector x-component (x-velocity) of PLAYER3. Compare XVEL
              01928 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01929 ;
              01930 ; $0B9B        PL4XVEL
              01931 ;
              01932 ;              Velocity vector x-component (x-velocity) of PLAYER4. Compare XVEL
              01933 ;              ($0B97). See also "ON VELOCITY VECTORS".
              01934 ;
              01935 ; $0BC8..$0BF8 YVEL
              01936 ;
              01937 ;              Table containing velocity vector y-components (y-velocities) (49
              01938 ;              bytes). Bytes 0..4 belong to velocity vectors of PLAYER space
              01939 ;              objects (Zylon ships, photon torpedoes, etc.). Bytes 5..48 belong
              01940 ;              to velocity vectors of PLAYFIELD space objects (stars, explosion
              01941 ;              fragments). Each y-velocity is stored in the binary format
              01942 ;              %sxxxxxxx where
              01943 ;                %s = 0   -> Positive sign (moving up)
              01944 ;                %s = 1   -> Negative sign (moving down)
              01945 ;                %xxxxxxx -> Unsigned 7-bit velocity value in <KM/H>
              01946 ;
              01947 ;              See also "ON VELOCITY VECTORS".
              01948 ;
              01949 ; $0BC8        PL0YVEL
              01950 ;
              01951 ;              Velocity vector y-component (y-velocity) of PLAYER0. Compare YVEL
              01952 ;              ($0BC8). See also "ON VELOCITY VECTORS". 
              01953 ;
              01954 ; $0BC9        PL1YVEL
              01955 ;
              01956 ;              Velocity vector y-component (y-velocity) of PLAYER1. Compare YVEL
              01957 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01958 ;
              01959 ; $0BCA        PL2YVEL
              01960 ;
              01961 ;              Velocity vector y-component (y-velocity) of PLAYER2. Compare YVEL
              01962 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01963 ;
              01964 ; $0BCB        PL3YVEL
              01965 ;
              01966 ;              Velocity vector y-component (y-velocity) of PLAYER3. Compare YVEL
              01967 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01968 ;
              01969 ; $0BCC        PL4YVEL
              01970 ;
              01971 ;              Velocity vector y-component (y-velocity) of PLAYER4. Compare YVEL
              01972 ;              ($0BC8). See also "ON VELOCITY VECTORS".
              01973 ;
              01974 ; $0BF9..$0C29 PIXELROWNEW
              01975 ;
              01976 ;              Table containing the new pixel row number of space objects (49
              01977 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              01978 ;              Player/Missile (PM) pixel row numbers. They are counted from
              01979 ;              vertical PM position 0, which is offscreen. Bytes 5..48 belong to
              01980 ;              PLAYFIELD space objects (stars, explosion fragments) and contain
              01981 ;              PLAYFIELD pixel row numbers. They are counted from the top border
              01982 ;              of the PLAYFIELD and have values of 0..99.
              01983 ;
              01984 ; $0BF9        PL0ROWNEW
              01985 ;
              01986 ;              New pixel row number of PLAYER0 in Player/Missile pixels. See
              01987 ;              also PIXELROWNEW ($0BF9).
              01988 ;
              01989 ; $0BFA        PL1ROWNEW
              01990 ;
              01991 ;              New pixel row number of PLAYER1 in Player/Missile pixels. See
              01992 ;              also PIXELROWNEW ($0BF9).
              01993 ;
              01994 ; $0BFB        PL2ROWNEW
              01995 ;
              01996 ;              New pixel row number of PLAYER2 in Player/Missile pixels. See
              01997 ;              also PIXELROWNEW ($0BF9).
              01998 ;
              01999 ; $0BFC        PL3ROWNEW
              02000 ;
              02001 ;              New pixel row number of PLAYER3 in Player/Missile pixels. See
              02002 ;              also PIXELROWNEW ($0BF9).
              02003 ;
              02004 ; $0BFD        PL4ROWNEW
              02005 ;
              02006 ;              New pixel row number of PLAYER4 in Player/Missile pixels. See
              02007 ;              also PIXELROWNEW ($0BF9).
              02008 ;
              02009 ; $0C2A..$0C5A PIXELCOLUMN
              02010 ;
              02011 ;              Table containing the pixel column number of space objects (49
              02012 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              02013 ;              Player/Missile (PM) pixel column numbers. They are counted from
              02014 ;              horizontal PM position 0, which is offscreen. Bytes 5..48 belong
              02015 ;              to PLAYFIELD space objects (stars, explosion fragments) and
              02016 ;              contain PLAYFIELD pixel column numbers. They are counted from the
              02017 ;              left border of the PLAYFIELD and have values of 0..159.
              02018 ;
              02019 ; $0C2A        PL0COLUMN
              02020 ;
              02021 ;              Pixel column number of PLAYER0 in Player/Missile pixels. See also
              02022 ;              PIXELCOLUMN ($0C2A).
              02023 ;
              02024 ; $0C2B        PL1COLUMN
              02025 ;
              02026 ;              Pixel column number of PLAYER1 in Player/Missile pixels. See also
              02027 ;              PIXELCOLUMN ($0C2A).
              02028 ;
              02029 ; $0C2C        PL2COLUMN
              02030 ;
              02031 ;              Pixel column number of PLAYER2 in Player/Missile pixels. See also
              02032 ;              PIXELCOLUMN ($0C2A).
              02033 ;
              02034 ; $0C2D        PL3COLUMN
              02035 ;
              02036 ;              Pixel column number of PLAYER3 in Player/Missile pixels. See also
              02037 ;              PIXELCOLUMN ($0C2A).
              02038 ;
              02039 ; $0C2E        PL4COLUMN
              02040 ;
              02041 ;              Pixel column number of PLAYER4 in Player/Missile pixels. See also
              02042 ;              PIXELCOLUMN ($0C2A).
              02043 ;
              02044 ; $0C5B..$0C8B PIXELROW
              02045 ;
              02046 ;              Table containing the pixel row number of space objects (49
              02047 ;              bytes). Bytes 0..4 belong to PLAYER space objects and contain
              02048 ;              Player/Missile (PM) pixel row numbers. They are counted from
              02049 ;              vertical PM position 0, which is offscreen. Bytes 5..48 belong to
              02050 ;              PLAYFIELD space objects (stars, explosion fragments) and contain
              02051 ;              PLAYFIELD pixel row numbers. They are counted from the top border
              02052 ;              of the PLAYFIELD and have values of 0..99.
              02053 ;
              02054 ; $0C5B        PL0ROW
              02055 ;
              02056 ;              Pixel row number of PLAYER0 in Player/Missile pixels. See also
              02057 ;              PIXELROW ($0C5B).
              02058 ;
              02059 ; $0C5C        PL1ROW
              02060 ;
              02061 ;              Pixel row number of PLAYER1 in Player/Missile pixels. See also
              02062 ;              PIXELROW ($0C5B).
              02063 ;
              02064 ; $0C5D        PL2ROW
              02065 ;
              02066 ;              Pixel row number of PLAYER2 in Player/Missile pixels. See also
              02067 ;              PIXELROW ($0C5B).
              02068 ;
              02069 ; $0C5E        PL3ROW
              02070 ;
              02071 ;              Pixel row number of PLAYER3 in Player/Missile pixels. See also
              02072 ;              PIXELROW ($0C5B).
              02073 ;
              02074 ; $0C5F        PL4ROW
              02075 ;
              02076 ;              Pixel row number of PLAYER4 in Player/Missile pixels. See also
              02077 ;              PIXELROW ($0C5B).
              02078 ;
              02079 ; $0C8C..$0CBC PIXELBYTEOFF
              02080 ;
              02081 ;              Table containing a byte offset into PLAYFIELD memory for each
              02082 ;              PLAYFIELD space object (stars, explosion fragments) (49 bytes):
              02083 ;              the number of bytes from the start of the PLAYFIELD row to the
              02084 ;              byte containing the space object pixel in the same PLAYFIELD row.
              02085 ;              In other words, the pixel column modulo 4 (1 byte = 4 GRAPHICS7
              02086 ;              pixels).
              02087 ;
              02088 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02089 ;              this way. Bytes 0..4 are used differently. See PL0SHAPTYPE
              02090 ;              ($0C8C)..PL4SHAPTYPE ($0C90).
              02091 ;
              02092 ; $0C8C        PL0SHAPTYPE
              02093 ;
              02094 ;              Shape type of PLAYER0. Used to index the PLAYER's set of shape
              02095 ;              cells in tables PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB ($BE7F).
              02096 ;              Used values are:
              02097 ;                $00 -> PHOTON TORPEDO
              02098 ;                $10 -> ZYLON FIGHTER
              02099 ;                $20 -> STARBASE RIGHT
              02100 ;                $30 -> STARBASE CENTER
              02101 ;                $40 -> STARBASE LEFT
              02102 ;                $50 -> TRANSFER VESSEL
              02103 ;                $60 -> METEOR
              02104 ;                $70 -> ZYLON CRUISER
              02105 ;                $80 -> ZYLON BASESTAR
              02106 ;                $90 -> HYPERWARP TARGET MARKER
              02107 ;
              02108 ; $0C8D        PL1SHAPTYPE
              02109 ;
              02110 ;              Shape type of PLAYER1. Compare PL0SHAPTYPE ($0C8C).
              02111 ;
              02112 ; $0C8E        PL2SHAPTYPE
              02113 ;
              02114 ;              Shape type of PLAYER2. Compare PL0SHAPTYPE ($0C8C).
              02115 ;
              02116 ; $0C8F        PL3SHAPTYPE
              02117 ;
              02118 ;              Shape type of PLAYER3. Compare PL0SHAPTYPE ($0C8C).
              02119 ;
              02120 ; $0C90        PL4SHAPTYPE
              02121 ;
              02122 ;              Shape type of PLAYER4. Compare PL0SHAPTYPE ($0C8C).
              02123 ;
              02124 ; $0CBD..$0CED PIXELSAVE
              02125 ;
              02126 ;              Table containing the byte of PLAYFIELD memory before drawing the
              02127 ;              PLAYFIELD space object pixel into it (star, explosion fragments),
              02128 ;              for each PLAYFIELD space object (49 bytes). 
              02129 ;
              02130 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02131 ;              this way. Bytes 0..4 are used differently. See PL0HEIGHT
              02132 ;              ($0CBD)..PL4HEIGHT ($0CC1).
              02133 ;
              02134 ; $0CBD        PL0HEIGHT
              02135 ;
              02136 ;              Shape height of PLAYER0
              02137 ;
              02138 ; $0CBE        PL1HEIGHT
              02139 ;
              02140 ;              Shape height of PLAYER1
              02141 ;
              02142 ; $0CBF        PL2HEIGHT
              02143 ;
              02144 ;              Shape height of PLAYER2
              02145 ;
              02146 ; $0CC0        PL3HEIGHT
              02147 ;
              02148 ;              Shape height of PLAYER3
              02149 ;
              02150 ; $0CC1        PL4HEIGHT
              02151 ;
              02152 ;              Shape height of PLAYER4
              02153 ;
              02154 ; $0CEE..$0D1E PIXELBYTE
              02155 ;
              02156 ;              Table containing a 1-byte bit pattern for 4 pixels in the color
              02157 ;              of the space object's pixel, for each PLAYFIELD space object (49
              02158 ;              bytes). 
              02159 ;
              02160 ;              NOTE: Only bytes 5..48 are used for PLAYFIELD space objects in
              02161 ;              this way. Bytes 0..4 are used differently. See PL0HEIGHTNEW
              02162 ;              ($0CEE)..PL4HEIGHTNEW ($0CF2).
              02163 ;
              02164 ; $0CEE        PL0HEIGHTNEW
              02165 ;
              02166 ;              New shape height of PLAYER0
              02167 ;
              02168 ; $0CEF        PL1HEIGHTNEW
              02169 ;
              02170 ;              New shape height of PLAYER1
              02171 ;
              02172 ; $0CF0        PL2HEIGHTNEW
              02173 ;
              02174 ;              New shape height of PLAYER2
              02175 ;
              02176 ; $0CF1        PL3HEIGHTNEW
              02177 ;
              02178 ;              New shape height of PLAYER3
              02179 ;
              02180 ; $0CF2        PL4HEIGHTNEW
              02181 ;
              02182 ;              New shape height of PLAYER4
              02183 ;
              02184 ; $0D1F..$0D32 TITLETXT
              02185 ;
              02186 ;              Title text line, contains ATASCII-coded characters (20 bytes)
              02187 ;
              02188 ; $0D35..$0DE8 GCPFMEM
              02189 ;
              02190 ;              Galactic Chart PLAYFIELD memory (20 characters x 9 rows = 180
              02191 ;              bytes)
              02192 ;
              02193 ; $0DE9..$0EE8 MAPTO80
              02194 ;
              02195 ;              Lookup table to convert values in $00..$FF to values of 0..80
              02196 ;              (255 bytes). Used to map position vector components (coordinates)
              02197 ;              to pixel row or column numbers relative to the PLAYFIELD center. 
              02198 ;
              02199 ; $0EE9..$0FE8 MAPTOBCD99
              02200 ;
              02201 ;              Lookup table to convert values in $00..$FF to BCD-values of
              02202 ;              00..99 (255 bytes). Used in subroutines UPDPANEL ($B804) and
              02203 ;              SHOWDIGITS ($B8CD) to convert values to a 2-digit decimal readout
              02204 ;              value of the Control Panel Display.
              02205 ;
              02206 ; $1000..$1F77 PFMEM
              02207 ;
              02208 ;              PLAYFIELD graphics memory (40 bytes x 100 rows = 4000 bytes, 1
              02209 ;              byte stores 4 pixels, 40 bytes = 160 pixels in GRAPHICS7 mode = 1
              02210 ;              PLAYFIELD row of pixels).
              02211 ;
              02212 ;              NOTE: The Display List displays only PLAYFIELD rows 0..98.
              02213
              02214 ;*******************************************************************************
              02215 ;*                                                                             *
              02216 ;*                         S Y S T E M   S Y M B O L S                         *
              02217 ;*                                                                             *
              02218 ;*******************************************************************************
              02219
    =0200     02220 VDSLST          = $0200                               ; Display List Interrupt (DLI) vector
    =0216     02221 VIMIRQ          = $0216                               ; Interrupt request (IRQ) immediate vector
    =0222     02222 VVBLKI          = $0222                               ; Vertical blank immediate vector
    =D000     02223 HPOSP0          = $D000                               ; Horizontal position of PLAYER0
    =D001     02224 HPOSP1          = $D001                               ; Horizontal position of PLAYER1
    =D002     02225 HPOSP2          = $D002                               ; Horizontal position of PLAYER2
    =D003     02226 HPOSP3          = $D003                               ; Horizontal position of PLAYER3
    =D004     02227 HPOSM0          = $D004                               ; Horizontal position of MISSILE0
    =D005     02228 HPOSM1          = $D005                               ; Horizontal position of MISSILE1
    =D006     02229 HPOSM2          = $D006                               ; Horizontal position of MISSILE2
    =D007     02230 HPOSM3          = $D007                               ; Horizontal position of MISSILE3
    =D008     02231 M0PL            = $D008                               ; MISSILE0 to PLAYER collisions
    =D009     02232 M1PL            = $D009                               ; MISSILE1 to PLAYER collisions
    =D00A     02233 M2PL            = $D00A                               ; MISSILE2 to PLAYER collisions
    =D00B     02234 M3PL            = $D00B                               ; MISSILE3 to PLAYER collisions
    =D00F     02235 P3PL            = $D00F                               ; PLAYER3 to PLAYER collisions
    =D010     02236 TRIG0           = $D010                               ; Joystick 0 trigger
    =D012     02237 COLPM0          = $D012                               ; Color and brightness of PLAYER0
    =D016     02238 COLPF0          = $D016                               ; Color and brightness of PLAYFIELD0
    =D01B     02239 PRIOR           = $D01B                               ; Priority selection register
    =D01D     02240 GRACTL          = $D01D                               ; Graphics control register
    =D01E     02241 HITCLR          = $D01E                               ; Clear collision register
    =D01F     02242 CONSOL          = $D01F                               ; Function keys register
    =D200     02243 AUDF1           = $D200                               ; Audio channel 1 frequency
    =D202     02244 AUDF2           = $D202                               ; Audio channel 2 frequency
    =D203     02245 AUDC2           = $D203                               ; Audio channel 2 control
    =D204     02246 AUDF3           = $D204                               ; Audio channel 3 frequency
    =D205     02247 AUDC3           = $D205                               ; Audio channel 3 control
    =D206     02248 AUDF4           = $D206                               ; Audio channel 4 frequency
    =D207     02249 AUDC4           = $D207                               ; Audio channel 4 control
    =D208     02250 AUDCTL          = $D208                               ; Audio control
    =D209     02251 KBCODE          = $D209                               ; Keyboard code
    =D209     02252 STIMER          = $D209                               ; Start POKEY timers
    =D20A     02253 RANDOM          = $D20A                               ; Random number generator
    =D20E     02254 IRQEN           = $D20E                               ; Interrupt request (IRQ) enable
    =D20F     02255 SKCTL           = $D20F                               ; Serial port control
    =D300     02256 PORTA           = $D300                               ; Port A
    =D302     02257 PACTL           = $D302                               ; Port A control
    =D400     02258 DMACTL          = $D400                               ; Direct Memory Access (DMA) control
    =D402     02259 DLIST           = $D402                               ; Display List pointer
    =D407     02260 PMBASE          = $D407                               ; Player/Missile base address (high byte)
    =D409     02261 CHBASE          = $D409                               ; Character set base address (high byte)
    =D40A     02262 WSYNC           = $D40A                               ; Wait for horizontal synchronization
    =D40B     02263 VCOUNT          = $D40B                               ; Vertical line counter
    =D40E     02264 NMIEN           = $D40E                               ; Non-maskable interrupt (NMI) enable
    =E000     02265 ROMCHARSET      = $E000                               ; ROM character set
              02266
              02267 ;*******************************************************************************
              02268 ;*                                                                             *
              02269 ;*                           G A M E   S Y M B O L S                           *
              02270 ;*                                                                             *
              02271 ;*******************************************************************************
              02272
    =0062     02273 MISSIONLEVEL    = $62
    =0063     02274 FKEYCODE        = $63
    =0064     02275 ISDEMOMODE      = $64
    =0065     02276 NEWTITLEPHR     = $65
    =0066     02277 IDLECNTHI       = $66
    =0067     02278 ISVBISYNC       = $67
    =0068     02279 MEMPTR          = $68
              02280
    =006A     02281 DIVIDEND        = $6A
    =006D     02282 JOYSTICKDELTA   = $6D
              02283
              02284
    =0070     02285 VELOCITYLO      = $70
    =0071     02286 NEWVELOCITY     = $71
    =0072     02287 COUNT8          = $72
    =0073     02288 EXPLLIFE        = $73
    =0074     02289 CLOCKTIM        = $74
    =0075     02290 DOCKSTATE       = $75
    =0076     02291 COUNT256        = $76
    =0077     02292 IDLECNTLO       = $77
    =0078     02293 ZYLONUNITTIM    = $78
    =0079     02294 MAXSPCOBJIND    = $79
    =007A     02295 SAVMAXSPCOBJIND = $7A
    =007B     02296 ISSTARBASESECT  = $7B
    =007C     02297 ISTRACKCOMPON   = $7C
    =007D     02298 ISSHIELDSON     = $7D
    =007E     02299 ISATTCOMPON     = $7E
    =007F     02300 ENERGYCNT       = $7F
    =0080     02301 DRAINRATE       = $80
    =0081     02302 SHIELDSCOLOR    = $81
    =0082     02303 PL3HIT          = $82
    =0083     02304 PL4HIT          = $83
    =0084     02305 OLDTRIG0        = $84
              02306
    =0086     02307 ISTRACKING      = $86
    =0087     02308 BARRELNR        = $87
    =0088     02309 LOCKONLIFE      = $88
    =0089     02310 PLTRACKED       = $89
    =008A     02311 HITBADNESS      = $8A
    =008B     02312 REDALERTLIFE    = $8B
    =008C     02313 WARPDEPRROW     = $8C
    =008D     02314 WARPDEPRCOLUMN  = $8D
    =008E     02315 WARPARRVROW     = $8E
    =008F     02316 WARPARRVCOLUMN  = $8F
    =0090     02317 CURRSECTOR      = $90
    =0091     02318 WARPENERGY      = $91
    =0092     02319 ARRVSECTOR      = $92
    =0093     02320 HUNTSECTOR      = $93
    =0094     02321 HUNTSECTCOLUMN  = $94
    =0095     02322 HUNTSECTROW     = $95
    =0096     02323 NEWZYLONDIST    = $96
    =009E     02324 OLDZYLONDIST    = $9E
    =009F     02325 HUNTTIM         = $9F
    =00A0     02326 BLIPCOLUMN      = $A0
    =00A1     02327 BLIPROW         = $A1
    =00A2     02328 BLIPCYCLECNT    = $A2
    =00A3     02329 ISINLOCKON      = $A3
    =00A4     02330 DIRLEN          = $A4
    =00A5     02331 PENROW          = $A5
    =00A6     02332 PENCOLUMN       = $A6
    =00A7     02333 CTRLDZYLON      = $A7
    =00A8     02334 ZYLONFLPAT0     = $A8
    =00A9     02335 ZYLONFLPAT1     = $A9
    =00AA     02336 MILESTTIM0      = $AA
    =00AB     02337 MILESTTIM1      = $AB
    =00AC     02338 MILESTVELINDZ0  = $AC
    =00AD     02339 MILESTVELINDZ1  = $AD
    =00AE     02340 MILESTVELINDX0  = $AE
    =00AF     02341 MILESTVELINDX1  = $AF
    =00B0     02342 MILESTVELINDY0  = $B0
    =00B1     02343 MILESTVELINDY1  = $B1
    =00B2     02344 ZYLONVELINDZ0   = $B2
    =00B3     02345 ZYLONVELINDZ1   = $B3
    =00B4     02346 ZYLONVELINDX0   = $B4
    =00B5     02347 ZYLONVELINDX1   = $B5
    =00B6     02348 ZYLONVELINDY0   = $B6
    =00B7     02349 ZYLONVELINDY1   = $B7
    =00B8     02350 ISBACKATTACK0   = $B8
    =00B9     02351 ISBACKATTACK1   = $B9
    =00BA     02352 ZYLONTIMX0      = $BA
    =00BB     02353 ZYLONTIMX1      = $BB
    =00BC     02354 ZYLONTIMY0      = $BC
    =00BD     02355 ZYLONTIMY1      = $BD
    =00BE     02356 TORPEDODELAY    = $BE
    =00BF     02357 ZYLONATTACKER   = $BF
    =00C0     02358 WARPSTATE       = $C0
    =00C1     02359 VELOCITYHI      = $C1
    =00C2     02360 TRAILDELAY      = $C2
    =00C3     02361 TRAILIND        = $C3
    =00C4     02362 WARPTEMPCOLUMN  = $C4
    =00C5     02363 WARPTEMPROW     = $C5
    =00C6     02364 VEERMASK        = $C6
    =00C7     02365 VICINITYMASK    = $C7
    =00C8     02366 JOYSTICKX       = $C8
    =00C9     02367 JOYSTICKY       = $C9
    =00CA     02368 KEYCODE         = $CA
    =00CB     02369 SCORE           = $CB
    =00CD     02370 SCOREDRANKIND   = $CD
    =00CE     02371 SCOREDCLASSIND  = $CE
    =00CF     02372 TITLELIFE       = $CF
    =00D0     02373 SHIPVIEW        = $D0
    =00D1     02374 TITLEPHR        = $D1
    =00D2     02375 BEEPFRQIND      = $D2
    =00D3     02376 BEEPREPEAT      = $D3
    =00D4     02377 BEEPTONELIFE    = $D4
    =00D5     02378 BEEPPAUSELIFE   = $D5
    =00D6     02379 BEEPPRIORITY    = $D6
    =00D7     02380 BEEPFRQSTART    = $D7
    =00D8     02381 BEEPLIFE        = $D8
    =00D9     02382 BEEPTOGGLE      = $D9
    =00DA     02383 NOISETORPTIM    = $DA
    =00DB     02384 NOISEEXPLTIM    = $DB
    =00DC     02385 NOISEAUDC2      = $DC
    =00DD     02386 NOISEAUDC3      = $DD
    =00DE     02387 NOISEAUDF1      = $DE
    =00DF     02388 NOISEAUDF2      = $DF
    =00E0     02389 NOISEFRQINC     = $E0
    =00E1     02390 NOISELIFE       = $E1
    =00E2     02391 NOISEZYLONTIM   = $E2
    =00E3     02392 NOISEHITLIFE    = $E3
    =00E4     02393 PL0SHAPOFF      = $E4
    =00E5     02394 PL1SHAPOFF      = $E5
    =00E6     02395 PL2SHAPOFF      = $E6
    =00E7     02396 PL3SHAPOFF      = $E7
    =00E8     02397 PL4SHAPOFF      = $E8
    =00E9     02398 PL0LIFE         = $E9
    =00EA     02399 PL1LIFE         = $EA
    =00EB     02400 PL2LIFE         = $EB
    =00EC     02401 PL3LIFE         = $EC
    =00ED     02402 PL4LIFE         = $ED
    =00EE     02403 PL0COLOR        = $EE
    =00EF     02404 PL1COLOR        = $EF
    =00F0     02405 PL2COLOR        = $F0
    =00F1     02406 PL3COLOR        = $F1
    =00F2     02407 PF0COLOR        = $F2
    =00F3     02408 PF1COLOR        = $F3
    =00F4     02409 PF2COLOR        = $F4
    =00F5     02410 PF3COLOR        = $F5
    =00F6     02411 BGRCOLOR        = $F6
    =00F7     02412 PF0COLORDLI     = $F7
    =00F8     02413 PF1COLORDLI     = $F8
    =00F9     02414 PF2COLORDLI     = $F9
    =00FA     02415 PF3COLORDLI     = $FA
    =00FB     02416 BGRCOLORDLI     = $FB
    =0280     02417 DSPLST          = $0280
    =0300     02418 PL4DATA         = $0300
    =0400     02419 PL0DATA         = $0400
    =0500     02420 PL1DATA         = $0500
    =0600     02421 PL2DATA         = $0600
    =0700     02422 PL3DATA         = $0700
    =0800     02423 PFMEMROWLO      = $0800
    =0864     02424 PFMEMROWHI      = $0864
    =08C9     02425 GCMEMMAP        = $08C9
    =0949     02426 PANELTXT        = $0949
    =094B     02427 VELOCD1         = $094B
    =0950     02428 KILLCNTD1       = $0950
    =0955     02429 ENERGYD1        = $0955
    =095A     02430 TRACKC1         = $095A
    =095C     02431 TRACKDIGIT      = $095C
    =0960     02432 THETAC1         = $0960
    =0966     02433 PHIC1           = $0966
    =096C     02434 RANGEC1         = $096C
    =0971     02435 GCTXT           = $0971
    =097D     02436 GCWARPD1        = $097D
    =098D     02437 GCTRGCNT        = $098D
    =0992     02438 GCSTATPHO       = $0992
    =0993     02439 GCSTATENG       = $0993
    =0994     02440 GCSTATSHL       = $0994
    =0995     02441 GCSTATCOM       = $0995
    =0996     02442 GCSTATLRS       = $0996
    =0997     02443 GCSTATRAD       = $0997
    =09A3     02444 GCSTARDAT       = $09A3
    =09AD     02445 ZPOSSIGN        = $09AD
    =09AF     02446 PL2ZPOSSIGN     = $09AF
    =09B0     02447 PL3ZPOSSIGN     = $09B0
    =09B1     02448 PL4ZPOSSIGN     = $09B1
    =09DE     02449 XPOSSIGN        = $09DE
    =09E0     02450 PL2XPOSSIGN     = $09E0
    =09E1     02451 PL3XPOSSIGN     = $09E1
    =09E2     02452 PL4XPOSSIGN     = $09E2
    =0A0F     02453 YPOSSIGN        = $0A0F
    =0A11     02454 PL2YPOSSIGN     = $0A11
    =0A12     02455 PL3YPOSSIGN     = $0A12
    =0A13     02456 PL4YPOSSIGN     = $0A13
    =0A40     02457 ZPOSHI          = $0A40
    =0A40     02458 PL0ZPOSHI       = $0A40
    =0A42     02459 PL2ZPOSHI       = $0A42
    =0A43     02460 PL3ZPOSHI       = $0A43
    =0A44     02461 PL4ZPOSHI       = $0A44
    =0A71     02462 XPOSHI          = $0A71
    =0A73     02463 PL2XPOSHI       = $0A73
    =0A74     02464 PL3XPOSHI       = $0A74
    =0A75     02465 PL4XPOSHI       = $0A75
    =0AA2     02466 YPOSHI          = $0AA2
    =0AA4     02467 PL2YPOSHI       = $0AA4
    =0AA5     02468 PL3YPOSHI       = $0AA5
    =0AA6     02469 PL4YPOSHI       = $0AA6
    =0AD3     02470 ZPOSLO          = $0AD3
    =0AD5     02471 PL2ZPOSLO       = $0AD5
    =0AD6     02472 PL3ZPOSLO       = $0AD6
    =0AD7     02473 PL4ZPOSLO       = $0AD7
    =0B04     02474 XPOSLO          = $0B04
    =0B06     02475 PL2XPOSLO       = $0B06
    =0B07     02476 PL3XPOSLO       = $0B07
    =0B08     02477 PL4XPOSLO       = $0B08
    =0B35     02478 YPOSLO          = $0B35
    =0B37     02479 PL2YPOSLO       = $0B37
    =0B38     02480 PL3YPOSLO       = $0B38
    =0B39     02481 PL4YPOSLO       = $0B39
    =0B66     02482 ZVEL            = $0B66
    =0B66     02483 PL0ZVEL         = $0B66
    =0B67     02484 PL1ZVEL         = $0B67
    =0B68     02485 PL2ZVEL         = $0B68
    =0B69     02486 PL3ZVEL         = $0B69
    =0B6A     02487 PL4ZVEL         = $0B6A
    =0B97     02488 XVEL            = $0B97
    =0B97     02489 PL0XVEL         = $0B97
    =0B98     02490 PL1XVEL         = $0B98
    =0B99     02491 PL2XVEL         = $0B99
    =0B9A     02492 PL3XVEL         = $0B9A
    =0B9B     02493 PL4XVEL         = $0B9B
    =0BC8     02494 YVEL            = $0BC8
    =0BC8     02495 PL0YVEL         = $0BC8
    =0BC9     02496 PL1YVEL         = $0BC9
    =0BCA     02497 PL2YVEL         = $0BCA
    =0BCB     02498 PL3YVEL         = $0BCB
    =0BCC     02499 PL4YVEL         = $0BCC
    =0BF9     02500 PIXELROWNEW     = $0BF9
    =0BF9     02501 PL0ROWNEW       = $0BF9
    =0BFA     02502 PL1ROWNEW       = $0BFA
    =0BFB     02503 PL2ROWNEW       = $0BFB
    =0BFC     02504 PL3ROWNEW       = $0BFC
    =0BFD     02505 PL4ROWNEW       = $0BFD
    =0C2A     02506 PIXELCOLUMN     = $0C2A
    =0C2A     02507 PL0COLUMN       = $0C2A
    =0C2B     02508 PL1COLUMN       = $0C2B
    =0C2C     02509 PL2COLUMN       = $0C2C
    =0C2D     02510 PL3COLUMN       = $0C2D
    =0C2E     02511 PL4COLUMN       = $0C2E
    =0C5B     02512 PIXELROW        = $0C5B
    =0C5B     02513 PL0ROW          = $0C5B
    =0C5C     02514 PL1ROW          = $0C5C
    =0C5D     02515 PL2ROW          = $0C5D
    =0C5E     02516 PL3ROW          = $0C5E
    =0C5F     02517 PL4ROW          = $0C5F
    =0C8C     02518 PIXELBYTEOFF    = $0C8C
    =0C8C     02519 PL0SHAPTYPE     = $0C8C
    =0C8D     02520 PL1SHAPTYPE     = $0C8D
    =0C8E     02521 PL2SHAPTYPE     = $0C8E
    =0C8F     02522 PL3SHAPTYPE     = $0C8F
    =0C90     02523 PL4SHAPTYPE     = $0C90
    =0CBD     02524 PIXELSAVE       = $0CBD
    =0CBD     02525 PL0HEIGHT       = $0CBD
    =0CBE     02526 PL1HEIGHT       = $0CBE
    =0CBF     02527 PL2HEIGHT       = $0CBF
    =0CC0     02528 PL3HEIGHT       = $0CC0
    =0CC1     02529 PL4HEIGHT       = $0CC1
    =0CEE     02530 PIXELBYTE       = $0CEE
    =0CEE     02531 PL0HEIGHTNEW    = $0CEE
    =0CEF     02532 PL1HEIGHTNEW    = $0CEF
    =0CF0     02533 PL2HEIGHTNEW    = $0CF0
    =0CF1     02534 PL3HEIGHTNEW    = $0CF1
    =0CF2     02535 PL4HEIGHTNEW    = $0CF2
    =0D1F     02536 TITLETXT        = $0D1F
    =0D35     02537 GCPFMEM         = $0D35
    =0DE9     02538 MAPTO80         = $0DE9
    =0EE9     02539 MAPTOBCD99      = $0EE9
    =1000     02540 PFMEM           = $1000
              02541
              02542                 *= $A000
              02543
              02544 ;*******************************************************************************
              02545 ;*                                                                             *
              02546 ;*                G A M E   D A T A   ( P A R T   1   O F   2 )                *
              02547 ;*                                                                             *
              02548 ;*******************************************************************************
              02549
              02550 ;*** Number of space objects ***************************************************
              02551
    =0010     02552 MAXSPCOBJIND.NL = 16                                  ; Max index of normal number of spc objs
    =0031     02553 MAXSPCOBJNUM    = 49                                  ; Maximum number of space objects
              02554
              02555 ;*** PLAYER shape data offsets *************************************************
              02556
    =0000     02557 SHAP.TORPEDO    = $00                                 ; Photon torpedo
    =0010     02558 SHAP.ZFIGHTER   = $10                                 ; Zylon fighter
    =0020     02559 SHAP.STARBASEL  = $20                                 ; Starbase (left part)
    =0030     02560 SHAP.STARBASEC  = $30                                 ; Starbase (center part)
    =0040     02561 SHAP.STARBASER  = $40                                 ; Starbase (right part)
    =0050     02562 SHAP.TRANSVSSL  = $50                                 ; Transfer vessel
    =0060     02563 SHAP.METEOR     = $60                                 ; Meteor
    =0070     02564 SHAP.ZCRUISER   = $70                                 ; Zylon cruiser
    =0080     02565 SHAP.ZBASESTAR  = $80                                 ; Zylon basestar
    =0090     02566 SHAP.HYPERWARP  = $90                                 ; Hyperwarp Target Marker
              02567
              02568 ;*** ROM character set constants ***********************************************
    =0000     02569 ROM.SPC         = $00                                 ; ROM character ' '
    =000E     02570 ROM.DOT         = $0E                                 ; ROM character '.'
    =0010     02571 ROM.0           = $10                                 ; ROM character '0'
    =0011     02572 ROM.1           = $11                                 ; ROM character '1'
    =0012     02573 ROM.2           = $12                                 ; ROM character '2'
    =0013     02574 ROM.3           = $13                                 ; ROM character '3'
    =0014     02575 ROM.4           = $14                                 ; ROM character '4'
    =0015     02576 ROM.5           = $15                                 ; ROM character '5'
    =0019     02577 ROM.9           = $19                                 ; ROM character '9'
    =001A     02578 ROM.COLON       = $1A                                 ; ROM character ':'
    =0021     02579 ROM.A           = $21                                 ; ROM character 'A'
    =0023     02580 ROM.C           = $23                                 ; ROM character 'C'
    =0024     02581 ROM.D           = $24                                 ; ROM character 'D'
    =0025     02582 ROM.E           = $25                                 ; ROM character 'E'
    =0027     02583 ROM.G           = $27                                 ; ROM character 'G'
    =002C     02584 ROM.L           = $2C                                 ; ROM character 'L'
    =002E     02585 ROM.N           = $2E                                 ; ROM character 'N'
    =0030     02586 ROM.P           = $30                                 ; ROM character 'P'
    =0032     02587 ROM.R           = $32                                 ; ROM character 'R'
    =0033     02588 ROM.S           = $33                                 ; ROM character 'S'
    =0034     02589 ROM.T           = $34                                 ; ROM character 'T'
    =0037     02590 ROM.W           = $37                                 ; ROM character 'W'
    =0039     02591 ROM.Y           = $39                                 ; ROM character 'Y'
              02592
              02593 ;*** Custom character set constants ********************************************
    =0040     02594 CCS.COL1        = $40                                 ; COLOR1 bits for text in GR1/2 text mode
    =0080     02595 CCS.COL2        = $80                                 ; COLOR2 bits for text in GR1/2 text mode
    =00C0     02596 CCS.COL3        = $C0                                 ; COLOR3 bits for text in GR1/2 text mode
              02597
    =0000     02598 CCS.0           = 0                                   ; Custom character '0'
    =0001     02599 CCS.1           = 1                                   ; Custom character '1'
    =0002     02600 CCS.2           = 2                                   ; Custom character '2'
    =0003     02601 CCS.3           = 3                                   ; Custom character '3'
    =0004     02602 CCS.4           = 4                                   ; Custom character '4'
    =0005     02603 CCS.5           = 5                                   ; Custom character '5'
    =0006     02604 CCS.6           = 6                                   ; Custom character '6'
    =0007     02605 CCS.7           = 7                                   ; Custom character '7'
    =0008     02606 CCS.8           = 8                                   ; Custom character '8'
    =0009     02607 CCS.9           = 9                                   ; Custom character '9'
    =000A     02608 CCS.SPC         = 10                                  ; Custom character ' '
    =000B     02609 CCS.COLON       = 11                                  ; Custom character ':'
    =000C     02610 CCS.BORDERSW    = 12                                  ; Custom character 'BORDER SOUTHWEST'
    =000D     02611 CCS.E           = 13                                  ; Custom character 'E'
    =000E     02612 CCS.INF         = 14                                  ; Custom character 'INFINITY'
    =000F     02613 CCS.MINUS       = 15                                  ; Custom character '-'
    =0010     02614 CCS.PLUS        = 16                                  ; Custom character '+'
    =0011     02615 CCS.PHI         = 17                                  ; Custom character 'PHI'
    =0012     02616 CCS.V           = 18                                  ; Custom character 'V'
    =0013     02617 CCS.R           = 19                                  ; Custom character 'R'
    =0014     02618 CCS.THETA       = 20                                  ; Custom character 'THETA'
    =0015     02619 CCS.K           = 21                                  ; Custom character 'K'
    =0016     02620 CCS.T           = 22                                  ; Custom character 'T'
    =0017     02621 CCS.C           = 23                                  ; Custom character 'C'
    =0018     02622 CCS.BORDERS     = 24                                  ; Custom character 'BORDER SOUTH'
    =0019     02623 CCS.BORDERW     = 25                                  ; Custom character 'BORDER WEST'
    =001A     02624 CCS.CORNERSW    = 26                                  ; Custom character 'CORNER SOUTHWEST'
    =001B     02625 CCS.STARBASE    = 27                                  ; Custom character 'STARBASE SECTOR'
    =001C     02626 CCS.4ZYLONS     = 28                                  ; Custom character '4-ZYLON SECTOR'
    =001D     02627 CCS.3ZYLONS     = 29                                  ; Custom character '3-ZYLON SECTOR'
    =001E     02628 CCS.2ZYLONS     = 30                                  ; Custom character '2-ZYLON SECTOR'
              02629
              02630 ;*** Custom character set ******************************************************
              02631 ;
              02632 ; 0        1        2        3        4        5        6        7
              02633 ; ........ ........ ........ ........ ........ ........ ........ ........
              02634 ; .####### ..##.... .####... .####... .##..... .####... .####... .#####..
              02635 ; .#...### ...#.... ....#... ....#... .##..... .#...... .#..#... .#...#..
              02636 ; .#...### ...#.... ....#... ....#... .##..... .#...... .#...... .....#..
              02637 ; .#...### ...#.... .####... .#####.. .##.##.. .####... .#...... ...###..
              02638 ; .#...### ..###... .#...... ....##.. .#####.. ....#... .######. ...#....
              02639 ; .#...### ..###... .#...... ....##.. ....##.. ....#... .#....#. ...#....
              02640 ; .####### ..###... .####... .#####.. ....##.. .####... .######. ...#....
              02641 ;
              02642 ; 8        9        10       11       12       13       14       15
              02643 ; ........ ........ ........ ..###... #....... ........ ........ ........
              02644 ; ..###... .#####.. ........ ..###... #....... ..####.. .##..##. ........
              02645 ; ..#.#... .#...#.. ........ ..###... #....... ..#..... #..##..# ........
              02646 ; ..#.#... .#...#.. ........ ........ #....... ..#..... #..##..# .######.
              02647 ; .#####.. .#####.. ........ ........ #....... .####... #..##..# ........
              02648 ; .##.##.. ....##.. ........ ..###... #....... .##..... .##..##. ........
              02649 ; .##.##.. ....##.. ........ ..###... #....... .##..... ........ ........
              02650 ; .#####.. ....##.. ........ ..###... ######## .#####.. ........ ........
              02651 ;
              02652 ; 16       17       18       19       20       21       22       23
              02653 ; ........ ........ .##..##. ........ ........ ........ #######. ######..
              02654 ; ...##... ...##... .##..##. .#####.. ...###.. .#...##. #..#..#. #...##..
              02655 ; ...##... .######. .##..##. .#...#.. ..#####. .#...##. ...#.... #...##..
              02656 ; ...##... ##.##.## .##..##. .#...#.. .##...## .#...#.. ...##... #.......
              02657 ; .######. #..##..# .##..##. .#####.. .#.###.# .#####.. ...##... #.......
              02658 ; ...##... ##.##.## ..#.##.. .##.#... .##...## .##..#.. ...##... #.......
              02659 ; ...##... .######. ..###... .##.##.. ..#####. .##..##. ...##... #....#..
              02660 ; ...##... ...##... ..##.... .##.##.. ...###.. .##..##. ...##... ######..
              02661 ;
              02662 ; 24       25       26       27       28       29       30
              02663 ; ........ #....... ........ #....... #....... #....... #.......
              02664 ; ........ #....... ........ #.#.#.#. #..##... #...###. #.##....
              02665 ; ........ #....... ........ #..###.. #....... #....... #..##...
              02666 ; ........ #....... ........ #.#####. #.##.##. #.###... #.#####.
              02667 ; ........ #....... ........ #..###.. #....... #....... #..##...
              02668 ; ........ #....... ........ #.#.#.#. #...##.. #..###.. #.##....
              02669 ; ........ #....... ........ #....... #....... #....... #.......
              02670 ; ######## #....... #....... ######## ######## ######## ########
              02671
A000 007F4747 02672 CHARSET         .BYTE $00,$7F,$47,$47,$47,$47,$47,$7F ; Custom character '0'
A004 4747477F
A008 00301010 02673                 .BYTE $00,$30,$10,$10,$10,$38,$38,$38 ; Custom character '1'
A00C 10383838
A010 00780808 02674                 .BYTE $00,$78,$08,$08,$78,$40,$40,$78 ; Custom character '2'
A014 78404078
A018 00780808 02675                 .BYTE $00,$78,$08,$08,$7C,$0C,$0C,$7C ; Custom character '3'
A01C 7C0C0C7C
A020 00606060 02676                 .BYTE $00,$60,$60,$60,$6C,$7C,$0C,$0C ; Custom character '4'
A024 6C7C0C0C
A028 00784040 02677                 .BYTE $00,$78,$40,$40,$78,$08,$08,$78 ; Custom character '5'
A02C 78080878
A030 00784840 02678                 .BYTE $00,$78,$48,$40,$40,$7E,$42,$7E ; Custom character '6'
A034 407E427E
A038 007C4404 02679                 .BYTE $00,$7C,$44,$04,$1C,$10,$10,$10 ; Custom character '7'
A03C 1C101010
A040 00382828 02680                 .BYTE $00,$38,$28,$28,$7C,$6C,$6C,$7C ; Custom character '8'
A044 7C6C6C7C
A048 007C4444 02681                 .BYTE $00,$7C,$44,$44,$7C,$0C,$0C,$0C ; Custom character '9'
A04C 7C0C0C0C
A050 00000000 02682                 .BYTE $00,$00,$00,$00,$00,$00,$00,$00 ; Custom character ' '
A054 00000000
A058 38383800 02683                 .BYTE $38,$38,$38,$00,$00,$38,$38,$38 ; Custom character '.'
A05C 00383838
A060 80808080 02684                 .BYTE $80,$80,$80,$80,$80,$80,$80,$FF ; Custom character 'BORDER SOUTHWEST'
A064 808080FF
A068 003C2020 02685                 .BYTE $00,$3C,$20,$20,$78,$60,$60,$7C ; Custom character 'E'
A06C 7860607C
A070 00669999 02686                 .BYTE $00,$66,$99,$99,$99,$66,$00,$00 ; Custom character 'INFINITY'
A074 99660000
A078 0000007E 02687                 .BYTE $00,$00,$00,$7E,$00,$00,$00,$00 ; Custom character '-'
A07C 00000000
A080 00181818 02688                 .BYTE $00,$18,$18,$18,$7E,$18,$18,$18 ; Custom character '+'
A084 7E181818
A088 00187EDB 02689                 .BYTE $00,$18,$7E,$DB,$99,$DB,$7E,$18 ; Custom character 'PHI'
A08C 99DB7E18
A090 66666666 02690                 .BYTE $66,$66,$66,$66,$66,$2C,$38,$30 ; Custom character 'V'
A094 662C3830
A098 007C4444 02691                 .BYTE $00,$7C,$44,$44,$7C,$68,$6C,$6C ; Custom character 'R'
A09C 7C686C6C
A0A0 001C3E63 02692                 .BYTE $00,$1C,$3E,$63,$5D,$63,$3E,$1C ; Custom character 'THETA'
A0A4 5D633E1C
A0A8 00464644 02693                 .BYTE $00,$46,$46,$44,$7C,$64,$66,$66 ; Custom character 'K'
A0AC 7C646666
A0B0 FE921018 02694                 .BYTE $FE,$92,$10,$18,$18,$18,$18,$18 ; Custom character 'T'
A0B4 18181818
A0B8 FC8C8C80 02695                 .BYTE $FC,$8C,$8C,$80,$80,$80,$84,$FC ; Custom character 'C'
A0BC 808084FC
A0C0 00000000 02696                 .BYTE $00,$00,$00,$00,$00,$00,$00,$FF ; Custom character 'BORDER SOUTH'
A0C4 000000FF
A0C8 80808080 02697                 .BYTE $80,$80,$80,$80,$80,$80,$80,$80 ; Custom character 'BORDER WEST'
A0CC 80808080
A0D0 00000000 02698                 .BYTE $00,$00,$00,$00,$00,$00,$00,$80 ; Custom character 'CORNER SOUTHWEST'
A0D4 00000080
A0D8 80AA9CBE 02699                 .BYTE $80,$AA,$9C,$BE,$9C,$AA,$80,$FF ; Custom character 'STARBASE SECTOR'
A0DC 9CAA80FF
A0E0 809880B6 02700                 .BYTE $80,$98,$80,$B6,$80,$8C,$80,$FF ; Custom character '4-ZYLON SECTOR'
A0E4 808C80FF
A0E8 808E80B8 02701                 .BYTE $80,$8E,$80,$B8,$80,$9C,$80,$FF ; Custom character '3-CYCLON SECTOR'
A0EC 809C80FF
A0F0 80B098BE 02702                 .BYTE $80,$B0,$98,$BE,$98,$B0,$80,$FF ; Custom character '2-ZYLON SECTOR'
A0F4 98B080FF
              02703
              02704 ;*** Header text of Long-Range Scan view (shares spaces with following header) *
A0F8 00006C6F 02705 LRSHEADER       .BYTE $00,$00,$6C,$6F,$6E,$67,$00,$72 ; "  LONG RANGE SCAN"
A0FC 6E670072
A100 616E6765 02706                 .BYTE $61,$6E,$67,$65,$00,$73,$63,$61
A104 00736361
A108 6E       02707                 .BYTE $6E
              02708
              02709 ;*** Header text of Aft view (shares spaces with following header) *************
A109 00000000 02710 AFTHEADER       .BYTE $00,$00,$00,$00,$00,$00,$61,$66 ; "      AFT VIEW   "
A10D 00006166
A111 74007669 02711                 .BYTE $74,$00,$76,$69,$65,$77,$00,$00
A115 65770000
A119 00       02712                 .BYTE $00
              02713
              02714 ;*** Header text of Galactic Chart view ****************************************
A11A 00000067 02715 GCHEADER        .BYTE $00,$00,$00,$67,$61,$6C,$61,$63 ; "   GALACTIC CHART   "
A11E 616C6163
A122 74696300 02716                 .BYTE $74,$69,$63,$00,$63,$68,$61,$72
A126 63686172
A12A 74000000 02717                 .BYTE $74,$00,$00,$00
              02718
              02719 ;*** Display List of Galactic Chart view ***************************************
A12E 60       02720 DLSTGC          .BYTE $60                             ; BLK7
A12F 461AA1   02721                 .BYTE $46,<GCHEADER,>GCHEADER         ; GR2 @ GCHEADER
A132 F0       02722                 .BYTE $F0                             ; BLK8 + DLI
A133 47350D   02723                 .BYTE $47,<GCPFMEM,>GCPFMEM           ; GR1 @ GCPFMEM
A136 07       02724                 .BYTE $07                             ; GR1
A137 07       02725                 .BYTE $07                             ; GR1
A138 07       02726                 .BYTE $07                             ; GR1
A139 07       02727                 .BYTE $07                             ; GR1
A13A 07       02728                 .BYTE $07                             ; GR1
A13B 07       02729                 .BYTE $07                             ; GR1
A13C 07       02730                 .BYTE $07                             ; GR1
A13D 07       02731                 .BYTE $07                             ; GR1
A13E 80       02732                 .BYTE $80                             ; BLK1 + DLI
A13F 461F0D   02733                 .BYTE $46,<TITLETXT,>TITLETXT         ; GR2 @ TITLETXT
A142 467109   02734                 .BYTE $46,<GCTXT,>GCTXT               ; GR2 @ GCTXT
A145 06       02735                 .BYTE $06                             ; GR2
A146 06       02736                 .BYTE $06                             ; GR2
A147 418002   02737                 .BYTE $41,<DSPLST,>DSPLST             ; JMP @ DSPLST
              02738
              02739 ;*******************************************************************************
              02740 ;*                                                                             *
              02741 ;*                              G A M E   C O D E                              *
              02742 ;*                                                                             *
              02743 ;*******************************************************************************
              02744
              02745 ;*******************************************************************************
              02746 ;*                                                                             *
              02747 ;*                                  INITCOLD                                   *
              02748 ;*                                                                             *
              02749 ;*                       Initialize program (Cold start)                       *
              02750 ;*                                                                             *
              02751 ;*******************************************************************************
              02752
              02753 ; DESCRIPTION
              02754 ;
              02755 ; Initializes the program, then continues into the game loop at GAMELOOP
              02756 ; ($A1F3).
              02757 ;
              02758 ; There are four entry points to initialization:
              02759 ;
              02760 ; (1)  INITCOLD ($A14A) is entered at initial cartridge startup (cold start).
              02761 ;      This initializes POKEY, resets the idle counter, sets the mission level
              02762 ;      to NOVICE mission, and clears the function key code. POKEY is enabled to
              02763 ;      receive keyboard input. Code execution continues into INITSELECT ($A15A)
              02764 ;      below.
              02765 ;
              02766 ; (2)  INITSELECT ($A15A) is entered from GAMELOOP ($A1F3) after the SELECT
              02767 ;      function key has been pressed. This loads the title phrase offset for the
              02768 ;      copyright notice. Code execution continues into INITDEMO ($A15C) below. 
              02769 ;
              02770 ; (3)  INITDEMO ($A15C) is entered when the program switches into demo mode.
              02771 ;      This loads the demo mode flag. Code execution continues into INITSTART
              02772 ;      ($A15E) below.
              02773 ;
              02774 ; (4)  INITSTART ($A15E) is entered from GAMELOOP ($A1F3) after the START
              02775 ;      function key has been pressed. This enqueues the new title phrase and
              02776 ;      enables or disables demo mode, depending on the preloaded value.
              02777 ;
              02778 ; Initialization continues with the following steps: 
              02779 ;
              02780 ; (1)  Clear the custom chip registers and zero-page program variables from
              02781 ;      ISVBISYNC ($0067) on.
              02782 ;
              02783 ;      NOTE: Because of loop jamming there is a loop index overshoot. Instead of
              02784 ;      clearing memory at addresses $0067..$00FB, the memory at addresses
              02785 ;      $0067..$0166 is cleared. This does no harm because $0100..$0166 is a yet
              02786 ;      unused part of the 6502 CPU stack.
              02787 ;
              02788 ;      NOTE: At address $A175 a hack is necessary in the source code to fake a
              02789 ;      STA ISVBISYNC,X instruction with a 16-bit address. ISVBISYNC ($0067) is a
              02790 ;      zero-page address and regular assemblers would translate STA ISVBISYNC,X
              02791 ;      into the byte sequence $95 $67, not $9D $67 $00. This indicates that the
              02792 ;      original ROM was maybe created using a special assembler, perhaps a
              02793 ;      cross-assembler.  
              02794 ;
              02795 ; (2)  Initialize the 6502 CPU (reset the stack pointer, disable decimal mode).
              02796 ;
              02797 ; (3)  Clear program memory from $0200..$1FFF in subroutine CLRMEM ($AE0F).
              02798 ;
              02799 ; (4)  Set the address vectors of the IRQ, VBI, and DLI handlers.
              02800 ;
              02801 ; (5)  Enable input from Joystick 0.
              02802 ;
              02803 ; (6)  Enable Player/Missile graphics, providing a fifth PLAYER.
              02804 ;
              02805 ;      BUG (at $A1A6): The set PLAYER-PLAYFIELD priority arranges PLAYERs in
              02806 ;      front of the PLAYFIELD. This makes sense as space objects represented by
              02807 ;      PLAYERs (for example, Zylon ships, photon torpedoes, and meteors) move in
              02808 ;      front of the stars, which are part of the PLAYFIELD. However, PLAYERs
              02809 ;      also move in front of the cross hairs, which are also part of the
              02810 ;      PLAYFIELD. Suggested fix: None, technically not possible.
              02811 ;
              02812 ; (7)  Do more initialization in subroutine INITIALIZE ($B3BA).
              02813 ;
              02814 ; (8)  Set display to Front view.
              02815 ;
              02816 ; (9)  Show or hide the Control Panel Display (bottom text window) in subroutine
              02817 ;      MODDLST ($ADF1), depending on the demo mode flag.
              02818 ;
              02819 ; (10) Initialize our starship's velocity equivalent to speed key '6'.
              02820 ;
              02821 ; (11) Enable the Display List.
              02822 ;
              02823 ; (12) Initialize the number of space objects to 16 (5 PLAYER space objects + 12
              02824 ;      PLAYFIELD space objects (stars)).
              02825 ;
              02826 ; (13) Set the title phrase to the selected mission level in subroutine SETTITLE
              02827 ;      ($B223).
              02828 ;
              02829 ; (14) Enable the IRQ, DLI, and VBI interrupts.
              02830 ;
              02831 ; Code execution continues into the game loop at GAMELOOP ($A1F3).
              02832
A14A A900     02833 INITCOLD        LDA #0                  ;
A14C 8D0FD2   02834                 STA SKCTL               ; POKEY: Initialization
A14F 8566     02835                 STA IDLECNTHI           ; Reset idle counter
A151 8562     02836                 STA MISSIONLEVEL        ; Mission level := NOVICE mission
A153 8563     02837                 STA FKEYCODE            ; Clear function key code
A155 A903     02838                 LDA #$03                ; POKEY: Enable keyboard scan and debounce
A157 8D0FD2   02839                 STA SKCTL               ;
              02840
              02841 ;*** Entry point when SELECT function key was pressed **************************
A15A A02F     02842 INITSELECT      LDY #$2F                ; Prep title phrase "COPYRIGHT ATARI 1979"
              02843
              02844 ;*** Entry point when program switches into demo mode **************************
A15C A9FF     02845 INITDEMO        LDA #$FF                ; Prep demo mode flag
              02846
              02847 ;*** Entry point when START function key was pressed ***************************
A15E 8465     02848 INITSTART       STY NEWTITLEPHR         ; Enqueue new title phrase
A160 8564     02849                 STA ISDEMOMODE          ; Store demo mode flag
              02850
              02851 ;*** More initialization *******************************************************
A162 A900     02852                 LDA #0                  ; Clear custom chip registers, zero-page variables
A164 AA       02853                 TAX                     ;
A165 9D00D0   02854 LOOP001         STA HPOSP0,X            ; Clear $D000..$D0FF (GTIA registers)
A168 9D00D4   02855                 STA DMACTL,X            ; Clear $D400..$D4FF (ANTIC registers)
A16B E00F     02856                 CPX #$0F                ;
A16D B003     02857                 BCS SKIP001             ;
A16F 9D00D2   02858                 STA AUDF1,X             ; Clear $D200..$D20E (POKEY registers)
              02859
A172 9D00D3   02860 SKIP001         STA PORTA,X             ; Clear $D300..$D3FF (PIA registers)
              02861                                         ; Clear $0067..$0166 (zero-page program variables)
A175 9D       02862                 .BYTE $9D               ; HACK: Fake STA ISVBISYNC,X with 16-bit address
A176 6700     02863                 .WORD ISVBISYNC         ;
A178 E8       02864                 INX                     ;
A179 D0EA     02865                 BNE LOOP001             ;
              02866
A17B CA       02867                 DEX                     ; Reset 6502 CPU stack pointer
A17C 9A       02868                 TXS                     ;
              02869
A17D D8       02870                 CLD                     ; Clear 6502 CPU decimal mode
              02871
A17E A902     02872                 LDA #$02                ; Clear $0200..$1FFF (program memory)
A180 200FAE   02873                 JSR CLRMEM              ;
              02874
A183 A951     02875                 LDA #<IRQHNDLR          ; Set IRQ handler (VIMIRQ)
A185 8D1602   02876                 STA VIMIRQ              ;
A188 A9A7     02877                 LDA #>IRQHNDLR          ;
A18A 8D1702   02878                 STA VIMIRQ+1            ;
              02879
A18D A9D1     02880                 LDA #<VBIHNDLR          ; Set VBI and DLI handler (VVBLKI and VDSLST)
A18F 8D2202   02881                 STA VVBLKI              ;
A192 A918     02882                 LDA #<DLSTHNDLR         ;
A194 8D0002   02883                 STA VDSLST              ;
A197 A9A6     02884                 LDA #>VBIHNDLR          ;
A199 8D2302   02885                 STA VVBLKI+1            ;
A19C A9A7     02886                 LDA #>DLSTHNDLR         ;
A19E 8D0102   02887                 STA VDSLST+1            ;
              02888
A1A1 A904     02889                 LDA #$04                ; PIA: Enable PORTA (Joystick 0)
A1A3 8D02D3   02890                 STA PACTL               ;
A1A6 A911     02891                 LDA #$11                ; GTIA: Enable PLAYER4, prio: PLs > PFs > BGR (!)
A1A8 8D1BD0   02892                 STA PRIOR               ; (PLAYERs appear behind cross hairs)
A1AB A903     02893                 LDA #$03                ; GTIA: Enable DMA for PLAYERs and MISSILEs
A1AD 8D1DD0   02894                 STA GRACTL              ;
              02895
A1B0 20BAB3   02896                 JSR INITIALIZE          ; Init Display List, tables, Galactic Chart, etc.
              02897
A1B3 A20A     02898                 LDX #$0A                ; Set Front view
A1B5 2045B0   02899                 JSR SETVIEW             ;
              02900
A1B8 A564     02901                 LDA ISDEMOMODE          ; If in/not in demo mode hide/show...
A1BA 2980     02902                 AND #$80                ; ...Control Panel Display (bottom text window)
A1BC A8       02903                 TAY                     ;
A1BD A25F     02904                 LDX #$5F                ;
A1BF A908     02905                 LDA #$08                ;
A1C1 20F1AD   02906                 JSR MODDLST             ;
              02907
A1C4 A920     02908                 LDA #$20                ; Init our starship's velocity (= speed key '6')
A1C6 8571     02909                 STA NEWVELOCITY         ;
              02910
A1C8 A980     02911                 LDA #<DSPLST            ; ANTIC: Set Display List
A1CA 8D02D4   02912                 STA DLIST               ;
A1CD A902     02913                 LDA #>DSPLST            ;
A1CF 8D03D4   02914                 STA DLIST+1             ;
              02915
A1D2 A93E     02916                 LDA #$3E                ; ANTIC: Enable Display List DMA, single-line PM
A1D4 8D00D4   02917                 STA DMACTL              ; resolution, PM DMA, normal-width PLAYFIELD
              02918
A1D7 A900     02919                 LDA #0                  ; ANTIC: Set PM memory base address
A1D9 8D07D4   02920                 STA PMBASE              ;
              02921
A1DC A910     02922                 LDA #MAXSPCOBJIND.NL    ; Set normal number of space objects
A1DE 8579     02923                 STA MAXSPCOBJIND        ; (5 PLAYER spc objs + 12 PLAYFIELD spc objs (stars))
              02924
A1E0 A662     02925                 LDX MISSIONLEVEL        ; Set title phrase
A1E2 BC0CBF   02926                 LDY MISSIONPHRTAB,X     ; NOVICE, PILOT, WARRIOR, or COMMANDER MISSION
A1E5 2023B2   02927                 JSR SETTITLE            ;
              02928
A1E8 A940     02929                 LDA #$40                ; POKEY: Enable keyboard interrupt (IRQ)
A1EA 8D0ED2   02930                 STA IRQEN               ;
              02931
A1ED 58       02932                 CLI                     ; Enable all IRQs
              02933
A1EE A9C0     02934                 LDA #$C0                ; ANTIC: Enable DLI and VBI
A1F0 8D0ED4   02935                 STA NMIEN               ;
              02936
              02937 ;*******************************************************************************
              02938 ;*                                                                             *
              02939 ;*                                  GAMELOOP                                   *
              02940 ;*                                                                             *
              02941 ;*******************************************************************************
              02942
              02943 ; DESCRIPTION
              02944 ;
              02945 ; The game loop is the main part of the program. It is basically an infinite
              02946 ; loop that collects input, computes the game state, and updates the display. It
              02947 ; executes the following steps:
              02948 ;
              02949 ; (1)  Synchronize the start of the game loop with the vertical blank phase of
              02950 ;      the TV beam, which flagged by the Vertical Blank Interrupt handler
              02951 ;      VBIHNDLR ($A6D1). This prevents screen flicker while the PLAYFIELD is
              02952 ;      redrawn at the begin of the game loop, because during the vertical blank
              02953 ;      phase the TV beam is turned off and nothing is rendered on the TV
              02954 ;      display. 
              02955 ;
              02956 ; (2)  Erase all PLAYFIELD space objects (stars, explosion fragments) from the
              02957 ;      PLAYFIELD that were drawn in the previous game loop iteration.
              02958 ;
              02959 ; (3)  Draw the updated PLAYFIELD space objects (stars, explosion fragments)
              02960 ;      into the PLAYFIELD (skip this if in hyperspace).
              02961 ;
              02962 ; (4)  If the idle counter has reached its trigger value then clear the center
              02963 ;      of the PLAYFIELD, a 8 x 2 pixel rectangle with a top-left position at
              02964 ;      pixel column number 76 and pixel row number 49 (?).
              02965 ;
              02966 ; (5)  Clear all PLAYER shapes.
              02967 ;
              02968 ; (6)  Update the vertical position of all PLAYERs and update all PLAYER shapes.
              02969 ;
              02970 ; (7)  Update the horizontal position of all PLAYERs.
              02971 ;
              02972 ; (8)  Rotate the position vector of all space objects horizontally and
              02973 ;      vertically, according to the saved joystick position (skip this if in
              02974 ;      Galactic Chart view) using subroutine ROTATE ($B69B).
              02975 ;
              02976 ; (9)  Move our starship forward in space. Our starship is always located at the
              02977 ;      center of the program's 3D coordinate system, so all space objects are
              02978 ;      moved along the z-axis toward our starship by subtracting a displacement
              02979 ;      from their z-coordinate. The amount of the displacement depends on our
              02980 ;      starship's velocity.
              02981 ;
              02982 ;      BUG (at $A3C1): This operation is not applied to Photon torpedoes (?).
              02983 ;      Suggested fix: Remove LDA PL0SHAPTYPE,X and BEQ SKIP011. 
              02984 ;
              02985 ; (10) Add the proper velocity vector of all space objects to their position
              02986 ;      vector (except for stars, which do not have any proper motion).
              02987 ;
              02988 ;      BUG (at $A419): The correct maximum loop index is MAXSPCOBJNUM*3 = 147
              02989 ;      instead of 144. Suggested fix: Replace CMP #144 by CMP #147.
              02990 ;
              02991 ; (11) Correct the position vector components (coordinates) of all PLAYER space
              02992 ;      objects if they have over- or underflowed during the calculations of the
              02993 ;      previous steps.
              02994 ;
              02995 ; (12) Calculate the perspective projection of the position vectors of all space
              02996 ;      objects and from that their pixel row and column number (applies to Front
              02997 ;      and Aft view) using subroutines PROJECTION ($AA21), SCREENCOLUMN ($B6FB),
              02998 ;      and SCREENROW ($B71E). If a space object (star, explosion fragment) moved
              02999 ;      offscreen then a new space object is automatically created in subroutine
              03000 ;      SCREENCOLUMN ($B6FB).
              03001 ;
              03002 ; (13) Handle hyperwarp marker selection in the Galactic Chart view in
              03003 ;      subroutine SELECTWARP ($B162).
              03004 ;
              03005 ; (14) If in Long-Range Scan view, compute the pixel column number and the pixel
              03006 ;      row number of all PLAYFIELD space objects (stars, explosion fragments) on
              03007 ;      the plane established by the z and x axis of the 3D coordinate system
              03008 ;      using subroutines SCREENCOLUMN ($B6FB) and SCREENROW ($B71E). Our
              03009 ;      starship's shape is drawn using subroutine DRAWLINES ($A76F). If the
              03010 ;      Long-Range Scan is OK then PLAYFIELD space object pixel numbers are
              03011 ;      computed and drawn. This is skipped if the Long-Range Scan is destroyed. 
              03012 ;
              03013 ; (15) Update all PLAYER shapes, heights, and colors (see detailed description
              03014 ;      below).
              03015 ;
              03016 ; (16) Flash a red alert when leaving hyperspace into a sector containing Zylon
              03017 ;      ships by setting appropriate colors to PLAYFIELD2 and BACKGROUND.
              03018 ;
              03019 ; (17) Update the color of all PLAYFIELD space objects (stars, explosion
              03020 ;      fragments). The color calculation is similar to that of the PLAYER color
              03021 ;      calculation in (15). It also computes a range index and uses the same
              03022 ;      color lookup table FOURCOLORPIXEL ($BA90). If a star in the Aft view
              03023 ;      became too distant (z-coordinate < -$F000 (-4096) <KM>) its position is
              03024 ;      re-initialized in subroutine INITPOSVEC ($B764).
              03025 ;
              03026 ; (18) If in demo mode skip input handling and jump directly to function key
              03027 ;      handling (28).
              03028 ;
              03029 ; (19) Handle keyboard input in subroutine KEYBOARD ($AFFE).
              03030 ;
              03031 ; (20) Handle joystick input. Store the current joystick directions in JOYSTICKX
              03032 ;      ($C8) and JOYSTICKY ($C9).
              03033 ;
              03034 ; (21) Check if our starship's photon torpedoes have hit a target in subroutine
              03035 ;      COLLISION ($AF3D). This subroutine triggers a game over if all Zylon
              03036 ;      ships have been destroyed.
              03037 ;
              03038 ; (22) Handle the joystick trigger in subroutine TRIGGER ($AE29).
              03039 ;
              03040 ; (23) Handle the Attack Computer and Tracking Computer. If the Attack Computer
              03041 ;      is neither destroyed nor switched off then execute the following steps:
              03042 ;
              03043 ;      o   Update the Attack Computer Display's blip and lock-on markers in
              03044 ;          subroutine UPDATTCOMP ($A7BF) (if in Front view).
              03045 ;
              03046 ;      o   Update the tracking index of the currently tracked PLAYER space
              03047 ;          object. If a Zylon ship is tracked, then make sure to always track
              03048 ;          the Zylon ship that launched the last Zylon photon torpedo. If this
              03049 ;          Zylon ship is not alive then track the other Zylon ship - if alive.
              03050 ;
              03051 ;      o   If the Tracking Computer is on then switch to the view that shows the
              03052 ;          tracked PLAYER space object by emulating pressing the 'F' (Front
              03053 ;          view) or 'A' (Aft view) key (only if in Front or Aft view).
              03054 ;
              03055 ; (24) Handle docking at a starbase in subroutine DOCKING ($ACE6).
              03056 ;
              03057 ; (25) Handle maneuvering both of our starship's photon torpedoes, the single
              03058 ;      Zylon photon torpedo, and the attacking Zylon ships in subroutine
              03059 ;      MANEUVER ($AA79). This subroutine also automatically creates meteors and
              03060 ;      new Zylon ships.
              03061 ;
              03062 ; (26) Check if our starship was hit by a Zylon photon torpedo (skip this if in
              03063 ;      a starbase sector): Its x, y, and z coordinates must be within a range of
              03064 ;      -($0100)..+$00FF (-256..+255) <KM> of our starship.
              03065 ;
              03066 ; (27) If our starship was hit then execute the following steps:
              03067 ;
              03068 ;      o   Damage or destroy one of our starship's subsystems in subroutine
              03069 ;          DAMAGE ($AEE1).
              03070 ;
              03071 ;      o   Trigger an explosion in subroutine INITEXPL ($AC6B), 
              03072 ;
              03073 ;      o   Store the severity of the hit.
              03074 ;
              03075 ;      o   End the lifetime of the Zylon photon torpedo.
              03076 ;
              03077 ;      o   Subtract 100 energy units for being hit by the Zylon photon torpedo
              03078 ;          in subroutine DECENERGY ($B86F). 
              03079 ;
              03080 ;      o   Trigger the noise sound pattern SHIP EXPLOSION in subroutine NOISE
              03081 ;          ($AEA8). 
              03082 ;
              03083 ;      If the Shields were down during the hit, our starship is destroyed.
              03084 ;      Execute the following steps:
              03085 ;
              03086 ;      o   Switch to Front view.
              03087 ;
              03088 ;      o   Flash the title phrase "SHIP DESTROYED BY ZYLON FIRE".
              03089 ;
              03090 ;      o   Add the mission bonus to the internal game score in subroutine
              03091 ;          GAMEOVER ($B10A).
              03092 ;
              03093 ;      o   Hide the Control Panel Display (bottom text window) in subroutine
              03094 ;          MODDLST ($ADF1).
              03095 ;
              03096 ;      o   Clear the PLAYFIELD in subroutine CLRPLAYFIELD ($AE0D).
              03097 ;
              03098 ;      o   Enable a special explosion sound. 
              03099 ;
              03100 ; (28) Handle the function keys START and SELECT. If SELECT has been pressed
              03101 ;      cycle through the next of the 4 mission levels. If either START or SELECT
              03102 ;      have been pressed, reset the idle counter, then jump to the corresponding
              03103 ;      program initialization subroutines INITSTART ($A15E) or INITSELECT
              03104 ;      ($A15A), respectively. 
              03105 ;
              03106 ; (29) Update the Control Panel Display in subroutine UPDPANEL ($B804).
              03107 ;
              03108 ; (30) Handle hyperwarp in subroutine HYPERWARP ($A89B).
              03109 ;
              03110 ; (31) Update the text in the title line in subroutine UPDTITLE ($B216).
              03111 ;
              03112 ; (32) Move Zylon units, decrease lifetime of photon torpedoes, elapse game
              03113 ;      time, etc. in subroutine FLUSHGAMELOOP ($B4E4). This subroutine also
              03114 ;      triggers a game over if our starship's energy is zero.
              03115 ;
              03116 ; (33) Jump back to the start of the game loop for the next game loop iteration.
              03117
    =006A     03118 L.HEIGHTCNT     = $6A                   ; Height counter during copying a PLAYER shape
    =006E     03119 L.ZPOSOFF       = $6E                   ; Offset to z-coordinate
    =006B     03120 L.VELOCITYHI    = $6B                   ; Velocity vector component (high byte)
    =006A     03121 L.VECCOMPIND    = $6A                   ; Position vector component index. Used values are:
              03122                                         ;   0 -> z-component
              03123                                         ;   1 -> x-component
              03124                                         ;   2 -> y-component
    =006A     03125 L.RANGEINDEX    = $6A                   ; Range index for space object, computed from the
              03126                                         ; distance to our starship. Used to pick the shape
              03127                                         ; cell index of the PLAYERs shape data and shape
              03128                                         ; height. Used values are: 0..15.
    =006A     03129 L.FOURCOLORPIX  = $6A                   ; 1-byte bit pattern for 4 pixels of same color
    =006B     03130 L.COLORMASK     = $6B                   ; Color/brightness to modify PLAYER color
              03131
              03132 ;*** (1) Synchronize game loop with execution of VBI ***************************
A1F3 A567     03133 GAMELOOP        LDA ISVBISYNC           ; Wait for execution of VBI
A1F5 F0FC     03134                 BEQ GAMELOOP            ;
              03135
A1F7 A900     03136                 LDA #0                  ; VBI is executed, clear VBI sync flag
A1F9 8567     03137                 STA ISVBISYNC           ;
              03138
              03139 ;*** (2) Erase PLAYFIELD space objects (stars, explosion fragments) ************
A1FB A57A     03140                 LDA SAVMAXSPCOBJIND     ; Skip if no space objects in use
A1FD F020     03141                 BEQ SKIP002             ;
              03142
A1FF A204     03143                 LDX #4                  ; Loop over all PLAYFIELD space objs (X index > 4)
A201 E8       03144 LOOP002         INX                     ;
A202 BC5B0C   03145                 LDY PIXELROW,X          ; Load pixel row number of PLAYFIELD space object
              03146
A205 B90008   03147                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pixel's row...
A208 8568     03148                 STA MEMPTR              ; ...in PLAYFIELD memory
A20A B96408   03149                 LDA PFMEMROWHI,Y        ;
A20D 8569     03150                 STA MEMPTR+1            ;
              03151
A20F BC8C0C   03152                 LDY PIXELBYTEOFF,X      ; Get within-row-offset to byte with space obj pixel
A212 BDBD0C   03153                 LDA PIXELSAVE,X         ; Load saved byte
A215 9168     03154                 STA (MEMPTR),Y          ; Restore byte of PLAYFIELD memory
              03155
A217 E47A     03156                 CPX SAVMAXSPCOBJIND     ;
A219 90E6     03157                 BCC LOOP002             ; Next PLAYFIELD space object
              03158
A21B A900     03159                 LDA #0                  ; Clear number of space objects
A21D 857A     03160                 STA SAVMAXSPCOBJIND     ;
              03161
              03162 ;*** (3) Draw PLAYFIELD space objects (stars, explosion fragments) *************
A21F A5C0     03163 SKIP002         LDA WARPSTATE           ; Skip during hyperspace
A221 302D     03164                 BMI SKIP003             ;
              03165
A223 A679     03166                 LDX MAXSPCOBJIND        ; Update number of space objects
A225 867A     03167                 STX SAVMAXSPCOBJIND     ;
              03168
A227 BDF90B   03169 LOOP003         LDA PIXELROWNEW,X       ; Loop over all PLAYFIELD space objs (X index > 4)
A22A 9D5B0C   03170                 STA PIXELROW,X          ; Update pixel row number of PLAYFIELD space object
              03171
A22D A8       03172                 TAY                     ;
A22E B90008   03173                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pixel's row...
A231 8568     03174                 STA MEMPTR              ; ...in PLAYFIELD memory
A233 B96408   03175                 LDA PFMEMROWHI,Y        ;
A236 8569     03176                 STA MEMPTR+1            ;
              03177
A238 BD2A0C   03178                 LDA PIXELCOLUMN,X       ; Convert pixel column number to within-row-offset
A23B 4A       03179                 LSR A                   ; ...of byte with space obj pixel (4 pixels = 1 byte)
A23C 4A       03180                 LSR A                   ;
A23D 9D8C0C   03181                 STA PIXELBYTEOFF,X      ; Store within-row-offset
              03182
A240 A8       03183                 TAY                     ;
A241 B168     03184                 LDA (MEMPTR),Y          ; Load pixel's byte from PLAYFIELD memory
A243 9DBD0C   03185                 STA PIXELSAVE,X         ; Save it (for restoring it in next game loop)
A246 1DEE0C   03186                 ORA PIXELBYTE,X         ; Blend with pixel's color bit-pattern
A249 9168     03187                 STA (MEMPTR),Y          ; Store byte in PLAYFIELD memory
              03188
A24B CA       03189                 DEX                     ;
A24C E004     03190                 CPX #4                  ;
A24E D0D7     03191                 BNE LOOP003             ; Next PLAYFIELD space object
              03192
              03193 ;*** (4) Clear PLAYFIELD center if idle counter is up (?) **********************
              03194                                         ; PLAYFIELD addresses of...
    =17BB     03195 PFMEM.C76R49    = PFMEM+49*40+76/4      ; ...pixel column number 76, row number 49
    =17BC     03196 PFMEM.C80R49    = PFMEM+49*40+80/4      ; ...pixel column number 80, row number 49
    =17E3     03197 PFMEM.C76R50    = PFMEM+50*40+76/4      ; ...pixel column number 76, row number 50
    =17E4     03198 PFMEM.C80R50    = PFMEM+50*40+80/4      ; ...pixel column number 80, row number 50
              03199
A250 A566     03200 SKIP003         LDA IDLECNTHI           ; Skip if idle counter not negative
A252 100E     03201                 BPL SKIP004             ;
              03202
A254 A900     03203                 LDA #0                  ; Clear pixels of 8 x 2 pixel rectangle...
A256 8DE317   03204                 STA PFMEM.C76R50        ; ...@ column number 76, row number 49
A259 8DE417   03205                 STA PFMEM.C80R50        ;
A25C 8DBC17   03206                 STA PFMEM.C80R49        ;
A25F 8DBB17   03207                 STA PFMEM.C76R49        ;
              03208
              03209 ;*** (5) Clear all PLAYER shapes ***********************************************
A262 A900     03210 SKIP004         LDA #0                  ; Clear shape of PLAYER4
A264 AC5F0C   03211                 LDY PL4ROW              ;
A267 AEC10C   03212                 LDX PL4HEIGHT           ;
A26A 990003   03213 LOOP004         STA PL4DATA,Y           ;
A26D C8       03214                 INY                     ;
A26E CA       03215                 DEX                     ;
A26F 10F9     03216                 BPL LOOP004             ;
              03217
A271 AC5E0C   03218                 LDY PL3ROW              ; Clear shape of PLAYER3
A274 AEC00C   03219                 LDX PL3HEIGHT           ;
A277 990007   03220 LOOP005         STA PL3DATA,Y           ;
A27A C8       03221                 INY                     ;
A27B CA       03222                 DEX                     ;
A27C 10F9     03223                 BPL LOOP005             ;
              03224
A27E AC5D0C   03225                 LDY PL2ROW              ; Clear shape of PLAYER2
A281 AEBF0C   03226                 LDX PL2HEIGHT           ;
A284 990006   03227 LOOP006         STA PL2DATA,Y           ;
A287 C8       03228                 INY                     ;
A288 CA       03229                 DEX                     ;
A289 10F9     03230                 BPL LOOP006             ;
              03231
A28B AC5C0C   03232                 LDY PL1ROW              ; Clear shape of PLAYER1
A28E AEBE0C   03233                 LDX PL1HEIGHT           ;
A291 990005   03234 LOOP007         STA PL1DATA,Y           ;
A294 C8       03235                 INY                     ;
A295 CA       03236                 DEX                     ;
A296 10F9     03237                 BPL LOOP007             ;
              03238
A298 AC5B0C   03239                 LDY PL0ROW              ; Clear shape of PLAYER0
A29B AEBD0C   03240                 LDX PL0HEIGHT           ;
A29E 990004   03241 LOOP008         STA PL0DATA,Y           ;
A2A1 C8       03242                 INY                     ;
A2A2 CA       03243                 DEX                     ;
A2A3 10F9     03244                 BPL LOOP008             ;
              03245
              03246 ;*** (6) Update PLAYER vertical positions and update PLAYER shapes *************
A2A5 AD900C   03247                 LDA PL4SHAPTYPE         ; Prep: Is PLAYER4 a PHOTON TORPEDO (shape type 0)?
A2A8 C901     03248                 CMP #1                  ;
A2AA A4E8     03249                 LDY PL4SHAPOFF          ; Load PLAYER4 shape data offset
              03250
A2AC AEFD0B   03251                 LDX PL4ROWNEW           ; Update vertical position of PLAYER4
A2AF 8E5F0C   03252                 STX PL4ROW              ;
              03253
A2B2 ADF20C   03254                 LDA PL4HEIGHTNEW        ; Update PLAYER4 shape height
A2B5 856A     03255                 STA L.HEIGHTCNT         ;
A2B7 8DC10C   03256                 STA PL4HEIGHT           ;
              03257
A2BA B9E4B8   03258 LOOP009         LDA PLSHAP1TAB,Y        ; Load PLAYER4 shape byte from shape data table
A2BD B003     03259                 BCS SKIP005             ; Skip if PLAYER4 not PHOTON TORPEDO (shape type 0)
A2BF 2D0AD2   03260                 AND RANDOM              ; AND random bits to shape byte
A2C2 9D0003   03261 SKIP005         STA PL4DATA,X           ; Store shape byte in PLAYER4 data area
A2C5 C8       03262                 INY                     ;
A2C6 E8       03263                 INX                     ;
A2C7 C66A     03264                 DEC L.HEIGHTCNT         ;
A2C9 10EF     03265                 BPL LOOP009             ; Next row of PLAYER4 shape
              03266
A2CB AD8F0C   03267                 LDA PL3SHAPTYPE         ; Repeat above with PLAYER3
A2CE C901     03268                 CMP #1                  ;
A2D0 A4E7     03269                 LDY PL3SHAPOFF          ;
A2D2 AEFC0B   03270                 LDX PL3ROWNEW           ;
A2D5 8E5E0C   03271                 STX PL3ROW              ;
A2D8 ADF10C   03272                 LDA PL3HEIGHTNEW        ;
A2DB 856A     03273                 STA L.HEIGHTCNT         ;
A2DD 8DC00C   03274                 STA PL3HEIGHT           ;
A2E0 B9E4B8   03275 LOOP010         LDA PLSHAP1TAB,Y        ;
A2E3 B003     03276                 BCS SKIP006             ;
A2E5 2D0AD2   03277                 AND RANDOM              ;
A2E8 9D0007   03278 SKIP006         STA PL3DATA,X           ;
A2EB E8       03279                 INX                     ;
A2EC C8       03280                 INY                     ;
A2ED C66A     03281                 DEC L.HEIGHTCNT         ;
A2EF 10EF     03282                 BPL LOOP010             ;
              03283
A2F1 AD8E0C   03284                 LDA PL2SHAPTYPE         ; Repeat above with PLAYER2
A2F4 C901     03285                 CMP #1                  ;
A2F6 A4E6     03286                 LDY PL2SHAPOFF          ;
A2F8 AEFB0B   03287                 LDX PL2ROWNEW           ;
A2FB 8E5D0C   03288                 STX PL2ROW              ;
A2FE ADF00C   03289                 LDA PL2HEIGHTNEW        ;
A301 856A     03290                 STA L.HEIGHTCNT         ;
A303 8DBF0C   03291                 STA PL2HEIGHT           ;
A306 B9E4B8   03292 LOOP011         LDA PLSHAP1TAB,Y        ;
A309 B003     03293                 BCS SKIP007             ;
A30B 2D0AD2   03294                 AND RANDOM              ;
A30E 9D0006   03295 SKIP007         STA PL2DATA,X           ;
A311 E8       03296                 INX                     ;
A312 C8       03297                 INY                     ;
A313 C66A     03298                 DEC L.HEIGHTCNT         ;
A315 10EF     03299                 BPL LOOP011             ;
              03300
A317 A4E5     03301                 LDY PL1SHAPOFF          ; Repeat above with PLAYER1 (without torpedo part)
A319 AEFA0B   03302                 LDX PL1ROWNEW           ;
A31C 8E5C0C   03303                 STX PL1ROW              ;
A31F ADEF0C   03304                 LDA PL1HEIGHTNEW        ;
A322 856A     03305                 STA L.HEIGHTCNT         ;
A324 8DBE0C   03306                 STA PL1HEIGHT           ;
A327 B9B1B9   03307 LOOP012         LDA PLSHAP2TAB,Y        ;
A32A 9D0005   03308                 STA PL1DATA,X           ;
A32D E8       03309                 INX                     ;
A32E C8       03310                 INY                     ;
A32F C66A     03311                 DEC L.HEIGHTCNT         ;
A331 10F4     03312                 BPL LOOP012             ;
              03313
A333 A4E4     03314                 LDY PL0SHAPOFF          ; Repeat above with PLAYER0 (without torpedo part)
A335 AEF90B   03315                 LDX PL0ROWNEW           ;
A338 8E5B0C   03316                 STX PL0ROW              ;
A33B ADEE0C   03317                 LDA PL0HEIGHTNEW        ;
A33E 856A     03318                 STA L.HEIGHTCNT         ;
A340 8DBD0C   03319                 STA PL0HEIGHT           ;
A343 B9B1B9   03320 LOOP013         LDA PLSHAP2TAB,Y        ;
A346 9D0004   03321                 STA PL0DATA,X           ;
A349 E8       03322                 INX                     ;
A34A C8       03323                 INY                     ;
A34B C66A     03324                 DEC L.HEIGHTCNT         ;
A34D 10F4     03325                 BPL LOOP013             ;
              03326
              03327 ;*** (7) Update PLAYER horizontal positions ************************************
A34F AD2A0C   03328                 LDA PL0COLUMN           ; Update horizontal position of PLAYER0
A352 8D00D0   03329                 STA HPOSP0              ;
A355 AD2B0C   03330                 LDA PL1COLUMN           ; Update horizontal position of PLAYER1
A358 8D01D0   03331                 STA HPOSP1              ;
A35B AD2C0C   03332                 LDA PL2COLUMN           ; Update horizontal position of PLAYER2
A35E 8D02D0   03333                 STA HPOSP2              ;
A361 AD2D0C   03334                 LDA PL3COLUMN           ; Update horizontal position of PLAYER3
A364 8D03D0   03335                 STA HPOSP3              ;
A367 AD2E0C   03336                 LDA PL4COLUMN           ; Update horizontal position of PLAYER4
A36A 8D07D0   03337                 STA HPOSM3              ;
A36D 18       03338                 CLC                     ;
A36E 6902     03339                 ADC #2                  ;
A370 8D06D0   03340                 STA HPOSM2              ;
A373 6902     03341                 ADC #2                  ;
A375 8D05D0   03342                 STA HPOSM1              ;
A378 6902     03343                 ADC #2                  ;
A37A 8D04D0   03344                 STA HPOSM0              ;
              03345
              03346 ;*** (8) Rotate space objects horizontally and vertically **********************
A37D 24D0     03347                 BIT SHIPVIEW            ; Skip if in Galactic Chart view
A37F 303A     03348                 BMI SKIP009             ;
              03349
              03350 ;*** Rotate horizontally *******************************************************
A381 A5C8     03351                 LDA JOYSTICKX           ; Skip if joystick centered horizontally
A383 F019     03352                 BEQ SKIP008             ;
              03353
A385 856D     03354                 STA JOYSTICKDELTA       ; Save JOYSTICKX (used in subroutine ROTATE)
A387 A479     03355                 LDY MAXSPCOBJIND        ; Loop over all space objects in use
A389 846E     03356 LOOP014         STY L.ZPOSOFF           ; Save offset to z-coordinate
A38B 18       03357                 CLC                     ;
              03358
A38C 98       03359                 TYA                     ;
A38D AA       03360                 TAX                     ; X := offset to z-coordinate
A38E 6931     03361                 ADC #MAXSPCOBJNUM       ;
A390 A8       03362                 TAY                     ; Y := offset to x-coordinate
A391 209BB6   03363                 JSR ROTATE              ; Calc new x-coordinate (horizontal rot @ y-axis)
              03364
A394 98       03365                 TYA                     ;
A395 AA       03366                 TAX                     ; X := offset to x-coordinate
A396 A46E     03367                 LDY L.ZPOSOFF           ; Y := offset to z-coordinate
A398 209BB6   03368                 JSR ROTATE              ; Calc new z-coordinate (horizontal rot @ y-axis)
A39B 88       03369                 DEY                     ;
A39C 10EB     03370                 BPL LOOP014             ; Next space object
              03371
              03372 ;*** Rotate vertically *********************************************************
A39E A5C9     03373 SKIP008         LDA JOYSTICKY           ; Skip if joystick centered vertically
A3A0 F019     03374                 BEQ SKIP009             ;
              03375
A3A2 856D     03376                 STA JOYSTICKDELTA       ; Save JOYSTICKY (used in subroutine ROTATE)
A3A4 A479     03377                 LDY MAXSPCOBJIND        ; Loop over all space objects in use
A3A6 846E     03378 LOOP015         STY L.ZPOSOFF           ; Save offset to z-coordinate
A3A8 18       03379                 CLC                     ;
              03380
A3A9 98       03381                 TYA                     ;
A3AA AA       03382                 TAX                     ; X := offset to z-coordinate
A3AB 6962     03383                 ADC #MAXSPCOBJNUM*2     ;
A3AD A8       03384                 TAY                     ; Y := offset to y-coordinate
A3AE 209BB6   03385                 JSR ROTATE              ; Calc new y-coordinate (vertical rot @ x-axis)
              03386
A3B1 98       03387                 TYA                     ;
A3B2 AA       03388                 TAX                     ; X := offset to y-coordinate
A3B3 A46E     03389                 LDY L.ZPOSOFF           ; Y := offset to z-coordinate
A3B5 209BB6   03390                 JSR ROTATE              ; Calc new z-coordinate (vertical rot @ x-axis)
A3B8 88       03391                 DEY                     ;
A3B9 10EB     03392                 BPL LOOP015             ; Next space object
              03393
              03394 ;*** (9) Move all space objects along z-axis (toward our starship) *************
A3BB A679     03395 SKIP009         LDX MAXSPCOBJIND        ; Loop over all space objects in use
A3BD E005     03396 LOOP016         CPX #5                  ; Skip if PLAYFIELD space object (X index > 4)
A3BF B005     03397                 BCS SKIP010             ;
              03398
A3C1 BD8C0C   03399                 LDA PL0SHAPTYPE,X       ; Skip if next PLAYER space obj is PHOTON TORPEDO (!)
A3C4 F019     03400                 BEQ SKIP011             ;
              03401
A3C6 38       03402 SKIP010         SEC                     ; New z-coordinate := old z-coordinate -
A3C7 BDD30A   03403                 LDA ZPOSLO,X            ; ...our starship's velocity
A3CA E570     03404                 SBC VELOCITYLO          ; (signed 24-bit subtraction)
A3CC 9DD30A   03405                 STA ZPOSLO,X            ;
A3CF BD400A   03406                 LDA ZPOSHI,X            ;
A3D2 E5C1     03407                 SBC VELOCITYHI          ;
A3D4 9D400A   03408                 STA ZPOSHI,X            ;
A3D7 BDAD09   03409                 LDA ZPOSSIGN,X          ;
A3DA E900     03410                 SBC #0                  ;
A3DC 9DAD09   03411                 STA ZPOSSIGN,X          ;
              03412
A3DF CA       03413 SKIP011         DEX                     ;
A3E0 10DB     03414                 BPL LOOP016             ; Next space object
              03415
              03416 ;*** (10) Add space object's velocity vector to space object's position vector *
A3E2 A679     03417                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A3E4 E010     03418 LOOP017         CPX #16                 ; Skip if space object is star (X index 5..16)...
A3E6 D002     03419                 BNE SKIP012             ; ...because stars don't move by themselves
A3E8 A204     03420                 LDX #4                  ;
              03421
A3EA 8A       03422 SKIP012         TXA                     ;
A3EB A8       03423 LOOP018         TAY                     ; Loop over all 3 coordinates
              03424
A3EC A900     03425                 LDA #0                  ; Expand 8-bit velocity vector component to 16-bit:
A3EE 856B     03426                 STA L.VELOCITYHI        ; ...16-bit velocity (high byte) = L.VELOCITYHI := 0
A3F0 B9660B   03427                 LDA ZVEL,Y              ; ...16-bit velocity (low byte)  = A := ZVEL,Y
A3F3 1009     03428                 BPL SKIP013             ; Skip if 16-bit velocity >= 0 (positive)
              03429
A3F5 497F     03430                 EOR #$7F                ; 16-bit velocity < 0 (negative)...
A3F7 18       03431                 CLC                     ; ...calculate two's-complement of 16-bit velocity
A3F8 6901     03432                 ADC #1                  ;
A3FA B002     03433                 BCS SKIP013             ;
A3FC C66B     03434                 DEC L.VELOCITYHI        ;
              03435
A3FE 18       03436 SKIP013         CLC                     ; New coordinate := old coordinate + 16-bit velocity
A3FF 79D30A   03437                 ADC ZPOSLO,Y            ; (signed 24-bit addition)
A402 99D30A   03438                 STA ZPOSLO,Y            ;
A405 B9400A   03439                 LDA ZPOSHI,Y            ;
A408 656B     03440                 ADC L.VELOCITYHI        ;
A40A 99400A   03441                 STA ZPOSHI,Y            ;
A40D B9AD09   03442                 LDA ZPOSSIGN,Y          ;
A410 656B     03443                 ADC L.VELOCITYHI        ;
A412 99AD09   03444                 STA ZPOSSIGN,Y          ;
              03445
A415 98       03446                 TYA                     ;
A416 18       03447                 CLC                     ;
A417 6931     03448                 ADC #MAXSPCOBJNUM       ;
A419 C990     03449                 CMP #144                ; (!)
A41B 90CE     03450                 BCC LOOP018             ; Next coordinate
              03451
A41D CA       03452                 DEX                     ;
A41E 10C4     03453                 BPL LOOP017             ; Next space object
              03454
              03455 ;*** (11) Correct over/underflow of PLAYER space objects' position vector ******
A420 A004     03456                 LDY #4                  ;
A422 98       03457 LOOP019         TYA                     ; Loop over all PLAYER space objects (X index < 5)
A423 AA       03458                 TAX                     ;
              03459
A424 A902     03460                 LDA #2                  ; Loop over all 3 coordinates
A426 856A     03461                 STA L.VECCOMPIND        ;
              03462
A428 BDAD09   03463 LOOP020         LDA ZPOSSIGN,X          ; Load sign of coordinate
A42B C902     03464                 CMP #2                  ;
A42D 9010     03465                 BCC SKIP015             ; Skip if sign = 0 (negative) or 1 (positive)
              03466
A42F 0A       03467                 ASL A                   ; SUMMARY:
A430 A900     03468                 LDA #0                  ; If new coordinate > +65535 <KM> subtract 256 <KM>
A432 9DAD09   03469                 STA ZPOSSIGN,X          ; ...until new coordinate <= +65535 <KM>
A435 B005     03470                 BCS SKIP014             ; If new coordinate < -65536 <KM> add 256 <KM>
A437 FEAD09   03471                 INC ZPOSSIGN,X          ; ...until new coordinate >= -65536 <KM>
A43A 49FF     03472                 EOR #$FF                ;
A43C 9D400A   03473 SKIP014         STA ZPOSHI,X            ;
              03474
A43F 8A       03475 SKIP015         TXA                     ;
A440 18       03476                 CLC                     ;
A441 6931     03477                 ADC #MAXSPCOBJNUM       ;
A443 AA       03478                 TAX                     ;
A444 C66A     03479                 DEC L.VECCOMPIND        ;
A446 10E0     03480                 BPL LOOP020             ; Next coordinate
              03481
A448 88       03482                 DEY                     ;
A449 10D7     03483                 BPL LOOP019             ; Next space object
              03484
              03485 ;*** (12) Calc perspective projection of space objects *************************
A44B A5D0     03486                 LDA SHIPVIEW            ; Skip if in Long-Range Scan or Galactic Chart view
A44D C902     03487                 CMP #$02                ;
A44F B05C     03488                 BCS SKIP019             ;
              03489
A451 A679     03490                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A453 A9FF     03491 LOOP021         LDA #255                ; Prep magic offscreen pixel number value
A455 BCAD09   03492                 LDY ZPOSSIGN,X          ; Compare sign of z-coordinate with view mode
A458 C4D0     03493                 CPY SHIPVIEW            ;
A45A F04B     03494                 BEQ SKIP018             ; Equal? Space object is offscreen -> New space obj!
              03495
A45C BD0F0A   03496                 LDA YPOSSIGN,X          ; Prepare projection division...
A45F D012     03497                 BNE SKIP016             ; DIVIDEND (16-bit value) := ABS(y-coordinate)
A461 38       03498                 SEC                     ; (used in subroutine PROJECTION)
A462 A900     03499                 LDA #0                  ;
A464 FD350B   03500                 SBC YPOSLO,X            ;
A467 856A     03501                 STA DIVIDEND            ;
A469 A900     03502                 LDA #0                  ;
A46B FDA20A   03503                 SBC YPOSHI,X            ;
A46E 856B     03504                 STA DIVIDEND+1          ;
A470 4C7DA4   03505                 JMP JUMP001             ;
A473 BD350B   03506 SKIP016         LDA YPOSLO,X            ;
A476 856A     03507                 STA DIVIDEND            ;
A478 BDA20A   03508                 LDA YPOSHI,X            ;
A47B 856B     03509                 STA DIVIDEND+1          ;
              03510
A47D 2021AA   03511 JUMP001         JSR PROJECTION          ; Calc pixel row number rel. to screen center
A480 201EB7   03512                 JSR SCREENROW           ; Calc pixel row number rel. to top-left of screen
              03513
A483 BDDE09   03514                 LDA XPOSSIGN,X          ; Prepare projection division...
A486 D012     03515                 BNE SKIP017             ; DIVIDEND (16-bit value) := ABS(x-coordinate)
A488 38       03516                 SEC                     ; (used in subroutine PROJECTION)
A489 A900     03517                 LDA #0                  ;
A48B FD040B   03518                 SBC XPOSLO,X            ;
A48E 856A     03519                 STA DIVIDEND            ;
A490 A900     03520                 LDA #0                  ;
A492 FD710A   03521                 SBC XPOSHI,X            ;
A495 856B     03522                 STA DIVIDEND+1          ;
A497 4CA4A4   03523                 JMP JUMP002             ;
A49A BD040B   03524 SKIP017         LDA XPOSLO,X            ;
A49D 856A     03525                 STA DIVIDEND            ;
A49F BD710A   03526                 LDA XPOSHI,X            ;
A4A2 856B     03527                 STA DIVIDEND+1          ;
              03528
A4A4 2021AA   03529 JUMP002         JSR PROJECTION          ; Calc pixel column number rel. to screen center
A4A7 20FBB6   03530 SKIP018         JSR SCREENCOLUMN        ; Calc pixel column number rel. to top-left of screen
A4AA CA       03531                 DEX                     ;
A4AB 10A6     03532                 BPL LOOP021             ; Next space object
              03533
              03534 ;*** (13) Handle hyperwarp marker selection in Galactic Chart view *************
A4AD 2062B1   03535 SKIP019         JSR SELECTWARP          ; Handle hyperwarp marker in Galactic Chart view
              03536
              03537 ;*** (14) Compute and draw Long-Range Scan view star field on z-x plane ********
A4B0 24D0     03538                 BIT SHIPVIEW            ; Skip if not in Long-Range Scan view
A4B2 5031     03539                 BVC SKIP022             ;
              03540
A4B4 A231     03541                 LDX #$31                ; Draw our starship's shape
A4B6 206FA7   03542                 JSR DRAWLINES           ;
              03543
A4B9 2C9609   03544                 BIT GCSTATLRS           ; Skip if Long-Range Scan destroyed
A4BC 7027     03545                 BVS SKIP022             ;
              03546
A4BE A679     03547                 LDX MAXSPCOBJIND        ; Loop over all space objects in use
A4C0 BD400A   03548 LOOP022         LDA ZPOSHI,X            ; Load z-coordinate (high byte)
A4C3 BCAD09   03549                 LDY ZPOSSIGN,X          ; Load sign of z-coordinate
A4C6 D002     03550                 BNE SKIP020             ;
A4C8 49FF     03551                 EOR #$FF                ; A := ABS(z-coordinate (high byte))
A4CA A8       03552 SKIP020         TAY                     ;
A4CB B9E90D   03553                 LDA MAPTO80,Y           ; Calc pixel row number rel. to screen center
A4CE 201EB7   03554                 JSR SCREENROW           ; Calc pixel row number rel. to top-left of screen
              03555
A4D1 BD710A   03556                 LDA XPOSHI,X            ; Load x-coordinate (high byte)
A4D4 BCDE09   03557                 LDY XPOSSIGN,X          ; Load sign of x-coordinate
A4D7 D002     03558                 BNE SKIP021             ;
A4D9 49FF     03559                 EOR #$FF                ; A := ABS(x-coordinate (high byte))
A4DB A8       03560 SKIP021         TAY                     ;
A4DC B9E90D   03561                 LDA MAPTO80,Y           ; Calc pixel column number rel. to screen center
A4DF 20FBB6   03562                 JSR SCREENCOLUMN        ; Calc pixel column number rel. to top-left of screen
              03563
A4E2 CA       03564                 DEX                     ;
A4E3 10DB     03565                 BPL LOOP022             ; Next space object
              03566
              03567 ;*** (15) Update PLAYER shapes, heights, and colors ****************************
              03568
              03569 ; DESCRIPTION
              03570 ;
              03571 ; In a loop over all PLAYERs, the following steps are executed:
              03572 ;
              03573 ; o   Clear the PLAYER shape offset and height.
              03574 ;
              03575 ; o   If in Galactic Chart view or in Long-Range Scan view, preload a random
              03576 ;     color and a magic z-coordinate (distance value) for PLAYER3..4
              03577 ;     (representing hyperwarp markers in Galactic Chart view and blips in the
              03578 ;     Long-Range Scan view, like, for example, Zylon ships, meteors - or even
              03579 ;     the Hyperwarp Target Marker during hyperwarp!).
              03580 ;
              03581 ; o   If in Front or Aft view, execute the following steps:
              03582 ;
              03583 ;      o   Skip dead PLAYERs.
              03584 ;
              03585 ;      o   Preload the distance value for the remaining live PLAYERs.
              03586 ;
              03587 ;      o   If we are in a starbase sector, combine PLAYER0..2 into a three-part
              03588 ;          starbase shape. Compute the pixel column numbers and pixel row
              03589 ;          numbers of PLAYER0..1 such that they are arranged left (PLAYER0) and
              03590 ;          right (PLAYER1) of PLAYER2. In addition, preload a color mask, a
              03591 ;          counter actually, that will make the starbase pulsate in brightness.
              03592 ;
              03593 ;     BUG (at $A512): The code at $A512 that skips the combination operation for
              03594 ;     PLAYER2..4 jumps for PLAYER3..4 to SKIP025 at $A52A instead of SKIP026 at
              03595 ;     $A52E. Thus it stores a color mask which does not only make the starbase
              03596 ;     PLAYER0..2 pulsate in brightness but also PLAYER3..4 in a starbase sector,
              03597 ;     for example the transfer vessel, photon torpedoes, etc. - or even the
              03598 ;     Hyperwarp Target Marker when hyperwarping out of such a sector! Suggested
              03599 ;     fix: None, code hard to untwist.
              03600 ;
              03601 ; o   After storing the color mask, check if the PLAYER shape is still above the
              03602 ;     bottom edge of the PLAYFIELD.
              03603 ;
              03604 ;     BUG (at $A534): The test checks the vertical position of the top edge of
              03605 ;     the PLAYER against the bottom edge of the PLAYFIELD above the Console
              03606 ;     Panel Display (= Player/Missile pixel row number 204). This is not
              03607 ;     completely accurate as the Console Panel Display starts at PM pixel row
              03608 ;     number 208. For example, if you carefully navigate a starbase to the
              03609 ;     bottom edge of the PLAYFIELD, at a certain point the center of the
              03610 ;     starbase shape bleeds over the bottom edge of the PLAYFIELD (while
              03611 ;     sometimes even losing its left and right wings!). Suggested fix: None, as
              03612 ;     a more elaborate test may consume too many bytes of the cartridge ROM
              03613 ;     memory in order to fix a rarely noticed visual glitch.
              03614 ;
              03615 ; o   Convert the preloaded distance value of a PLAYER space object closer than
              03616 ;     $2000 (8192) <KM> into a range index of 0..15. PLAYER space objects more
              03617 ;     distant than $2000 (8192) <KM> are skipped and not displayed.
              03618 ;
              03619 ;     Later, this range index will pick not only the correct brightness for the
              03620 ;     PLAYER (the closer the space object the brighter its PLAYER) but also the
              03621 ;     correct PLAYER shape cell and height (the closer the space object the
              03622 ;     larger the PLAYER shape and height). 
              03623 ;
              03624 ; o   Update the PLAYER's shape offset and height. On the way to the shape
              03625 ;     offset and height add the PLAYER's shape type to the range index and
              03626 ;     divide it by 2 to arrive at the shape offset index and height index (the
              03627 ;     same value). Use this index to pick the correct shape data and shape
              03628 ;     heights from a set of shape cells and their corresponding heights, stored
              03629 ;     in tables PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB ($BE7F), respectively.
              03630 ;
              03631 ;     Remember that magic distance value used in the Galactic Chart and
              03632 ;     Long-Range Scan view? Its value of $F2 is actually part of a negative
              03633 ;     z-coordinate which is inverted to $0D00, leading to a range index of 13,
              03634 ;     which, after the division by 2, picks shape cell 6. Shape cell 6 (the
              03635 ;     seventh shape cell) of all space objects (except the starbase) is the
              03636 ;     Long-Range Scan blip's dot (see PLSHAPOFFTAB ($BE2F) and PLSHPHEIGHTTAB
              03637 ;     ($BE7F)).
              03638 ;
              03639 ; o   Update the PLAYER's color/brightness by picking the appropriate values
              03640 ;     with the range index from lookup tables PLSHAPCOLORTAB ($BFD1) and
              03641 ;     PLSHAPBRITTAB ($BFDB). Apply some special effects to the color/brightness
              03642 ;     of certain PLAYERs, such as using random colors for Zylon basestars, or
              03643 ;     using the precomputed pulsating brightness value for a starbase.
              03644
A4E5 A205     03645 SKIP022         LDX #5                  ; Loop over all PLAYER space objects (X index < 5)
A4E7 CA       03646 LOOP023         DEX                     ;
A4E8 1003     03647                 BPL SKIP023             ; Jump into loop body below
A4EA 4C79A5   03648                 JMP JUMP003             ; Loop is finished, skip loop body
              03649
              03650 ;*** Clear PLAYER shape offsets and heights ************************************
A4ED A900     03651 SKIP023         LDA #0                  ;
A4EF 95E4     03652                 STA PL0SHAPOFF,X        ; Clear PLAYER shape offset
A4F1 9DEE0C   03653                 STA PL0HEIGHTNEW,X      ; Clear new PLAYER shape height
              03654
              03655 ;*** Preload stuff for hyperwarp markers and Long-Range Scan blips *************
A4F4 24D0     03656                 BIT SHIPVIEW            ; Skip if not in Galactic Chart view
A4F6 100B     03657                 BPL SKIP024             ;
              03658
A4F8 E003     03659                 CPX #3                  ; Next PLAYER space object if not PLAYER3..4
A4FA 90EB     03660                 BCC LOOP023             ;
A4FC AD0AD2   03661 LOOP024         LDA RANDOM              ; Prep random color mask for warp markers/LRS blips
A4FF A0F2     03662                 LDY #$F2                ; Prep magic z-coordinate for warp markers/LRS blips
A501 302B     03663                 BMI SKIP026             ; Unconditional jump
              03664
A503 D5E9     03665 SKIP024         CMP PL0LIFE,X           ; Next PLAYER space object if this PLAYER not alive
A505 F0E0     03666                 BEQ LOOP023             ;
              03667
A507 70F3     03668                 BVS LOOP024             ; Skip back if in Long-Range Scan view
              03669
              03670 ;*** Preload stuff for other views *********************************************
              03671
A509 BC400A   03672                 LDY PL0ZPOSHI,X         ; Prep z-coordinate (high byte)
              03673
              03674 ;*** Combine PLAYER0..2 to starbase shape **************************************
A50C 247B     03675                 BIT ISSTARBASESECT      ; Skip if no starbase in this sector
A50E 501E     03676                 BVC SKIP026             ;
              03677
A510 E002     03678                 CPX #2                  ; Skip if not PLAYER0..1
A512 B016     03679                 BCS SKIP025             ; (!)
              03680
A514 AD2C0C   03681                 LDA PL2COLUMN           ; Calc new PM pixel column number for PLAYER0..1:
A517 18       03682                 CLC                     ; Load PLAYER2 (starbase center) pixel column number
A518 7DDBBE   03683                 ADC PLSTARBAOFFTAB,X    ; ...add PLAYER left/right offset (starbase wings)
A51B 9D2A0C   03684                 STA PL0COLUMN,X         ; Store new PM pixel column number of starbase wing
              03685
A51E ADFB0B   03686                 LDA PL2ROWNEW           ; Calc new PM pixel row number for PLAYER0..1:
A521 18       03687                 CLC                     ; Add vertical offset (= 4 PM pixels) to PLAYER2's
A522 6904     03688                 ADC #4                  ;
A524 9DF90B   03689                 STA PL0ROWNEW,X         ; Store new PM pixel row number of starbase wing
              03690
A527 AC420A   03691                 LDY PL2ZPOSHI           ; Prep Y with z-coordinate (high byte) of starbase
A52A A576     03692 SKIP025         LDA COUNT256            ; Prep color mask with B3..0 of counter
A52C 290F     03693                 AND #$0F                ; ...(= brightness bits cause pulsating brightness)
              03694
A52E 856B     03695 SKIP026         STA L.COLORMASK         ; Store color mask
              03696
              03697 ;*** Check if PLAYER is below PLAYFIELD bottom edge ****************************
A530 98       03698                 TYA                     ; A := z-coordinate (high byte)
              03699
A531 BCF90B   03700                 LDY PL0ROWNEW,X         ; Next PLAYER space object if top of PM shape...
A534 C0CC     03701                 CPY #204                ; ...is below PLAYFIELD bottom... (!)
A536 B0AF     03702                 BCS LOOP023             ; ...(PM pixel row number >= 204)
              03703
              03704 ;*** Convert PLAYER z-coordinate to range index in 0..15 ***********************
A538 A4D0     03705                 LDY SHIPVIEW            ; Skip if in Front view...
A53A F002     03706                 BEQ SKIP027             ;
A53C 49FF     03707                 EOR #$FF                ; ...else invert z-coordinate (high byte)
              03708
A53E C920     03709 SKIP027         CMP #$20                ; Next PLAYER space object if this one too far away
A540 B0A5     03710                 BCS LOOP023             ; ...(z-coordinate >= $20** (8192) <KM>)
              03711
A542 C910     03712                 CMP #16                 ; Load z-coordinate (high byte) and...
A544 9002     03713                 BCC SKIP028             ;
A546 A90F     03714                 LDA #15                 ;
A548 856A     03715 SKIP028         STA L.RANGEINDEX        ; ...trim to range index in 0..15
              03716
              03717 ;*** Update PLAYER shape offset and height *************************************
A54A 1D8C0C   03718                 ORA PL0SHAPTYPE,X       ; Calc offset to shape table (shape type+range index)
A54D 4A       03719                 LSR A                   ;
A54E A8       03720                 TAY                     ; Divide by 2 to get actual offset into shape data
A54F B92FBE   03721                 LDA PLSHAPOFFTAB,Y      ; Update new PLAYER shape offset
A552 95E4     03722                 STA PL0SHAPOFF,X        ;
A554 B97FBE   03723                 LDA PLSHPHEIGHTTAB,Y    ; Update new PLAYER shape height
A557 9DEE0C   03724                 STA PL0HEIGHTNEW,X      ;
              03725
              03726 ;*** Calculate PLAYER color/brightness value ***********************************
A55A 98       03727                 TYA                     ; Pick color (B7..4) using PLAYER shape type
A55B 4A       03728                 LSR A                   ;
A55C 4A       03729                 LSR A                   ;
A55D 4A       03730                 LSR A                   ;
A55E A8       03731                 TAY                     ;
A55F B9D1BF   03732                 LDA PLSHAPCOLORTAB,Y    ;
A562 C008     03733                 CPY #8                  ; Pick random color if ZYLON BASESTAR (shape type 8)
A564 D003     03734                 BNE SKIP029             ;
A566 4D0AD2   03735                 EOR RANDOM              ;
A569 A46A     03736 SKIP029         LDY L.RANGEINDEX        ;
A56B 59DBBF   03737                 EOR PLSHAPBRITTAB,Y     ; Pick brightness (B3..0) using range index and merge
              03738
A56E 456B     03739                 EOR L.COLORMASK         ; Modify color/brightness of PLAYER
              03740
A570 BCDFB8   03741                 LDY PLCOLOROFFTAB,X     ; Get PLAYER color offset
A573 99EE00   03742                 STA PL0COLOR,Y          ; Store color in PLAYER color register
A576 4CE7A4   03743                 JMP LOOP023             ; Next PLAYER space object
              03744
              03745 ;*** (16) Flash red alert ******************************************************
A579 A0AF     03746 JUMP003         LDY #$AF                ; Prep PLAYFIELD2 color {BRIGHT BLUE-GREEN}
A57B A681     03747                 LDX SHIELDSCOLOR        ; Prep Shields color {DARK GREEN} or {BLACK}
              03748
A57D A58B     03749                 LDA REDALERTLIFE        ; Skip if red alert is over
A57F F00C     03750                 BEQ SKIP030             ;
              03751
A581 C68B     03752                 DEC REDALERTLIFE        ; Decrement lifetime of red alert
A583 A04F     03753                 LDY #$4F                ; Prep PLAYFIELD2 color {BRIGHT ORANGE}
              03754
A585 2920     03755                 AND #$20                ; Switch colors every 64 game loops
A587 F004     03756                 BEQ SKIP030             ;
              03757
A589 A242     03758                 LDX #$42                ; Load BACKGROUND color {DARK ORANGE}
A58B A060     03759                 LDY #$60                ; Load PLAYFIELD2 color {DARK PURPLE BLUE}
              03760
A58D 84F4     03761 SKIP030         STY PF2COLOR            ; Store PLAYFIELD2 color
A58F 86F6     03762                 STX BGRCOLOR            ; Store BACKGROUND color
              03763
              03764 ;*** (17) Update color of PLAYFIELD space objects (stars, explosion fragments) *
A591 A679     03765                 LDX MAXSPCOBJIND        ; Loop over all PLAYFIELD space objs (X index > 4)
A593 BD400A   03766 LOOP025         LDA ZPOSHI,X            ; Prep z-coordinate (high byte)
A596 A4D0     03767                 LDY SHIPVIEW            ;
A598 C001     03768                 CPY #1                  ; Skip if not in Aft view
A59A D009     03769                 BNE SKIP032             ;
              03770
A59C C9F0     03771                 CMP #$F0                ; Skip if star not too far (z < $F0** (-4096) <KM>
A59E B003     03772                 BCS SKIP031             ;
A5A0 2064B7   03773                 JSR INITPOSVEC          ; Re-init position vector
A5A3 49FF     03774 SKIP031         EOR #$FF                ; Invert z-coordinate (high byte)
              03775
A5A5 C910     03776 SKIP032         CMP #16                 ; Convert z-coordinate (high byte)
A5A7 9002     03777                 BCC SKIP033             ; ...into range index 0..15
A5A9 A90F     03778                 LDA #15                 ;
              03779
A5AB 0A       03780 SKIP033         ASL A                   ; Compute index to pixel color table:
A5AC 291C     03781                 AND #$1C                ; Use bits B3..1 from range index as B4..2.
A5AE 0572     03782                 ORA COUNT8              ; Combine with random bits B3..0 from counter
              03783
A5B0 A8       03784                 TAY                     ;
A5B1 B990BA   03785                 LDA FOURCOLORPIXEL,Y    ; Load 1-byte bit pattern for 4 pixels of same color
A5B4 856A     03786                 STA L.FOURCOLORPIX      ; ...and temporarily save it
              03787
A5B6 BD2A0C   03788                 LDA PIXELCOLUMN,X       ; Load pixel mask to mask 1 pixel out of 4 pixels:
A5B9 2903     03789                 AND #$03                ; Use B1..0 from pixel column number...
A5BB A8       03790                 TAY                     ;
A5BC B9B0BA   03791                 LDA PIXELMASKTAB,Y      ; ...to pick mask to filter pixel in byte
A5BF 256A     03792                 AND L.FOURCOLORPIX      ; ...AND with 1-byte bit pattern for 4 pixels
A5C1 9DEE0C   03793                 STA PIXELBYTE,X         ; ...store byte (used in repaint step of game loop)
              03794
A5C4 CA       03795                 DEX                     ;
A5C5 E005     03796                 CPX #5                  ;
A5C7 B0CA     03797                 BCS LOOP025             ; Next PLAYFIELD space object
              03798
              03799 ;*** (18) Skip input handling if in demo mode **********************************
A5C9 2464     03800                 BIT ISDEMOMODE          ; If in demo mode skip to function keys
A5CB 5003     03801                 BVC SKIP034             ;
A5CD 4C9BA6   03802                 JMP SKIP040             ;
              03803
              03804 ;*** (19) Handle keyboard input ************************************************
A5D0 20FEAF   03805 SKIP034         JSR KEYBOARD            ; Handle keyboard input
              03806
              03807 ;*** (20) Handle joystick input ************************************************
A5D3 AD00D3   03808                 LDA PORTA               ; Load Joystick 0 directions
A5D6 A8       03809                 TAY                     ; ...Bits B0..3 -> Right, left, down, up.
A5D7 2903     03810                 AND #$03                ; ...Bit = 0/1 -> Stick pressed/not pressed
A5D9 AA       03811                 TAX                     ; JOYSTICKY := +1 -> Up
A5DA BDF5BA   03812                 LDA STICKINCTAB,X       ; JOYSTICKY :=  0 -> Centered
A5DD 85C9     03813                 STA JOYSTICKY           ; JOYSTICKY := -1 -> Down
A5DF 98       03814                 TYA                     ;
A5E0 4A       03815                 LSR A                   ;
A5E1 4A       03816                 LSR A                   ;
A5E2 2903     03817                 AND #$03                ;
A5E4 AA       03818                 TAX                     ; JOYSTICKX := -1 -> Left
A5E5 BDF5BA   03819                 LDA STICKINCTAB,X       ; JOYSTICKX :=  0 -> Centered
A5E8 85C8     03820                 STA JOYSTICKX           ; JOYSTICKX := +1 -> Right
              03821
              03822 ;*** (21) Check if our starship's photon torpedoes have hit a target ***********
A5EA 203DAF   03823                 JSR COLLISION           ; Check if our starship's photon torpedoes have hit
              03824
              03825 ;*** (22) Handle joystick trigger **********************************************
A5ED 2029AE   03826                 JSR TRIGGER             ; Handle joystick trigger
              03827
              03828 ;*** (23) Handle Attack Computer and Tracking Computer *************************
A5F0 2C9509   03829                 BIT GCSTATCOM           ; Skip if Attack Computer destroyed
A5F3 7040     03830                 BVS SKIP038             ;
              03831
A5F5 A57E     03832                 LDA ISATTCOMPON         ; Skip if Attack Computer off
A5F7 F03C     03833                 BEQ SKIP038             ;
              03834
A5F9 A5D0     03835                 LDA SHIPVIEW            ; Skip if not in Front view
A5FB D003     03836                 BNE SKIP035             ;
              03837
A5FD 20BFA7   03838                 JSR UPDATTCOMP          ; Update Attack Computer Display
              03839
A600 AE5C09   03840 SKIP035         LDX TRACKDIGIT          ; Load index of tracked space object
              03841
A603 A5BF     03842                 LDA ZYLONATTACKER       ; Skip if ship of current Zylon torpedo is tracked
A605 3005     03843                 BMI SKIP036             ;
A607 AA       03844                 TAX                     ; ...else override Tracking Computer...
A608 0980     03845                 ORA #$80                ;
A60A 85BF     03846                 STA ZYLONATTACKER       ; ...and mark Zylon torpedo's ship as being tracked
              03847
A60C B5E9     03848 SKIP036         LDA PL0LIFE,X           ; Skip if tracked space object still alive
A60E D00B     03849                 BNE SKIP037             ;
              03850
A610 8A       03851                 TXA                     ;
A611 4901     03852                 EOR #$01                ;
A613 AA       03853                 TAX                     ;
A614 B5E9     03854                 LDA PL0LIFE,X           ; Check if other Zylon ship still alive
A616 D003     03855                 BNE SKIP037             ; ...yes -> Keep new index
A618 AE5C09   03856                 LDX TRACKDIGIT          ; ...no  -> Revert to old index of tracked space obj
              03857
A61B 8E5C09   03858 SKIP037         STX TRACKDIGIT          ; Store index of tracked space object
              03859
A61E A57C     03860                 LDA ISTRACKCOMPON       ; Skip if tracking computer is turned off
A620 F013     03861                 BEQ SKIP038             ;
              03862
A622 A5D0     03863                 LDA SHIPVIEW            ; Skip if in Long-Range Scan or Galactic Chart view
A624 C902     03864                 CMP #2                  ;
A626 B00D     03865                 BCS SKIP038             ;
              03866
A628 4901     03867                 EOR #$01                ;
A62A DDAD09   03868                 CMP ZPOSSIGN,X          ; Compare tracked space obj's sign of z-coordinate...
A62D F006     03869                 BEQ SKIP038             ; ...with view direction. Skip if both are the same.
              03870
A62F AA       03871                 TAX                     ;
A630 BDCFBE   03872                 LDA TRACKKEYSTAB,X      ; Pick 'F' or 'A' (Front or Aft view) keyboard code
A633 85CA     03873                 STA KEYCODE             ; ...and store it (= emulate pressing 'F' or 'A' key)
              03874
              03875 ;*** (24) Handle docking to starbase *******************************************
A635 20E6AC   03876 SKIP038         JSR DOCKING             ; Handle docking to starbase
              03877
              03878 ;*** (25) Handle maneuvering ***************************************************
A638 2079AA   03879                 JSR MANEUVER            ; Handle maneuvering photon torpedoes and Zylon ships
              03880
              03881 ;*** (26) Was our starship hit by Zylon photon torpedo? ************************
A63B A57B     03882                 LDA ISSTARBASESECT      ; Skip hit check if in starbase sector
A63D D05C     03883                 BNE SKIP040             ;
              03884
A63F A5EB     03885                 LDA PL2LIFE             ; Skip hit check if PLAYER2 (Zylon photon torpedo)...
A641 F058     03886                 BEQ SKIP040             ; ...not alive
              03887
A643 AC420A   03888                 LDY PL2ZPOSHI           ; Our starship was not hit if Zylon photon torpedo's
A646 C8       03889                 INY                     ; ...z-coordinate is not in -256..255 <KM> or...
A647 C002     03890                 CPY #$02                ;
A649 B050     03891                 BCS SKIP040             ;
              03892
A64B AC730A   03893                 LDY PL2XPOSHI           ; ...x-coordinate is not in -256..255 <KM> or...
A64E C8       03894                 INY                     ;
A64F C002     03895                 CPY #$02                ;
A651 B048     03896                 BCS SKIP040             ;
              03897
A653 ACA40A   03898                 LDY PL2YPOSHI           ; ...y-coordinate is not in -256..255 <KM>.
A656 C8       03899                 INY                     ;
A657 C002     03900                 CPY #$02                ;
A659 B040     03901                 BCS SKIP040             ;
              03902
              03903 ;*** (27) Our starship was hit! ************************************************
A65B 20E1AE   03904                 JSR DAMAGE              ; Damage or destroy some subsystem
              03905
A65E A002     03906                 LDY #2                  ; Trigger explosion at PLAYER2 (Zylon photon torpedo)
A660 206BAC   03907                 JSR INITEXPL            ;
              03908
A663 A27F     03909                 LDX #$7F                ; Prep HITBADNESS := SHIELDS HIT
A665 A581     03910                 LDA SHIELDSCOLOR        ; Skip if Shields are up (SHIELDSCOLOR not {BLACK}).
A667 D01E     03911                 BNE SKIP039             ;
              03912
A669 A20A     03913                 LDX #$0A                ; Set Front view
A66B 2045B0   03914                 JSR SETVIEW             ;
              03915
A66E A023     03916                 LDY #$23                ; Set title phrase "SHIP DESTROYED BY ZYLON FIRE"
A670 A208     03917                 LDX #8                  ; Set mission bonus offset
A672 200AB1   03918                 JSR GAMEOVER            ; Game over
              03919
A675 A25F     03920                 LDX #$5F                ; Hide Control Panel Display (bottom text window)
A677 A080     03921                 LDY #$80                ;
A679 A908     03922                 LDA #$08                ;
A67B 20F1AD   03923                 JSR MODDLST             ;
              03924
A67E 200DAE   03925                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
              03926
A681 A240     03927                 LDX #64                 ; Enable special explosion noise in SOUND
A683 86E3     03928                 STX NOISEHITLIFE        ;
              03929
A685 A2FF     03930                 LDX #$FF                ; Prep HITBADNESS := STARSHIP DESTROYED
              03931
A687 868A     03932 SKIP039         STX HITBADNESS          ; Store HITBADNESS
A689 A900     03933                 LDA #0                  ; Zylon photon torpedo lifetime := 0 game loops
A68B 85EB     03934                 STA PL2LIFE             ;
A68D A902     03935                 LDA #2                  ; Init Zylon photon torpedo trigger
A68F 85BE     03936                 STA TORPEDODELAY        ;
              03937
A691 A201     03938                 LDX #1                  ; ENERGY := ENERGY - 100 after photon torpedo hit
A693 206FB8   03939                 JSR DECENERGY           ;
              03940
A696 A20A     03941                 LDX #$0A                ; Play noise sound pattern SHIP EXPLOSION
A698 20A8AE   03942                 JSR NOISE               ;
              03943
              03944 ;*** (28) Handle function keys *************************************************
A69B A463     03945 SKIP040         LDY FKEYCODE            ; Prep old function key code
A69D AD1FD0   03946                 LDA CONSOL              ; POKEY: Load function key code
              03947
A6A0 49FF     03948                 EOR #$FF                ; Store inverted and masked function key code
A6A2 2903     03949                 AND #$03                ;
A6A4 8563     03950                 STA FKEYCODE            ;
A6A6 F01A     03951                 BEQ SKIP042             ; Skip if no function key pressed
              03952
A6A8 88       03953                 DEY                     ;
A6A9 1017     03954                 BPL SKIP042             ; Skip if SELECT or START still pressed
A6AB 8566     03955                 STA IDLECNTHI           ; Reset idle counter to a value in 1..3 (?)
A6AD C902     03956                 CMP #2                  ; Skip if SELECT function key pressed
A6AF B006     03957                 BCS SKIP041             ;
              03958
A6B1 A900     03959                 LDA #0                  ; START function key pressed:
A6B3 A8       03960                 TAY                     ; Prep empty title phrase offset
A6B4 4C5EA1   03961                 JMP INITSTART           ; Reenter game loop via INITSTART
              03962
A6B7 E662     03963 SKIP041         INC MISSIONLEVEL        ; SELECT function key pressed:
A6B9 A562     03964                 LDA MISSIONLEVEL        ; Cycle through next of 4 mission levels
A6BB 2903     03965                 AND #$03                ;
A6BD 8562     03966                 STA MISSIONLEVEL        ;
A6BF 4C5AA1   03967                 JMP INITSELECT          ; Reenter game loop via INITSELECT
              03968
              03969 ;*** (29) Update Control Panel Display *****************************************
A6C2 2004B8   03970 SKIP042         JSR UPDPANEL            ; Update Control Panel Display
              03971
              03972 ;*** (30) Handle hyperwarp *****************************************************
A6C5 209BA8   03973                 JSR HYPERWARP           ; Handle hyperwarp
              03974
              03975 ;*** (31) Update title line ****************************************************
A6C8 2016B2   03976                 JSR UPDTITLE            ; Update title line
              03977
              03978 ;*** (32) Flush game loop iteration ********************************************
A6CB 20E4B4   03979                 JSR FLUSHGAMELOOP       ; Move Zylon units, age torpedoes, elapse time
              03980
              03981 ;*** (33) Jump back to begin of game loop **************************************
A6CE 4CF3A1   03982                 JMP GAMELOOP            ; Next game loop iteration
              03983
              03984 ;*******************************************************************************
              03985 ;*                                                                             *
              03986 ;*                                  VBIHNDLR                                   *
              03987 ;*                                                                             *
              03988 ;*                      Vertical Blank Interrupt Handler                       *
              03989 ;*                                                                             *
              03990 ;*******************************************************************************
              03991
              03992 ; DESCRIPTION
              03993 ;
              03994 ; This subroutine is executed during the Vertical Blank Interrupt (VBI) when the
              03995 ; TV beam has reached the bottom-right corner of the TV screen and is switched
              03996 ; off to return to the top-left position. This situation is called the "vertical
              03997 ; blank phase".
              03998 ;
              03999 ; This subroutine signals its execution with flag ISVBISYNC ($67) (which is
              04000 ; examined by GAMELOOP ($A1F3) to synchronize the execution of the game loop
              04001 ; with the start of this subroutine). Then it switches the character set to the
              04002 ; ROM character set, sets the BACKGROUND color depending on the severity of a
              04003 ; Zylon photon torpedo hit and view mode, copies PLAYER and PLAYFIELD color
              04004 ; registers to their corresponding hardware registers, clears the Player/Missile
              04005 ; collision registers, calls the sound effects code in subroutine SOUND ($B2AB),
              04006 ; and increments the idle counter. If the idle counter reaches the value $8000
              04007 ; the title phrase is cleared and the program is switched to demo mode.
              04008 ;
              04009 ; BUG (at $A6EC): Because the values of SHIPVIEW ($D0) are $00, $01, $40, and
              04010 ; $80, a value of 3 overspecifies the comparison. Suggested fix: Replace CMP #3
              04011 ; with CMP #2, which may make the code clearer.
              04012 ;
              04013 ; BUG (at $A712): Demo mode is entered via a JMP instruction, which proceeds
              04014 ; directly into GAMELOOP ($A1F3). Thus code execution never returns to pop the
              04015 ; registers pushed on the stack during entry of this subroutine. Suggested fix:
              04016 ; None.
              04017
A6D1 A9FF     04018 VBIHNDLR        LDA #$FF                ; Signals entering Vertical Blank Interrupt
A6D3 8567     04019                 STA ISVBISYNC           ;
              04020
A6D5 A9E0     04021                 LDA #>ROMCHARSET        ; Switch character set to ROM character set
A6D7 8D09D4   04022                 STA CHBASE              ;
              04023
A6DA A6F6     04024                 LDX BGRCOLOR            ; Preload BACKGROUND color
A6DC AD0AD2   04025                 LDA RANDOM              ; Preload random number
A6DF 248A     04026                 BIT HITBADNESS          ; Check if our starship was hit
A6E1 5007     04027                 BVC SKIP044             ; If HITBADNESS has a value of...
A6E3 3004     04028                 BMI SKIP043             ; $00 -> NO HIT             (BGR color := unchanged)
A6E5 2972     04029                 AND #$72                ; $7F -> SHIELDS HIT        (BGR color := %01rr00r0)
A6E7 0940     04030                 ORA #$40                ; $FF -> STARSHIP DESTROYED (BGR color := %01rr00r0)
A6E9 AA       04031 SKIP043         TAX                     ;
A6EA A5D0     04032 SKIP044         LDA SHIPVIEW            ; Skip if in Front or Aft view
A6EC C903     04033                 CMP #3                  ; (!)
A6EE 9002     04034                 BCC SKIP045             ;
A6F0 A2A0     04035                 LDX #$A0                ; Preload BACKGROUND color {DARK BLUE GREEN}...
A6F2 86F6     04036 SKIP045         STX BGRCOLOR            ; Store BACKGROUND color
              04037
A6F4 A208     04038                 LDX #8                  ; Copy all color registers to hardware registers
A6F6 B5EE     04039 LOOP026         LDA PL0COLOR,X          ;
A6F8 9D12D0   04040                 STA COLPM0,X            ;
A6FB CA       04041                 DEX                     ;
A6FC 10F8     04042                 BPL LOOP026             ;
              04043
A6FE 8D1ED0   04044                 STA HITCLR              ; Clear Player/Missile collision registers
              04045
A701 20ABB2   04046                 JSR SOUND               ; Call sound effects
              04047
A704 E677     04048                 INC IDLECNTLO           ; Increment 16-bit idle counter
A706 D00D     04049                 BNE SKIP046             ;
A708 A566     04050                 LDA IDLECNTHI           ;
A70A 3009     04051                 BMI SKIP046             ;
A70C E666     04052                 INC IDLECNTHI           ;
A70E 1005     04053                 BPL SKIP046             ; Skip if counter value of $8000 not reached yet
              04054
A710 A000     04055                 LDY #$00                ; Prep empty title phrase offset
A712 4C5CA1   04056                 JMP INITDEMO            ; Enter demo mode (!)
              04057
A715 4C4BA7   04058 SKIP046         JMP JUMP004             ; Return via DLI return code
              04059
              04060 ;*******************************************************************************
              04061 ;*                                                                             *
              04062 ;*                                  DLSTHNDLR                                  *
              04063 ;*                                                                             *
              04064 ;*                       Display List Interrupt Handler                        *
              04065 ;*                                                                             *
              04066 ;*******************************************************************************
              04067
              04068 ; DESCRIPTION
              04069 ;
              04070 ; This subroutine is executed during the Display List Interrupt (DLI). It
              04071 ; switches the character set to the ROM character set if the DLI occurs at ANTIC
              04072 ; line 96 (video line 192), otherwise to the custom character set. The former
              04073 ; happens in the Galactic Chart view where the ROM character set is used in the
              04074 ; Galactic Chart Panel Display.
              04075 ;
              04076 ; Then, the DLI PLAYFIELD colors are copied to the corresponding hardware
              04077 ; registers and the values of the collision hardware registers for PLAYER3..4
              04078 ; (our starship's photon torpedoes) are copied to the corresponding zero-page
              04079 ; variables PL3HIT ($82) and PL4HIT ($83).
              04080
A718 48       04081 DLSTHNDLR       PHA                     ; Push A
A719 8A       04082                 TXA                     ;
A71A 48       04083                 PHA                     ; Push X
A71B 98       04084                 TYA                     ;
A71C 48       04085                 PHA                     ; Push Y
              04086
A71D A9E0     04087                 LDA #>ROMCHARSET        ; Switch to ROM charset if ANTIC line counter = 96
A71F AC0BD4   04088                 LDY VCOUNT              ; ...else switch to custom character set
A722 C060     04089                 CPY #96                 ;
A724 F002     04090                 BEQ SKIP047             ;
A726 A9A0     04091                 LDA #>CHARSET           ;
A728 8D09D4   04092 SKIP047         STA CHBASE              ;
              04093
A72B A204     04094                 LDX #4                  ; Loop over all PLAYFIELD colors
A72D 8D0AD4   04095                 STA WSYNC               ; Stop and wait for horizontal TV beam sync
A730 B5F7     04096 LOOP027         LDA PF0COLORDLI,X       ; Copy DLI PLAYFIELD colors to hardware registers
A732 9D16D0   04097                 STA COLPF0,X            ;
A735 CA       04098                 DEX                     ;
A736 10F8     04099                 BPL LOOP027             ; Next PLAYFIELD color
              04100
A738 AD08D0   04101                 LDA M0PL                ; Merge MISSILE-to-PLAYER collision registers...
A73B 0D09D0   04102                 ORA M1PL                ;
A73E 0D0AD0   04103                 ORA M2PL                ;
A741 0D0BD0   04104                 ORA M3PL                ;
A744 8583     04105                 STA PL4HIT              ; ...and store them in PL4HIT
A746 AD0FD0   04106                 LDA P3PL                ; Copy PLAYER3-to-PLAYER coll. register to PL3HIT
A749 8582     04107                 STA PL3HIT              ;
              04108
A74B 68       04109 JUMP004         PLA                     ; Pop Y
A74C A8       04110                 TAY                     ;
A74D 68       04111                 PLA                     ; Pop X
A74E AA       04112                 TAX                     ;
A74F 68       04113                 PLA                     ; Pop A
A750 40       04114                 RTI                     ; Return from interrupt
              04115
              04116 ;*******************************************************************************
              04117 ;*                                                                             *
              04118 ;*                                  IRQHNDLR                                   *
              04119 ;*                                                                             *
              04120 ;*                       Interrupt Request (IRQ) Handler                       *
              04121 ;*                                                                             *
              04122 ;*******************************************************************************
              04123
              04124 ; DESCRIPTION
              04125 ;
              04126 ; This subroutine is executed during immediate interrupt requests (IRQs), such
              04127 ; as after pressing a key on the keyboard. It clears and disables all IRQs
              04128 ; except the interrupt raised by a pressed key. If a key has been pressed, its
              04129 ; hardware code is collected and the bits of the SHIFT and CONTROL keys are
              04130 ; added. The resulting keyboard code is stored in KEYCODE ($CA).
              04131
A751 48       04132 IRQHNDLR        PHA                     ; Push A
A752 A900     04133                 LDA #0                  ; POKEY: Disable all IRQs
A754 8D0ED2   04134                 STA IRQEN               ;
A757 A940     04135                 LDA #$40                ; POKEY: Enable keyboard interrupt (IRQ)
A759 8D0ED2   04136                 STA IRQEN               ;
A75C AD09D2   04137                 LDA KBCODE              ; POKEY: Load keyboard key code
A75F 09C0     04138                 ORA #$C0                ; Combine with SHIFT and CONTROL key bits
A761 85CA     04139                 STA KEYCODE             ; Store keyboard code
A763 68       04140                 PLA                     ; Pop A
A764 40       04141                 RTI                     ; Return from interrupt
              04142
              04143 ;*******************************************************************************
              04144 ;*                                                                             *
              04145 ;*                                  DRAWLINES                                  *
              04146 ;*                                                                             *
              04147 ;*                     Draw horizontal and vertical lines                      *
              04148 ;*                                                                             *
              04149 ;*******************************************************************************
              04150
              04151 ; DESCRIPTION
              04152 ;
              04153 ; Draws the Attack Computer Display (in Front view), cross hairs (in Front and
              04154 ; Aft view), and our starship's shape (in Long-Range Scan view) on the PLAYFIELD
              04155 ; (if the Attack Computer is not destroyed) by being passed an offset to table
              04156 ; DRAWLINESTAB ($BAF9). This table consists of a list of 3-byte elements,
              04157 ; terminated by an end marker byte ($FE). Each such element defines a single
              04158 ; horizontal or vertical line, and is passed via memory addresses DIRLEN ($A4),
              04159 ; PENROW ($A5), and PENCOLUMN ($A6) to subroutine DRAWLINE ($A782), which
              04160 ; executes the actual drawing. See subroutine DRAWLINE ($A782) and table
              04161 ; DRAWLINESTAB ($BAF9) for a description of the 3-byte elements. 
              04162 ;
              04163 ; With every call of this subroutine the blip cycle counter is initialized to
              04164 ; the start of the DELAY phase (see subroutine UPDATTCOMP ($A7BF)).
              04165 ;
              04166 ; NOTE: The entry to this subroutine is in mid-code, not at the beginning.
              04167 ;
              04168 ; INPUT
              04169 ;
              04170 ;   X = Offset into DRAWLINESTAB ($BAF9). Used values are:
              04171 ;     $00 -> Draw Attack Computer Display and cross hairs (Front view)
              04172 ;     $2A -> Draw Aft view cross hairs (Aft view)
              04173 ;     $31 -> Draw our starship's shape (Long-Range Scan view)
              04174
A765 99A400   04175 LOOP028         STA DIRLEN,Y            ; Store byte of 3-byte element
A768 E8       04176                 INX                     ;
A769 88       04177                 DEY                     ;
A76A 100E     04178                 BPL SKIP048             ; Next byte of 3-byte element until 3 bytes copied
A76C 2082A7   04179                 JSR DRAWLINE            ; Draw line on PLAYFIELD
              04180
A76F A905     04181 DRAWLINES       LDA #5                  ; Init blip cycle to DELAY phase...
A771 85A2     04182                 STA BLIPCYCLECNT        ; ...delays drawing each row
              04183
A773 2C9509   04184                 BIT GCSTATCOM           ; Return if Attack Computer destroyed
A776 7009     04185                 BVS SKIP049             ;
              04186
A778 A002     04187                 LDY #2                  ;
A77A BDF9BA   04188 SKIP048         LDA DRAWLINESTAB,X      ; Load byte of 3-byte element
A77D C9FE     04189                 CMP #$FE                ; Loop until end marker byte ($FE) encountered
A77F D0E4     04190                 BNE LOOP028             ;
A781 60       04191 SKIP049         RTS                     ; Return
              04192
              04193 ;*******************************************************************************
              04194 ;*                                                                             *
              04195 ;*                                  DRAWLINE                                   *
              04196 ;*                                                                             *
              04197 ;*                  Draw a single horizontal or vertical line                  *
              04198 ;*                                                                             *
              04199 ;*******************************************************************************
              04200
              04201 ; DESCRIPTION
              04202 ;
              04203 ; Draws a single horizontal or vertical transparent line.
              04204 ;
              04205 ; There are two entries to this subroutine:
              04206 ;
              04207 ; (1)  DRAWLINE ($A782) is entered from subroutine DRAWLINES ($A76F) to draw a
              04208 ;      line in COLOR1.
              04209 ;
              04210 ; (2)  DRAWLINE2 ($A784) is entered from subroutine UPDATTCOMP ($A7BF) to draw
              04211 ;      the blip in COLOR2 in the Attack Computer Display.
              04212 ;
              04213 ; The position, direction, and length of the line is defined by three bytes
              04214 ; passed in memory addresses DIRLEN ($A4), PENROW ($A5), and PENCOLUMN ($A6). 
              04215 ;
              04216 ; A drawing operation draws one transparent line. It uses both the color
              04217 ; register number of the overwritten (old) and the overwriting (new) pixel to
              04218 ; decide on the new pixel color register number. This results in a transparent
              04219 ; drawing effect. See the table below for all resulting combinations of color
              04220 ; registers.
              04221 ;
              04222 ; +-----------+---------------+
              04223 ; |           |   Old Color   |
              04224 ; |           |   Register    |
              04225 ; | New Color +---------------+
              04226 ; | Register  | 0 | 1 | 2 | 3 |
              04227 ; +-----------+---+---+---+---+
              04228 ; |         0 | 0 | 1 | 2 | 3 |
              04229 ; +-----------+---+---+---+---+
              04230 ; |         1 | 1 | 1 | 3 | 3 |
              04231 ; +-----------+---+---+---+---+
              04232 ; |         2 | 2 | 3 | 2 | 3 |
              04233 ; +-----------+---+---+---+---+
              04234 ; |         3 | 3 | 3 | 3 | 3 |
              04235 ; +-----------+---+---+---+---+
              04236 ;
              04237 ; For example, COLOR1 overwritten by COLOR2 yields COLOR3. If you look closely
              04238 ; at the blip (in COLOR2) on the Attack Computer Display (in COLOR1) the lines
              04239 ; of the Attack Computer Display shine through (in COLOR3) where they overlap.
              04240 ;
              04241 ; INPUT
              04242 ;
              04243 ;   DIRLEN    ($A4) = B7 = 0 -> Draw line to the left
              04244 ;                     B7 = 1 -> Draw line downward
              04245 ;                     B6..0  -> Length of line in pixels
              04246 ;   PENROW    ($A5) = Start pixel row number of line
              04247 ;   PENCOLUMN ($A6) = Start pixel column number of line
              04248
    =006A     04249 L.PIXELBYTEOFF  = $6A                   ; Within-row-offset to byte with pixel in PLAYFIELD
    =006B     04250 L.BITPAT        = $6B                   ; 1-byte bit pattern for 4 pixels of same color
    =006E     04251 L.DIRSAV        = $6E                   ; Saves DIRLEN
              04252
A782 A955     04253 DRAWLINE        LDA #$55                ; Copy 1-byte bit pattern for 4 pixels of COLOR1
A784 856B     04254 DRAWLINE2       STA L.BITPAT            ;
A786 A5A4     04255                 LDA DIRLEN              ; Copy direction (and length) of line
A788 856E     04256                 STA L.DIRSAV            ;
A78A 297F     04257                 AND #$7F                ; Strip direction bit
A78C 85A4     04258                 STA DIRLEN              ; Store length of line
              04259
A78E A4A5     04260 LOOP029         LDY PENROW              ; Loop over length of line to be drawn
A790 B90008   04261                 LDA PFMEMROWLO,Y        ; Point MEMPTR to start of pen's pixel row...
A793 8568     04262                 STA MEMPTR              ; ...in PLAYFIELD memory
A795 B96408   04263                 LDA PFMEMROWHI,Y        ;
A798 8569     04264                 STA MEMPTR+1            ;
              04265
A79A A5A6     04266                 LDA PENCOLUMN           ; Calc and store pen's byte-within-row offset
A79C 4A       04267                 LSR A                   ;
A79D 4A       04268                 LSR A                   ;
A79E 856A     04269                 STA L.PIXELBYTEOFF      ;
              04270
A7A0 A5A6     04271                 LDA PENCOLUMN           ; Calc pixel-within-byte index
A7A2 2903     04272                 AND #$03                ;
A7A4 A8       04273                 TAY                     ;
              04274
A7A5 B9B0BA   04275                 LDA PIXELMASKTAB,Y      ; Pick mask to filter pixel in byte
A7A8 256B     04276                 AND L.BITPAT            ; ...AND with bit pattern for 4 pixels of same color
A7AA A46A     04277                 LDY L.PIXELBYTEOFF      ;
A7AC 1168     04278                 ORA (MEMPTR),Y          ; Blend byte with new pixel and PLAYFIELD byte
A7AE 9168     04279                 STA (MEMPTR),Y          ; ...and store it back in PLAYFIELD memory
              04280
A7B0 246E     04281                 BIT L.DIRSAV            ; Check direction bit B7
A7B2 1004     04282                 BPL SKIP050             ;
A7B4 E6A5     04283                 INC PENROW              ; If B7 = 1 -> Increment pen's pixel row number
A7B6 D002     04284                 BNE SKIP051             ;
A7B8 E6A6     04285 SKIP050         INC PENCOLUMN           ; If B7 = 0 -> Increment pen's pixel column number
              04286
A7BA C6A4     04287 SKIP051         DEC DIRLEN              ;
A7BC D0D0     04288                 BNE LOOP029             ; Next pixel of line
A7BE 60       04289                 RTS                     ; Return
              04290
              04291 ;*******************************************************************************
              04292 ;*                                                                             *
              04293 ;*                                 UPDATTCOMP                                  *
              04294 ;*                                                                             *
              04295 ;*                       Update Attack Computer Display                        *
              04296 ;*                                                                             *
              04297 ;*******************************************************************************
              04298
              04299 ; DESCRIPTION
              04300 ;
              04301 ; Draws the blip of the tracked space object and the lock-on markers into the
              04302 ; Attack Computer Display. The actual drawing follows a cycle of 11 game loop
              04303 ; iterations (numbered by this subroutine as "blip cycles" 0..10), which can be
              04304 ; divided into three phases:
              04305 ;
              04306 ; (1)  Blip cycle 0..4: Draw blip shape row-by-row
              04307 ;
              04308 ;      Draw the blip's shape into the Attack Computer Display, one row each blip
              04309 ;      cycle. After 5 blip cycles the blip shape is complete and completely
              04310 ;      visible because between blip cycles, that is, game loop iterations, the
              04311 ;      PLAYFIELD is not erased (only the PLAYFIELD space objects are). Drawing
              04312 ;      is executed by branching to entry DRAWLINE2 ($A784) of subroutine
              04313 ;      DRAWLINE ($A782). The blip shape is retrieved from table BLIPSHAPTAB
              04314 ;      ($BF6E).
              04315 ;
              04316 ; (2)  Blip cycle 5..9: Delay
              04317 ;
              04318 ;      Delay the execution of blip cycle 10.
              04319 ;
              04320 ; (3)  Blip cycle 10: Update Attack Computer Display
              04321 ;
              04322 ;      After verifying that the tracked space object is alive, calculate the
              04323 ;      blip's relative top-left pixel column and row number. Resulting values
              04324 ;      are in -11..11 and -6..4, relative to the blip's top-left reference
              04325 ;      position at pixel column number 131 and pixel row number 77,
              04326 ;      respectively. 
              04327 ;
              04328 ;      Filter the Attack Computer Display area: Only pixels of COLOR1 within the
              04329 ;      inner frame area (a 28 pixel wide x 15 pixel high rectangle with its
              04330 ;      top-left corner at pixel column number 120 and pixel row number 71) pass
              04331 ;      the filter operation. This effectively erases the blip.
              04332 ;
              04333 ;      If the blip is within -2..+2 pixels off its horizontal reference position
              04334 ;      (pixel column numbers 129..132) then the tracked space object is in x
              04335 ;      lock-on. Draw the x lock-on marker. 
              04336 ;
              04337 ;      If the tracked space object is in x lock-on and the blip is within -2..+1
              04338 ;      pixels off its vertical reference position (pixel column numbers 75..78)
              04339 ;      then the tracked space object is in x and y lock-on. Draw also the y
              04340 ;      lock-on marker. 
              04341 ;
              04342 ;      If the tracked space object is in x and y lock-on and the tracked space
              04343 ;      object's z-coordinate < +3072 (+$0C**) <KM> then the tracked space object
              04344 ;      is in x, y and z lock-on. Draw also the z lock-on marker. 
              04345 ;
              04346 ;      If the tracked space object is in x, y, and z lock-on (and thus in
              04347 ;      optimal firing range) set the ISINLOCKON ($A3) flag.
              04348 ;
              04349 ;      The following sketches show the Attack Computer Display area overlaid
              04350 ;      with the Attack Computer Display frame:
              04351 ;
              04352 ;          119                                 119
              04353 ;      70 ##############################    70 ##############################
              04354 ;         #         ....#....          #       #             #              #
              04355 ;         #         ....#....          #       #             #              #
              04356 ;         #         ....#....          #       #             #              #
              04357 ;         #         ....#....          #       #             #              #
              04358 ;         #      ###############       #       #......###############.......#
              04359 ;         #XXXX  #  .........  #   XXXX#       #......#.............#.......#
              04360 ;         #      #  ..$......  #       #       #......#....$........#.......#
              04361 ;         ########  .........  #########       ########.............#########
              04362 ;         #      #  .........  #       #       #......#.............#.......#
              04363 ;         #      #  .........  #       #       #YYYY..#.............#...YYYY#
              04364 ;         #      ###############       #       #......###############.......#
              04365 ;         #         ....#....          #       #.............#..............#
              04366 ;         #         ....#....          #       #             #              #
              04367 ;         #         ....#....          #       #             #              #
              04368 ;         #         ....#....          #       #             #              #
              04369 ;         ##############################       ##############################
              04370 ;
              04371 ;         X = x lock-on marker                 Y = y lock-on marker
              04372 ;         . = x lock-on blip zone              . = y lock-on blip zone
              04373 ;         $ = Blip's top-left reference        $ = Blip's top-left reference
              04374 ;             position                             position
              04375 ;
              04376 ;         119
              04377 ;      70 ##############################
              04378 ;         #             #              #
              04379 ;         #             #              #
              04380 ;         #             #              #
              04381 ;         #             #              #
              04382 ;         #      ###############       #
              04383 ;         #      #             #       #
              04384 ;         #      #    $        #       #
              04385 ;         ########             #########
              04386 ;         #      #             #       #
              04387 ;         #      #             #       #
              04388 ;         #      ###############       #
              04389 ;         #             #              #
              04390 ;         #             #              #
              04391 ;         #        ZZ   #  ZZ          #
              04392 ;         #        ZZ   #  ZZ          #
              04393 ;         ##############################
              04394 ;
              04395 ;         Z = z lock-on marker
              04396 ;         $ = Blip's top-left reference
              04397 ;             position
              04398
    =006C     04399 L.SHIFTSHAPE    = $6C                   ; Saves shifted byte of blip shape bit pattern
              04400
A7BF AE5C09   04401 UPDATTCOMP      LDX TRACKDIGIT          ; Load index of tracked space object
A7C2 A4A2     04402                 LDY BLIPCYCLECNT        ; Load blip cycle counter
A7C4 C005     04403                 CPY #5                  ;
A7C6 B024     04404                 BCS SKIP054             ; Skip drawing blip if blip cycle > 5
              04405
              04406 ;*** Blip cycle 0..4: Draw blip shape one row each cycle ***********************
A7C8 A5A0     04407                 LDA BLIPCOLUMN          ; Init pen's pixel column number...
A7CA 85A6     04408                 STA PENCOLUMN           ; ...with top position of blip shape
A7CC B96EBF   04409                 LDA BLIPSHAPTAB,Y       ; Load bit pattern of one row of blip shape
A7CF 0A       04410 LOOP030         ASL A                   ; Shift bit pattern one position to the left
A7D0 856C     04411                 STA L.SHIFTSHAPE        ; Temporarily save shifted shape byte
A7D2 900D     04412                 BCC SKIP052             ; Skip if shifted-out bit = 0
              04413
A7D4 A981     04414                 LDA #$81                ; Store "draw a line of 1 pixel length downward"
A7D6 85A4     04415                 STA DIRLEN              ; ...for call to DRAWLINE2
              04416
A7D8 A5A1     04417                 LDA BLIPROW             ; Init pen's pixel row number...
A7DA 85A5     04418                 STA PENROW              ; ...with leftmost position of blip shape
A7DC A9AA     04419                 LDA #$AA                ; Load 1-byte bit pattern for 4 pixels of COLOR2
A7DE 2084A7   04420                 JSR DRAWLINE2           ; Draw pixel on PLAYFIELD
              04421
A7E1 E6A6     04422 SKIP052         INC PENCOLUMN           ; Move pen one pixel to the right
A7E3 A56C     04423                 LDA L.SHIFTSHAPE        ; Reload shifted shape byte
A7E5 D0E8     04424                 BNE LOOP030             ; Next horizontal pixel of blip shape
              04425
A7E7 E6A1     04426                 INC BLIPROW             ; Move pen one pixel downward
A7E9 E6A2     04427 SKIP053         INC BLIPCYCLECNT        ; Increment blip cycle counter
A7EB 60       04428                 RTS                     ; Return
              04429
              04430 ;*** Blip cycle 5..9: Delay ****************************************************
A7EC C00A     04431 SKIP054         CPY #10                 ; Return if blip cycle < 10
A7EE 90F9     04432                 BCC SKIP053             ;
              04433
              04434 ;*** Blip cycle 10: Calculate new blip pixel row and column numbers ************
A7F0 B5E9     04435                 LDA PL0LIFE,X           ; Skip if tracked object not alive
A7F2 F03C     04436                 BEQ SKIP059             ;
              04437
A7F4 BD710A   04438                 LDA XPOSHI,X            ; Map x-coordinate of tracked space obj to -11..11:
A7F7 BCDE09   04439                 LDY XPOSSIGN,X          ; Skip if tracked object on left screen half (x >= 0)
A7FA F008     04440                 BEQ SKIP055             ;
              04441
A7FC C90C     04442                 CMP #12                 ; Skip if x of tracked obj < +$0C** (< 3327) <KM>
A7FE 900A     04443                 BCC SKIP056             ;
A800 A90B     04444                 LDA #11                 ; Prep relative pixel column number of 11, skip
A802 1006     04445                 BPL SKIP056             ;
              04446
A804 C9F5     04447 SKIP055         CMP #-11                ; Skip if x of tracked obj >= -($0B**) (>=-2816) <KM>
A806 B002     04448                 BCS SKIP056             ;
A808 A9F5     04449                 LDA #-11                ; Prep relative pixel column number of -11
              04450
A80A 18       04451 SKIP056         CLC                     ; Add 131 (= blip's top-left reference pixel column)
A80B 6983     04452                 ADC #131                ;
A80D 85A0     04453                 STA BLIPCOLUMN          ; BLIPCOLUMN := 131 + -11..11
              04454
A80F BDA20A   04455                 LDA YPOSHI,X            ; Map y-coordinate of tracked space obj to -6..4:
A812 49FF     04456                 EOR #$FF                ; Mirror y-coordinate on y-axis (displacement of +1)
A814 BC0F0A   04457                 LDY YPOSSIGN,X          ; Skip if tracked obj on lower screen half (y < 0)
A817 D008     04458                 BNE SKIP057             ;
              04459
A819 C905     04460                 CMP #5                  ; Skip if mirrored y of tracked obj < +$05** <KM>
A81B 900A     04461                 BCC SKIP058             ;
A81D A904     04462                 LDA #4                  ; Prep relative pixel row number of 4, skip
A81F 1006     04463                 BPL SKIP058             ;
              04464
A821 C9FA     04465 SKIP057         CMP #-6                 ; Skip if mirrored y of tracked obj >= -($06**) <KM>
A823 B002     04466                 BCS SKIP058             ;
A825 A9FA     04467                 LDA #-6                 ; Prep relative pixel row number of -6
              04468
A827 18       04469 SKIP058         CLC                     ; Add 77 (= blip's top-left ref. pixel row number)
A828 694D     04470                 ADC #77                 ;
A82A 85A1     04471                 STA BLIPROW             ; BLIPROW := 77 + -6..4
              04472
A82C A900     04473                 LDA #0                  ; Reset blip cycle
A82E 85A2     04474                 STA BLIPCYCLECNT        ;
              04475
              04476 ;*** Filter Attack Computer Display frame area *********************************
              04477                                         ; PLAYFIELD address of top-left of Attack Computer
    =1B36     04478 PFMEM.C120R71   = PFMEM+71*40+120/4     ; Display's inner frame @ pixel column 120, row 71
              04479
A830 A936     04480 SKIP059         LDA #<PFMEM.C120R71     ; Point MEMPTR to start of frame's...
A832 8568     04481                 STA MEMPTR              ; ...inner top-left corner at column 120, row 71...
A834 A91B     04482                 LDA #>PFMEM.C120R71     ; ...in PLAYFIELD memory
A836 8569     04483                 STA MEMPTR+1            ;
              04484
A838 A20E     04485                 LDX #14                 ; Traverse a 28 x 15 pixel rect of PLAYFIELD memory
A83A A006     04486 LOOP031         LDY #6                  ;
A83C B168     04487 LOOP032         LDA (MEMPTR),Y          ; Load byte (4 pixels) from PLAYFIELD memory
A83E 2955     04488                 AND #$55                ; Filter COLOR1 pixels
A840 9168     04489                 STA (MEMPTR),Y          ; Store byte (4 pixels) back to PLAYFIELD memory
A842 88       04490                 DEY                     ;
A843 10F7     04491                 BPL LOOP032             ; Next 4 pixels in x-direction
              04492
A845 18       04493                 CLC                     ; Add 40 to MEMPTR
A846 A568     04494                 LDA MEMPTR              ; (40 bytes = 160 pixels = 1 PLAYFIELD row of pixels)
A848 6928     04495                 ADC #40                 ;
A84A 8568     04496                 STA MEMPTR              ;
A84C 9002     04497                 BCC SKIP060             ;
A84E E669     04498                 INC MEMPTR+1            ;
              04499
A850 CA       04500 SKIP060         DEX                     ;
A851 10E7     04501                 BPL LOOP031             ; Next row of pixels in y-direction
              04502
              04503 ;*** Prepare lock-on marker checks *********************************************
A853 AE5C09   04504                 LDX TRACKDIGIT          ; Preload index of tracked space obj to check z-range
A856 C8       04505                 INY                     ; Y := 0, preloaded value of ISINLOCKON
              04506
              04507 ;*** Draw lock-on markers ******************************************************
              04508                                         ; PLAYFIELD addresses of
    =1BFE     04509 PFMEM.C120R76   = PFMEM+76*40+120/4     ; ...x lock-on marker @ pixel column 120, row 76
    =1C04     04510 PFMEM.C144R76   = PFMEM+76*40+144/4     ; ...x lock-on marker @ pixel column 144, row 76
    =1C9E     04511 PFMEM.C120R80   = PFMEM+80*40+120/4     ; ...y lock-on marker @ pixel column 120, row 80
    =1CA4     04512 PFMEM.C144R80   = PFMEM+80*40+144/4     ; ...y lock-on marker @ pixel column 144, row 80
    =1D40     04513 PFMEM.C128R84   = PFMEM+84*40+128/4     ; ...z lock-on marker @ pixel column 128, row 84
    =1D68     04514 PFMEM.C128R85   = PFMEM+85*40+128/4     ; ...z lock-on marker @ pixel column 128, row 85
    =1D42     04515 PFMEM.C136R84   = PFMEM+84*40+136/4     ; ...z lock-on marker @ pixel column 136, row 84
    =1D6A     04516 PFMEM.C136R85   = PFMEM+85*40+136/4     ; ...z lock-on marker @ pixel column 136, row 85
              04517
A857 A588     04518                 LDA LOCKONLIFE          ; If lock-on lifetime expired redraw lock-on markers
A859 F004     04519                 BEQ SKIP061             ;
              04520
A85B C688     04521                 DEC LOCKONLIFE          ; else decr lock-on lifetime, skip drawing markers
A85D D039     04522                 BNE SKIP062             ;
              04523
A85F A5A0     04524 SKIP061         LDA BLIPCOLUMN          ; Skip x, y, and z lock-on marker if blip's...
A861 C981     04525                 CMP #129                ; ...top-left pixel column number not in 129..132
A863 9033     04526                 BCC SKIP062             ;
A865 C985     04527                 CMP #133                ;
A867 B02F     04528                 BCS SKIP062             ;
              04529
A869 A9AA     04530                 LDA #$AA                ; Draw x lock-on marker (4 horiz. pixels of COLOR2)
A86B 8DFE1B   04531                 STA PFMEM.C120R76       ; ...at pixel column 120, row 76
A86E 8D041C   04532                 STA PFMEM.C144R76       ; ...at pixel column 144, row 76
              04533
A871 A5A1     04534                 LDA BLIPROW             ; Skip y and z lock-on marker if blip's...
A873 C94B     04535                 CMP #75                 ; ...top-left pixel row number not in 75...78
A875 9021     04536                 BCC SKIP062             ;
A877 C94F     04537                 CMP #79                 ;
A879 B01D     04538                 BCS SKIP062             ;
              04539
A87B A9AA     04540                 LDA #$AA                ; Draw y lock-on marker (4 horiz. pixels of COLOR2)
A87D 8D9E1C   04541                 STA PFMEM.C120R80       ; ...at pixel column 120, row 80
A880 8DA41C   04542                 STA PFMEM.C144R80       ; ...at pixel column 144, row 80
              04543
A883 BD400A   04544                 LDA ZPOSHI,X            ; Skip z lock-on marker if z >= +$0C** (>= 3072) <KM>
A886 C90C     04545                 CMP #12                 ;
A888 B00E     04546                 BCS SKIP062             ;
              04547
A88A A0A0     04548                 LDY #$A0                ; Draw z lock-on marker (2 horiz. pixels of COLOR2)
A88C 8C401D   04549                 STY PFMEM.C128R84       ; ...at pixel column 128, row 84 (prep lock-on flag)
A88F 8C681D   04550                 STY PFMEM.C128R85       ; ...at pixel column 128, row 85
A892 8C421D   04551                 STY PFMEM.C136R84       ; ...at pixel column 136, row 84
A895 8C6A1D   04552                 STY PFMEM.C136R85       ; ...at pixel column 136, row 85
              04553
A898 84A3     04554 SKIP062         STY ISINLOCKON          ; Store lock-on flag (> 0 -> Tracked obj locked on)
A89A 60       04555                 RTS                     ; Return
              04556
              04557 ;*******************************************************************************
              04558 ;*                                                                             *
              04559 ;*                                  HYPERWARP                                  *
              04560 ;*                                                                             *
              04561 ;*                              Handle hyperwarp                               *
              04562 ;*                                                                             *
              04563 ;*******************************************************************************
              04564
              04565 ; DESCRIPTION
              04566 ;
              04567 ; Handles the hyperwarp sequence, which transports our starship from one sector
              04568 ; to another. It can be divided into four phases:
              04569 ;
              04570 ; (1)  ACCELERATION PHASE
              04571 ;
              04572 ;      The ACCELERATION PHASE is entered after the hyperwarp sequence has been
              04573 ;      engaged in subroutine KEYBOARD ($AFFE) by pressing the 'H' key. The
              04574 ;      Hyperwarp Target Marker appears and our starship begins to accelerate.
              04575 ;      When our starship's velocity reaches 128 <KM/H> (the VELOCITY readout of
              04576 ;      the Control Panel Display displays "50"), the STAR TRAIL phase is
              04577 ;      entered. 
              04578 ;
              04579 ;      The Hyperwarp Target Marker is represented by a space object some fixed
              04580 ;      distance away in front of our starship as PLAYER3. It has a lifetime of
              04581 ;      144 game loop iterations and is tracked. Thus, tracking handling in
              04582 ;      subroutine UPDATTCOMP ($A7BF) provides drawing the x and y lock-on
              04583 ;      markers in the Attack Computer Display when the Hyperwarp Target Marker
              04584 ;      is centered. 
              04585 ;
              04586 ;      A temporary arrival location on the Galactic Chart was saved when the
              04587 ;      hyperwarp was engaged in subroutine KEYBOARD ($AFFE). During the
              04588 ;      ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE) this location is
              04589 ;      constantly updated depending on how much the Hyperwarp Target Marker
              04590 ;      veers off its center position.
              04591 ;
              04592 ;      The actual arrival hyperwarp marker row and column numbers on the
              04593 ;      Galactic Chart are the sum of the temporary arrival hyperwarp marker row
              04594 ;      and column numbers stored when engaging the hyperwarp in subroutine
              04595 ;      KEYBOARD ($AFFE) and the number of Player/Missile (PM) pixels which the
              04596 ;      Hyperwarp Target Marker is off-center vertically and horizontally,
              04597 ;      respectively, at the end of the STAR TRAIL PHASE.
              04598 ;
              04599 ;      NOTE: The used vertical center value of 119 PM pixels is the PM pixel row
              04600 ;      number of the top edge of the centered Hyperwarp Target Marker (from top
              04601 ;      to bottom: 8 PM pixels to the start of Display List + 16 PM pixels blank
              04602 ;      lines + 100 PM pixels to the vertical PLAYFIELD center - 5 PM pixels
              04603 ;      relative offset of the Hyperwarp Target Marker's shape center to the
              04604 ;      shape's top edge = 119 PM pixels). Recall also that PLAYERs at
              04605 ;      single-line resolution have PM pixels that are half as high as they are
              04606 ;      wide.
              04607 ;
              04608 ;      NOTE: The used horizontal center value of 125 PM pixels is the PM pixel
              04609 ;      row number of the left edge of the centered Hyperwarp Target Marker (from
              04610 ;      left to right: 127 PM pixels to the PLAYFIELD center - 3 PM pixels
              04611 ;      relative offset of the Hyperwarp Target Marker's shape center to the
              04612 ;      shape's left edge = 125 PM pixels).
              04613 ;
              04614 ;      If during the ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE)
              04615 ;      you switch the Front view to another view, the Hyperwarp Target Marker
              04616 ;      changes to a random position which results in arriving at a random
              04617 ;      destination sector.
              04618 ;
              04619 ;      During the ACCELERATION PHASE (and the subsequent STAR TRAIL PHASE) in
              04620 ;      all but NOVICE missions, the Hyperwarp Target Marker veers off with
              04621 ;      random velocity in x and y direction, which is changed during 6% of game
              04622 ;      loop iterations. Table VEERMASKTAB ($BED7) limits the maximum veer-off
              04623 ;      velocity depending on the mission level:
              04624 ;
              04625 ;      +-----------+-----------------------------+
              04626 ;      |  Mission  |      Veer-Off Velocity      |
              04627 ;      +-----------+-----------------------------+
              04628 ;      | NOVICE    |                   0  <KM/H> |
              04629 ;      | PILOT     |  -63..-16, +16..+63  <KM/H> |
              04630 ;      | WARRIOR   |  -95..-16, +16..+95  <KM/H> |
              04631 ;      | COMMANDER | -127..-16, +16..+127 <KM/H> |
              04632 ;      +-----------+-----------------------------+
              04633 ;
              04634 ; (2)  STAR TRAIL PHASE
              04635 ;
              04636 ;      When our starship's velocity reaches a velocity of 128 <KM/H> (the
              04637 ;      VELOCITY readout of the Control Panel Display displays "50"), in addition
              04638 ;      to all effects of the ACCELERATION PHASE, multiple star trails begin to
              04639 ;      appear while our starship continues to accelerate. Each star trail is
              04640 ;      initialized in subroutine INITTRAIL ($A9B4).
              04641 ;
              04642 ; (3)  HYPERSPACE PHASE
              04643 ;
              04644 ;      When our starship's velocity reaches a velocity of 254 <KM/H> (the
              04645 ;      VELOCITY readout of the Control Panel Display displays "99") our starship
              04646 ;      enters the HYPERSPACE PHASE (the VELOCITY readout of the Control Panel
              04647 ;      Display displays the infinity symbol).
              04648 ;
              04649 ;      During the first pass of the HYPERSPACE PHASE the hyperwarp state is set
              04650 ;      to HYPERSPACE. This makes the stars and the Hyperwarp Target Marker
              04651 ;      disappear in GAMELOOP ($A1F3). Then, the beeper sound pattern HYPERWARP
              04652 ;      TRANSIT is played in subroutine BEEP ($B3A6), the hyperwarp distance and
              04653 ;      required hyperwarp energy is calculated in subroutine CALCWARP ($B1A7),
              04654 ;      and the title line is preloaded with "HYPERSPACE". Code execution returns
              04655 ;      via calling subroutine CLEANUPWARP ($A98D) where program variables are
              04656 ;      already initialized to their post-hyperwarp values.
              04657 ;
              04658 ;      During subsequent passes of the HYPERSPACE PHASE, the calculated
              04659 ;      hyperwarp energy is decremented in chunks of 10 energy units. Code
              04660 ;      execution returns via calling subroutine DECENERGY ($B86F), which
              04661 ;      decrements our starship's energy. After the calculated hyperwarp energy
              04662 ;      is spent the DECELERATION PHASE is entered.
              04663 ;
              04664 ; (4)  DECELERATION PHASE
              04665 ;
              04666 ;      The title line flashes "HYPERWARP COMPLETE", the star field reappears and
              04667 ;      our starship decelerates to a stop. The Engines and the hyperwarp are
              04668 ;      disengaged and stopped in subroutine ENDWARP ($A987), the arrival
              04669 ;      coordinates on the Galactic Chart are initialized, as well as the
              04670 ;      vicinity mask.
              04671 ;
              04672 ;      The vicinity mask limits the position vector components (coordinates) of
              04673 ;      space objects in the arrival sector relative to our starship. The
              04674 ;      vicinity mask is picked from table VICINITYMASKTAB ($BFB3) by an index
              04675 ;      calculated by the arrival y-coordinate modulo 8: The more you have placed
              04676 ;      the arrival hyperwarp marker in the vertical center of a sector on the
              04677 ;      Galactic Chart, the closer space objects in this sector will be to our
              04678 ;      starship. For example, if you placed the arrival hyperwarp marker exactly
              04679 ;      in the vertical middle of the sector the index will be 3, thus the space
              04680 ;      objects inside the arrival sector will be in the vicinity of <= 4095 <KM>
              04681 ;      of our starship. The following table lists the possible coordinates
              04682 ;      depending on the calculated index:
              04683 ;
              04684 ;      +-------+-----------------------+
              04685 ;      | Index |    ABS(Coordinate)    |
              04686 ;      +-------+-----------------------+
              04687 ;      |   0   | <= 65535 ($FF**) <KM> |
              04688 ;      |   1   | <= 65535 ($FF**) <KM> |
              04689 ;      |   2   | <= 16383 ($3F**) <KM> |
              04690 ;      |   3   | <=  4095 ($0F**) <KM> |
              04691 ;      |   4   | <= 16383 ($3F**) <KM> |
              04692 ;      |   5   | <= 32767 ($7F**) <KM> |
              04693 ;      |   6   | <= 65535 ($FF**) <KM> |
              04694 ;      |   7   | <= 65535 ($FF**) <KM> |
              04695 ;      +-------+-----------------------+
              04696 ;
              04697 ;      If there is a starbase in the arrival sector, its x and y coordinates are
              04698 ;      initialized to random values within the interval defined by the vicinity
              04699 ;      mask by using subroutine RNDINVXY ($B7BE). Its z-coordinate is forced to
              04700 ;      a value >= +$71** (+28928) <KM>. Its velocity vector components are set
              04701 ;      to 0 <KM/H>. 
              04702 ;
              04703 ;      If there are Zylon ships in the arrival sector then a red alert is
              04704 ;      initialized by setting the red alert lifetime to 255 game loop
              04705 ;      iterations, playing the beeper sound pattern RED ALERT in subroutine BEEP
              04706 ;      ($B3A6) and setting the title phrase to "RED ALERT".
              04707
A89B A4C0     04708 HYPERWARP       LDY WARPSTATE           ; Return if hyperwarp not engaged
A89D F061     04709                 BEQ SKIP066             ;
              04710
A89F A570     04711                 LDA VELOCITYLO          ; If velocity >= 254 <KM/H> skip to HYPERSPACE PHASE
A8A1 C9FE     04712                 CMP #254                ;
A8A3 B05C     04713                 BCS SKIP067             ;
              04714
A8A5 C980     04715                 CMP #128                ; If velocity < 128 <KM/H> skip to ACCELERATION PHASE
A8A7 9003     04716                 BCC SKIP063             ;
              04717
              04718 ;*** STAR TRAIL PHASE **********************************************************
A8A9 20B4A9   04719                 JSR INITTRAIL           ; Init star trail
              04720
              04721 ;*** ACCELERATION PHASE ********************************************************
A8AC A903     04722 SKIP063         LDA #3                  ; Track Hyperwarp Target Marker (PLAYER3)
A8AE 8D5C09   04723                 STA TRACKDIGIT          ;
              04724
A8B1 A990     04725                 LDA #SHAP.HYPERWARP     ; PLAYER3 is HYPERWARP TARGET MARKER (shape type 9)
A8B3 8D8F0C   04726                 STA PL3SHAPTYPE         ;
A8B6 85EC     04727                 STA PL3LIFE             ; PLAYER3 lifetime := 144 game loops
              04728
A8B8 A91F     04729                 LDA #$1F                ; PLAYER3 z-coordinate := $1F** (7936..8191) <KM>
A8BA 8D430A   04730                 STA PL3ZPOSHI           ;
              04731
A8BD 38       04732                 SEC                     ; New arrival hyperwarp marker row number is...
A8BE ADFC0B   04733                 LDA PL3ROWNEW           ; WARPARRVROW := WARPTEMPROW + PL3ROWNEW...
A8C1 E977     04734                 SBC #119                ; ... - 119 PM pixels (top edge of centered...
A8C3 18       04735                 CLC                     ; ...Hyperwarp Target Marker)
A8C4 65C5     04736                 ADC WARPTEMPROW         ;
A8C6 297F     04737                 AND #$7F                ; Limit WARPARRVROW to 0..127
A8C8 858E     04738                 STA WARPARRVROW         ;
              04739
A8CA 38       04740                 SEC                     ; New arrival hyperwarp marker column number is...
A8CB AD2D0C   04741                 LDA PL3COLUMN           ; WARPARRVCOLUMN := WARPTEMPCOLUMN + PL3COLUMN...
A8CE E97D     04742                 SBC #125                ; ... - 125 PM pixels (left edge of centered...
A8D0 18       04743                 CLC                     ; ...Hyperwarp Target Marker)
A8D1 65C4     04744                 ADC WARPTEMPCOLUMN      ;
A8D3 297F     04745                 AND #$7F                ; Limit WARPARRVCOLUMN to 0..127
A8D5 858F     04746                 STA WARPARRVCOLUMN      ;
              04747
A8D7 A562     04748                 LDA MISSIONLEVEL        ; Skip if NOVICE mission
A8D9 F011     04749                 BEQ SKIP065             ;
              04750
A8DB AD0AD2   04751                 LDA RANDOM              ; Prep random number
A8DE A4D0     04752                 LDY SHIPVIEW            ; Skip if in Front view
A8E0 F006     04753                 BEQ SKIP064             ;
              04754
A8E2 8D2D0C   04755                 STA PL3COLUMN           ; Randomize PM pixel row and column number...
A8E5 8DFC0B   04756                 STA PL3ROWNEW           ; ...of Hyperwarp Target Marker
              04757
A8E8 C910     04758 SKIP064         CMP #16                 ; Return in 94% (240:256) of game loops
A8EA B014     04759                 BCS SKIP066             ;
              04760
              04761 ;*** Veer off Hyperwarp Target Marker and return *******************************
A8EC AD0AD2   04762 SKIP065         LDA RANDOM              ; Prep random x-velocity of Hyperwarp Target Marker
A8EF 0910     04763                 ORA #$10                ; Velocity value >= 16 <KM/H>
A8F1 25C6     04764                 AND VEERMASK            ; Limit velocity value by mission level
A8F3 8D9A0B   04765                 STA PL3XVEL             ; PLAYER3 x-velocity := velocity value
              04766
A8F6 AD0AD2   04767                 LDA RANDOM              ; Prep random y-velocity of Hyperwarp Target Marker
A8F9 0910     04768                 ORA #$10                ; Velocity value >= 16 <KM/H>
A8FB 25C6     04769                 AND VEERMASK            ; Limit velocity value by mission level
A8FD 8DCB0B   04770                 STA PL3YVEL             ; PLAYER3 y-velocity := velocity value
A900 60       04771 SKIP066         RTS                     ; Return
              04772
              04773 ;*** HYPERSPACE PHASE **********************************************************
A901 98       04774 SKIP067         TYA                     ; Skip if already in HYPERSPACE PHASE
A902 3011     04775                 BMI SKIP068             ;
              04776
              04777 ;*** HYPERSPACE PHASE (First pass) *********************************************
A904 A9FF     04778                 LDA #$FF                ; Set hyperwarp state to HYPERSAPCE PHASE
A906 85C0     04779                 STA WARPSTATE           ;
              04780
A908 A200     04781                 LDX #$00                ; Play beeper sound pattern HYPERWARP TRANSIT
A90A 20A6B3   04782                 JSR BEEP                ;
              04783
A90D 20A7B1   04784                 JSR CALCWARP            ; Calc hyperwarp energy
              04785
A910 A01B     04786                 LDY #$1B                ; Prep title phrase "HYPERSPACE"
A912 4C8DA9   04787                 JMP CLEANUPWARP         ; Return via CLEANUPWARP
              04788
              04789 ;*** HYPERSPACE PHASE (Second and later passes) ********************************
A915 C691     04790 SKIP068         DEC WARPENERGY          ; Decrement energy in chunks of 10 energy units
A917 F005     04791                 BEQ SKIP069             ; Skip to DECELERATION PHASE if hyperwarp energy zero
              04792
A919 A202     04793                 LDX #2                  ; ENERGY := ENERGY - 10 and return
A91B 4C6FB8   04794                 JMP DECENERGY           ;
              04795
              04796 ;*** DECELERATION PHASE ********************************************************
A91E A019     04797 SKIP069         LDY #$19                ; Prep title phrase "HYPERWARP COMPLETE"
A920 2087A9   04798                 JSR ENDWARP             ; Stop our starship
              04799
A923 A58F     04800                 LDA WARPARRVCOLUMN      ; Make the arrival hyperwarp marker column number...
A925 858D     04801                 STA WARPDEPRCOLUMN      ; ...the departure hyperwarp marker column number
A927 A58E     04802                 LDA WARPARRVROW         ; Make the arrival hyperwarp marker row number...
A929 858C     04803                 STA WARPDEPRROW         ; ...the departure hyperwarp marker row number
              04804
A92B 4A       04805                 LSR A                   ; B3..1 of arrival hyperwarp marker row number...
A92C 2907     04806                 AND #$07                ; ...pick vicinity mask
A92E AA       04807                 TAX                     ;
A92F BDB3BF   04808                 LDA VICINITYMASKTAB,X   ;
A932 85C7     04809                 STA VICINITYMASK        ; Store vicinity mask (limits space obj coordinates)
              04810
A934 A492     04811                 LDY ARRVSECTOR          ; Make the arrival sector the current sector
A936 8490     04812                 STY CURRSECTOR          ;
              04813
              04814 ;*** Init starbase in arrival sector *******************************************
A938 A900     04815                 LDA #0                  ; Clear starbase-in-sector flag
A93A 857B     04816                 STA ISSTARBASESECT      ;
              04817
A93C BEC908   04818                 LDX GCMEMMAP,Y          ; Skip if no starbase in arrival sector
A93F 102E     04819                 BPL SKIP070             ;
              04820
A941 A9FF     04821                 LDA #$FF                ; Set starbase-in-sector flag
A943 857B     04822                 STA ISSTARBASESECT      ;
              04823
              04824 ;*** Set position vector and velocity vector of starbase ***********************
A945 A000     04825                 LDY #0                  ;
A947 A900     04826 LOOP033         LDA #0                  ; Loop over all coordinates of starbase
A949 99680B   04827                 STA PL2ZVEL,Y           ; Starbase velocity vector component := 0 <KM/H>
A94C A901     04828                 LDA #1                  ;
A94E 99AF09   04829                 STA PL2ZPOSSIGN,Y       ; Starbase coordinate sign := + (positive)
A951 AD0AD2   04830                 LDA RANDOM              ; Prep random number...
A954 25C7     04831                 AND VICINITYMASK        ; ...limit number range by vicinity mask, then...
A956 99420A   04832                 STA PL2ZPOSHI,Y         ; ...store in starbase coordinate (high byte)
              04833
A959 98       04834                 TYA                     ;
A95A 18       04835                 CLC                     ;
A95B 6931     04836                 ADC #MAXSPCOBJNUM       ;
A95D A8       04837                 TAY                     ;
A95E C993     04838                 CMP #MAXSPCOBJNUM*3     ;
A960 90E5     04839                 BCC LOOP033             ; Next starbase coordinate
              04840
A962 AD420A   04841                 LDA PL2ZPOSHI           ; Force starbase z-coordinate >= +$71** <KM>
A965 0971     04842                 ORA #$71                ;
A967 8D420A   04843                 STA PL2ZPOSHI           ;
A96A A202     04844                 LDX #2                  ; Randomly invert starbase x and y coordinates...
A96C 4CBEB7   04845                 JMP RNDINVXY            ; ...and return
              04846
              04847 ;*** Flash red alert if Zylon sector entered ***********************************
A96F F00E     04848 SKIP070         BEQ SKIP071             ; Skip if no Zylon ships in sector
              04849
A971 A9FF     04850                 LDA #255                ; Red alert lifetime := 255 game loops
A973 858B     04851                 STA REDALERTLIFE        ;
              04852
A975 A206     04853                 LDX #$06                ; Play beeper sound pattern RED ALERT
A977 20A6B3   04854                 JSR BEEP                ;
              04855
A97A A075     04856                 LDY #$75                ; Set title phrase "RED ALERT"
A97C 2023B2   04857                 JSR SETTITLE            ;
              04858
A97F 60       04859 SKIP071         RTS                     ; Return
              04860
              04861 ;*******************************************************************************
              04862 ;*                                                                             *
              04863 ;*                                  ABORTWARP                                  *
              04864 ;*                                                                             *
              04865 ;*                               Abort hyperwarp                               *
              04866 ;*                                                                             *
              04867 ;*******************************************************************************
              04868
              04869 ; DESCRIPTION
              04870 ;
              04871 ; Aborts hyperwarp.
              04872 ;
              04873 ; This subroutine is entered from subroutine KEYBOARD ($AFFE). It subtracts 100
              04874 ; energy units for aborting the hyperwarp and preloads the title phrase with
              04875 ; "HYPERWARP ABORTED". Code execution continues into subroutine ENDWARP
              04876 ; ($A987). 
              04877
A980 A201     04878 ABORTWARP       LDX #1                  ; ENERGY := ENERGY - 100 after hyperwarp abort
A982 206FB8   04879                 JSR DECENERGY           ;
              04880
A985 A017     04881                 LDY #$17                ; Prep title phrase "HYPERWARP ABORTED"
              04882
              04883 ;*******************************************************************************
              04884 ;*                                                                             *
              04885 ;*                                   ENDWARP                                   *
              04886 ;*                                                                             *
              04887 ;*                                End hyperwarp                                *
              04888 ;*                                                                             *
              04889 ;*******************************************************************************
              04890
              04891 ; DESCRIPTION
              04892 ;
              04893 ; Ends hyperwarp.
              04894 ;
              04895 ; This subroutine stops our starship's Engines and resets the hyperwarp state.
              04896 ; Code execution continues into subroutine CLEANUPWARP ($A98D).
              04897
A987 A900     04898 ENDWARP         LDA #0                  ; Stop Engines
A989 8571     04899                 STA NEWVELOCITY         ;
A98B 85C0     04900                 STA WARPSTATE           ; Disengage hyperwarp
              04901
              04902 ;*******************************************************************************
              04903 ;*                                                                             *
              04904 ;*                                 CLEANUPWARP                                 *
              04905 ;*                                                                             *
              04906 ;*                        Clean up hyperwarp variables                         *
              04907 ;*                                                                             *
              04908 ;*******************************************************************************
              04909
              04910 ; DESCRIPTION
              04911 ;
              04912 ; Cleans up after a hyperwarp.
              04913 ;
              04914 ; This subroutine restores many hyperwarp related variables to their
              04915 ; post-hyperwarp values: The number of used space objects is set to the regular
              04916 ; value of 16 (5 PLAYER space objects + 12 PLAYFIELD space objects (stars)), our
              04917 ; starship's velocity (high byte) is cleared as well as the explosion lifetime,
              04918 ; the hit badness, the PLAYER3 shape type (Hyperwarp Target Marker), the Engines
              04919 ; energy drain rate, and the lifetimes of the PLAYERs. The docking state is
              04920 ; reset as well as the tracking digit. The title phrase is updated with either
              04921 ; "HYPERSPACE" or "HYPERWARP ABORTED".
              04922 ;
              04923 ; INPUT
              04924 ;
              04925 ;   Y = Title phrase offset. Used values are: 
              04926 ;     $17 -> "HYPERWARP ABORTED"
              04927 ;     $1B -> "HYPERSPACE"
              04928
A98D A910     04929 CLEANUPWARP     LDA #MAXSPCOBJIND.NL    ; Set normal number of space objects
A98F 8579     04930                 STA MAXSPCOBJIND        ; (5 PLAYER spc objs + 12 PLAYFIELD spc objs (stars))
              04931
A991 A900     04932                 LDA #0                  ;
A993 85C1     04933                 STA VELOCITYHI          ; Turn off hyperwarp velocity
A995 8573     04934                 STA EXPLLIFE            ; Explosion lifetime := 0 game loops
A997 858A     04935                 STA HITBADNESS          ; HITBADNESS := NO HIT
A999 8D8F0C   04936                 STA PL3SHAPTYPE         ; Clear PLAYER3 shape type
A99C 8580     04937                 STA DRAINRATE           ; Clear Engines energy drain rate
A99E C017     04938                 CPY #$17                ; Skip if hyperwarp was aborted
A9A0 F004     04939                 BEQ SKIP072             ;
              04940
A9A2 85E9     04941                 STA PL0LIFE             ; Zylon ship 0 lifetime := 0 game loops
A9A4 85EA     04942                 STA PL1LIFE             ; Zylon ship 1 lifetime := 0 game loops
              04943
A9A6 85EB     04944 SKIP072         STA PL2LIFE             ; Zylon photon torpedo lifetime := 0 game loops
A9A8 85EC     04945                 STA PL3LIFE             ; Hyperwarp Target Marker lifetime := 0 game loops
A9AA 85ED     04946                 STA PL4LIFE             ; Photon torpedo 1 lifetime := 0  game loops
A9AC 8575     04947                 STA DOCKSTATE           ; DOCKSTATE := NO DOCKING
A9AE 8D5C09   04948                 STA TRACKDIGIT          ; Clear index of tracked space object
A9B1 4C23B2   04949                 JMP SETTITLE            ; Set title phrase and return
              04950
              04951 ;*******************************************************************************
              04952 ;*                                                                             *
              04953 ;*                                  INITTRAIL                                  *
              04954 ;*                                                                             *
              04955 ;*         Initialize star trail during STAR TRAIL PHASE of hyperwarp          *
              04956 ;*                                                                             *
              04957 ;*******************************************************************************
              04958
              04959 ; DESCRIPTION
              04960 ;
              04961 ; BACKGROUND
              04962 ;
              04963 ; Star trails are displayed during the STAR TRAIL PHASE, that is, after the
              04964 ; ACCELERATION PHASE and before the HYPERSPACE PHASE of the hyperwarp. 
              04965 ;
              04966 ; A star trail is formed by 6 stars represented by 6 PLAYFIELD space objects
              04967 ; with continuous position vector indices in 17..48 (indices are wrapped around
              04968 ; when greater than 48). Between the creation of two star trails there is delay
              04969 ; of 4 game loop iterations.
              04970 ;
              04971 ; DETAILS
              04972 ;
              04973 ; This subroutine first decrements this star trail creation delay, returning if
              04974 ; the delay is still counting down. If the delay falls below 0 then it continues
              04975 ; accelerating our starship's velocity toward hyperwarp speed and then creates a
              04976 ; new star trail:
              04977 ;
              04978 ; First, it raises the maximum index of used space objects to 48 (increasing the
              04979 ; number of displayed space objects to 49), resets the star trail creation delay
              04980 ; to 4 game loop iterations, then forms a new star trail of 6 stars represented
              04981 ; by 6 PLAYFIELD space objects. The x and y coordinates for all 6 stars are the
              04982 ; same, picked randomly from tables WARPSTARXTAB ($BB3A) and WARPSTARYTAB
              04983 ; ($BB3E), respectively, with their signes changed randomly. Their z-coordinates
              04984 ; are computed in increasing depth from at least +4608 (+$12**) <KM> in
              04985 ; intervals of +80 (+$0050) <KM>. Their velocity vector components are set to 0
              04986 ; <KM/H>.
              04987
    =0068     04988 L.RANGE         = $68                   ; z-coordinate of star in star trail (16-bit value)
    =006E     04989 L.TRAILCNT      = $6E                   ; Star's index in star trail. Used values are: 0..5.
              04990
A9B4 C6C2     04991 INITTRAIL       DEC TRAILDELAY          ; Decrement star trail delay
A9B6 1068     04992                 BPL SKIP074             ; Return if delay still counting
              04993
A9B8 A901     04994                 LDA #1                  ; Turn on hyperwarp velocity
A9BA 85C1     04995                 STA VELOCITYHI          ;
              04996
A9BC A930     04997                 LDA #MAXSPCOBJNUM-1     ; Max index of space objects (for star trail stars)
A9BE 8579     04998                 STA MAXSPCOBJIND        ;
              04999
A9C0 A903     05000                 LDA #3                  ; Star trail delay := 3(+1) game loops
A9C2 85C2     05001                 STA TRAILDELAY          ;
              05002
A9C4 A6C3     05003                 LDX TRAILIND            ; Next avail. space obj index for star of star trail
              05004
A9C6 A912     05005                 LDA #$12                ; Star z-coordinate := >= +$12** (+4608) <KM>
A9C8 8569     05006                 STA L.RANGE+1           ;
              05007
A9CA AD0AD2   05008                 LDA RANDOM              ; Calc random index to pick initial star coordinates
A9CD 2903     05009                 AND #$03                ;
A9CF A8       05010                 TAY                     ;
A9D0 B93ABB   05011                 LDA WARPSTARXTAB,Y      ; Pick x-coordinate (high byte) of star from table
A9D3 9D710A   05012                 STA XPOSHI,X            ;
A9D6 B93EBB   05013                 LDA WARPSTARYTAB,Y      ;
A9D9 9DA20A   05014                 STA YPOSHI,X            ; Pick y-coordinate (high byte) of star from table
A9DC 20BEB7   05015                 JSR RNDINVXY            ; Randomize signs of x and y coordinates of star
              05016
A9DF 8A       05017                 TXA                     ; Save space object index
A9E0 A8       05018                 TAY                     ;
A9E1 A905     05019                 LDA #5                  ; Loop over 5(+1) stars that form the star trail
A9E3 856E     05020                 STA L.TRAILCNT          ; Store star counter of star trail
              05021
A9E5 18       05022 LOOP034         CLC                     ; Place stars in z-coordinate intervals of +80 <KM>
A9E6 A568     05023                 LDA L.RANGE             ;
A9E8 6950     05024                 ADC #80                 ;
A9EA 8568     05025                 STA L.RANGE             ;
A9EC 9DD30A   05026                 STA ZPOSLO,X            ;
A9EF A569     05027                 LDA L.RANGE+1           ;
A9F1 6900     05028                 ADC #0                  ;
A9F3 8569     05029                 STA L.RANGE+1           ;
A9F5 9D400A   05030                 STA ZPOSHI,X            ;
              05031
A9F8 A900     05032                 LDA #0                  ; Star's velocity vector components := 0 <KM/H>
A9FA 9D660B   05033                 STA ZVEL,X              ;
A9FD 9D970B   05034                 STA XVEL,X              ;
AA00 9DC80B   05035                 STA YVEL,X              ;
AA03 A901     05036                 LDA #1                  ; Star's z-coordinate sign := + (= ahead of starship)
AA05 9DAD09   05037                 STA ZPOSSIGN,X          ;
              05038
AA08 A963     05039                 LDA #99                 ; Init pixel row and column numbers to magic...
AA0A 9DF90B   05040                 STA PIXELROWNEW,X       ; ...offscreen value (triggers automatic recalc in...
AA0D 9D2A0C   05041                 STA PIXELCOLUMN,X       ; ...GAMELOOP's calls to SCREENCOLUMN and SCREENROW)
              05042
AA10 20C1AC   05043                 JSR COPYPOSXY           ; Copy x and y coordinate from previous star in trail
              05044
AA13 CA       05045                 DEX                     ; Decrement space object index to next star
AA14 E011     05046                 CPX #MAXSPCOBJIND.NL+1  ; If index reaches minimum value...
AA16 B002     05047                 BCS SKIP073             ;
AA18 A230     05048                 LDX #MAXSPCOBJNUM-1     ; ...wrap-around to maximum space object index
AA1A C66E     05049 SKIP073         DEC L.TRAILCNT          ;
AA1C 10C7     05050                 BPL LOOP034             ; Next star of star trail
              05051
AA1E 86C3     05052                 STX TRAILIND            ; Save space object index of star trail's last star
AA20 60       05053 SKIP074         RTS                     ; Return
              05054
              05055 ;*******************************************************************************
              05056 ;*                                                                             *
              05057 ;*                                 PROJECTION                                  *
              05058 ;*                                                                             *
              05059 ;*         Calculate pixel column (or row) number from position vector         *
              05060 ;*                                                                             *
              05061 ;*******************************************************************************
              05062
              05063 ; Calculates the pixel column (or row) number of a position vector x (or y)
              05064 ; component relative to the PLAYFIELD center by computing the perspective
              05065 ; projection quotient
              05066 ;
              05067 ;     QUOTIENT := DIVIDEND / DIVISOR * 128
              05068 ;
              05069 ; with
              05070 ;
              05071 ;     DIVIDEND := ABS(x-coordinate (or y-coordinate)) / 2
              05072 ;     DIVISOR  := ABS(z-coordinate) / 2  
              05073 ;
              05074 ; If the QUOTIENT is in 0..255, it is used as an index to pick the pixel column
              05075 ; (or row) number from table MAPTO80 ($0DE9), returning values in 0..80.
              05076 ;
              05077 ; If the QUOTIENT is larger than 255 ("dividend overflow") or if the
              05078 ; z-coordinate = 0 ("division by zero") then the error value 255 is returned.
              05079 ;
              05080 ; INPUT
              05081 ;
              05082 ;   X                   = Position vector index. Used values are: 0..48.
              05083 ;   DIVIDEND ($6A..$6B) = Dividend (positive 16-bit value), contains the
              05084 ;                         absolute value of the x (or y) coordinate.
              05085 ;
              05086 ; OUTPUT
              05087 ;
              05088 ;   A = Pixel column (or row) number relative to PLAYFIELD center. Used values
              05089 ;       are: 
              05090 ;     0..80 -> Pixel number
              05091 ;     255   -> Error value indicating "dividend overflow" or "division by zero"
              05092
    =0068     05093 L.DIVISOR       = $68                   ; Divisor (16-bit value)
    =006D     05094 L.QUOTIENT      = $6D                   ; Division result (unsigned 8-bit value)
    =006E     05095 L.LOOPCNT       = $6E                   ; Division loop counter. Used values are: 7..0.
              05096
AA21 A900     05097 PROJECTION      LDA #0                  ; Init quotient result
AA23 856D     05098                 STA L.QUOTIENT          ;
              05099
AA25 A907     05100                 LDA #7                  ; Init division loop counter
AA27 856E     05101                 STA L.LOOPCNT           ;
              05102
AA29 466B     05103                 LSR DIVIDEND+1          ; DIVIDEND := x-coordinate (or y-coordinate) / 2
AA2B 666A     05104                 ROR DIVIDEND            ; (division by 2 to make B15 = 0?) (?)
              05105
AA2D A5D0     05106                 LDA SHIPVIEW            ; Skip if in Aft view
AA2F D00F     05107                 BNE SKIP075             ;
              05108
AA31 BD400A   05109                 LDA ZPOSHI,X            ; If in Front view -> DIVISOR := z-coordinate / 2
AA34 4A       05110                 LSR A                   ; (division by 2 to make B15 = 0?) (?)
AA35 8569     05111                 STA L.DIVISOR+1         ;
AA37 BDD30A   05112                 LDA ZPOSLO,X            ;
AA3A 6A       05113                 ROR A                   ;
AA3B 8568     05114                 STA L.DIVISOR           ;
AA3D 4C52AA   05115                 JMP LOOP035             ;
              05116
AA40 38       05117 SKIP075         SEC                     ; If in Aft view -> DIVISOR := - z-coordinate / 2
AA41 A900     05118                 LDA #0                  ; (division by 2 to make B15 = 0?) (?)
AA43 FDD30A   05119                 SBC ZPOSLO,X            ;
AA46 8568     05120                 STA L.DIVISOR           ;
AA48 A900     05121                 LDA #0                  ;
AA4A FD400A   05122                 SBC ZPOSHI,X            ;
AA4D 4A       05123                 LSR A                   ;
AA4E 8569     05124                 STA L.DIVISOR+1         ;
AA50 6668     05125                 ROR L.DIVISOR           ;
              05126
AA52 066D     05127 LOOP035         ASL L.QUOTIENT          ; QUOTIENT := DIVIDEND / DIVISOR * 128
AA54 38       05128                 SEC                     ;
AA55 A56A     05129                 LDA DIVIDEND            ;
AA57 E568     05130                 SBC L.DIVISOR           ;
AA59 A8       05131                 TAY                     ;
AA5A A56B     05132                 LDA DIVIDEND+1          ;
AA5C E569     05133                 SBC L.DIVISOR+1         ;
AA5E 9006     05134                 BCC SKIP076             ;
              05135
AA60 856B     05136                 STA DIVIDEND+1          ;
AA62 846A     05137                 STY DIVIDEND            ;
AA64 E66D     05138                 INC L.QUOTIENT          ;
              05139
AA66 066A     05140 SKIP076         ASL DIVIDEND            ;
AA68 266B     05141                 ROL DIVIDEND+1          ;
AA6A 9003     05142                 BCC SKIP077             ;
              05143
AA6C A9FF     05144                 LDA #255                ; Return 255 if division by zero or dividend overflow
AA6E 60       05145                 RTS                     ;
              05146
AA6F C66E     05147 SKIP077         DEC L.LOOPCNT           ;
AA71 10DF     05148                 BPL LOOP035             ; Next division loop iteration
              05149
AA73 A46D     05150                 LDY L.QUOTIENT          ; Prep with quotient
AA75 B9E90D   05151                 LDA MAPTO80,Y           ; Pick and return pixel column (or row) number...
AA78 60       05152 SKIP078         RTS                     ; ...relative to PLAYFIELD center
              05153
              05154 ;*******************************************************************************
              05155 ;*                                                                             *
              05156 ;*                                  MANEUVER                                   *
              05157 ;*                                                                             *
              05158 ;*     Maneuver our starship's and Zylon photon torpedoes and Zylon ships      *
              05159 ;*                                                                             *
              05160 ;*******************************************************************************
              05161
              05162 ; DESCRIPTION
              05163 ;
              05164 ; This subroutine maneuvers both of our starship's photon torpedoes, the single
              05165 ; Zylon photon torpedo, and the one or two Zylon ships that are simultaneously
              05166 ; displayed on the screen. It also creates meteors and new Zylon ships. This
              05167 ; subroutine is executed only if our starship is not in a starbase sector and
              05168 ; hyperwarp is not engaged.
              05169 ;
              05170 ; BACKGROUND
              05171 ;
              05172 ; When a Zylon ship is initialized, a "flight pattern" is assigned to it. There
              05173 ; are 3 flight patterns (0, 1, and 4) which are picked from table ZYLONFLPATTAB
              05174 ; ($BF91).
              05175 ;
              05176 ; The flight pattern determines the maximum velocity with which a Zylon ship can
              05177 ; move along each axis of the 3D coordinate system, that is the maximum value of
              05178 ; a velocity vector component. Velocity vector components for Zylon ships are
              05179 ; picked from the Zylon velocity table ZYLONVELTAB ($BF99):
              05180 ;
              05181 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05182 ; | Velocity Index  |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
              05183 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05184 ; | Velocity <KM/H> | +62 | +30 | +16 |  +8 |  +4 |  +2 |  +1 |  0  |
              05185 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05186 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05187 ; | Velocity Index  |  8  |  9  |  10 |  11 |  12 |  13 |  14 |  15 |
              05188 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05189 ; | Velocity <KM/H> |  0  |  -1 |  -2 |  -4 |  -8 | -16 | -30 | -62 |
              05190 ; +-----------------+-----+-----+-----+-----+-----+-----+-----+-----+
              05191 ;
              05192 ; The index into the Zylon velocity table ZYLONVELTAB ($BF99) corresponding to
              05193 ; the maximum velocity is called the "maximum velocity index". The following
              05194 ; table shows the flight patterns, their maximum velocity indices, and their
              05195 ; corresponding velocities:
              05196 ;
              05197 ; +----------------+------------------+------------------+
              05198 ; | Flight Pattern | Maximum Velocity | Maximum Velocity |
              05199 ; |                |      Index       |                  |
              05200 ; +----------------+------------------+------------------+
              05201 ; |       0        |         0        |    +62 <KM/H>    |
              05202 ; |       0        |        15        |    -62 <KM/H>    |
              05203 ; |       1        |         1        |    +30 <KM/H>    |
              05204 ; |       1        |        14        |    -30 <KM/H>    |
              05205 ; |       4        |         4        |     +4 <KM/H>    |
              05206 ; |       4        |        11        |     -4 <KM/H>    |
              05207 ; +----------------+------------------+------------------+
              05208 ;
              05209 ; Because flight pattern 0 produces the fastest-moving Zylon ships, which
              05210 ; maneuver aggressively, it is called the "attack flight pattern".
              05211 ;
              05212 ; Each Zylon ship has a set of 3 maximum velocity indices, one for each of its
              05213 ; velocity vector components.
              05214 ;
              05215 ; Each Zylon ship has also one more set of 3 velocity indices, called "Zylon
              05216 ; velocity indices", one for each of its velocity vector components. They are
              05217 ; used to pick the current values of the velocity vector components from the
              05218 ; Zylon velocity table ZYLONVELTAB ($BF99).
              05219 ;
              05220 ; In order to maneuver Zylon ships this subroutine uses the concept of
              05221 ; "milestone velocity indices". By using delay timers, called "Zylon timers",
              05222 ; this subroutine gradually increases or decreases the Zylon velocity indices
              05223 ; with every game loop iteration to eventually match the corresponding milestone
              05224 ; velocity indices. By incrementing a Zylon velocity index a Zylon ship
              05225 ; accelerates toward the negative direction of a coordinate axis. By
              05226 ; decrementing a Zylon velocity index a Zylon ship accelerates toward the
              05227 ; positive direction of a coordinate axis. If one milestone velocity index is
              05228 ; matched or a "milestone timer" has counted down to 0, a new milestone velocity
              05229 ; index is calculated and the matching of the current Zylon velocity indices
              05230 ; with the new milestone velocity indices repeats.
              05231 ;
              05232 ; DETAILS
              05233 ;
              05234 ; For quick lookup, the following table lists the PLAYERs and what space objects
              05235 ; they represent in this subroutine:
              05236 ;
              05237 ; +--------+---------------------------------+
              05238 ; | PLAYER |           Represents            |
              05239 ; +--------+---------------------------------+
              05240 ; |    0   | Zylon Ship 0                    |
              05241 ; |    1   | Zylon Ship 1                    |
              05242 ; |    2   | Zylon Photon Torpedo, Meteor    |
              05243 ; |    3   | Our starship's Photon Torpedo 0 |
              05244 ; |    4   | Our starship's Photon Torpedo 1 |
              05245 ; +--------+---------------------------------+
              05246 ;
              05247 ; This subroutine executes the following steps:
              05248 ;
              05249 ; (1)  Update the x and y velocity vector components of both of our starship's
              05250 ;      photon torpedoes 0 and 1.
              05251 ;
              05252 ;      The x and y velocity vector components of both of our starship's photon
              05253 ;      torpedoes 0 and 1 are only updated if they are tracking (homing in on) a
              05254 ;      target.
              05255 ;
              05256 ;      To update the y-velocity vector components of both of our starship's
              05257 ;      photon torpedoes 0 and 1 the PLAYER row number difference between the
              05258 ;      PLAYER of tracked target sapce object and the current location of the
              05259 ;      PLAYER of our starship's photon torpedo 0 is passed to subroutine
              05260 ;      HOMINGVEL ($AECA). It returns the new y-velocity vector component value
              05261 ;      for both of our starship's photon torpedoes in <KM/H>. If the target is
              05262 ;      located below our starship's photon torpedo 0 a value of 0 <KM/H> is
              05263 ;      used.
              05264 ;
              05265 ;      NOTE: The new y-velocity vector components depend only on the PLAYER row
              05266 ;      number of our starship's photon torpedo 0.
              05267 ;
              05268 ;      To update the x-velocity vector components of both of our starship's
              05269 ;      photon torpedoes, the above calculation is repeated for the PLAYER column
              05270 ;      numbers of each of our starship's photon torpedoes 0 and 1.
              05271 ;
              05272 ; (2)  Make the Zylon ships follow the rotation of our starship.
              05273 ;
              05274 ;      If you rotate our starship away from Zylon ships they adjust their course
              05275 ;      such that they reappear in our starship's view.
              05276 ;
              05277 ;      This is achieved by 4 Zylon timers, one for each of both Zylon ships'
              05278 ;      current x and y Zylon velocity indices. The Zylon timers are decremented
              05279 ;      every game loop iteration. If any of them reach a value of 0, the
              05280 ;      corresponding Zylon velocity index is incremented or decremented
              05281 ;      depending on the current joystick position.
              05282 ;
              05283 ;      For example, if the Zylon timer for the x-velocity of Zylon ship 0
              05284 ;      reaches 0 and at the same time the joystick is pushed left then the
              05285 ;      x-Zylon velocity index of this Zylon ship is incremented. This
              05286 ;      accelerates the Zylon ship toward negative x-direction ("left"): The
              05287 ;      Zylon ship follows our starship's rotation. This works in Aft view, too,
              05288 ;      where the direction of change of the Zylon velocity index is reversed.
              05289 ;      After setting the new Zylon velocity index, it is used to pick a new
              05290 ;      Zylon timer value for this Zylon velocity index: 
              05291 ;
              05292 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05293 ;      | Velocity Index                 |  0 |  1 |  2 |  3 |  4 |  5 |  6 |  7 |
              05294 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05295 ;      | Zylon Timer Value (Game Loops) |  0 |  2 |  4 |  6 |  8 | 10 | 12 | 14 |
              05296 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05297 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05298 ;      | Velocity Index                 |  8 |  9 | 10 | 11 | 12 | 13 | 14 | 15 |
              05299 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05300 ;      | Zylon Timer Value (Game Loops) | 14 | 12 | 10 |  8 |  6 |  4 |  2 |  0 |
              05301 ;      +--------------------------------+----+----+----+----+----+----+----+----+
              05302 ;
              05303 ; (3)  Update the x and y velocity vector components of the single Zylon photon
              05304 ;      torpedo.
              05305 ;
              05306 ;      If a Zylon photon torpedo is moving toward our starship then update its x
              05307 ;      and y velocity vector components. They are picked from table
              05308 ;      ZYLONHOMVELTAB ($BF85) and depend on the mission level. The signs of the
              05309 ;      velocity vector components are always set such that the Zylon photon
              05310 ;      torpedo is guided toward our starship. 
              05311 ;
              05312 ; (4)  Create a meteor?
              05313 ;
              05314 ;      If PLAYER2, the PLAYER to represent a meteor, is either initial or not
              05315 ;      alive, then attempt in 7 out of 8 game loop iterations to create a new
              05316 ;      meteor. 
              05317 ;
              05318 ;      With a probability of 2% (4:256) a new meteor is created: Its shape type
              05319 ;      is set to METEOR, its position vector components to random coordinates in
              05320 ;      subroutine INITPOSVEC ($B764), its lifetime to 60 game loop iterations,
              05321 ;      and its velocity vector components (velocities) to x-velocity: 0 <KM/H>,
              05322 ;      y-velocity: 0 <KM/H>, z-velocity: -8 <KM/H>. Then code execution returns.
              05323 ;
              05324 ; (5)  Toggle Zylon ship control.
              05325 ;
              05326 ;      Every other game loop iteration, the program takes control of and
              05327 ;      maneuvers the other Zylon ship.
              05328 ;
              05329 ; (6)  Create new Zylon ship?
              05330 ;
              05331 ;      If the program-controlled Zylon ship is not alive, check if both Zylon
              05332 ;      ships are not alive and this is an empty sector. If so, then attempt to
              05333 ;      create a meteor. Otherwise create a new Zylon ship with infinite
              05334 ;      lifetime. Randomly pick its shape type from table ZYLONSHAPTAB ($BF89)
              05335 ;      (BASESTAR, ZYLON CRUISER, or ZYLON FIGHTER) and its flight pattern from
              05336 ;      table ZYLONFLPATTAB ($BF91) (attack flight pattern 0 is always picked in
              05337 ;      a NOVICE mission). Then set the milestone timer to 1 game loop iteration
              05338 ;      and the position vector of the Zylon ship to a position of at least
              05339 ;      +28928 (+$71**) <KM> in front of our starship. The y-coordinate depends
              05340 ;      on the value of VICINITYMASK ($C7). The x-coordinate is the sum of the
              05341 ;      y-coordinate plus at least 4864..5119 ($13**) <KM>. Randomly choose the
              05342 ;      signs of the x and y coordinates.
              05343 ;
              05344 ; (7)  Set the current flight pattern to attack flight pattern?
              05345 ;
              05346 ;      The current flight pattern of the Zylon ship will change to attack flight
              05347 ;      pattern if it is close enough (z-coordinate < +8192 (+$20**) <KM>) and
              05348 ;      one of the following conditions is met:
              05349 ;
              05350 ;      o   The Zylon ship is located behind our starship.
              05351 ;
              05352 ;      o   The shape of the Zylon ship is not initial and does not currently
              05353 ;          appear as a blip in the Long-Range Scan view.
              05354 ;
              05355 ; (8)  Update the back-attack flag and the milestone velocity indices.
              05356 ;
              05357 ;      The milestone timer is decremented for the program-controlled Zylon ship.
              05358 ;      If this timer reaches a value of 0 the following steps are executed:
              05359 ;
              05360 ;      o   The milestone timer is reset to a value of 120 game loop iterations.
              05361 ;
              05362 ;      o   The back-attack flag is updated. It determines if the
              05363 ;          program-controlled Zylon ship not only attacks from the front of our
              05364 ;          starship but also from the back. A back-attack takes place with a
              05365 ;          probability of 19% (48:256) in WARRIOR or COMMANDER missions.
              05366 ;
              05367 ;      o   Course corrections are prepared for the program-controlled Zylon ship
              05368 ;          by computing the new milestone vector indices, resulting in new
              05369 ;          velocity vector components for this Zylon ship. The new milestone
              05370 ;          velocity indices for each velocity vector component are randomly
              05371 ;          chosen depending of the flight pattern. Recall that the Zylon
              05372 ;          velocity index is changed gradually to match the milestone velocity
              05373 ;          index. It corresponds to a maximum velocity vector component when
              05374 ;          using this index to pick a velocity vector component from Zylon
              05375 ;          velocity table ZYLONVELTAB ($BF99):
              05376 ;
              05377 ;          +----------------+----------------+------------------+
              05378 ;          | Flight Pattern | New Milestone  | Maximum Velocity |
              05379 ;          |                | Velocity Index | Vector Component |
              05380 ;          +----------------+----------------+------------------+
              05381 ;          |       0        |        0       |    +62 <KM/H>    |
              05382 ;          |       0        |       15       |    -62 <KM/H>    |
              05383 ;          |       1        |        1       |    +30 <KM/H>    |
              05384 ;          |       1        |       14       |    -30 <KM/H>    |
              05385 ;          |       4        |        4       |     +4 <KM/H>    |
              05386 ;          |       4        |       11       |     -4 <KM/H>    |
              05387 ;          +----------------+----------------+------------------+
              05388 ;
              05389 ; (9)  Update milestone velocity indices in attack flight pattern.
              05390 ;
              05391 ;      If a Zylon ship executes the attack flight pattern, its milestone
              05392 ;      velocity indices are changed depending on the current location of the
              05393 ;      Zylon ship as follows:
              05394 ;
              05395 ;      +--------------+-------------+----------------+------------+----------------+
              05396 ;      | x-Coordinate |  Where on   |   Milestone    |  Velocity  | Zylon Ship     |
              05397 ;      |              |   Screen    | Velocity Index |            | Accelerates... |
              05398 ;      +--------------+-------------+----------------+------------+----------------+
              05399 ;      | x <  0 <KM>  | left half   |       0        | +62 <KM/H> | to the right   |
              05400 ;      | x >= 0 <KM>  | right half  |      15        | -62 <KM/H> | to the left    |
              05401 ;      +--------------+-------------+----------------+------------+----------------+
              05402 ;      +--------------+-------------+----------------+------------+----------------+
              05403 ;      | y-Coordinate |  Where on   |   Milestone    |  Velocity  | Zylon Ship     |
              05404 ;      |              |   Screen    | Velocity Index |            | Accelerates... |
              05405 ;      +--------------+-------------+----------------+------------+----------------+
              05406 ;      | y <  0 <KM>  | bottom half |       0        | +62 <KM/H> | up             |
              05407 ;      | y >= 0 <KM>  | top half    |      15        | -62 <KM/H> | down           |
              05408 ;      +--------------+-------------+----------------+------------+----------------+
              05409 ;
              05410 ;      Thus, with respect to its x and y coordinates, the Zylon ship oscillates
              05411 ;      around the center of the Front or Aft view.
              05412 ;
              05413 ;      This is the behavior of the Zylon ship along the z-axis:
              05414 ;
              05415 ;      If the Zylon ship attacks from the front:
              05416 ;
              05417 ;      +--------------------------+----------------+------------+----------------+
              05418 ;      |       z-Coordinate       |   Milestone    |  Velocity  | Zylon Ship     |
              05419 ;      |                          | Velocity Index |            | Accelerates... |
              05420 ;      +--------------------------+----------------+------------+----------------+
              05421 ;      | z <  +2560 (+$0A00) <KM> |       0        | +62 <KM/H> | outbound       |
              05422 ;      | z >= +2560 (+$0A00) <KM> |      15        | -62 <KM/H> | inbound        |
              05423 ;      +--------------------------+----------------+------------+----------------+
              05424 ;
              05425 ;      In other words, the Zylon ship accelerates into positive z-direction
              05426 ;      (outbound) up to a distance of +2560 (+$0A00) <KM>, then reverses its
              05427 ;      course and returns back to our starship (inbound).
              05428 ;
              05429 ;      If the Zylon ship attacks from the back:
              05430 ;
              05431 ;      +--------------------------+----------------+------------+----------------+
              05432 ;      |       z-Coordinate       |   Milestone    |  Velocity  | Zylon Ship     |
              05433 ;      |                          | Velocity Index |            | Accelerates... |
              05434 ;      +--------------------------+----------------+------------+----------------+
              05435 ;      | z <  -2816 (-$F500) <KM> |       0        | +62 <KM/H> | inbound        |
              05436 ;      | z >= -2816 (-$F500) <KM> |      15        | -62 <KM/H> | outbound       |
              05437 ;      +--------------------------+----------------+------------+----------------+
              05438 ;
              05439 ;      In other words, the Zylon ship accelerates into negative z-direction
              05440 ;      (outbound) up to a distance of -2816 (-$(0B00)) <KM>, then reverses its
              05441 ;      course and returns back to our starship (inbound).
              05442 ;
              05443 ; (10) Change Zylon velocity index toward milestone velocity index.
              05444 ;
              05445 ;      Compare all 3 Zylon velocity indices of the program-controlled Zylon ship
              05446 ;      with their corresponding milestone velocity indices. Increment or
              05447 ;      decrement the former to better match the latter. Use the new Zylon
              05448 ;      velocity indices to pick the current velocity values from Zylon velocity
              05449 ;      table ZYLONVELTAB ($BF99). 
              05450 ;
              05451 ; (11) Launch a Zylon photon torpedo?
              05452 ;
              05453 ;      Prepare launching a Zylon photon torpedo if either of the following
              05454 ;      conditions are met:
              05455 ;
              05456 ;      o   PLAYER2 is not used as a photon torpedo
              05457 ;
              05458 ;      o   The y-coordinate of the Zylon ship is in the range of -768..+767
              05459 ;          (-$0300..+$2FF) <KM>. 
              05460 ;
              05461 ;      or if
              05462 ;
              05463 ;      o   The Zylon photon torpedo is not alive
              05464 ;
              05465 ;      o   The corresponding Zylon photon torpedo delay timer has reached a
              05466 ;          value of 0
              05467 ;
              05468 ;      o   The y-coordinate of the Zylon ship is in the range of -768..+767
              05469 ;          (-$0300..+$2FF) <KM>. 
              05470 ;
              05471 ;      At this point the z-velocity vector component of the Zylon photon torpedo
              05472 ;      is preloaded with a value of -80 or +80 <KM/H> depending on the Zylon
              05473 ;      ship being in front or behind of our starship, respectively. 
              05474 ;
              05475 ;      Launch a Zylon photon torpedo if both of the following conditions are
              05476 ;      met:
              05477 ;
              05478 ;      o   The Zylon ship is in front or behind of our starship, with the
              05479 ;          exception of a Zylon ship behind our starship in a NOVICE mission
              05480 ;          (our starship will never be shot in the back in a NOVICE mission).
              05481 ;
              05482 ;      o   The z-coordinate of the Zylon ship (no matter if in front or behind
              05483 ;          our starship) is closer than 8192 ($20**) <KM>.
              05484 ;
              05485 ;      Finally, the Zylon photon torpedo is launched with a lifetime of 62 game
              05486 ;      loop iterations. Its position vector is copied from the launching Zylon
              05487 ;      ship in subroutine COPYPOSVEC ($ACAF). In addition, the Zylon ship is
              05488 ;      earmarked for the tracking computer.
              05489
    =006A     05490 L.CTRLDZYLON    = $6A                   ; Index of currently program-controlled Zylon ship.
              05491                                         ; Used values are:
              05492                                         ;   0 -> Control Zylon ship 0
              05493                                         ;   1 -> Control Zylon ship 1
    =0080     05494 NEG             = $80                   ; Negative sign bit for velocity vector component
              05495
AA79 A5C0     05496 MANEUVER        LDA WARPSTATE           ; Return if in starbase sector or hyperwarp engaged
AA7B 057B     05497                 ORA ISSTARBASESECT      ;
AA7D D0F9     05498                 BNE SKIP078             ;
              05499
              05500 ;*** Update x and y velocity of both our starship's photon torpedoes 0 and 1 ***
AA7F A586     05501                 LDA ISTRACKING          ; Skip this if ship's torpedoes not tracking a target
AA81 F030     05502                 BEQ SKIP080             ;
              05503
AA83 A689     05504                 LDX PLTRACKED           ; Load PLAYER index of tracked target space object
              05505
AA85 38       05506                 SEC                     ; Prep A := PLAYER row number of target...
AA86 BDF90B   05507                 LDA PL0ROWNEW,X         ; ...- PLAYER row number photon torpedo 0
AA89 EDFC0B   05508                 SBC PL3ROWNEW           ;
AA8C 9002     05509                 BCC SKIP079             ; Skip if target above our starship's photon torpedo
AA8E A900     05510                 LDA #0                  ; Prep A := 0
AA90 20CAAE   05511 SKIP079         JSR HOMINGVEL           ; Get y-velocity for homing photon torpedo 0 and 1
AA93 8DCB0B   05512                 STA PL3YVEL             ; Store y-velocity photon torpedo 0
AA96 8DCC0B   05513                 STA PL4YVEL             ; Store y-velocity photon torpedo 1
              05514
AA99 38       05515                 SEC                     ; Prep A := PLAYER column number of target...
AA9A AD2D0C   05516                 LDA PL3COLUMN           ; ...- PLAYER column number of photon torpedo 0
AA9D FD2A0C   05517                 SBC PL0COLUMN,X         ;
AAA0 20CAAE   05518                 JSR HOMINGVEL           ; Get x-velocity for homing photon torpedo 0
AAA3 8D9A0B   05519                 STA PL3XVEL             ; Store x-velocity of photon torpedo 0
              05520
AAA6 38       05521                 SEC                     ; Prep A := PLAYER column number of target...
AAA7 AD2E0C   05522                 LDA PL4COLUMN           ; ...- PLAYER column number of photon torpedo 1
AAAA FD2A0C   05523                 SBC PL0COLUMN,X         ;
AAAD 20CAAE   05524                 JSR HOMINGVEL           ; Get x-velocity for homing photon torpedo 1
AAB0 8D9B0B   05525                 STA PL4XVEL             ; Store x-velocity of photon torpedo 1
              05526
              05527 ;*** Make Zylon ships follow rotation of our starship **************************
AAB3 A203     05528 SKIP080         LDX #3                  ; Loop over x and y velocity indices of both Zylons
AAB5 D6BA     05529 LOOP036         DEC ZYLONTIMX0,X        ; Decrement Zylon timer
AAB7 1027     05530                 BPL SKIP085             ; Next timer if this one still counting down
              05531
AAB9 8A       05532                 TXA                     ; Prep joystick (x or y) value in -1, 0, +1
AABA 4A       05533                 LSR A                   ;
AABB A8       05534                 TAY                     ;
AABC B9C800   05535                 LDA JOYSTICKX,Y         ;
              05536
AABF A4D0     05537                 LDY SHIPVIEW            ; Skip if in Front view
AAC1 F005     05538                 BEQ SKIP081             ;
              05539
AAC3 49FF     05540                 EOR #$FF                ; Invert joystick value (when in Aft view)
AAC5 18       05541                 CLC                     ; (two's-complement)
AAC6 6901     05542                 ADC #1                  ;
              05543
AAC8 18       05544 SKIP081         CLC                     ; Add joystick value to Zylon velocity index
AAC9 75B4     05545                 ADC ZYLONVELINDX0,X     ;
AACB 1002     05546                 BPL SKIP082             ;
AACD A900     05547                 LDA #0                  ;
AACF C910     05548 SKIP082         CMP #16                 ; Limit new Zylon velocity index to 0..15 ...
AAD1 9002     05549                 BCC SKIP083             ;
AAD3 A90F     05550                 LDA #15                 ;
AAD5 95B4     05551 SKIP083         STA ZYLONVELINDX0,X     ; ...and store new Zylon velocity index
              05552
AAD7 C908     05553                 CMP #8                  ; Calc new Zylon timer value in 0, 2, ..., 14
AAD9 9002     05554                 BCC SKIP084             ;
AADB 490F     05555                 EOR #$0F                ;
AADD 0A       05556 SKIP084         ASL A                   ;
AADE 95BA     05557                 STA ZYLONTIMX0,X        ; ...and store new Zylon timer value
              05558
AAE0 CA       05559 SKIP085         DEX                     ;
AAE1 10D2     05560                 BPL LOOP036             ; Next Zylon timer
              05561
              05562 ;*** Update x and y velocity of single Zylon photon torpedo ********************
AAE3 AD8E0C   05563                 LDA PL2SHAPTYPE         ; Skip if PLAYER2 not PHOTON TORPEDO (shape type 0)
AAE6 D01B     05564                 BNE SKIP088             ;
              05565
AAE8 A462     05566                 LDY MISSIONLEVEL        ; Depending on mission level...
AAEA B985BF   05567                 LDA ZYLONHOMVELTAB,Y    ; ...pick (initially negative) Zylon torpedo velocity
              05568
AAED AEA40A   05569                 LDX PL2YPOSHI           ; If photon torpedo in upper screen half (y >= 0)...
AAF0 1002     05570                 BPL SKIP086             ; ...don't toggle velocity sign -> torpedo goes down
AAF2 297F     05571                 AND #$7F                ; ...toggle velocity sign       -> torpedo goes up
AAF4 8DCA0B   05572 SKIP086         STA PL2YVEL             ; Store new y-velocity of Zylon photon torpedo
              05573
AAF7 0980     05574                 ORA #NEG                ; Restore negative sign bit of velocity
              05575
AAF9 AE730A   05576                 LDX PL2XPOSHI           ; If photon torpedo in right screen half (x >= 0)...
AAFC 1002     05577                 BPL SKIP087             ; ...don't toggle velocity sign -> torpedo goes left
AAFE 297F     05578                 AND #$7F                ; ...toggle velocity sign       -> torpedo goes right
AB00 8D990B   05579 SKIP087         STA PL2XVEL             ; Store new x-velocity of Zylon photon torpedo
              05580
              05581 ;*** Create new meteor? ********************************************************
AB03 A576     05582 SKIP088         LDA COUNT256            ; Attempt meteor creation in 7 out of 8 game loops
AB05 2903     05583                 AND #$03                ;
AB07 F02E     05584                 BEQ SKIP092             ;
              05585
AB09 A5E6     05586 SKIP089         LDA PL2SHAPOFF          ; If PLAYER2 shape is initial try to create a meteor
AB0B F004     05587                 BEQ SKIP090             ;
              05588
AB0D A5EB     05589                 LDA PL2LIFE             ; Return if PLAYER2 alive
AB0F D025     05590                 BNE SKIP091             ;
              05591
AB11 AD0AD2   05592 SKIP090         LDA RANDOM              ; Return in 98% (252:256) (do not create meteor)
AB14 C904     05593                 CMP #4                  ;
AB16 B01E     05594                 BCS SKIP091             ;
              05595
              05596 ;*** Create new meteor! ********************************************************
AB18 A960     05597                 LDA #SHAP.METEOR        ; PLAYER2 is METEOR (shape type 6)
AB1A 8D8E0C   05598                 STA PL2SHAPTYPE         ;
AB1D A202     05599                 LDX #2                  ; Randomize position vector of meteor
AB1F 2064B7   05600                 JSR INITPOSVEC          ;
AB22 A93C     05601                 LDA #60                 ; Meteor lifetime := 60 game loops
AB24 85EB     05602                 STA PL2LIFE             ;
AB26 A988     05603                 LDA #NEG!8              ; SUMMARY:
AB28 8D680B   05604                 STA PL2ZVEL             ; x-velocity :=  0 <KM/H>
AB2B A900     05605                 LDA #0                  ; y-velocity :=  0 <KM/H>
AB2D 8D2C0C   05606                 STA PL2COLUMN           ; z-velocity := -8 <KM/H>
AB30 8D990B   05607                 STA PL2XVEL             ;
AB33 8DCA0B   05608                 STA PL2YVEL             ; PLAYER2 column number := 0 (offscreen)
AB36 60       05609 SKIP091         RTS                     ; Return
              05610
              05611 ;*** Toggle Zylon ship control *************************************************
AB37 A5A7     05612 SKIP092         LDA CTRLDZYLON          ; Toggle control to the other Zylon ship
AB39 4901     05613                 EOR #$01                ;
AB3B 85A7     05614                 STA CTRLDZYLON          ;
              05615
              05616 ;*** Create a new Zylon ship? **************************************************
AB3D AA       05617                 TAX                     ; Save index of controlled Zylon ship
AB3E B5E9     05618                 LDA PL0LIFE,X           ; Skip creating Zylon ship if its PLAYER still alive
AB40 D042     05619                 BNE SKIP094             ;
              05620
AB42 A5E9     05621                 LDA PL0LIFE             ; If both Zylon ships are not alive...
AB44 05EA     05622                 ORA PL1LIFE             ;
AB46 2901     05623                 AND #$01                ;
AB48 A490     05624                 LDY CURRSECTOR          ; ...and this an empty sector...
AB4A D9C908   05625                 CMP GCMEMMAP,Y          ;
AB4D B0BA     05626                 BCS SKIP089             ; ...attempt to create meteor and return
              05627
              05628 ;*** Create a new Zylon ship! **************************************************
AB4F A9FF     05629                 LDA #255                ; Zylon ship lifetime := 255 game loops (infinite)
AB51 95E9     05630                 STA PL0LIFE,X           ;
              05631
AB53 AD0AD2   05632                 LDA RANDOM              ; Pick a Zylon ship shape type (1 out of 8)
AB56 2907     05633                 AND #$07                ;
AB58 A8       05634                 TAY                     ;
AB59 B989BF   05635                 LDA ZYLONSHAPTAB,Y      ;
AB5C 9D8C0C   05636                 STA PL0SHAPTYPE,X       ;
              05637
AB5F A562     05638                 LDA MISSIONLEVEL        ; Init Zylon's flight pattern (0 if NOVICE mission)
AB61 F003     05639                 BEQ SKIP093             ;
AB63 B991BF   05640                 LDA ZYLONFLPATTAB,Y     ;
AB66 95A8     05641 SKIP093         STA ZYLONFLPAT0,X       ;
              05642
AB68 A901     05643                 LDA #1                  ; Zylon ship's milestone timer := 1 game loop
AB6A 95AA     05644                 STA MILESTTIM0,X        ;
              05645
AB6C 9DAD09   05646                 STA ZPOSSIGN,X          ; Put Zylon ship in front of our starship
AB6F AD0AD2   05647                 LDA RANDOM              ;
AB72 25C7     05648                 AND VICINITYMASK        ; y-coordinate (high byte) := RND(0..VICINITYMASK)
AB74 9DA20A   05649                 STA YPOSHI,X            ;
AB77 6913     05650                 ADC #19                 ; x-coordinate (high byte) := y (high byte) + 19
AB79 9D710A   05651                 STA XPOSHI,X            ;
AB7C 0971     05652                 ORA #$71                ; z-coordinate (high byte) := >= +28928 (+$71**) <KM>
AB7E 9D400A   05653                 STA ZPOSHI,X            ;
AB81 20BEB7   05654                 JSR RNDINVXY            ; Randomly invert x and y coordinate of pos vector
              05655
              05656 ;*** Set current flight pattern to attack flight pattern? **********************
AB84 BD400A   05657 SKIP094         LDA ZPOSHI,X            ; Skip if Zylon too distant (z >= +$20** <KM>)
AB87 C920     05658                 CMP #$20                ;
AB89 B011     05659                 BCS SKIP096             ;
              05660
AB8B BDAD09   05661                 LDA ZPOSSIGN,X          ; Set attack flight pattern if Zylon is behind
AB8E F008     05662                 BEQ SKIP095             ;
              05663
AB90 B5E4     05664                 LDA PL0SHAPOFF,X        ; Skip if Zylon shape initial
AB92 F008     05665                 BEQ SKIP096             ;
              05666
AB94 C929     05667                 CMP #$29                ; Skip if Zylon shape is Long-Range Scan blip
AB96 F004     05668                 BEQ SKIP096             ;
              05669
AB98 A900     05670 SKIP095         LDA #0                  ; Set attack flight pattern
AB9A 95A8     05671                 STA ZYLONFLPAT0,X       ;
              05672
              05673 ;*** Update back-attack flag and milestone velocity indices ********************
AB9C D6AA     05674 SKIP096         DEC MILESTTIM0,X        ; Skip if milestone timer still counting down
AB9E 1024     05675                 BPL SKIP099             ;
              05676
ABA0 A978     05677                 LDA #120                ; Milestone timer := 120 game loops
ABA2 95AA     05678                 STA MILESTTIM0,X        ;
              05679
ABA4 A562     05680                 LDA MISSIONLEVEL        ; Back-attack flag := 1 in 19% (48:256) of...
ABA6 AC0AD2   05681                 LDY RANDOM              ; ...WARRIOR or COMMANDER missions
ABA9 C030     05682                 CPY #48                 ; ...              := 0 otherwise
ABAB 9001     05683                 BCC SKIP097             ;
ABAD 4A       05684                 LSR A                   ;
ABAE 4A       05685 SKIP097         LSR A                   ;
ABAF 95B8     05686                 STA ISBACKATTACK0,X     ;
              05687
              05688                                         ; Loop over all 3 milestone velocity indices
ABB1 B5A8     05689                 LDA ZYLONFLPAT0,X       ; Set new milestone velocity index:
ABB3 2C0AD2   05690 LOOP037         BIT RANDOM              ; If Zylon flight pattern is...
ABB6 1002     05691                 BPL SKIP098             ; ...0 -> milestone velocity index := either 0 or 15
ABB8 490F     05692                 EOR #$0F                ; ...1 -> milestone velocity index := either 1 or 14
ABBA 95AC     05693 SKIP098         STA MILESTVELINDZ0,X    ; ...4 -> milestone velocity index := either 4 or 11
ABBC E8       05694                 INX                     ;
ABBD E8       05695                 INX                     ;
ABBE E006     05696                 CPX #6                  ;
ABC0 90F1     05697                 BCC LOOP037             ; Next Zylon milestone velocity index
              05698
              05699 ;*** Update milestone velocity indices in attack flight pattern ****************
ABC2 A6A7     05700                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
              05701
ABC4 B5A8     05702 SKIP099         LDA ZYLONFLPAT0,X       ; Skip if not in attack flight pattern
ABC6 D032     05703                 BNE SKIP105             ;
              05704
ABC8 A4A7     05705                 LDY CTRLDZYLON          ; Reload index of controlled Zylon ship
              05706
              05707                                         ; Loop over all 3 milestone velocity indices
ABCA C031     05708 LOOP038         CPY #$31                ; Skip to handle x and y velocity index
ABCC B013     05709                 BCS SKIP101             ;
              05710                                         ; SUMMARY:
ABCE B9B800   05711                 LDA ISBACKATTACK0,Y     ; Handle z-velocity index:
ABD1 4A       05712                 LSR A                   ;
ABD2 B9400A   05713                 LDA ZPOSHI,Y            ; If Zylon attacks from front...
ABD5 B006     05714                 BCS SKIP100             ; z <  $0A00 <KM> -> mil vel index := 0  (+62 <KM/H>)
ABD7 C90A     05715                 CMP #$0A                ; z >= $0A00 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABD9 900E     05716                 BCC SKIP103             ;
ABDB B004     05717                 BCS SKIP101             ; If Zylon attacks from back...
ABDD C9F5     05718 SKIP100         CMP #$F5                ; z >= $F500 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABDF B004     05719                 BCS SKIP102             ; z <  $F500 <KM> -> mil vel index := 0  (+62 <KM/H>)
              05720
ABE1 B9AD09   05721 SKIP101         LDA ZPOSSIGN,Y          ; Handle x and y velocity index:
ABE4 4A       05722                 LSR A                   ;
ABE5 A90F     05723 SKIP102         LDA #15                 ; x >= 0 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABE7 B002     05724                 BCS SKIP104             ; x <  0 <KM> -> mil vel index := 0  (+62 <KM/H>)
ABE9 A900     05725 SKIP103         LDA #0                  ; y >= 0 <KM> -> mil vel index := 15 (-62 <KM/H>)
ABEB 95AC     05726 SKIP104         STA MILESTVELINDZ0,X    ; y <  0 <KM> -> mil vel index := 0  (+62 <KM/H>)
              05727
ABED 18       05728                 CLC                     ; Adjust position vector component index
ABEE 98       05729                 TYA                     ;
ABEF 6931     05730                 ADC #MAXSPCOBJNUM       ;
ABF1 A8       05731                 TAY                     ;
              05732
ABF2 E8       05733                 INX                     ;
ABF3 E8       05734                 INX                     ;
ABF4 E006     05735                 CPX #6                  ;
ABF6 90D2     05736                 BCC LOOP038             ; Next milestone velocity index
              05737
              05738 ;*** Change Zylon velocity index toward milestone velocity index ***************
ABF8 A6A7     05739                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
ABFA A4A7     05740 SKIP105         LDY CTRLDZYLON          ; Reload index of controlled Zylon ship
              05741
              05742                                         ; Loop over all 3 milestone velocity indices
ABFC B5B2     05743 LOOP039         LDA ZYLONVELINDZ0,X     ; Compare Zylon velocity index with milestone index
ABFE D5AC     05744                 CMP MILESTVELINDZ0,X    ;
AC00 F008     05745                 BEQ SKIP107             ; Skip if equal
AC02 B004     05746                 BCS SKIP106             ;
AC04 F6B2     05747                 INC ZYLONVELINDZ0,X     ; Increm. Zylon velocity index if < milestone index
AC06 9002     05748                 BCC SKIP107             ;
AC08 D6B2     05749 SKIP106         DEC ZYLONVELINDZ0,X     ; Decrem. Zylon velocity index if >= milestone index
              05750
AC0A 866A     05751 SKIP107         STX L.CTRLDZYLON        ; Save index of controlled Zylon ship
AC0C AA       05752                 TAX                     ;
AC0D BD99BF   05753                 LDA ZYLONVELTAB,X       ; Pick new velocity value by Zylon velocity index
AC10 A66A     05754                 LDX L.CTRLDZYLON        ; Reload index of controlled Zylon ship
AC12 99660B   05755                 STA ZVEL,Y              ; Store new velocity vector component of Zylon ship
              05756
AC15 98       05757                 TYA                     ; Next velocity vector component
AC16 18       05758                 CLC                     ;
AC17 6931     05759                 ADC #MAXSPCOBJNUM       ;
AC19 A8       05760                 TAY                     ;
              05761
AC1A E8       05762                 INX                     ;
AC1B E8       05763                 INX                     ;
AC1C E006     05764                 CPX #6                  ;
AC1E 90DC     05765                 BCC LOOP039             ; Next milestone velocity index
              05766
              05767 ;*** Launch Zylon photon torpedo? **********************************************
              05768
              05769 ;*** Check PLAYER2 shape and lifetime ******************************************
AC20 A6A7     05770                 LDX CTRLDZYLON          ; Reload index of controlled Zylon ship
              05771
AC22 AD8E0C   05772                 LDA PL2SHAPTYPE         ; Skip if PLAYER2 not PHOTON TORPEDO (shape type 0)
AC25 D00B     05773                 BNE SKIP109             ;
              05774
AC27 A5EB     05775                 LDA PL2LIFE             ; Return if Zylon photon torpedo still alive
AC29 D006     05776                 BNE SKIP108             ;
              05777
AC2B A5BE     05778                 LDA TORPEDODELAY        ; Count down Zylon photon torpedo delay timer...
AC2D F003     05779                 BEQ SKIP109             ; ...before launching next Zylon photon torpedo
AC2F C6BE     05780                 DEC TORPEDODELAY        ;
AC31 60       05781 SKIP108         RTS                     ; Return
              05782
              05783 ;*** Check y-coordinate of Zylon ship ******************************************
AC32 18       05784 SKIP109         CLC                     ; Return if Zylon ship's y-coordinate not...
AC33 BDA20A   05785                 LDA YPOSHI,X            ; ...in -768..+767 (-$(0300)..+$2FF) <KM>.
AC36 6902     05786                 ADC #2                  ;
AC38 C905     05787                 CMP #5                  ;
AC3A B0F5     05788                 BCS SKIP108             ;
              05789
              05790 ;*** Set Zylon photon torpedo's z-velocity *************************************
AC3C A0D0     05791                 LDY #NEG!80             ; Prep Zylon torpedo's z-velocity := -80 <KM/H>
              05792
AC3E BDAD09   05793                 LDA ZPOSSIGN,X          ; Prep Zylon ship's sign of z-coordinate
AC41 4A       05794                 LSR A                   ;
AC42 BD400A   05795                 LDA ZPOSHI,X            ; Prep Zylon ship's z-coordinate
AC45 B008     05796                 BCS SKIP110             ; Skip if Zylon ship in front...
AC47 49FF     05797                 EOR #$FF                ; ...else invert loaded Zylon ship's z-coordinate
              05798
AC49 A462     05799                 LDY MISSIONLEVEL        ; Return (no torpedo from back) if NOVICE mission
AC4B F0E4     05800                 BEQ SKIP108             ;
              05801
AC4D A050     05802                 LDY #80                 ; Preload Zylon torpedo's z-velocity := +80 <KM/H>
              05803
              05804 ;*** Is Zylon ship in range? ***************************************************
AC4F C920     05805 SKIP110         CMP #$20                ; Return if Zylon ship too far...
AC51 B0DE     05806                 BCS SKIP108             ; ... (ABS(z-coordinate) > 8192 ($20**) <KM>)
              05807
AC53 8C680B   05808                 STY PL2ZVEL             ; Store Zylon photon torpedo's z-velocity
              05809
              05810 ;*** Launch Zylon photon torpedo! **********************************************
              05811
AC56 A900     05812                 LDA #0                  ; PLAYER2 is PHOTON TORPEDO (shape type 0)
AC58 8D8E0C   05813                 STA PL2SHAPTYPE         ;
AC5B 8D2C0C   05814                 STA PL2COLUMN           ; Zylon torpedo PLAYER column number := 0 (offscreen)
AC5E A93E     05815                 LDA #62                 ;
AC60 85EB     05816                 STA PL2LIFE             ; Zylon torpedo lifetime := 62 game loops
              05817
AC62 A202     05818                 LDX #2                  ; Prep source index for position vector copy
AC64 A4A7     05819                 LDY CTRLDZYLON          ; Prep destination index for position vector copy
AC66 84BF     05820                 STY ZYLONATTACKER       ; Save Zylon ship index for tracking computer
AC68 4CAFAC   05821                 JMP COPYPOSVEC          ; Copy position vector from Zylon ship to its torpedo
              05822
              05823 ;*******************************************************************************
              05824 ;*                                                                             *
              05825 ;*                                  INITEXPL                                   *
              05826 ;*                                                                             *
              05827 ;*                            Initialize explosion                             *
              05828 ;*                                                                             *
              05829 ;*******************************************************************************
              05830
              05831 ; DESCRIPTION
              05832 ;
              05833 ; Initializes the explosion's lifetime, the explosion fragments' position and
              05834 ; velocity vectors as well as their pixel row and column numbers.
              05835 ;
              05836 ; An explosion has a lifetime of 128 game loop iterations. It consists of 32
              05837 ; explosion fragment space objects with indices 17..48. The position vector of
              05838 ; each explosion fragment is copied from the exploding PLAYER space object.
              05839 ;
              05840 ; The pixel column number of each explosion fragment is initialized to
              05841 ;
              05842 ;     PIXEL COLUMN NUMBER := PLAYER column number - 48 + RND(0..15)
              05843 ;
              05844 ; To convert PLAYER column numbers (in Player/Missile (PM) pixels) into pixel
              05845 ; column numbers, the PLAYER column number of the left PLAYFIELD border (= 48)
              05846 ; is subtracted and a random number is added.
              05847 ;
              05848 ; BUG (at $AC76): The added random number should not be in 0..15 but in 0..7
              05849 ; because the exploding PLAYER is 8 pixels wide. The PLAYER column number
              05850 ; represents the left edge of the PLAYER shape. When using a random number in
              05851 ; 0..15, half of the pixels are located off to the right of the PLAYER, outside
              05852 ; the PLAYER area. Suggested fix: Replace instruction AND #$0F with AND #$07. 
              05853 ;
              05854 ; The pixel row number of each explosion fragment is initialized to
              05855 ;
              05856 ;     PIXEL ROW NUMBER := (PLAYER row number - RND(0..15)) / 2 - 16
              05857 ;
              05858 ; BUG (at $AC88): To convert PLAYER row numbers (in PM pixels) into pixel row
              05859 ; numbers, the PLAYER row number to the top PLAYFIELD border (= 16) should be
              05860 ; subtracted first, then the division by 2 (instruction LRS A) should be applied
              05861 ; to reduce the double-line PM resolution to the single-line PLAYFIELD
              05862 ; resolution. Suggested fix: Swap instruction LRS A with SBC #16 which leads to
              05863 ; the following formula for the pixel row number:
              05864 ;
              05865 ;     PIXEL ROW NUMBER := (PLAYER row number - 16 + RND(0..15)) / 2
              05866 ;
              05867 ; Incidentally, adding a random number in 0..15 is correct. PLAYER row number
              05868 ; represents the top edge of the PLAYER shape, which is typically 16 PM pixels
              05869 ; tall when representing a close space object.
              05870 ;
              05871 ; The velocity vector of explosion fragments is set to random x, y, and z
              05872 ; velocity vector components in -7..+7 <KM/H>.
              05873 ;
              05874 ; INPUT
              05875 ;
              05876 ;   Y = PLAYER index from which the explosion originates. Used values are:
              05877 ;     0 -> Explosion of PLAYER0 (Zylon ship 0)
              05878 ;     1 -> Explosion of PLAYER1 (Zylon ship 1)
              05879 ;     2 -> Explosion of PLAYER2 (Zylon photon torpedo, starbase, or meteor)
              05880
AC6B A980     05881 INITEXPL        LDA #128                ; Explosion lifetime := 128 game loops
AC6D 8573     05882                 STA EXPLLIFE            ;
              05883
AC6F A230     05884                 LDX #MAXSPCOBJNUM-1     ; Max index of space objects (for explosion frags)
AC71 8679     05885                 STX MAXSPCOBJIND        ;
              05886
              05887                                         ; Loop over all explosion fragment position vectors
              05888                                         ; (index 48..17)
AC73 AD0AD2   05889 LOOP040         LDA RANDOM              ; PIXEL COLUMN NUM := PLAYER column - 48 + RND(0..15)
AC76 290F     05890                 AND #$0F                ; (!)
AC78 792A0C   05891                 ADC PL0COLUMN,Y         ;
AC7B E930     05892                 SBC #48                 ;
AC7D 9D2A0C   05893                 STA PIXELCOLUMN,X       ;
              05894
AC80 AD0AD2   05895                 LDA RANDOM              ; PIXEL ROW NUM := (PLAYER row + RND(0..15)) / 2 - 16
AC83 290F     05896                 AND #$0F                ;
AC85 79F90B   05897                 ADC PL0ROWNEW,Y         ;
AC88 4A       05898                 LSR A                   ; (!)
AC89 E910     05899                 SBC #16                 ;
AC8B 9DF90B   05900                 STA PIXELROWNEW,X       ;
              05901
AC8E 20AFAC   05902                 JSR COPYPOSVEC          ; Copy position vector of PLAYER to explosion frag
              05903
AC91 AD0AD2   05904                 LDA RANDOM              ; z-velocity := RND(-7..+7) <KM/H>
AC94 2987     05905                 AND #NEG!7              ;
AC96 9D660B   05906                 STA ZVEL,X              ;
AC99 AD0AD2   05907                 LDA RANDOM              ; x-velocity := RND(-7..+7) <KM/H>
AC9C 2987     05908                 AND #NEG!7              ;
AC9E 9D970B   05909                 STA XVEL,X              ;
ACA1 AD0AD2   05910                 LDA RANDOM              ; y-velocity := RND(-7..+7) <KM/H>
ACA4 2987     05911                 AND #NEG!7              ;
ACA6 9DC80B   05912                 STA YVEL,X              ;
              05913
ACA9 CA       05914                 DEX                     ; Next explosion fragment position vector
ACAA E010     05915                 CPX #16                 ;
ACAC D0C5     05916                 BNE LOOP040             ;
ACAE 60       05917                 RTS                     ; Return
              05918
              05919 ;*******************************************************************************
              05920 ;*                                                                             *
              05921 ;*                                 COPYPOSVEC                                  *
              05922 ;*                                                                             *
              05923 ;*                           Copy a position vector                            *
              05924 ;*                                                                             *
              05925 ;*******************************************************************************
              05926
              05927 ; DESCRIPTION
              05928 ;
              05929 ; Copies a position vector.
              05930 ;
              05931 ; Actually, this subroutine copies the z-coordinate only, then code execution
              05932 ; continues into subroutine COPYPOSXY ($ACC1) to copy the x and y coordinate.
              05933 ;
              05934 ; INPUT
              05935 ;
              05936 ;   X = Destination position vector index. Used values are: 0..48.
              05937 ;   Y = Source position vector index. Used values are: 0..48.
              05938
ACAF B9AD09   05939 COPYPOSVEC      LDA ZPOSSIGN,Y          ;
ACB2 9DAD09   05940                 STA ZPOSSIGN,X          ;
ACB5 B9400A   05941                 LDA ZPOSHI,Y            ;
ACB8 9D400A   05942                 STA ZPOSHI,X            ;
ACBB B9D30A   05943                 LDA ZPOSLO,Y            ;
ACBE 9DD30A   05944                 STA ZPOSLO,X            ;
              05945
              05946 ;*******************************************************************************
              05947 ;*                                                                             *
              05948 ;*                                  COPYPOSXY                                  *
              05949 ;*                                                                             *
              05950 ;*          Copy x and y components (coordinates) of position vector           *
              05951 ;*                                                                             *
              05952 ;*******************************************************************************
              05953
              05954 ; DESCRIPTION
              05955 ;
              05956 ; Copies the x and y components (coordinates) of a position vector.
              05957 ;
              05958 ; INPUT
              05959 ;
              05960 ;   X = Destination position vector index. Used values are: 0..48.
              05961 ;   Y = Source position vector index. Used values are: 0..48.
              05962
ACC1 B9DE09   05963 COPYPOSXY       LDA XPOSSIGN,Y          ;
ACC4 9DDE09   05964                 STA XPOSSIGN,X          ;
ACC7 B9710A   05965                 LDA XPOSHI,Y            ;
ACCA 9D710A   05966                 STA XPOSHI,X            ;
ACCD B90F0A   05967                 LDA YPOSSIGN,Y          ;
ACD0 9D0F0A   05968                 STA YPOSSIGN,X          ;
ACD3 B9A20A   05969                 LDA YPOSHI,Y            ;
ACD6 9DA20A   05970                 STA YPOSHI,X            ;
ACD9 B9040B   05971                 LDA XPOSLO,Y            ;
ACDC 9D040B   05972                 STA XPOSLO,X            ;
ACDF B9350B   05973                 LDA YPOSLO,Y            ;
ACE2 9D350B   05974                 STA YPOSLO,X            ;
ACE5 60       05975 SKIP111         RTS                     ; Return
              05976
              05977 ;*******************************************************************************
              05978 ;*                                                                             *
              05979 ;*                                   DOCKING                                   *
              05980 ;*                                                                             *
              05981 ;*      Handle docking at starbase, launch and return of transfer vessel       *
              05982 ;*                                                                             *
              05983 ;*******************************************************************************
              05984
              05985 ; DESCRIPTION
              05986 ;
              05987 ; Handles docking at a starbase, launching and returning the transfer vessel,
              05988 ; and repairing our starship's subsystems. 
              05989 ;
              05990 ; This subroutine changes, if in Front view, the PLAYER-PLAYFIELD priority such
              05991 ; that PLAYERs like the starbase appear behind the cross hairs, which are part
              05992 ; of the PLAYFIELD.
              05993 ;
              05994 ; BUG (at $ACEE): The starbase also appears behind the stars, which are also
              05995 ; part of the PLAYFIELD - a rarely noticed glitch. In Aft view, the arrangement
              05996 ; is reversed: PLAYERs are arranged in front of the PLAYFIELD. Then the starbase
              05997 ; (and the transfer vessel) appear in front of the cross hairs! Suggested fix:
              05998 ; None, technically not possible.
              05999 ;
              06000 ; The starbase is tracked and the PLAYER0..2 shape types are set to STARBASE
              06001 ; RIGHT, STARBASE LEFT, and STARBASE CENTER, respectively, combining them into a
              06002 ; 3-part starbase shape. 
              06003 ;
              06004 ; If this sector is still marked as a starbase sector but no more so on the
              06005 ; Galactic Chart (if in the meantime either Zylon units have surrounded this
              06006 ; sector and destroyed the starbase or you have destroyed the starbase with a
              06007 ; photon torpedo) then the noise sound pattern SHIP EXPLOSION is played in
              06008 ; subroutine NOISE ($AEA8) and code execution returns.
              06009 ;
              06010 ; Otherwise a minimum distance to the starbase of +32 (+$0020) <KM> is enforced
              06011 ; and the conditions for a successful docking are checked:
              06012 ;
              06013 ; DOCKING CONDITIONS
              06014 ;
              06015 ; A docking is successful if all of the following conditions are met:
              06016 ;
              06017 ; (1)  The PLAYER2 (STARBASE CENTER) column number is in 120..135. 
              06018 ;
              06019 ;      BUG (at $AD39): At first glance, the PLAYER column interval of 120..135
              06020 ;      corresponds to an almost symmetric interval of -8..+7 PM pixels relative
              06021 ;      to the horizontal center of the PLAYFIELD, at PLAYER column number 128
              06022 ;      (48 PM pixels offset to left PLAYFIELD border + 80 PM pixels to the
              06023 ;      PLAYFIELD center). This is correct only if the PLAYER column number were
              06024 ;      to designate the horizontal center of the PLAYER. However it designates
              06025 ;      its left edge! Thus the used pixel column number range 120..135 creates
              06026 ;      an asymmetric horizontal docking position: A docking is successful if the
              06027 ;      horizontal position of the starbase shape's center is roughly -5..+10 PM
              06028 ;      pixels relative to the horizontal center of the PLAYFIELD. Suggested fix:
              06029 ;      Replace SBC #120 with SBC #117. This leads to an interval of -8..+7
              06030 ;      pixels relative to the horizontal center of the PLAYFIELD and better
              06031 ;      symmetry in the horizontal docking position.
              06032 ;
              06033 ; (2)  The PLAYER2 (STARBASE CENTER) row number is in 104..119.
              06034 ;
              06035 ;      BUG (at $AD43): The PLAYER row interval of 104..119 corresponds to an
              06036 ;      asymmetric interval of -20..-5 PM pixels relative to the vertical center
              06037 ;      of the PLAYFIELD, at pixel row number 80 or PLAYER row number 124. It
              06038 ;      lets you dock at a starbase that "sits" on top of the horizontal cross
              06039 ;      hairs but not at one that "hangs" from them. Suggested fix: Replace SBC
              06040 ;      #104 with SBC #108. This leads to an interval of -8..+7 pixels relative
              06041 ;      to the vertical center of the PLAYFIELD (assuming a PLAYER2 shape of 16
              06042 ;      pixel height, which is typical during docking) and better symmetry in the
              06043 ;      vertical docking position. 
              06044 ;
              06045 ; (3)  The starbase is in correct distance in front of our starship: The
              06046 ;      starbase's z-coordinate must be < +512 (+$02**) <KM>.
              06047 ;
              06048 ; (4)  Our starship is horizontally level with the starbase: The starbase's
              06049 ;      y-coordinate must be < +256 (+$01**) <KM>.
              06050 ;
              06051 ; (5)  Our starship is at a complete halt.
              06052 ;
              06053 ; DOCKING SUCCESSFUL
              06054 ;
              06055 ; If the conditions for a successful docking are met, the subsequent docking and
              06056 ; transfer operation can be divided in the following states, starting with state
              06057 ; NOT DOCKED:
              06058 ;
              06059 ; (1)  NOT DOCKED 
              06060 ;
              06061 ;      The docking state is set to ORBIT ESTABLISHED and the title line is
              06062 ;      updated with "ORBIT ESTABLISHED".
              06063 ;
              06064 ; (2)  ORBIT ESTABLISHED 
              06065 ;
              06066 ;      After waiting until the title line "ORBIT ESTABLISHED" has disappeared,
              06067 ;      the transfer vessel is initialized and launched: The PLAYER4 shape type
              06068 ;      is set to TRANSFER VESSEL. Its position vector is set to a position above
              06069 ;      and in front of our starship, but behind the starbase:
              06070 ;
              06071 ;          x-coordinate :=     +0..+255 (+$00**) <KM>
              06072 ;          y-coordinate :=   +256..+511 (+$01**) <KM> 
              06073 ;          z-coordinate := +4096..+4351 (+$10**) <KM>
              06074 ;
              06075 ;      Its velocity vector is set to
              06076 ;
              06077 ;          x-velocity   := +1 <KM/H> 
              06078 ;          y-velocity   := -1 <KM/H> 
              06079 ;          z-velocity   := -7 <KM/H>
              06080 ;
              06081 ;      This will move the transfer vessel from behind the starbase into a
              06082 ;      direction toward and a little to the lower right of our starship. The
              06083 ;      lifetime of the transfer vessel (and its return journey) is set to 129
              06084 ;      game loop iterations. Finally, the docking state is set to RETURN
              06085 ;      TRANSFER VESSEL.
              06086 ;
              06087 ; (3)  RETURN TRANSFER VESSEL 
              06088 ;
              06089 ;      After checking if the transfer vessel has passed behind our starship, the
              06090 ;      beeper sound pattern ACKNOWLEDGE is played in subroutine BEEP ($B3A6),
              06091 ;      the title line is updated with "TRANSFER COMPLETE", our starship's
              06092 ;      subsystems are repaired, and our starship's ENERGY readout is restored to
              06093 ;      9999 energy units. by inverting the z-velocity the velocity vector of the
              06094 ;      transfer vessel is changed to
              06095 ;
              06096 ;          x-velocity   := +1 <KM/H> 
              06097 ;          y-velocity   := -1 <KM/H> 
              06098 ;          z-velocity   := +7 <KM/H>
              06099 ;
              06100 ;      thus launching the transfer vessel on its return journey to the starbase.
              06101 ;      The docking state is set to TRANSFER COMPLETE. Finally, the screen is
              06102 ;      updated in subroutine UPDSCREEN ($B07B).
              06103 ;
              06104 ; (4)  TRANSFER COMPLETE 
              06105 ;
              06106 ;      This docking state marks the end of a successful docking and transfer
              06107 ;      operation.
              06108 ;
              06109 ; DOCKING ABORTED
              06110 ;
              06111 ; If the docking conditions above are not met and the docking state is already
              06112 ; ORBIT ESTABLISHED or RETURN TRANSFER VESSEL then the message "DOCKING ABORTED"
              06113 ; is displayed and the docking state is set to NOT DOCKED.
              06114
ACE6 A57B     06115 DOCKING         LDA ISSTARBASESECT      ; Return if not in starbase sector
ACE8 F0FB     06116                 BEQ SKIP111             ;
              06117
ACEA A5D0     06118                 LDA SHIPVIEW            ; Skip if not in Front view
ACEC D005     06119                 BNE SKIP112             ;
ACEE A914     06120                 LDA #$14                ; GTIA: enable PLAYER4, prio: PFs > PLs > BGR (!)
ACF0 8D1BD0   06121                 STA PRIOR               ; (Cross hairs appear behind PLAYERs)
              06122
ACF3 A902     06123 SKIP112         LDA #2                  ; Track starbase (PLAYER2)
ACF5 8D5C09   06124                 STA TRACKDIGIT          ;
              06125
              06126 ;** Initialize starbase shape **************************************************
ACF8 A930     06127                 LDA #SHAP.STARBASEC     ; PLAYER2 is STARBASE CENTER (shape type 3)
ACFA 8D8E0C   06128                 STA PL2SHAPTYPE         ;
ACFD A920     06129                 LDA #SHAP.STARBASEL     ; PLAYER1 is STARBASE LEFT (shape type 2)
ACFF 8D8D0C   06130                 STA PL1SHAPTYPE         ;
AD02 A940     06131                 LDA #SHAP.STARBASER     ; PLAYER0 is STARBASE RIGHT (shape type 4)
AD04 8D8C0C   06132                 STA PL0SHAPTYPE         ;
              06133
AD07 A9FF     06134                 LDA #255                ; Prep starbase lifetime := 255 game loops (infinite)
              06135
AD09 A690     06136                 LDX CURRSECTOR          ; Skip if starbase in current sector
AD0B BCC908   06137                 LDY GCMEMMAP,X          ;
AD0E 3002     06138                 BMI SKIP113             ;
              06139
AD10 A900     06140                 LDA #0                  ; Prep starbase lifetime := 0 game loops (fast death)
              06141
AD12 85E9     06142 SKIP113         STA PL0LIFE             ; PLAYER0 lifetime := either 0 or 255 game loops
AD14 85EA     06143                 STA PL1LIFE             ; PLAYER1 lifetime := either 0 or 255 game loops
AD16 85EB     06144                 STA PL2LIFE             ; PLAYER2 lifetime := either 0 or 255 game loops
AD18 857B     06145                 STA ISSTARBASESECT      ; Store starbase-in-sector flag
AD1A 300A     06146                 BMI SKIP114             ; Skip if starbase in current sector
              06147
AD1C A002     06148                 LDY #2                  ; Init explosion at PLAYER2 (STARBASE CENTER)
AD1E 206BAC   06149                 JSR INITEXPL            ;
              06150
AD21 A20A     06151                 LDX #$0A                ; Play noise sound pattern SHIP EXPLOSION and return
AD23 4CA8AE   06152                 JMP NOISE               ;
              06153
              06154 ;*** Keep minimum distance to starbase *****************************************
AD26 AD420A   06155 SKIP114         LDA PL2ZPOSHI           ; Skip if starbase z-coordinate > +255 (+$00**) <KM>
AD29 D00A     06156                 BNE SKIP115             ;
              06157
AD2B ADD50A   06158                 LDA PL2ZPOSLO           ; Approach starbase not closer than +32 (+$0020) <KM>
AD2E C920     06159                 CMP #32                 ;
AD30 B003     06160                 BCS SKIP115             ;
AD32 EED50A   06161                 INC PL2ZPOSLO           ; ...else push starbase back
              06162
              06163 ;*** Check if in docking range *************************************************
AD35 AD2C0C   06164 SKIP115         LDA PL2COLUMN           ; Abort docking if PLAYER column number of...
AD38 38       06165                 SEC                     ; ...PLAYER2 (STARBASE CENTER) not in 120..135.
AD39 E978     06166                 SBC #120                ; (!)
AD3B C910     06167                 CMP #16                 ;
AD3D B022     06168                 BCS SKIP116             ;
              06169
AD3F ADFB0B   06170                 LDA PL2ROWNEW           ; Abort docking if PLAYER row number of...
AD42 38       06171                 SEC                     ; ...PLAYER2 (STARBASE CENTER) not in 104..119.
AD43 E968     06172                 SBC #104                ; (!)
AD45 C910     06173                 CMP #16                 ;
AD47 B018     06174                 BCS SKIP116             ;
              06175
AD49 AD420A   06176                 LDA PL2ZPOSHI           ; Abort docking if...
AD4C C902     06177                 CMP #2                  ; ... z-coordinate of starbase >= +512 (+$02**) <KM>
AD4E B011     06178                 BCS SKIP116             ;
              06179
AD50 ADAF09   06180                 LDA PL2ZPOSSIGN         ; Abort docking...
AD53 2D110A   06181                 AND PL2YPOSSIGN         ; ...if starbase not in front and upper screen half
AD56 4901     06182                 EOR #$01                ;
AD58 0570     06183                 ORA VELOCITYLO          ; ...if our starship's velocity not zero
AD5A 0DA40A   06184                 ORA PL2YPOSHI           ; ...if starbase not roughly vertically centered
AD5D 0571     06185                 ORA NEWVELOCITY         ; ...if our starship's new velocity not zero
AD5F F010     06186                 BEQ SKIP119             ; Else skip and handle docking
              06187
              06188 ;*** Docking aborted ***********************************************************
AD61 A575     06189 SKIP116         LDA DOCKSTATE           ; Skip if DOCKSTATE is NOT DOCKED, TRANSFER COMPLETE
AD63 C902     06190                 CMP #2                  ;
AD65 9005     06191                 BCC SKIP117             ;
              06192
AD67 A01F     06193                 LDY #$1F                ; Set title phrase "DOCKING ABORTED"
AD69 2023B2   06194                 JSR SETTITLE            ;
              06195
AD6C A900     06196 SKIP117         LDA #0                  ; DOCKSTATE := NOT DOCKED
AD6E 8575     06197                 STA DOCKSTATE           ;
AD70 60       06198 SKIP118         RTS                     ; Return
              06199
              06200 ;*** Docking successful, check docking state ***********************************
AD71 2475     06201 SKIP119         BIT DOCKSTATE           ; Check DOCKSTATE
AD73 700D     06202                 BVS SKIP120             ; If DOCKSTATE = ORBIT ESTABLISHED hide title line
AD75 3042     06203                 BMI SKIP122             ; If DOCKSTATE = RETURN TRANSFER VESSEL return it
AD77 A575     06204                 LDA DOCKSTATE           ;
AD79 D0F5     06205                 BNE SKIP118             ; Return if DOCKSTATE not NOT DOCKED
AD7B C675     06206                 DEC DOCKSTATE           ; DOCKSTATE := ORBIT ESTABLISHED
              06207
AD7D A01C     06208                 LDY #$1C                ; Set title phrase "ORBIT ESTABLISHED" and return
AD7F 4C23B2   06209                 JMP SETTITLE            ;
              06210
              06211 ;*** Orbit established *********************************************************
AD82 A200     06212 SKIP120         LDX #0                  ; Enqueue new, empty title phrase
AD84 8665     06213                 STX NEWTITLEPHR         ;
              06214
AD86 A4D1     06215                 LDY TITLEPHR            ; Return if "ORBIT ESTABLISHED" still displayed
AD88 D0E6     06216                 BNE SKIP118             ;
              06217
              06218 ;*** Launch transfer vessel ****************************************************
AD8A A950     06219                 LDA #SHAP.TRANSVSSL     ; PLAYER4 is TRANSFER VESSEL (shape 5)
AD8C 8D900C   06220                 STA PL4SHAPTYPE         ;
              06221
AD8F A901     06222                 LDA #1                  ; Place transfer vessel behind starbase:
AD91 8DB109   06223                 STA PL4ZPOSSIGN         ; x-coordinate :=    +0..+255  (+$00**) <KM>
AD94 8DE209   06224                 STA PL4XPOSSIGN         ; y-coordinate :=  +256..+511  (+$01**) <KM>
AD97 8D130A   06225                 STA PL4YPOSSIGN         ; z-coordinate := +4096..+4351 (+$10**) <KM>
AD9A 8DA60A   06226                 STA PL4YPOSHI           ;
AD9D 8D9B0B   06227                 STA PL4XVEL             ; Move transfer vessel toward our starship:
ADA0 A910     06228                 LDA #$10                ; x-velocity := +1 <KM/H>
ADA2 8D440A   06229                 STA PL4ZPOSHI           ; y-velocity := -1 <KM/H>
ADA5 A900     06230                 LDA #$00                ; z-velocity := -7 <KM/H>
ADA7 8D750A   06231                 STA PL4XPOSHI           ;
ADAA A987     06232                 LDA #NEG!7              ;
ADAC 8D6A0B   06233                 STA PL4ZVEL             ;
ADAF A981     06234                 LDA #NEG!1              ; DOCKSTATE := RETURN TRANSFER VESSEL
ADB1 8575     06235                 STA DOCKSTATE           ;
ADB3 8DCC0B   06236                 STA PL4YVEL             ;
ADB6 85ED     06237                 STA PL4LIFE             ; Transfer vessel lifetime := 129 game loops
ADB8 60       06238 SKIP121         RTS                     ; Return
              06239
              06240 ;*** Return transfer vessel ****************************************************
ADB9 ADB109   06241 SKIP122         LDA PL4ZPOSSIGN         ; Return if transfer vessel in front of our starship
ADBC D0FA     06242                 BNE SKIP121             ;
              06243
ADBE A20C     06244                 LDX #$0C                ; Play beeper sound pattern ACKNOWLEGDE
ADC0 20A6B3   06245                 JSR BEEP                ;
              06246
ADC3 A021     06247                 LDY #$21                ; Set title phrase "TRANSFER COMPLETE"
ADC5 2023B2   06248                 JSR SETTITLE            ;
              06249
ADC8 A205     06250                 LDX #5                  ; Repair all 6 subsystems
ADCA BD8BBB   06251 LOOP041         LDA PANELTXTTAB+73,X    ;
ADCD 9D9209   06252                 STA GCSTATPHO,X         ;
ADD0 CA       06253                 DEX                     ;
ADD1 10F7     06254                 BPL LOOP041             ;
              06255
ADD3 A989     06256                 LDA #CCS.COL2!CCS.9     ; Set starship's ENERGY readout to "9999" in COLOR2
ADD5 A203     06257                 LDX #3                  ;
ADD7 9D5509   06258 LOOP042         STA ENERGYD1,X          ;
ADDA CA       06259                 DEX                     ;
ADDB 10FA     06260                 BPL LOOP042             ;
              06261
ADDD A907     06262                 LDA #7                  ; Move transfer vessel back toward starbase:
ADDF 8D6A0B   06263                 STA PL4ZVEL             ; x-velocity := -1 <KM/H>
ADE2 A981     06264                 LDA #NEG!1              ; y-velocity := +1 <KM/H>
ADE4 8D9B0B   06265                 STA PL4XVEL             ; z-velocity := +7 <KM/H>
ADE7 A901     06266                 LDA #1                  ;
ADE9 8DCC0B   06267                 STA PL4YVEL             ;
              06268
ADEC 8575     06269                 STA DOCKSTATE           ; DOCKSTATE := TRANSFER COMPLETE
ADEE 4C7BB0   06270                 JMP UPDSCREEN           ; Update screen and return
              06271
              06272 ;*******************************************************************************
              06273 ;*                                                                             *
              06274 ;*                                   MODDLST                                   *
              06275 ;*                                                                             *
              06276 ;*                             Modify Display List                             *
              06277 ;*                                                                             *
              06278 ;*******************************************************************************
              06279
              06280 ; DESCRIPTION
              06281 ;
              06282 ; Modifies the Display List to show and hide title, headers, and the Control
              06283 ; Panel Display.
              06284 ;
              06285 ; INPUT
              06286 ;
              06287 ;   A = Number of bytes to copy into the Display List
              06288 ;   X = Offset into Display List DSPLST ($0280)
              06289 ;   Y = Offset into Display List fragment table DLSTFRAG ($BA62). If Y = $80
              06290 ;       then no bytes are copied but the specified locations of the Display List
              06291 ;       are overwritten with Display List instruction $0D (one row of
              06292 ;       GRAPHICS7).
              06293 ;
              06294 ;   Used values are:
              06295 ;
              06296 ;    A    X    Y
              06297 ;   $08  $5F  $00 -> Show Control Panel Display (bottom text window)
              06298 ;   $08  $5F  $80 -> Hide Control Panel Display (bottom text window)
              06299 ;   $07  $0F  $23 -> Show title line
              06300 ;   $07  $0F  $80 -> Hide title line
              06301 ;   $08  $02  $1B -> Show Display List header line of Front view
              06302 ;   $08  $02  $13 -> Show Display List header line of Aft view
              06303 ;   $08  $02  $0B -> Show Display List header line of Long-Range Scan view
              06304 ;   $08  $02  $08 -> Show Display List header line of Galactic Chart view
              06305
    =006A     06306 L.NUMBYTES      = $6A                   ; Number of bytes to copy
              06307
ADF1 78       06308 MODDLST         SEI                     ; Disable IRQ
ADF2 856A     06309                 STA L.NUMBYTES          ; Save number of bytes to copy
              06310
ADF4 AD0BD4   06311 LOOP043         LDA VCOUNT              ; Wait for ANTIC line counter >= 124 (PLAYFIELD...
ADF7 C97C     06312                 CMP #124                ; ...bottom) before changing the Display List
ADF9 90F9     06313                 BCC LOOP043             ;
              06314
ADFB B962BA   06315 LOOP044         LDA DLSTFRAG,Y          ; Load byte from Display List fragment table
ADFE C8       06316                 INY                     ;
ADFF 1002     06317                 BPL SKIP123             ; Skip if fragment table index < $80
AE01 A90D     06318                 LDA #$0D                ; Prep Display List instruction $0D (GRAPHICS7)
AE03 9D8002   06319 SKIP123         STA DSPLST,X            ; Store byte in Display List
AE06 E8       06320                 INX                     ;
AE07 C66A     06321                 DEC L.NUMBYTES          ;
AE09 D0F0     06322                 BNE LOOP044             ; Copy next byte
              06323
AE0B 58       06324                 CLI                     ; Enable IRQ
AE0C 60       06325                 RTS                     ; Return
              06326
              06327 ;*******************************************************************************
              06328 ;*                                                                             *
              06329 ;*                                CLRPLAYFIELD                                 *
              06330 ;*                                                                             *
              06331 ;*                           Clear PLAYFIELD memory                            *
              06332 ;*                                                                             *
              06333 ;*******************************************************************************
              06334
              06335 ; DESCRIPTION
              06336 ;
              06337 ; Clears PLAYFIELD memory from $1000 to $1FFF.
              06338 ;
              06339 ; This subroutine sets the start address of the memory to be cleared then code
              06340 ; execution continues into subroutine CLRMEM ($AE0F) where the memory is
              06341 ; actually cleared.
              06342
AE0D A910     06343 CLRPLAYFIELD    LDA #$10
              06344
              06345 ;*******************************************************************************
              06346 ;*                                                                             *
              06347 ;*                                   CLRMEM                                    *
              06348 ;*                                                                             *
              06349 ;*                                Clear memory                                 *
              06350 ;*                                                                             *
              06351 ;*******************************************************************************
              06352
              06353 ; DESCRIPTION
              06354 ;
              06355 ; Clears memory from a given start address to memory address $1FFF. This
              06356 ; subroutine is called in the following situations:
              06357 ;
              06358 ; (1)  In routine INITCOLD ($A14A) at the beginning of the program to initialize
              06359 ;      the program's variables 
              06360 ;
              06361 ; (2)  In subroutine CLRPLAYFIELD ($AE0D) to clear PLAYFIELD memory.
              06362 ;
              06363 ; As a side effect this subroutine also clears the saved number of space objects
              06364 ; and the lock-on flag.
              06365 ;
              06366 ; INPUT
              06367 ;
              06368 ;   A = Start address (high byte) of memory to be cleared. Used values are:
              06369 ;     $02 -> Clear memory $0200..$1FFF during program initialization
              06370 ;     $10 -> Clear PLAYFIELD memory $1000..$1FFF
              06371
AE0F 8569     06372 CLRMEM          STA MEMPTR+1            ; Store start address (high byte) to be cleared
AE11 A900     06373                 LDA #0                  ; Store start address (low byte) to be cleared
AE13 A8       06374                 TAY                     ;
AE14 8568     06375                 STA MEMPTR              ;
              06376
AE16 85A3     06377                 STA ISINLOCKON          ; Clear lock-on flag
AE18 857A     06378                 STA SAVMAXSPCOBJIND     ; Clear saved number of space objects
              06379
AE1A 9168     06380 LOOP045         STA (MEMPTR),Y          ; Clear memory location
AE1C C8       06381                 INY                     ;
AE1D D0FB     06382                 BNE LOOP045             ;
              06383
AE1F E669     06384                 INC MEMPTR+1            ; Next page (= 256-byte block)
AE21 A469     06385                 LDY MEMPTR+1            ;
AE23 C020     06386                 CPY #$20                ;
AE25 A8       06387                 TAY                     ;
AE26 90F2     06388                 BCC LOOP045             ; Loop until memory address $2000 reached
AE28 60       06389                 RTS                     ; Return
              06390
              06391 ;*******************************************************************************
              06392 ;*                                                                             *
              06393 ;*                                   TRIGGER                                   *
              06394 ;*                                                                             *
              06395 ;*                           Handle joystick trigger                           *
              06396 ;*                                                                             *
              06397 ;*******************************************************************************
              06398
              06399 ; DESCRIPTION
              06400 ;
              06401 ; This subroutine handles the joystick trigger and launches one of our
              06402 ; starship's photon torpedo. If a target is in full lock-on then a second photon
              06403 ; torpedo is prepared for automatic launch in the next game loop iteration.
              06404 ;
              06405 ; DETAILS
              06406 ;
              06407 ; If the trigger is pressed then reset the idle counter and, if not in
              06408 ; hyperwarp, launch a photon torpedo with the following steps:
              06409 ;
              06410 ; (1)  If the trigger was pressed in this game loop iteration, a photon torpedo
              06411 ;      will be launched if a previously launched photon torpedo is already under
              06412 ;      way for at least 255 - 232 = 23 game loop iterations. This avoids firing
              06413 ;      photon torpedoes too rapidly. 
              06414 ;
              06415 ; (2)  Start tracking a space object. If it is in full lock-on, set up the
              06416 ;      lock-on timer, activate photon torpedo tracking, and tweak the last saved
              06417 ;      trigger state such that our other photon torpedo (if available) is
              06418 ;      launched automatically in the next game loop iteration.
              06419 ;
              06420 ; (3)  If the Photon Torpedoes are destroyed, do nothing.
              06421 ;
              06422 ; (4)  If the Photon Torpedoes are damaged, launch a photon torpedo from the
              06423 ;      same barrel than the previous one. 
              06424 ;
              06425 ; (5)  If the Photon Torpedoes are not damaged, launch a photon torpedo from the
              06426 ;      other barrel. 
              06427 ;
              06428 ; (6)  Set the lifetime of our starship's photon torpedo to infinite, set the
              06429 ;      PLAYER shape to PHOTON TORPEDO. 
              06430 ;
              06431 ; (7)  Initialize the position vector of our starship's photon torpedo to:
              06432 ;
              06433 ;          x-coordinate := +256 (+$0100) <KM> (Right barrel)
              06434 ;                          -256 (-$FF00) <KM> (Left barrel)
              06435 ;          y-coordinate := -256 (-$FF00) <KM>
              06436 ;          z-coordinate :=   +1 (+$0001) <KM>
              06437 ;
              06438 ; (8)  Initialize the velocity vector of our starship's photon torpedo to:
              06439 ;
              06440 ;          x-velocity   :=   +0 <KM/H>
              06441 ;          y-velocity   :=   +0 <KM/H>
              06442 ;          z-velocity   := +102 <KM/H> (All views but Aft view)
              06443 ;                          -102 <KM/H> (Aft view)
              06444 ;
              06445 ; (9)  Subtract 10 energy units for launching our starship's photon torpedo.
              06446 ;
              06447 ; (10) Play the noise sound pattern PHOTON TORPEDO LAUNCHED by continuing code
              06448 ;      execution into subroutine NOISE ($AEA8).
              06449
AE29 A584     06450 TRIGGER         LDA OLDTRIG0            ; Prep last trigger state
              06451
AE2B AC10D0   06452                 LDY TRIG0               ; Copy current trigger state
AE2E 8484     06453                 STY OLDTRIG0            ;
AE30 D00E     06454                 BNE SKIP124             ; Return if trigger currently not pressed
              06455
AE32 8466     06456                 STY IDLECNTHI           ; Reset idle counter
              06457
AE34 A6C0     06458                 LDX WARPSTATE           ; Return if hyperwarp engaged
AE36 D008     06459                 BNE SKIP124             ;
              06460
AE38 A687     06461                 LDX BARRELNR            ; Prep barrel number (0 -> left, 1 -> right)
              06462
AE3A C901     06463                 CMP #1                  ; If trigger is newly pressed -> handle tracking...
AE3C F003     06464                 BEQ SKIP125             ; ...and launch our starship's photon torpedo...
AE3E B018     06465                 BCS SKIP127             ; ...else launch our starship's photon torpedo only
AE40 60       06466 SKIP124         RTS                     ; Return
              06467
              06468 ;*** Set up our starship's photon torpedo tracking *****************************
AE41 B5EC     06469 SKIP125         LDA PL3LIFE,X           ; Return if torpedo's lifetime >= 232 game loops
AE43 C9E8     06470                 CMP #232                ;
AE45 B0F9     06471                 BCS SKIP124             ;
              06472
AE47 AC5C09   06473                 LDY TRACKDIGIT          ; Store index of tracked space object
AE4A 8489     06474                 STY PLTRACKED           ;
              06475
AE4C A90C     06476                 LDA #12                 ; Prep lock-on lifetime := 12 game loops
AE4E A4A3     06477                 LDY ISINLOCKON          ; If target is in full lock-on...
AE50 8486     06478                 STY ISTRACKING          ; ...activate photon torpedo tracking
              06479
AE52 F002     06480                 BEQ SKIP126             ; Skip if target not in full lock-on
AE54 A900     06481                 LDA #0                  ; Prep lock-on lifetime := 0 game loops
AE56 8588     06482 SKIP126         STA LOCKONLIFE          ; Store lock-on lifetime (either 0 or 12 game loops)
              06483
              06484 ;*** Launch our starship's photon torpedo **************************************
AE58 8484     06485 SKIP127         STY OLDTRIG0            ; Update last trigger state
AE5A 2C9209   06486                 BIT GCSTATPHO           ; Return if Photon Torpedoes are destroyed
AE5D 70E1     06487                 BVS SKIP124             ;
              06488
AE5F 3005     06489                 BMI SKIP128             ; If Photon Torpedoes damaged launch from same barrel
AE61 8A       06490                 TXA                     ; ...else switch barrel from which to launch torpedo
AE62 4901     06491                 EOR #$01                ;
AE64 8587     06492                 STA BARRELNR            ;
              06493
AE66 8A       06494 SKIP128         TXA                     ; SUMMARY: Our starship's photon torpedo's...
AE67 9DE109   06495                 STA PL3XPOSSIGN,X       ; x-coordinate := +256 (+$0100) <KM> (right barrel)
AE6A BD73BF   06496                 LDA BARRELXTAB,X        ; x-coordinate := -256 (-$FF00) <KM> (left barrel)
AE6D 9D740A   06497                 STA PL3XPOSHI,X         ; y-coordinate := -256 (-$FF00) <KM>
AE70 A9FF     06498                 LDA #255                ; z-coordinate :=   +1 (+$0001) <KM>
AE72 95EC     06499                 STA PL3LIFE,X           ; ...lifetime := 255 game loops
AE74 9DA50A   06500                 STA PL3YPOSHI,X         ;
AE77 A900     06501                 LDA #0                  ;
AE79 9D8F0C   06502                 STA PL3SHAPTYPE,X       ; PLAYER3 or PLAYER4 is PHOTON TORPEDO (shape type 0)
AE7C 9D430A   06503                 STA PL3ZPOSHI,X         ;
AE7F 9D070B   06504                 STA PL3XPOSLO,X         ;
AE82 9D120A   06505                 STA PL3YPOSSIGN,X       ;
AE85 9D380B   06506                 STA PL3YPOSLO,X         ;
AE88 A901     06507                 LDA #1                  ;
AE8A 9DB009   06508                 STA PL3ZPOSSIGN,X       ;
AE8D 9DD60A   06509                 STA PL3ZPOSLO,X         ;
              06510
AE90 A5D0     06511                 LDA SHIPVIEW            ; SUMMARY: Our starship's photon torpedo's...
AE92 4A       06512                 LSR A                   ; x-velocity :=   +0 <KM/H>
AE93 6A       06513                 ROR A                   ; y-velocity :=   +0 <KM/H>
AE94 0966     06514                 ORA #102                ; z-velocity := +102 <KM/H> (Other views)
AE96 9D690B   06515                 STA PL3ZVEL,X           ; z-velocity := -102 <KM/H> (Aft view)
AE99 A900     06516                 LDA #0                  ;
AE9B 9D9A0B   06517                 STA PL3XVEL,X           ;
AE9E 9DCB0B   06518                 STA PL3YVEL,X           ;
              06519
AEA1 A202     06520                 LDX #2                  ; ENERGY := ENERGY - 10 for launching photon torpedo
AEA3 206FB8   06521                 JSR DECENERGY           ;
              06522
AEA6 A200     06523                 LDX #$00                ; Play noise sound pattern PHOTON TORPEDO LAUNCHED
              06524
              06525 ;*******************************************************************************
              06526 ;*                                                                             *
              06527 ;*                                    NOISE                                    *
              06528 ;*                                                                             *
              06529 ;*                          Copy noise sound pattern                           *
              06530 ;*                                                                             *
              06531 ;*******************************************************************************
              06532
              06533 ; DESCRIPTION
              06534 ;
              06535 ; Copies a 10-byte noise sound pattern from table NOISEPATTAB ($BF20). The first
              06536 ; 8 bytes are copied to the noise sound pattern area NOISETORPTIM
              06537 ; ($DA)..NOISELIFE ($E1), the remaining 2 bytes are copied to audio registers
              06538 ; AUDCTL ($D208) and AUDF3 ($D204). The noise sound pattern is automatically
              06539 ; played in subroutine SOUND ($B2AB).
              06540 ;
              06541 ; NOTE: the first 8 bytes of each pattern in table NOISEPATTAB ($BF20) are
              06542 ; copied in reverse order from memory. See subroutine SOUND ($B2AB) for details
              06543 ; on the noise sound patterns stored in NOISEPATTAB ($BF20).
              06544 ;
              06545 ; Playing a SHIP EXPLOSION or ZYLON EXPLOSION noise sound pattern overrides a
              06546 ; currently playing PHOTON TORPEDO LAUNCHED noise sound pattern.
              06547 ;
              06548 ; Playing a PHOTON TORPEDO LAUNCHED noise sound pattern overrides a currently
              06549 ; playing PHOTON TORPEDO LAUNCHED noise sound pattern if the latter has < 24
              06550 ; TICKs to play.
              06551 ;
              06552 ; INPUT
              06553 ;
              06554 ;   X = Offset into table NOISEPATTAB ($BF20) to index noise sound patterns.
              06555 ;       Used values are:
              06556 ;     $00 -> PHOTON TORPEDO LAUNCHED
              06557 ;     $0A -> SHIP EXPLOSION (either our starship or a starbase explodes)
              06558 ;     $14 -> ZYLON EXPLOSION
              06559
AEA8 8A       06560 NOISE           TXA                     ; Skip if SHIP EXPLOSION or ZYLON EXPLOSION playing
AEA9 D006     06561                 BNE SKIP129             ;
              06562
AEAB A5E1     06563                 LDA NOISELIFE           ; Return if PHOTON TORPEDO LAUNCHED noise sound pat.
AEAD C918     06564                 CMP #24                 ; ...playing for yet more than 24 TICKs
AEAF B018     06565                 BCS SKIP130             ;
              06566
AEB1 A007     06567 SKIP129         LDY #7                  ; Copy noise sound pattern (in reverse order)
AEB3 BD20BF   06568 LOOP046         LDA NOISEPATTAB,X       ;
AEB6 99DA00   06569                 STA NOISETORPTIM,Y      ;
AEB9 E8       06570                 INX                     ;
AEBA 88       06571                 DEY                     ;
AEBB 10F6     06572                 BPL LOOP046             ;
              06573
AEBD BD20BF   06574                 LDA NOISEPATTAB,X       ; Copy AUDCTL from noise sound pattern table
AEC0 8D08D2   06575                 STA AUDCTL              ;
AEC3 BD21BF   06576                 LDA NOISEPATTAB+1,X     ; Copy AUDF3 from noise sound pattern table
AEC6 8D04D2   06577                 STA AUDF3               ;
              06578
AEC9 60       06579 SKIP130         RTS                     ; Return
              06580
              06581 ;*******************************************************************************
              06582 ;*                                                                             *
              06583 ;*                                  HOMINGVEL                                  *
              06584 ;*                                                                             *
              06585 ;*      Calculate homing velocity of our starship's photon torpedo 0 or 1      *
              06586 ;*                                                                             *
              06587 ;*******************************************************************************
              06588
              06589 ; DESCRIPTION
              06590 ;
              06591 ; Calculates the x (or y) velocity vector component of our starship's photon
              06592 ; torpedo 0 or 1 when it is tracking (homing in on) a target space object.
              06593 ;
              06594 ; Our starship's photon torpedo's x (or y) velocity vector component depends on
              06595 ; the PLAYER column (or row) number difference between the target PLAYER and our
              06596 ; starship's photon torpedo PLAYER in Player/Missile (PM) pixels. This
              06597 ; difference is used as an index to pick the new x (or y) velocity vector
              06598 ; component of out starship's photon torpedo from table HOMVELTAB ($BFC9):
              06599 ;
              06600 ; +---------------+--------------+
              06601 ; | Difference in | New Velocity |
              06602 ; |   PM Pixels   |  Component   |
              06603 ; +---------------+--------------+
              06604 ; |    >= +7      |   -64 <KM/H> |
              06605 ; |       +6      |   -56 <KM/H> |
              06606 ; |       +5      |   -48 <KM/H> |    
              06607 ; |       +4      |   -40 <KM/H> |
              06608 ; |       +3      |   -24 <KM/H> |
              06609 ; |       +2      |   -16 <KM/H> |    
              06610 ; |       +1      |    -8 <KM/H> |
              06611 ; |        0      |     0 <KM/H> |
              06612 ; |       -1      |    +8 <KM/H> |    
              06613 ; |       -2      |   +16 <KM/H> |
              06614 ; |       -3      |   +24 <KM/H> |
              06615 ; |       -4      |   +40 <KM/H> |    
              06616 ; |       -5      |   +48 <KM/H> |
              06617 ; |       -6      |   +56 <KM/H> |    
              06618 ; |    <= -7      |   +64 <KM/H> |
              06619 ; +---------------+--------------+      
              06620 ;
              06621 ; INPUT
              06622 ;
              06623 ;   A     = PLAYER column (or row) number difference between the target PLAYER
              06624 ;           and our starship's photon torpedo PLAYER in Player/Missile pixels
              06625 ;   CARRY = Sign of the PLAYER column (or row) number difference. Used values
              06626 ;           are:
              06627 ;     0 -> Negative difference (target PLAYER column (or row) number < our
              06628 ;          starship's photon torpedo PLAYER column (or row) number
              06629 ;     1 -> Positive difference (target PLAYER column (or row) number >= our
              06630 ;          starship's photon torpedo PLAYER column (or row) number
              06631 ;
              06632 ; OUTPUT
              06633 ;
              06634 ;   A = New velocity vector component of our starship's photon torpedo in <KM/H>
              06635
    =006A     06636 L.VELSIGN       = $6A                   ; Saves velocity sign
              06637
AECA A080     06638 HOMINGVEL       LDY #NEG                ; Preload negative velocity sign
AECC B004     06639                 BCS SKIP131             ; Skip if difference is positive
              06640
AECE 49FF     06641                 EOR #$FF                ; Invert to get absolute value of difference
AED0 A000     06642                 LDY #0                  ; Preload positive velocity sign
              06643
AED2 846A     06644 SKIP131         STY L.VELSIGN           ; Save velocity sign
AED4 C908     06645                 CMP #8                  ;
AED6 9002     06646                 BCC SKIP132             ;
AED8 A907     06647                 LDA #7                  ; Limit difference to 0..7
AEDA A8       06648 SKIP132         TAY                     ;
AEDB A56A     06649                 LDA L.VELSIGN           ; Reload velocity sign
AEDD 19C9BF   06650                 ORA HOMVELTAB,Y         ; Combine with homing velocity from table
AEE0 60       06651                 RTS                     ; Return
              06652
              06653 ;*******************************************************************************
              06654 ;*                                                                             *
              06655 ;*                                   DAMAGE                                    *
              06656 ;*                                                                             *
              06657 ;*             Damage or destroy one of our starship's subsystems              *
              06658 ;*                                                                             *
              06659 ;*******************************************************************************
              06660
              06661 ; DESCRIPTION
              06662 ;
              06663 ; Damages or destroys one of our starship's subsystems. There are 6 subsystems:
              06664 ;
              06665 ; (1)  Photon Torpedoes
              06666 ; (2)  Engines
              06667 ; (3)  Shields
              06668 ; (4)  Attack Computer
              06669 ; (5)  Long-Range Scan
              06670 ; (6)  Subspace Radio
              06671 ;
              06672 ; Their status is stored and displayed in the Galactic Chart Panel Display by
              06673 ; the colored letters PESCLR. The color of each letter represents the
              06674 ; subsystem's status:
              06675 ;
              06676 ; +---------------+------------------+
              06677 ; | Letter Color  | Subsystem Status |
              06678 ; +---------------+------------------+
              06679 ; | {LIGHT GREEN} | OK               |
              06680 ; | {CORN YELLOW} | Damaged          |
              06681 ; | {PINK}        | Destroyed        |
              06682 ; +---------------+------------------+
              06683 ;
              06684 ; This subroutine first makes sure that we are not in demo mode. Then it picks a
              06685 ; random value in 0..255 and the damage probability value. The latter value
              06686 ; depends on the mission level and is picked from table DAMAGEPROBTAB ($BF10):
              06687 ;
              06688 ; +-----------+-------------------+---------------+
              06689 ; |  Mission  |       Damage      |    Damage     |
              06690 ; |   Level   | Probability Value |  Probability  |
              06691 ; +-----------+-------------------+---------------+
              06692 ; | NOVICE    |          0        |  0% (  0:256) | 
              06693 ; | PILOT     |         80        | 31% ( 80:256) |
              06694 ; | WARRIOR   |        180        | 70% (180:256) |
              06695 ; | COMMANDER |        254        | 99% (254:256) |
              06696 ; +-----------+-------------------+---------------+
              06697 ;
              06698 ; If the random number is lower than the damage probability value, a randomly
              06699 ; picked subsystem is about to get damaged (or destroyed). There is a built-in
              06700 ; upfront probability of 25% (2:8) that no subsystem gets harmed.
              06701 ;
              06702 ; If the picked subsystem is already destroyed then another subsystem is picked.
              06703 ;
              06704 ; Then the title phrase offset is picked from table DAMAGEPHRTAB ($BF14) to
              06705 ; display the damaged subsystem in the title line. Next, color bits are picked
              06706 ; that indicate a damaged system.
              06707 ;
              06708 ; If the Zylon photon torpedo's lifetime >= 30 game loop iterations the
              06709 ; subsystem will not only be damaged but destroyed.
              06710 ;
              06711 ; NOTE: The Zylon photon torpedo lifetime decreases from 62 to 0 game loop
              06712 ; iterations. With a remaining lifetime >= 30 game loop iterations it is
              06713 ; considered strong enough to destroy one of our starship's subsystems. There
              06714 ; are two exceptions to this rule: If the Attack Computer was picked to be
              06715 ; destroyed it will be damaged only - not destroyed - if the Long-Range Scan has
              06716 ; been already destroyed, and vice versa.
              06717 ;
              06718 ; Then the title phrase offset from table DESTROYPHRTAB ($BF1A) is picked to
              06719 ; display the destroyed subsystem in the title line. Next, color bits are picked
              06720 ; that indicate a destroyed system.
              06721 ;
              06722 ; The color of the subsystem's status letter is adjusted in the Galactic Chart
              06723 ; Panel Display. Next, the title phrase describing the subsystem's status is
              06724 ; enqueued for display in the title line. If the Attack Computer has been
              06725 ; destroyed it is switched off and the PLAYFIELD is cleared. The title line is
              06726 ; updated with the "DAMAGE CONTROL" message. Finally, the beeper sound pattern
              06727 ; DAMAGE REPORT is played in subroutine BEEP ($B3A6).
              06728
AEE1 2464     06729 DAMAGE          BIT ISDEMOMODE          ; Return if in demo mode
AEE3 3057     06730                 BMI SKIP137             ;
              06731
              06732 ;*** Damage some subsystem *****************************************************
AEE5 A662     06733                 LDX MISSIONLEVEL        ; Prep mission level
AEE7 AD0AD2   06734 LOOP047         LDA RANDOM              ; Return if random number >= damage probability
AEEA DD10BF   06735                 CMP DAMAGEPROBTAB,X     ; ...(the latter depends on mission level)
AEED B04D     06736                 BCS SKIP137             ;
              06737
AEEF 2907     06738                 AND #$07                ; Randomly pick 1 of 6 subsystems
AEF1 C906     06739                 CMP #6                  ; Return if no subsystem picked
AEF3 B047     06740                 BCS SKIP137             ;
              06741
AEF5 AA       06742                 TAX                     ;
AEF6 BD9209   06743                 LDA GCSTATPHO,X         ; Get picked subsystem status letter
AEF9 0A       06744                 ASL A                   ; Check bit B6 (= destroyed) of letter code
AEFA 30EB     06745                 BMI LOOP047             ; Try again if subsystem already destroyed
              06746
AEFC A5EB     06747                 LDA PL2LIFE             ; Load Zylon photon torpedo lifetime...
AEFE C91E     06748                 CMP #30                 ; ...and compare it to 30 game loops
              06749
AF00 A980     06750                 LDA #CCS.COL2           ; Preload COLOR2 text color bits (= damaged status)
AF02 BC14BF   06751                 LDY DAMAGEPHRTAB,X      ; Preload title phrase offset of damaged subsystem
              06752
AF05 9017     06753                 BCC SKIP135             ; Skip if Zylon torpedo lifetime < 30 game loops
              06754
AF07 E003     06755                 CPX #3                  ; Skip if selected subsystem not Attack Computer
AF09 D005     06756                 BNE SKIP133             ;
AF0B 2C9609   06757                 BIT GCSTATLRS           ; Skip if Long-Range Scan already destroyed
AF0E 700E     06758                 BVS SKIP135             ;
AF10 E004     06759 SKIP133         CPX #4                  ; Skip if selected subsystem is not Long-Range Scan
AF12 D005     06760                 BNE SKIP134             ;
AF14 2C9509   06761                 BIT GCSTATCOM           ; Skip if Attack Computer already destroyed
AF17 7005     06762                 BVS SKIP135             ;
              06763
AF19 A9C0     06764 SKIP134         LDA #CCS.COL3           ; Preload COLOR3 text color bits (= destroyed status)
AF1B BC1ABF   06765                 LDY DESTROYPHRTAB,X     ; Preload title phrase offset of destroyed subsystem
              06766
AF1E 1D9209   06767 SKIP135         ORA GCSTATPHO,X         ; Combine status letter with new color
AF21 9D9209   06768                 STA GCSTATPHO,X         ;
AF24 8465     06769                 STY NEWTITLEPHR         ; Enqueue damage status title phrase
AF26 2C9509   06770                 BIT GCSTATCOM           ; Skip if Attack Computer OK or damaged
AF29 5007     06771                 BVC SKIP136             ;
              06772
AF2B A900     06773                 LDA #0                  ; Switch Attack Computer off
AF2D 857E     06774                 STA ISATTCOMPON         ;
AF2F 200DAE   06775                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
              06776
AF32 A052     06777 SKIP136         LDY #$52                ; Set title phrase "DAMAGE CONTROL..."
AF34 2023B2   06778                 JSR SETTITLE            ;
              06779
AF37 A212     06780                 LDX #$12                ; Play beeper sound pattern DAMAGE REPORT
AF39 20A6B3   06781                 JSR BEEP                ;
              06782
AF3C 60       06783 SKIP137         RTS                     ; Return
              06784
              06785 ;*******************************************************************************
              06786 ;*                                                                             *
              06787 ;*                                  COLLISION                                  *
              06788 ;*                                                                             *
              06789 ;*            Detect a collision of our starship's photon torpedoes            *
              06790 ;*                                                                             *
              06791 ;*******************************************************************************
              06792
              06793 ; DESCRIPTION
              06794 ;
              06795 ; Both of our starship's photon torpedoes are checked if they have collided with
              06796 ; a space object represented by PLAYER0..2, such as a Zylon ship, a Zylon photon
              06797 ; torpedo, a starbase, or a meteor. 
              06798 ;
              06799 ; For quick lookup, the following table lists the PLAYERs and what space objects
              06800 ; they represent:
              06801 ;
              06802 ; +--------+--------------------------------------------------+
              06803 ; | PLAYER |                   Represents                     |
              06804 ; +--------+--------------------------------------------------+
              06805 ; |   0    | Zylon ship 0, Starbase Left                      |
              06806 ; |   1    | Zylon ship 1, Starbase Right                     |
              06807 ; |   2    | Zylon photon torpedo, Starbase Center, Meteor    | 
              06808 ; |   3    | Our starship's photon torpedo 0                  |
              06809 ; |   4    | Our starship's photon torpedo 1, Transfer Vessel |
              06810 ; +--------+--------------------------------------------------+
              06811 ;
              06812 ; NOTE: Only space objects represented by PLAYER0..2 are checked for collisions.
              06813 ; The transfer vessel of the starbase, represented by PLAYER4, is not checked
              06814 ; and therefore cannot be destroyed by one of our starship's photon torpedoes.
              06815 ;
              06816 ; This subroutine first checks if our starship's photon torpedoes are
              06817 ; represented by alive PLAYERs with PHOTON TORPEDO shape.
              06818 ;
              06819 ; In order to detect a collision with a space object, our starship's photon
              06820 ; torpedo must compare its x, y, and z coordinates with the ones of the space
              06821 ; object.
              06822 ;
              06823 ; Instead of comparing the x and y coordinates, however, this subroutines uses a
              06824 ; much more efficent method by inspecting the Player/Missile collision
              06825 ; registers, as the x and y axis of the 3D coordinate system establish the plane
              06826 ; in which the TV screen lies. Each of our starship's photon torpedoes has its
              06827 ; own Player/Missile collision register: PL3HIT ($82) for our starship's photon
              06828 ; torpedo 0 and PL4HIT ($83) for our starship's photon torpedo 1. By inspecting
              06829 ; these registers the hit space object is determined: 
              06830 ;
              06831 ; +---------------------------------------------------+-------------------------+
              06832 ; |          Bits B2..0 of Collision Register         |        Hit PLAYER       |
              06833 ; |              (0 -> Not Hit, 1 -> Hit)             |                         |
              06834 ; +-----------------+----------------+----------------+                         |
              06835 ; |     PLAYER2     |     PLAYER1    |    PLAYER0     |                         |
              06836 ; | (Zylon torpedo) | (Zylon ship 1) | (Zylon ship 0) |                         |
              06837 ; +-----------------+----------------+----------------+-------------------------+
              06838 ; |        0        |        0       |        0       | None                    |
              06839 ; |        0        |        0       |        1       | PLAYER0 (Zylon ship 0)  |
              06840 ; |        0        |        1       |        0       | PLAYER1 (Zylon ship 1)  |
              06841 ; |        0        |        1       |        1       | PLAYER1 (Zylon ship 1)  |
              06842 ; |        1        |        0       |        0       | PLAYER2 (Zylon torpedo) |
              06843 ; |        1        |        0       |        1       | PLAYER2 (Zylon torpedo) |
              06844 ; |        1        |        1       |        0       | PLAYER1 (Zylon ship 1)  |
              06845 ; |        1        |        1       |        1       | PLAYER1 (Zylon ship 1)  |
              06846 ; +-----------------+----------------+----------------+-------------------------+
              06847 ;
              06848 ; If the lifetime of the hit space object has already expired, then the hit is
              06849 ; ignored.
              06850 ;
              06851 ; A collision along the z-axis happens if the z-coordinate of our starship's
              06852 ; photon torpedo is close enough to the z-coordinate of the space object:
              06853 ;
              06854 ; The absolute value of the z-coordinate of the space object is converted into a
              06855 ; range index in 0..7. This index picks a minimum and a maximum z-coordinate
              06856 ; from tables HITMINZTAB ($BF7D) and HITMAXZTAB ($BF75). If the absolute value
              06857 ; of the z-coordinate of our starship's photon torpedo is inside this interval,
              06858 ; then our starship's photon torpedo has hit the space object. The following
              06859 ; table lists the relevant values: 
              06860 ;
              06861 ; +-----------------------+-------+--------------------------+--------------------------+
              06862 ; | ABS(z-Coordinate)     | Range | Min ABS(z-Coordinate)    | Max ABS(z-Coordinate)    |
              06863 ; | of Space Object       | Index | of Photon Torpedo to Hit | of Photon Torpedo to Hit |
              06864 ; +-----------------------+-------+--------------------------+--------------------------+
              06865 ; | <=   511 ($01**) <KM> |   0   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06866 ; | <=  1023 ($03**) <KM> |   1   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06867 ; | <=  1535 ($05**) <KM> |   2   |           0 ($00**) <KM> |      < 3328 ($0C**) <KM> |
              06868 ; | <=  2047 ($07**) <KM> |   3   |         512 ($02**) <KM> |      < 3328 ($0C**) <KM> |
              06869 ; | <=  2559 ($09**) <KM> |   4   |        1024 ($04**) <KM> |      < 3840 ($0E**) <KM> |
              06870 ; | <=  3071 ($0B**) <KM> |   5   |        1536 ($06**) <KM> |      < 3840 ($0E**) <KM> |
              06871 ; | <=  3583 ($0D**) <KM> |   6   |        2048 ($08**) <KM> |      < 3840 ($0E**) <KM> |
              06872 ; | <= 65535 ($FF**) <KM> |   7   |        3072 ($0C**) <KM> |      < 8448 ($20**) <KM> |
              06873 ; +-----------------------+-------+--------------------------+--------------------------+
              06874 ;
              06875 ; if a collision has been detected, the "age" (= initial lifetime - remaining
              06876 ; lifetime) of our starship's photon torpedo is calculated. This age is used to
              06877 ; delay playing the ZYLON EXPLOSION noise sound pattern but also to determine
              06878 ; the strength of our starship's photon torpedo. Only photon torpedoes of an age
              06879 ; < 15 game loop iterations can destroy a Zylon basestar.
              06880 ;
              06881 ; Some clean-up work is done before the actual explosion: The lock-on timer, our
              06882 ; starship's photon torpedo lifetime, and the hit space object's PLAYER lifetime
              06883 ; is set to 0. 
              06884 ;
              06885 ; If a meteor or a Zylon photon torpedo have been hit, then the score is not
              06886 ; changed, skipping right to the explosion part. Otherwise, our starship's
              06887 ; photon torpedo tracking flag is cleared and the Galactic Chart Map is updated.
              06888 ; If a starbase was destroyed, then 3 points are added to the score. If a Zylon
              06889 ; ship was destroyed, then 6 points are added to the score and the Zylon KILL
              06890 ; COUNTER readout of the Control Panel Display is incremented. Next, the
              06891 ; explosion is initialized in subroutine INITEXPL ($AC6B).
              06892 ;
              06893 ; NOTE: This subroutine lacks proper explosion initialization if the starbase
              06894 ; was hit. The actual explosion initialization is done in subroutine DOCKING
              06895 ; ($ACE6) when the code finds out that the starbase sector is no more marked as
              06896 ; such in the Galactic Chart.
              06897 ;
              06898 ; Finally, the Galactic Chart Map is searched for a remaining Zylon unit. If
              06899 ; none is found then the mission is complete and code excecution continues into
              06900 ; subroutine GAMEOVER2 ($B121), ending the game. 
              06901
    =006B     06902 L.PLHIT         = $6B                   ; Saves PLAYER (and space object) index of hit PLAYER
    =006C     06903 L.VIEWDIR       = $6C                   ; Saves view direction. Used values are:
              06904                                         ;   $00 -> Front view
              06905                                         ;   $FF -> Aft view
              06906
AF3D A202     06907 COLLISION       LDX #2                  ; Loop over our starship's two photon torpedoes
AF3F CA       06908 LOOP048         DEX                     ;
AF40 1001     06909                 BPL SKIP138             ; Branch into loop body below
AF42 60       06910                 RTS                     ; Return
              06911
              06912 ;*** Photon torpedo sanity checks **********************************************
AF43 BD8F0C   06913 SKIP138         LDA PL3SHAPTYPE,X       ; Next photon torpedo if PLAYER not a PHOTON TORPEDO
AF46 D0F7     06914                 BNE LOOP048             ;
              06915
AF48 B5EC     06916                 LDA PL3LIFE,X           ; Next photon torpedo if PLAYER not alive
AF4A F0F3     06917                 BEQ LOOP048             ;
              06918
              06919 ;*** Check if our starship's photon torpedo has hit in x-y plane ***************
AF4C B582     06920                 LDA PL3HIT,X            ; Check Player/Missile collision register
AF4E 2907     06921                 AND #$07                ; Next torpedo if no torpedo-to-PLAYER collision
AF50 F0ED     06922                 BEQ LOOP048             ;
              06923
AF52 4A       06924                 LSR A                   ; Find out which PLAYER was hit in PLAYFIELD
AF53 C903     06925                 CMP #3                  ;
AF55 D001     06926                 BNE SKIP139             ;
AF57 4A       06927                 LSR A                   ;
AF58 A8       06928 SKIP139         TAY                     ; Save resulting index of hit PLAYER
              06929
AF59 B9E900   06930                 LDA PL0LIFE,Y           ; Next torpedo if PLAYER0..2 (= targets) not alive
AF5C F0E1     06931                 BEQ LOOP048             ;
              06932
              06933 ;*** Has our starship's photon torpedo hit within valid z-coordinate interval? *
AF5E A5D0     06934                 LDA SHIPVIEW            ; Skip if in Front view
AF60 F002     06935                 BEQ SKIP140             ;
AF62 A9FF     06936                 LDA #$FF                ; Calculate range index...
AF64 856C     06937 SKIP140         STA L.VIEWDIR           ; Saves view direction
AF66 59400A   06938                 EOR ZPOSHI,Y            ; Calc ABS(z-coordinate (high byte)) of hit object
AF69 C910     06939                 CMP #16                 ; Limit range index to 0..7
AF6B 9002     06940                 BCC SKIP141             ;
AF6D A90F     06941                 LDA #15                 ;
AF6F 4A       06942 SKIP141         LSR A                   ;
AF70 846B     06943                 STY L.PLHIT             ; Save index of hit PLAYER
              06944
AF72 A8       06945                 TAY                     ;
AF73 A56C     06946                 LDA L.VIEWDIR           ; Reload view direction
AF75 5D430A   06947                 EOR PL3ZPOSHI,X         ; Calc ABS(z-coordinate (high byte)) of torpedo
              06948
AF78 D975BF   06949                 CMP HITMAXZTAB,Y        ; Next torpedo if torpedo >= max hit z-coordinate
AF7B B0C2     06950                 BCS LOOP048             ;
              06951
AF7D D97DBF   06952                 CMP HITMINZTAB,Y        ; Next torpedo if torpedo < min hit z-coordinate
AF80 90BD     06953                 BCC LOOP048             ;
              06954
              06955 ;*** Our starship's photon torpedo has hit within valid z-coordinate interval! *
AF82 A46B     06956                 LDY L.PLHIT             ; Reload index of hit PLAYER
AF84 38       06957                 SEC                     ; Calc "age" of photon torpedo in game loops to...
AF85 A9FF     06958                 LDA #255                ; delay playing ZYLON EXPLOSION noise sound pattern
AF87 F5EC     06959                 SBC PL3LIFE,X           ;
AF89 85E2     06960                 STA NOISEZYLONTIM       ;
              06961
AF8B C90F     06962                 CMP #15                 ; Skip if photon torpedo "age" < 15
AF8D 9005     06963                 BCC SKIP142             ;
AF8F B98C0C   06964                 LDA PL0SHAPTYPE,Y       ; CARRY := PLAYER is ZYLON BASESTAR (shape type 8)
AF92 C980     06965                 CMP #SHAP.ZBASESTAR     ; (and torpedo "age" good to destroy ZYLON BASESTAR)
              06966
              06967 ;*** Clean up our starship's photon torpedo and hit PLAYER *********************
AF94 A900     06968 SKIP142         LDA #0                  ; Lock-on lifetime := 0 game loops
AF96 8588     06969                 STA LOCKONLIFE          ;
AF98 95EC     06970                 STA PL3LIFE,X           ; Photon torpedo's lifetime := 0 game loops
AF9A B04B     06971                 BCS SKIP144             ; If CARRY set do not score, just do explosion
              06972
AF9C 99E900   06973                 STA PL0LIFE,Y           ; Hit PLAYER lifetime := 0 game loops
              06974
AF9F B98C0C   06975                 LDA PL0SHAPTYPE,Y       ; If hit PLAYER is...
AFA2 F043     06976                 BEQ SKIP144             ; ...a PHOTON TORPEDO (shape type 0)...
AFA4 C960     06977                 CMP #SHAP.METEOR        ; ...or a METEOR (shape type 6)...
AFA6 F03F     06978                 BEQ SKIP144             ; ...do not score, just do explosion
              06979
AFA8 A900     06980                 LDA #0                  ; Clear photon torpedo tracking flag
AFAA 8586     06981                 STA ISTRACKING          ;
              06982
              06983 ;*** Zylon ship (or starbase) destroyed! ***************************************
AFAC A690     06984                 LDX CURRSECTOR          ; Decrement Zylon count on Galactic Chart
AFAE DEC908   06985                 DEC GCMEMMAP,X          ;
AFB1 1013     06986                 BPL SKIP143             ; Skip if destroyed space object was Zylon ship
              06987
              06988 ;*** Starbase destroyed! *******************************************************
AFB3 A900     06989                 LDA #0                  ; Remove destroyed starbase from Galactic Chart
AFB5 9DC908   06990                 STA GCMEMMAP,X          ;
AFB8 38       06991                 SEC                     ; SCORE := SCORE - 3 for destroying starbase
AFB9 A5CB     06992                 LDA SCORE               ;
AFBB E903     06993                 SBC #3                  ;
AFBD 85CB     06994                 STA SCORE               ;
AFBF A5CC     06995                 LDA SCORE+1             ;
AFC1 E900     06996                 SBC #0                  ;
AFC3 85CC     06997                 STA SCORE+1             ;
AFC5 60       06998                 RTS                     ; Return
              06999
              07000 ;*** Zylon ship destroyed! *****************************************************
AFC6 18       07001 SKIP143         CLC                     ; SCORE := SCORE + 6 for destroying Zylon ship
AFC7 A5CB     07002                 LDA SCORE               ;
AFC9 6906     07003                 ADC #6                  ;
AFCB 85CB     07004                 STA SCORE               ;
AFCD A5CC     07005                 LDA SCORE+1             ;
AFCF 6900     07006                 ADC #0                  ;
AFD1 85CC     07007                 STA SCORE+1             ;
              07008
AFD3 A201     07009                 LDX #1                  ; Increment Zylon KILL COUNTER readout...
AFD5 FE5009   07010 LOOP049         INC KILLCNTD1,X         ; ...of Control Panel Display
AFD8 BD5009   07011                 LDA KILLCNTD1,X         ;
AFDB C94A     07012                 CMP #[CCS.COL1!CCS.9]+1 ;
AFDD 9008     07013                 BCC SKIP144             ;
AFDF A940     07014                 LDA #[CCS.COL1!CCS.0]   ;
AFE1 9D5009   07015                 STA KILLCNTD1,X         ;
AFE4 CA       07016                 DEX                     ;
AFE5 10EE     07017                 BPL LOOP049             ;
              07018
AFE7 206BAC   07019 SKIP144         JSR INITEXPL            ; Init explosion at hit PLAYER
              07020
              07021 ;*** Any Zylon ships left? *****************************************************
AFEA A27F     07022                 LDX #127                ; Scan all sectors of Galactic Chart
AFEC BDC908   07023 LOOP050         LDA GCMEMMAP,X          ;
AFEF 3002     07024                 BMI SKIP145             ;
AFF1 D00A     07025                 BNE SKIP146             ; Return if Zylon sector found
AFF3 CA       07026 SKIP145         DEX                     ;
AFF4 10F6     07027                 BPL LOOP050             ;
              07028
              07029 ;*** Game over (Mission Complete) **********************************************
AFF6 A03F     07030                 LDY #$3F                ; Set title phrase "MISSION COMPLETE"
AFF8 A200     07031                 LDX #0                  ; Set mission bonus offset
AFFA 2021B1   07032                 JSR GAMEOVER2           ; Game over
AFFD 60       07033 SKIP146         RTS                     ; Return
              07034
              07035 ;*******************************************************************************
              07036 ;*                                                                             *
              07037 ;*                                  KEYBOARD                                   *
              07038 ;*                                                                             *
              07039 ;*                            Handle Keyboard Input                            *
              07040 ;*                                                                             *
              07041 ;*******************************************************************************
              07042
              07043 ; DESCRIPTION
              07044 ;
              07045 ; If a keyboard code has been collected during a keyboard IRQ in the Immediate
              07046 ; Interrupt Request handler IRQHNDLR ($A751), the idle counter is reset and the
              07047 ; PLAYER-PLAYFIELD priority arranges the PLAYERs in front of the PLAYFIELD.
              07048 ; Then, the keyboard code is compared with keyboard codes of table KEYTAB
              07049 ; ($BABE). If no match is found the "WHAT'S WRONG" message is displayed in the
              07050 ; title line and code execution returns.
              07051 ;
              07052 ; If one of the speed keys '0'..'9' has been pressed, a pending hyperwarp is
              07053 ; aborted in subroutine ABORTWARP ($A980) and code execution returns. Otherwise
              07054 ; the Engines drain rate is adjusted as well as the new velocity of our
              07055 ; starship. If the Engines are damaged, a maximum speed is possible equivalent
              07056 ; to speed key '5'.
              07057 ;
              07058 ; If one of our starship's view keys 'F' (Front), 'A' (Aft), 'G' (Galactic
              07059 ; Chart), or 'L' (Long-Range Scan) have been pressed, the Display List is
              07060 ; modified accordingly in subroutine MODDLST ($ADF1) and a new star field of 12
              07061 ; stars is created with the help of subroutine INITPOSVEC ($B764). Code
              07062 ; execution returns via subroutine UPDSCREEN ($B07B).
              07063 ;
              07064 ; If one of the 'T' (Tracking Computer), 'S' (Shields) or 'C' (Attack Computer)
              07065 ; keys have been pressed, the corresponding status bits are toggled and the
              07066 ; title line is updated with the corresponding title phrase. The beeper sound
              07067 ; pattern ACKNOWLEDGE is played in subroutine BEEP ($B3A6). The tracking letter
              07068 ; of the Control Panel Display is updated and the PLAYFIELD is cleared in
              07069 ; subroutine CLRPLAYFIELD ($AE0D). If the Attack Computer is on, the Front or
              07070 ; Aft view cross hairs are drawn, depending on the current view of our starship,
              07071 ; via subroutine DRAWLINES ($A76F).
              07072 ;
              07073 ; If the 'H' (Hyperwarp) key has been pressed then the hyperwarp is engaged. Our
              07074 ; starship's velocity is set to the maximum value, the Engines drain rate is
              07075 ; increased to the equivalent of speed key '7'. Star trails are prepared. The
              07076 ; position vector of the Hyperwarp Target Marker (PLAYER3) is set to the
              07077 ; following values:
              07078 ;
              07079 ;     x-coordinate :=   +0 (+$0000) <KM>
              07080 ;     y-coordinate := +256 (+$0100) <KM>
              07081 ;     z-coordinate :=    + (+$****) <KM> (sign only)
              07082 ;
              07083 ; The velocity vector is set to the following values:
              07084 ;
              07085 ;     x-velocity   :=  (not initialized)
              07086 ;     y-velocity   :=  (not initialized)
              07087 ;     z-velocity   :=          +0 <KM/H>
              07088 ;
              07089 ; The temporary arrival hyperwarp marker column and row numbers are saved. If
              07090 ; not in a NOVICE mission, the maximum veer-off velocity of the Hyperwarp Target
              07091 ; Marker during hyperwarp is picked from table VEERMASKTAB ($BED7). This value
              07092 ; depends on the selected hyperwarp energy (and thus on the distance to
              07093 ; hyperwarp). Finally, the title line displays the "HYPERWARP ENGAGED" message.
              07094 ;
              07095 ; If the 'M' (Manual target selector) key has been pressed, the tracked target
              07096 ; space object is swapped and the corresponding digit of the Control Panel
              07097 ; Display is toggled between 0 and 1.
              07098 ;
              07099 ; If the 'P' (Pause) key has been pressed, an endless loop waits until the
              07100 ; joystick is pushed.
              07101 ;
              07102 ; BUG (at $B103): The endless loop branches back one instruction too far.
              07103 ; Suggested fix: Branch to instruction LDA PORTA at $B0FE.
              07104 ;
              07105 ; If the 'INV' (Abort mission) key has been pressed, the mission is aborted by
              07106 ; setting the mission bonus offset, then displaying the "MISSION ABORTED"
              07107 ; message in the title line. Code execution continues into subroutine GAMEOVER
              07108 ; ($B10A).
              07109 ;
              07110 ; NOTE: This subroutine has two additional entry points:
              07111 ;
              07112 ; (1)  SETVIEW ($B045), which is used to enforce the Front view. It is entered
              07113 ;      from the game loop GAMELOOP ($A1F3) and subroutines INITSTART ($A15E) and
              07114 ;      DECENERGY ($B86F).
              07115 ;
              07116 ; (2)  UPDSCREEN ($B07B), which draws the cross hairs, the Attack Computer
              07117 ;      Display and sets the tracking letter of the Control Panel Display. It is
              07118 ;      entered from subroutine DOCKING ($ACE6).
              07119
    =006A     07120 L.KEYCODE       = $6A                   ; Saves pressed keyboard code
              07121
AFFE A5CA     07122 KEYBOARD        LDA KEYCODE             ; Return if no keyboard code collected
B000 F03E     07123                 BEQ SKIP150             ;
              07124
B002 A214     07125                 LDX #20                 ; Prep keyboard code table loop index
B004 856A     07126                 STA L.KEYCODE           ; Save keyboard code
              07127
B006 A900     07128                 LDA #0                  ; Reset idle counter
B008 8566     07129                 STA IDLECNTHI           ;
B00A 85CA     07130                 STA KEYCODE             ; Clear keyboard code
              07131
B00C A911     07132                 LDA #$11                ; GTIA: enable PLAYER4, prio: PLs > PFs > BGR
B00E 8D1BD0   07133                 STA PRIOR               ; (PLAYERs appear behind cross hairs)
              07134
              07135 ;*** Search keyboard code in lookup table **************************************
              07136
B011 BDBEBA   07137 LOOP051         LDA KEYTAB,X            ; Loop over all valid keyboard codes
B014 C56A     07138                 CMP L.KEYCODE           ;
B016 F008     07139                 BEQ SKIP147             ; Branch if matching entry found
B018 CA       07140                 DEX                     ;
B019 10F6     07141                 BPL LOOP051             ; Next keyboard code
              07142
B01B A010     07143                 LDY #$10                ; No match found...
B01D 4C23B2   07144                 JMP SETTITLE            ; ...set title phrase "WHATS WRONG?" and return
              07145
              07146 ;*** Handle '0'..'9' keyboard keys (speed) *************************************
B020 E00A     07147 SKIP147         CPX #10                 ; Skip section if keyboard code does not match
B022 B01D     07148                 BCS SKIP151             ;
              07149
B024 A5C0     07150                 LDA WARPSTATE           ; Skip if hyperwarp disengaged...
B026 F003     07151                 BEQ SKIP148             ;
B028 4C80A9   07152                 JMP ABORTWARP           ; ...else abort hyperwarp
              07153
B02B 2C9309   07154 SKIP148         BIT GCSTATENG           ; Skip if Engines are OK or destroyed
B02E 5006     07155                 BVC SKIP149             ;
B030 E006     07156                 CPX #6                  ; Allow max velocity equivalent to speed key '5'
B032 9002     07157                 BCC SKIP149             ;
B034 A205     07158                 LDX #5                  ;
              07159
B036 BDD3BA   07160 SKIP149         LDA DRAINRATETAB,X      ; Set Engines drain rate
B039 8580     07161                 STA DRAINRATE           ;
B03B BDB4BA   07162                 LDA VELOCITYTAB,X       ; Set new velocity
B03E 8571     07163                 STA NEWVELOCITY         ;
B040 60       07164 SKIP150         RTS                     ; Return
              07165
              07166 ;*** Handle 'F', 'A', 'L', 'G' keyboard keys (our starship's views) ************
B041 E00E     07167 SKIP151         CPX #14                 ; Skip section if keyboard code does not match
B043 B01B     07168                 BCS SKIP152             ;
              07169
              07170 ;*** Entry to force Front view after program init and failed missions **********
B045 BD18BE   07171 SETVIEW         LDA VIEWMODETAB-10,X    ; Store our starship's view type
B048 85D0     07172                 STA SHIPVIEW            ;
              07173
B04A BC82BA   07174                 LDY DLSTFRAGOFFTAB-10,X ; Get DL fragment offset (Front, Aft, LRS, GC)
B04D A202     07175                 LDX #$02                ; Switch to corresponding view
B04F A908     07176                 LDA #$08                ;
B051 20F1AD   07177                 JSR MODDLST             ;
              07178
B054 A210     07179                 LDX #16                 ; Create new star field of 12 stars
B056 2064B7   07180 LOOP052         JSR INITPOSVEC          ;
B059 CA       07181                 DEX                     ;
B05A E005     07182                 CPX #5                  ;
B05C B0F8     07183                 BCS LOOP052             ;
              07184
B05E 901B     07185                 BCC UPDSCREEN           ; Return via updating screen (below)
              07186
              07187 ;*** Handle 'T', 'S', 'C' keyboard keys (Tracking, Shields, Attack Computer) ***
B060 E011     07188 SKIP152         CPX #17                 ; Skip section if keyboard code does not match
B062 B035     07189                 BCS SKIP156             ;
              07190
B064 BC18BE   07191                 LDY MSGOFFTAB-14,X      ; Prep title phrase offset "... OFF"
B067 B56E     07192                 LDA ISTRACKCOMPON-14,X  ; Toggle status bits (also energy consumption values)
B069 5D1BBE   07193                 EOR MSGBITTAB-14,X      ;
B06C 956E     07194                 STA ISTRACKCOMPON-14,X  ;
B06E F003     07195                 BEQ SKIP153             ;
B070 BC1EBE   07196                 LDY MSGONTAB-14,X       ; Prep title phrase offset "... ON"
B073 2023B2   07197 SKIP153         JSR SETTITLE            ; Set title phrase to "... ON" or "... OFF" version
              07198
B076 A20C     07199                 LDX #$0C                ; Play beeper sound pattern ACKNOWLEDGE
B078 20A6B3   07200                 JSR BEEP                ;
              07201
              07202 ;*** Update PLAYFIELD (Cross hairs, Attack Computer, set tracking letter) ******
B07B A216     07203 UPDSCREEN       LDX #CCS.T              ; Get custom char 'T' (entry point TRANSFER COMPLETE)
B07D A47C     07204                 LDY ISTRACKCOMPON       ;
B07F F001     07205                 BEQ SKIP154             ; Skip if Tracking Computer is on
              07206
B081 E8       07207                 INX                     ; Get custom char 'C'
              07208
B082 8E5A09   07209 SKIP154         STX TRACKC1             ; Store tracking character in Control Panel Display
B085 200DAE   07210                 JSR CLRPLAYFIELD        ; Clear PLAYFIELD
B088 A57E     07211                 LDA ISATTCOMPON         ; Return if Attack Computer off
B08A F0B4     07212                 BEQ SKIP150             ;
              07213
B08C A6D0     07214                 LDX SHIPVIEW            ; If Aft view   -> Draw Aft cross hairs and return
B08E F006     07215                 BEQ SKIP155             ; If Front view -> Draw Front cross hairs and ...
B090 E001     07216                 CPX #$01                ;                  ...Attack Computer and return
B092 D0AC     07217                 BNE SKIP150             ;
B094 A22A     07218                 LDX #$2A                ;
B096 4C6FA7   07219 SKIP155         JMP DRAWLINES           ;
              07220
              07221 ;*** Handle 'H' keyboard key (Hyperwarp) ***************************************
B099 E011     07222 SKIP156         CPX #17                 ; Skip if keyboard code does not match
B09B D050     07223                 BNE SKIP158             ;
              07224
              07225 ;*** Engage Hyperwarp **********************************************************
B09D A5C0     07226                 LDA WARPSTATE           ; Return if hyperwarp engaged
B09F D05A     07227                 BNE SKIP159             ;
              07228
B0A1 A97F     07229                 LDA #$7F                ; Engage hyperwarp
B0A3 85C0     07230                 STA WARPSTATE           ;
B0A5 A9FF     07231                 LDA #255                ; Set new velocity
B0A7 8571     07232                 STA NEWVELOCITY         ;
B0A9 A91E     07233                 LDA #30                 ; Set drain rate equivalent to speed key '7'
B0AB 8580     07234                 STA DRAINRATE           ;
              07235
B0AD A930     07236                 LDA #48                 ; Set space obj index of first star of star trail
B0AF 85C3     07237                 STA TRAILIND            ;
B0B1 A900     07238                 LDA #0                  ; Clear star trail delay
B0B3 85C2     07239                 STA TRAILDELAY          ;
              07240
B0B5 8D740A   07241                 STA PL3XPOSHI           ; Init position vector and velocity vector of...
B0B8 8D070B   07242                 STA PL3XPOSLO           ; ... Hyperwarp Target Marker (PLAYER3):
B0BB 8D380B   07243                 STA PL3YPOSLO           ; x-coordinate :=   +0 (+$0000) <KM>
B0BE 8D690B   07244                 STA PL3ZVEL             ; y-coordinate := +256 (+$0100) <KM>
B0C1 A901     07245                 LDA #1                  ; z-coordinate :=    + (+$****) <KM> (sign only)
B0C3 8DB009   07246                 STA PL3ZPOSSIGN         ; z-velocity := +0 <KM/H>
B0C6 8DE109   07247                 STA PL3XPOSSIGN         ;
B0C9 8D120A   07248                 STA PL3YPOSSIGN         ;
B0CC 8DA50A   07249                 STA PL3YPOSHI           ;
              07250
B0CF A58F     07251                 LDA WARPARRVCOLUMN      ; Store temp arrival hyperwarp marker column number
B0D1 85C4     07252                 STA WARPTEMPCOLUMN      ;
B0D3 A58E     07253                 LDA WARPARRVROW         ; Store temp arrival hyperwarp marker row number
B0D5 85C5     07254                 STA WARPTEMPROW         ;
              07255
B0D7 A562     07256                 LDA MISSIONLEVEL        ; Skip if NOVICE mission
B0D9 F00B     07257                 BEQ SKIP157             ;
              07258
B0DB A591     07259                 LDA WARPENERGY          ; Bits B0..1 of hyperwarp energy index a table...
B0DD 2A       07260                 ROL A                   ; ...containing the maximum value of how much the...
B0DE 2A       07261                 ROL A                   ; ...Hyperwarp Target Marker will veer off during...
B0DF 2A       07262                 ROL A                   ; ...hyperwarp
B0E0 2903     07263                 AND #$03                ;
B0E2 A8       07264                 TAY                     ;
B0E3 B9D7BE   07265                 LDA VEERMASKTAB,Y       ;
              07266
B0E6 85C6     07267 SKIP157         STA VEERMASK            ; Store veer-off velocity limitation mask
              07268
B0E8 A011     07269                 LDY #$11                ; Set title phrase "HYPERWARP ENGAGED" and return
B0EA 4C23B2   07270                 JMP SETTITLE            ;
              07271
              07272 ;*** Handle 'M' keyboard key (Manual Target Selector) key **********************
B0ED E013     07273 SKIP158         CPX #19                 ; Skip if keyboard code does not match
B0EF B00B     07274                 BCS SKIP160             ;
              07275
B0F1 AD5C09   07276                 LDA TRACKDIGIT          ; Toggle digit of tracked space object of...
B0F4 4901     07277                 EOR #$01                ; ... Control Panel Display
B0F6 2901     07278                 AND #$01                ;
B0F8 8D5C09   07279                 STA TRACKDIGIT          ;
B0FB 60       07280 SKIP159         RTS                     ; Return
              07281
              07282 ;*** Handle 'P' keyboard key (Pause) *******************************************
B0FC D008     07283 SKIP160         BNE SKIP161             ; Skip if keyboard code does not match
              07284
B0FE AD00D3   07285                 LDA PORTA               ; Push joystick to resume action
B101 C9FF     07286                 CMP #$FF                ;
B103 F0F7     07287                 BEQ SKIP160             ; (!)
B105 60       07288                 RTS                     ; Return
              07289
              07290 ;*** Handle 'INV' keyboard key (Abort Mission) *********************************
B106 A076     07291 SKIP161         LDY #$76                ; Preload title phrase "MISSION ABORTED..."
B108 A204     07292                 LDX #$04                ; Set mission bonus offset
              07293
              07294 ;*******************************************************************************
              07295 ;*                                                                             *
              07296 ;*                                  GAMEOVER                                   *
              07297 ;*                                                                             *
              07298 ;*                              Handle game over                               *
              07299 ;*                                                                             *
              07300 ;*******************************************************************************
              07301
              07302 ; DESCRIPTION
              07303 ;
              07304 ; Handles game over, including calculating the scored rank and class.
              07305 ;
              07306 ; This subroutine has two entry points: 
              07307 ;
              07308 ; (1)  GAMEOVER ($B10A) is entered at the end of a failed mission (mission
              07309 ;      aborted, zero energy, or starship destroyed by Zylon fire). Essentially,
              07310 ;      our starship is shut down. Code execution continues into GAMEOVER2
              07311 ;      ($B121) below.
              07312 ;
              07313 ; (2)  GAMEOVER2 ($B121) is entered at the end of a successful mission (all
              07314 ;      Zylon ships destroyed). It puts the program in demo mode, enqueues the
              07315 ;      corresponding game over message, and calculates the scored rank and
              07316 ;      class.
              07317 ;
              07318 ;      The scored rank and class are based on the total score: the score
              07319 ;      accumulated during the game plus a mission bonus, which depends on the
              07320 ;      mission level and how the mission ended (mission complete, mission
              07321 ;      aborted, or starship destroyed by Zylon fire). The mission bonus is
              07322 ;      picked from table BONUSTAB ($BEDD).
              07323 ;
              07324 ;      The scored rank index is taken from bits B8..4 of the total score and
              07325 ;      limited to values of 0..18. It indexes table RANKTAB ($BEE9) for the rank
              07326 ;      string. The rank string is displayed in subroutine SETTITLE ($B223).
              07327 ;
              07328 ;      The scored class index is taken from bits B3..0 (for rank indices 0,
              07329 ;      11..14) and computed from bits B4..1 (for rank indices 1..10 and 15..18).
              07330 ;      It takes values of 0..15. It indexes table CLASSTAB ($BEFC) for the class
              07331 ;      digit. The class digit is displayed in subroutine SETTITLE ($B223).
              07332 ;
              07333 ;      For quick lookup, the following table lists rank and class from the total
              07334 ;      score. Pick the cell with the closest value <= your score then read the
              07335 ;      rank and class off the left and the top of the table, respectively.
              07336 ;
              07337 ;      For example, a score of 90 results in a ranking of "Novice Class 4", a
              07338 ;      score of 161 results in a ranking of "Pilot Class 3".
              07339 ;
              07340 ; +------------------------------+---------------------------------------------------------------+
              07341 ; |     Minimum Total Score      |                        Class Index                            |
              07342 ; |                              |  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15|
              07343 ; +-------+----------------------+---------------------------------------------------------------+
              07344 ; | Rank  |                      |                           Class                               |
              07345 ; | Index |         Rank         |  5   5   5   4   4   4   4   3   3   3   2   2   2   1   1   1|
              07346 ; +-------+----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
              07347 ; |     0 | Galactic Cook        |  0|  1|  2|  3|  4|  5|  6|  7|  8|  9| 10| 11| 12| 13| 14| 15|
              07348 ; |     1 | Garbage Scow Captain | 16| 18| 20| 22| 24| 26| 28| 30|   |   |   |   |   |   |   |   |
              07349 ; |     2 | Garbage Scow Captain |   |   |   |   |   |   |   |   | 32| 34| 36| 38| 40| 42| 44| 46|
              07350 ; |     3 | Rookie               | 48| 50| 52| 54| 56| 58| 60| 62|   |   |   |   |   |   |   |   |
              07351 ; |     4 | Rookie               |   |   |   |   |   |   |   |   | 64| 66| 68| 70| 72| 74| 76| 78|
              07352 ; |     5 | Novice               | 80| 82| 84| 86| 88| 90| 92| 94|   |   |   |   |   |   |   |   |
              07353 ; |     6 | Novice               |   |   |   |   |   |   |   |   | 96| 98|100|102|104|106|108|110|
              07354 ; |     7 | Ensign               |112|114|116|118|120|122|124|126|   |   |   |   |   |   |   |   |
              07355 ; |     8 | Ensign               |   |   |   |   |   |   |   |   |128|130|132|134|136|138|140|142|
              07356 ; |     9 | Pilot                |144|146|148|150|152|154|156|158|   |   |   |   |   |   |   |   |
              07357 ; |    10 | Pilot                |   |   |   |   |   |   |   |   |160|162|164|166|168|170|172|174|
              07358 ; |    11 | Ace                  |176|177|178|179|180|181|182|183|184|185|186|187|188|189|190|191|
              07359 ; |    12 | Lieutenant           |192|193|194|195|196|197|198|199|200|201|202|203|204|205|206|207|
              07360 ; |    13 | Warrior              |208|209|210|211|212|213|214|215|216|217|218|219|220|221|222|223|
              07361 ; |    14 | Captain              |224|225|226|227|228|229|230|231|232|233|234|235|236|237|238|239|
              07362 ; |    15 | Commander            |240|242|244|246|248|250|252|254|   |   |   |   |   |   |   |   |
              07363 ; |    16 | Commander            |   |   |   |   |   |   |   |   |256|258|260|262|264|266|268|270|
              07364 ; |    17 | Star Commander       |272|274|276|278|280|282|284|286|   |   |   |   |   |   |   |   |
              07365 ; |    18 | Star Commander       |   |   |   |   |   |   |   |   |288|290|292|294|296|298|300|302|
              07366 ; +-------+----------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
              07367 ;
              07368 ;      NOTE: This subroutine also clears the vertical and horizontal joystick
              07369 ;      directions.
              07370 ;
              07371 ; INPUT
              07372 ;
              07373 ;   Y = Title phrase offset. Used values are:
              07374 ;     $3F -> "MISSION COMPLETE"
              07375 ;     $31 -> "MISSION ABORTED ZERO ENERGY"
              07376 ;     $23 -> "SHIP DESTROYED BY ZYLON FIRE"
              07377 ;
              07378 ;   X = Offset to index table BONUSTAB ($BEDD) of mission bonus values. Used
              07379 ;       values are:
              07380 ;     $00 -> Mission complete
              07381 ;     $04 -> Mission was aborted due to zero energy
              07382 ;     $08 -> Our starship was destroyed by Zylon fire
              07383
              07384 ;*** Game over (Mission failed) ************************************************
B10A A900     07385 GAMEOVER        LDA #0                  ;
B10C 85EC     07386                 STA PL3LIFE             ; PLAYER3 lifetime := 0 game loops
B10E 85D6     07387                 STA BEEPPRIORITY        ; Mute beeper
B110 85D1     07388                 STA TITLEPHR            ; Clear title line
B112 858B     07389                 STA REDALERTLIFE        ; Red alert flash lifetime := 0 game loops
B114 8D07D2   07390                 STA AUDC4               ; Mute audio channel 4
B117 8571     07391                 STA NEWVELOCITY         ; Shut down Engines
B119 8581     07392                 STA SHIELDSCOLOR        ; Set Shields color to {BLACK}
B11B 857D     07393                 STA ISSHIELDSON         ; Switch off Shields
B11D 85C0     07394                 STA WARPSTATE           ; Disengage hyperwarp
B11F 85C1     07395                 STA VELOCITYHI          ; Turn off hyperwarp velocity
              07396
              07397 ;*** Game over (Mission successful) ********************************************
B121 A9FF     07398 GAMEOVER2       LDA #$FF                ; Enter demo mode
B123 8564     07399                 STA ISDEMOMODE          ;
              07400
B125 8465     07401                 STY NEWTITLEPHR         ; Enqueue title phrase
              07402
              07403 ;*** Calculate total score *****************************************************
B127 8A       07404                 TXA                     ;
B128 0562     07405                 ORA MISSIONLEVEL        ;
B12A AA       07406                 TAX                     ;
B12B BDDDBE   07407                 LDA BONUSTAB,X          ; Retrieve mission bonus
B12E 18       07408                 CLC                     ; Add mission bonus and game score
B12F 65CB     07409                 ADC SCORE               ;
B131 AA       07410                 TAX                     ;
B132 A900     07411                 LDA #0                  ;
              07412
B134 85C9     07413                 STA JOYSTICKY           ; Clear vertical joystick delta
B136 85C8     07414                 STA JOYSTICKX           ; Clear horizontal joystick delta
              07415
B138 65CC     07416                 ADC SCORE+1             ;
B13A 3025     07417                 BMI SKIP165             ; Return if total score < 0 (= total score of 0)
              07418
              07419 ;*** Calculate scored rank *****************************************************
B13C 4A       07420                 LSR A                   ;
B13D 8A       07421                 TXA                     ;
B13E 6A       07422                 ROR A                   ;
B13F 4A       07423                 LSR A                   ;
B140 4A       07424                 LSR A                   ;
B141 4A       07425                 LSR A                   ; Use bits B8..4 of total score as rank index
B142 C913     07426                 CMP #19                 ; Limit scored rank index to 0..18
B144 9004     07427                 BCC SKIP162             ;
B146 A912     07428                 LDA #18                 ;
B148 A20F     07429                 LDX #15                 ; Prep class index of 15
B14A 85CD     07430 SKIP162         STA SCOREDRANKIND       ; Store scored rank index
              07431
              07432 ;*** Calculate scored class ****************************************************
B14C A8       07433                 TAY                     ;
B14D 8A       07434                 TXA                     ;
B14E C000     07435                 CPY #0                  ;
B150 F00B     07436                 BEQ SKIP164             ;
B152 C00B     07437                 CPY #11                 ;
B154 9004     07438                 BCC SKIP163             ;
B156 C00F     07439                 CPY #15                 ;
B158 9003     07440                 BCC SKIP164             ;
B15A 4A       07441 SKIP163         LSR A                   ;
B15B 4908     07442                 EOR #$08                ;
B15D 290F     07443 SKIP164         AND #$0F                ;
B15F 85CE     07444                 STA SCOREDCLASSIND      ; Store scored class index, is 0..15
              07445
B161 60       07446 SKIP165         RTS                     ; Return
              07447
              07448 ;*******************************************************************************
              07449 ;*                                                                             *
              07450 ;*                                 SELECTWARP                                  *
              07451 ;*                                                                             *
              07452 ;*             Select hyperwarp arrival location on Galactic Chart             *
              07453 ;*                                                                             *
              07454 ;*******************************************************************************
              07455
              07456 ; DESCRIPTION
              07457 ;
              07458 ; This subroutine executes the following steps:
              07459 ;
              07460 ; (1)  Check if we are in Galactic Chart view and not in hyperwarp.
              07461 ;
              07462 ; (2)  Update the Galactic Chart in subroutine DRAWGC ($B4B9) if the Subspace
              07463 ;      Radio is not damaged.
              07464 ;
              07465 ; (3)  Move the arrival hyperwarp marker (PLAYER4) across the Galactic Chart
              07466 ;      every other game loop iteration. The current location of our starship is
              07467 ;      indicated by the departure hyperwarp marker (PLAYER3).
              07468 ;
              07469 ; Code execution continues into subroutine CALCWARP ($B1A7) to calculate the
              07470 ; required hyperwarp energy.
              07471 ;
              07472 ; NOTE: To calculate the horizontal position of PLAYER3..4 an offset of 61 is
              07473 ; added (from left to right: 48 Player/Missile (PM) pixels to the left edge of
              07474 ; the screen + 16 PM pixels to the left border of the Galactic Chart - 3 PM
              07475 ; pixels relative offset of the PLAYER shape's horizontal center to its left
              07476 ; edge = 61 PM pixels).
              07477 ;
              07478 ; NOTE: To calculate the vertical position of PLAYER3..4 an offset of 63 is
              07479 ; added (from top to bottom: 8 Player/Missile (PM) pixels to the start of the
              07480 ; Display List + 56 PM pixels to the first row of sectors - 1 PM pixel relative
              07481 ; offset of the PLAYER shape's vertical center to its top edge (?) = 63 PM
              07482 ; pixels).
              07483
B162 A5C0     07484 SELECTWARP      LDA WARPSTATE           ; Return if hyperwarp engaged
B164 D004     07485                 BNE SKIP166             ;
              07486
B166 A5D0     07487                 LDA SHIPVIEW            ; Return if not in Galactic Chart view
B168 3001     07488                 BMI SKIP167             ;
B16A 60       07489 SKIP166         RTS                     ; Return
              07490
B16B 2C9709   07491 SKIP167         BIT GCSTATRAD           ; Skip if Subspace Radio is damaged or destroyed
B16E 3003     07492                 BMI SKIP168             ;
              07493
B170 20B9B4   07494                 JSR DRAWGC              ; Redraw Galactic Chart
              07495
B173 A572     07496 SKIP168         LDA COUNT8              ; Move hyperwarp markers only every other game loop
B175 2901     07497                 AND #$01                ;
B177 D02E     07498                 BNE CALCWARP            ;
              07499
              07500 ;*** Calc arrival hyperwarp marker column and row numbers, update PLAYER4 pos **
B179 18       07501                 CLC                     ;
B17A A58F     07502                 LDA WARPARRVCOLUMN      ; Load arrival hyperwarp marker column number
B17C 65C8     07503                 ADC JOYSTICKX           ; Add joystick x-delta
B17E 297F     07504                 AND #$7F                ; Limit value to 0..127
B180 858F     07505                 STA WARPARRVCOLUMN      ; Save new arrival hyperwarp marker column number
B182 18       07506                 CLC                     ;
B183 693D     07507                 ADC #61                 ; Add offset of 61
B185 8D2E0C   07508                 STA PL4COLUMN           ; Store as PLAYER4 column number
              07509
B188 18       07510                 CLC                     ;
B189 A58E     07511                 LDA WARPARRVROW         ; Load arrival hyperwarp marker row number
B18B 65C9     07512                 ADC JOYSTICKY           ; Add joystick y-delta
B18D 297F     07513                 AND #$7F                ; Limit value to 0..127
B18F 858E     07514                 STA WARPARRVROW         ; Save new arrival hyperwarp marker row number
B191 18       07515                 CLC                     ;
B192 693F     07516                 ADC #63                 ; Add offset of 63
B194 8DFD0B   07517                 STA PL4ROWNEW           ; Store as PLAYER4 row number
              07518
              07519 ;*** Calc departure hyperwarp marker column and row numbers, update PLAYER3 pos 
B197 A58C     07520                 LDA WARPDEPRROW         ; Load departure hyperwarp marker row number
B199 18       07521                 CLC                     ;
B19A 693F     07522                 ADC #63                 ; Add offset of 63
B19C 8DFC0B   07523                 STA PL3ROWNEW           ; Store as PLAYER3 row number
              07524
B19F A58D     07525                 LDA WARPDEPRCOLUMN      ; Load departure hyperwarp marker column number
B1A1 18       07526                 CLC                     ;
B1A2 693D     07527                 ADC #61                 ; Add offset of 61
B1A4 8D2D0C   07528                 STA PL3COLUMN           ; Store as PLAYER3 column number
              07529
              07530 ;*******************************************************************************
              07531 ;*                                                                             *
              07532 ;*                                  CALCWARP                                   *
              07533 ;*                                                                             *
              07534 ;*                   Calculate and display hyperwarp energy                    *
              07535 ;*                                                                             *
              07536 ;*******************************************************************************
              07537
              07538 ; DESCRIPTION
              07539 ;
              07540 ; Calculates and displays the hyperwarp energy in the Galactic Chart view.
              07541 ;
              07542 ; This subroutine executes the following steps:
              07543 ;
              07544 ; (1)  Determine the arrival sector from the arrival hyperwarp marker position.
              07545 ;
              07546 ; (2)  If the Subspace Radio is not destroyed, update the target number digit of
              07547 ;      the Galactic Chart Panel Display.
              07548 ;
              07549 ; (3)  Calculate the hyperwarp energy that is required to hyperwarp from the
              07550 ;      departure hyperwarp marker to the arrival hyperwarp marker based on the
              07551 ;      "block-distance":
              07552 ;
              07553 ;          DISTANCE := DELTAC + DELTAR / 2
              07554 ;
              07555 ;          where
              07556 ;
              07557 ;          DELTAC := ABS(WARPARRVCOLUMN - WARPDEPRCOLUMN)
              07558 ;          DELTAR := ABS(WARPARRVROW - WARPDEPRROW)
              07559 ;
              07560 ;      NOTE: Dividing DELTAR by 2 is because PLAYERs at single-line resolution
              07561 ;      have Player/Missile pixels that are half as high as they are wide.
              07562 ;
              07563 ;      The hyperwarp energy, divided by 10, is the sum of a value picked from
              07564 ;      the hyperwarp energy table WARPENERGYTAB ($BADD) indexed by DISTANCE / 8)
              07565 ;      plus a remainder computed from Bits B1..0 of DISTANCE. 
              07566 ;
              07567 ; (4)  Store the hyperwarp energy value in WARPENERGY ($91).
              07568 ;
              07569 ; (5)  Update the HYPERWARP ENERGY readout of the Galactic Chart Panel Display.
              07570
    =006A     07571 L.WARPARRVCOL   = $6A                   ; Saves arrival sector column number
    =006A     07572 L.DIFFC         = $6A                   ; Saves diff column value
              07573
              07574 ;*** Calculate arrival sector **************************************************
B1A7 A58F     07575 CALCWARP        LDA WARPARRVCOLUMN      ;
B1A9 4A       07576                 LSR A                   ;
B1AA 4A       07577                 LSR A                   ;
B1AB 4A       07578                 LSR A                   ;
B1AC 856A     07579                 STA L.WARPARRVCOL       ; A := arrival sector column 0..15
B1AE A58E     07580                 LDA WARPARRVROW         ;
B1B0 2970     07581                 AND #$70                ; A := arrival sector row (0..7) * 16
B1B2 056A     07582                 ORA L.WARPARRVCOL       ;
B1B4 8592     07583                 STA ARRVSECTOR          ; Save arrival sector (format %0rrrcccc)
              07584
              07585 ;*** Update target number digit of Galactic Chart Panel Display ****************
B1B6 AA       07586                 TAX                     ;
B1B7 BDC908   07587                 LDA GCMEMMAP,X          ; Get number of Zylon ships in arrival sector
B1BA 1002     07588                 BPL SKIP169             ; Skip if no starbase in arrival sector
B1BC A900     07589                 LDA #0                  ; Clear number of Zylon ships
B1BE 0990     07590 SKIP169         ORA #CCS.COL2!ROM.0     ; Merge COLOR2 bits with number of Zylon ships
B1C0 2C9709   07591                 BIT GCSTATRAD           ; Skip if Subspace Radio destroyed
B1C3 7003     07592                 BVS SKIP170             ;
              07593
B1C5 8D8D09   07594                 STA GCTRGCNT            ; Set target number digit of Galactic Chart Panel
              07595
              07596 ;*** Calculate energy to hyperwarp between hyperwarp markers *******************
B1C8 38       07597 SKIP170         SEC                     ; A := DIFFC := ABS(WARPARRVCOLUMN - WARPDEPRCOLUMN)
B1C9 A58F     07598                 LDA WARPARRVCOLUMN      ; (Column value difference)
B1CB E58D     07599                 SBC WARPDEPRCOLUMN      ;
B1CD B004     07600                 BCS SKIP171             ;
B1CF 49FF     07601                 EOR #$FF                ;
B1D1 6901     07602                 ADC #1                  ;
B1D3 856A     07603 SKIP171         STA L.DIFFC             ;
              07604
B1D5 38       07605                 SEC                     ; A := DIFFR := ABS(WARPARRVROW - WARPDEPRROW)
B1D6 A58E     07606                 LDA WARPARRVROW         ; (Row value difference)
B1D8 E58C     07607                 SBC WARPDEPRROW         ;
B1DA B004     07608                 BCS SKIP172             ;
B1DC 49FF     07609                 EOR #$FF                ;
B1DE 6901     07610                 ADC #1                  ;
              07611
B1E0 4A       07612 SKIP172         LSR A                   ; A := DISTANCE := DIFFR / 2 + DIFFC
B1E1 18       07613                 CLC                     ;
B1E2 656A     07614                 ADC L.DIFFC             ;
              07615
B1E4 A8       07616                 TAY                     ; Save DISTANCE
B1E5 4A       07617                 LSR A                   ; Calc index into hyperwarp energy table
B1E6 4A       07618                 LSR A                   ;
B1E7 4A       07619                 LSR A                   ;
B1E8 AA       07620                 TAX                     ;
              07621
B1E9 98       07622                 TYA                     ; Load DISTANCE value
B1EA 2903     07623                 AND #$03                ; Get DISTANCE bits B1..0
B1EC 18       07624                 CLC                     ;
B1ED 7DDDBA   07625                 ADC WARPENERGYTAB,X     ; Add hyperwarp energy from table
B1F0 8591     07626                 STA WARPENERGY          ; Save hyperwarp energy
              07627
              07628 ;*** Update HYPERWARP ENERGY readout of Galactic Chart Panel Display ***********
B1F2 A8       07629                 TAY                     ; Prep with hyperwarp energy value
              07630
B1F3 A910     07631                 LDA #ROM.0              ; Set HYPERWARP ENERGY readout digit1..3 to '0'
B1F5 8D7D09   07632                 STA GCWARPD1            ;
B1F8 8D7E09   07633                 STA GCWARPD1+1          ;
B1FB 8D7F09   07634                 STA GCWARPD1+2          ;
              07635
B1FE A202     07636 LOOP053         LDX #2                  ; Loop over HYPERWARP ENERGY readout digit3..1
B200 FE7D09   07637 LOOP054         INC GCWARPD1,X          ; Increment digit value
B203 BD7D09   07638                 LDA GCWARPD1,X          ;
B206 C91A     07639                 CMP #ROM.9+1            ;
B208 9008     07640                 BCC SKIP173             ; Skip if energy digit <= '9'
              07641
B20A A910     07642                 LDA #ROM.0              ; Replace energy digit with '0'
B20C 9D7D09   07643                 STA GCWARPD1,X          ;
B20F CA       07644                 DEX                     ;
B210 10EE     07645                 BPL LOOP054             ; Next energy digit
              07646
B212 88       07647 SKIP173         DEY                     ; Decrement HYPERWARP ENERGY readout value
B213 D0E9     07648                 BNE LOOP053             ;
B215 60       07649                 RTS                     ; Return
              07650
              07651 ;*******************************************************************************
              07652 ;*                                                                             *
              07653 ;*                                  UPDTITLE                                   *
              07654 ;*                                                                             *
              07655 ;*                              Update title line                              *
              07656 ;*                                                                             *
              07657 ;*******************************************************************************
              07658
              07659 ; DESCRIPTION
              07660 ;
              07661 ; Updates the title phrase displayed in the title line.
              07662 ;
              07663 ; If no title phrase has been set then fetch the offset of the next ("enqueued")
              07664 ; title phrase to be displayed. If one has been set then code execution
              07665 ; continues into subroutine SETTITLE ($B223), otherwise code execution returns.
              07666 ;
              07667 ; If a title phrase has been set then decrement the lifetime of the currently
              07668 ; displayed title phrase segment. If its lifetime has reached a value of 0 then
              07669 ; branch to subroutine SETTITLE ($B223) to display the next segment.
              07670
B216 A5D1     07671 UPDTITLE        LDA TITLEPHR            ; Skip if no title phrase set
B218 F005     07672                 BEQ SKIP175             ;
              07673
B21A C6CF     07674                 DEC TITLELIFE           ; Decrement title phrase segment lifetime
B21C F010     07675                 BEQ SKIP176             ; If lifetime expired show next title segment
              07676
B21E 60       07677 SKIP174         RTS                     ; Return
              07678
B21F A465     07679 SKIP175         LDY NEWTITLEPHR         ; Prep enqueued new title phrase
B221 F0FB     07680                 BEQ SKIP174             ; Return if not set
              07681
              07682 ;*******************************************************************************
              07683 ;*                                                                             *
              07684 ;*                                  SETTITLE                                   *
              07685 ;*                                                                             *
              07686 ;*                       Set title phrase in title line                        *
              07687 ;*                                                                             *
              07688 ;*******************************************************************************
              07689
              07690 ; DESCRIPTION
              07691 ;
              07692 ; Displays a title phrase in the title line. 
              07693 ;
              07694 ; INTRODUCTION
              07695 ;
              07696 ; Title phrases are picked from the title phrase table PHRASETAB ($BBAA). They
              07697 ; consist of one or more phrase tokens. Each token is a byte representing a word
              07698 ; in word table WORDTAB ($BC2B). Two special tokens are placeholders for the
              07699 ; scored class ($FC) and scored rank ($FD) strings.
              07700 ;
              07701 ; A title phrase is split up into one or more title phrase segments, each
              07702 ; fitting into the title line. One title phrase segment is displayed after the
              07703 ; other after a delay called the "title segment lifetime".
              07704 ;
              07705 ; Phrase tokens, except the tokens for the scored class ($FC) and for the scored
              07706 ; rank ($FD), contain the number of a word in word table WORDTAB ($BC2B) and may
              07707 ; contain an end-of-segment or end-of-phrase marker bit.
              07708 ;
              07709 ; DETAILS
              07710 ;
              07711 ; The Display List is modified by subroutine MODDLST ($ADF1) to display the
              07712 ; title line. Then, the title line is cleared and the words of the title phrase
              07713 ; are copied into it using the passed offset into title phrase table PHRASETAB
              07714 ; ($BBAA). If the offset has a value of $FF the title line is hidden in
              07715 ; subroutine MODDLST ($ADF1). 
              07716 ;
              07717 ; INPUT
              07718 ;
              07719 ;   Y = Offset into title phrase table PHRASETAB ($BBAA). Used values are:
              07720 ;     $FF  -> Hide title line
              07721 ;     else -> Offset into title phrase table PHRASETAB ($BBAA), with explicitly
              07722 ;             used values:
              07723 ;
              07724 ;     $01 -> "COMPUTER ON"
              07725 ;     $04 -> "COMPUTER OFF"
              07726 ;     $07 -> "SHIELDS ON"
              07727 ;     $09 -> "SHIELDS OFF"
              07728 ;     $0B -> "COMPUTER TRACKING ON"
              07729 ;     $0E -> "TRACKING OFF"
              07730 ;     $13 -> "STARBASE SURROUNDED"
              07731 ;     $15 -> "STARBASE DESTROYED"
              07732 ;     $1F -> "DOCKING ABORTED"
              07733 ;     $21 -> "TRANSFER COMPLETE"
              07734 ;     $4A -> "NOVICE MISSION"
              07735 ;     $4C -> "PILOT MISSION"
              07736 ;     $4E -> "WARRIOR MISSION"
              07737 ;     $50 -> "COMMANDER MISSION"
              07738 ;     $52 -> "DAMAGE CONTROL..."
              07739 ;     $75 -> "RED ALERT"
              07740
    =006A     07741 L.WORD          = $6A                   ; Saves word number of WORDTAB ($BC2A). Used values
              07742                                         ; are $00..$3F.
    =006B     07743 L.COLUMNPOS     = $6B                   ; Saves cursor column position during copying text
              07744                                         ; into title line
    =006C     07745 L.TOKEN         = $6C                   ; Saves title phrase token, contains bit-encoded
              07746                                         ; information about one word in the title phrase:
              07747                                         ; B7..6 = %00 -> Copy next word to title line
              07748                                         ; B7..6 = %01 -> End-of-phrase reached. Title
              07749                                         ;                segment lifetime = 60 game loops
              07750                                         ; B7..6 = %10 -> End-of-segment reached. Title
              07751                                         ;                segment lifetime = 60 game loops
              07752                                         ; B7..6 = %11 -> End-of-phrase reached. Title
              07753                                         ;                segment lifetime = 254 game loops
              07754                                         ;                Used with title phrases
              07755                                         ;                  "STARBASE SURROUNDED"
              07756                                         ;                  "STARBASE DESTROYED"
              07757                                         ;                  "HYPERSPACE"
              07758                                         ;                  "RED ALERT"
              07759                                         ; B5..0       -> Word number of WORDTAB ($BC2A)
              07760
B223 84D1     07761 SETTITLE        STY TITLEPHR            ; Save title phrase offset
              07762
B225 A023     07763                 LDY #$23                ; Show title line
B227 A20F     07764                 LDX #$0F                ;
B229 A907     07765                 LDA #$07                ;
B22B 20F1AD   07766                 JSR MODDLST             ;
              07767
              07768 ;*** Init cursor column position and clear title line **************************
B22E A213     07769 SKIP176         LDX #19                 ; There are 19(+1) characters to clear
B230 A900     07770                 LDA #0                  ;
B232 856B     07771                 STA L.COLUMNPOS         ; Init cursor column position
              07772
B234 9D1F0D   07773 LOOP055         STA TITLETXT,X          ; Clear character in title line
B237 CA       07774                 DEX                     ;
B238 10FA     07775                 BPL LOOP055             ;
              07776
              07777 ;*** If title phrase offset = $FF then hide title line *************************
B23A A6D1     07778 SKIP177         LDX TITLEPHR            ; Load title phrase offset
B23C E6D1     07779                 INC TITLEPHR            ; Prepare title phrase offset for next word
B23E D009     07780                 BNE SKIP178             ; ...skip if it turned 0
              07781
B240 A20F     07782                 LDX #$0F                ; Remove title line and return
B242 A080     07783                 LDY #$80                ;
B244 A907     07784                 LDA #$07                ;
B246 4CF1AD   07785                 JMP MODDLST             ;
              07786
B249 BDAABB   07787 SKIP178         LDA PHRASETAB,X         ; Get phrase token
              07788
              07789 ;*** Display scrored class? ****************************************************
B24C C9FC     07790                 CMP #$FC                ; Skip if not "scored class" token
B24E D00F     07791                 BNE SKIP179             ;
              07792
B250 A4CE     07793                 LDY SCOREDCLASSIND      ; Get scored class index, is in 0..15
B252 B9FCBE   07794                 LDA CLASSTAB,Y          ; Load scored class number digit
B255 A66B     07795                 LDX L.COLUMNPOS         ; Load cursor position
B257 9D1F0D   07796                 STA TITLETXT,X          ; Store class in title line
B25A A93C     07797                 LDA #60                 ; Title segment lifetime := 60 game loops
B25C 85CF     07798                 STA TITLELIFE           ;
B25E 60       07799                 RTS                     ; Return
              07800
              07801 ;*** Display scdored rank? *****************************************************
B25F C9FD     07802 SKIP179         CMP #$FD                ; Skip if not "scored rank" token
B261 D005     07803                 BNE SKIP180             ;
              07804
B263 A4CD     07805                 LDY SCOREDRANKIND       ; Get scored rank index, is in 0..18
B265 B9E9BE   07806                 LDA RANKTAB,Y           ; Load rank word number
              07807
              07808 ;*** Search word of token in word table ****************************************
B268 856C     07809 SKIP180         STA L.TOKEN             ; Save phrase token
B26A 293F     07810                 AND #$3F                ; Strip bits B6..7 from phrase token
B26C 856A     07811                 STA L.WORD              ; Store word number (bits B5..0)
              07812
B26E A92A     07813                 LDA #<[WORDTAB-1]       ; Point MEMPTR to WORDTAB-1
B270 8568     07814                 STA MEMPTR              ;
B272 A9BC     07815                 LDA #>[WORDTAB-1]       ;
B274 8569     07816                 STA MEMPTR+1            ;
              07817
B276 E668     07818 LOOP056         INC MEMPTR              ; Increment MEMPTR
B278 D002     07819                 BNE SKIP181             ;
B27A E669     07820                 INC MEMPTR+1            ;
              07821
B27C A000     07822 SKIP181         LDY #0                  ;
B27E B168     07823                 LDA (MEMPTR),Y          ; Load character of word
B280 10F4     07824                 BPL LOOP056             ; Loop until end-of-word marker (bit B7) found
B282 C66A     07825                 DEC L.WORD              ;
B284 D0F0     07826                 BNE LOOP056             ; Loop until word found
              07827
              07828 ;*** Copy word to title line, add space ****************************************
B286 293F     07829 LOOP057         AND #$3F                ; Strip color bits B6..7 from character
B288 49A0     07830                 EOR #CCS.COL2!$20       ; Merge COLOR2 bits and convert to ATASCII
B28A A66B     07831                 LDX L.COLUMNPOS         ; Copy character to title line
B28C E66B     07832                 INC L.COLUMNPOS         ; Increment cursor column position
B28E 9D1F0D   07833                 STA TITLETXT,X          ;
B291 C8       07834                 INY                     ;
B292 B168     07835                 LDA (MEMPTR),Y          ; Load next character of word
B294 10F0     07836                 BPL LOOP057             ; Next character of word if no end-of-word marker
B296 E66B     07837                 INC L.COLUMNPOS         ; Word was copied. Add space after word
              07838
              07839 ;*** Decide to copy another word, etc. *****************************************
B298 A93C     07840                 LDA #60                 ; SUMMARY:
B29A 246C     07841                 BIT L.TOKEN             ; If bits B7..6 of phrase token...
B29C 1004     07842                 BPL SKIP182             ; %00 -> Copy next word to title line
B29E 5008     07843                 BVC SKIP183             ; %01 -> End-of-phrase reached.
B2A0 A9FE     07844                 LDA #254                ;        Title segment lifetime := 60 game loops
B2A2 5096     07845 SKIP182         BVC SKIP177             ; %10 -> End-of-segment reached.
B2A4 A0FF     07846                 LDY #$FF                ;        Title segment lifetime := 60 game loops
B2A6 84D1     07847                 STY TITLEPHR            ; %11 -> End-of-phrase reached.
B2A8 85CF     07848 SKIP183         STA TITLELIFE           ;        Title segment lifetime := 254 game loops
B2AA 60       07849                 RTS                     ; Return
              07850
              07851 ;*******************************************************************************
              07852 ;*                                                                             *
              07853 ;*                                    SOUND                                    *
              07854 ;*                                                                             *
              07855 ;*                            Handles sound effects                            *
              07856 ;*                                                                             *
              07857 ;*******************************************************************************
              07858
              07859 ; DESCRIPTION
              07860 ;
              07861 ; This subroutine handles the sound effects. It is called every vertical blank
              07862 ; phase, that is, every TICK (1/60 s on an NTSC ATARI Home Computer system, 1/50
              07863 ; s on a PAL ATARI Home Computer system) from the Vertical Blank Interrupt
              07864 ; handler VBIHNDLR ($A6D1).
              07865 ;
              07866 ; The program uses all of the available 4 audio channels: Audio channels 1, 2,
              07867 ; and 3 are shared among the Engines sound effects and the "noise sound
              07868 ; patterns" (explosion and photon torpedo sound effects), while audio channel 4
              07869 ; is used for "beeper sound patterns" (status report sound effects). The
              07870 ; following sections explain the beeper sound patterns and the noise sound
              07871 ; patterns:
              07872 ;
              07873 ; o   BEEPER SOUND PATTERNS
              07874 ;
              07875 ;     There are the following beeper sound patterns:
              07876 ;
              07877 ;     (1)  HYPERWARP TRANSIT
              07878 ;     (2)  RED ALERT
              07879 ;     (3)  ACKNOWLEDGE
              07880 ;     (4)  DAMAGE REPORT
              07881 ;     (5)  MESSAGE FROM STARBASE
              07882 ;
              07883 ;     They are encoded in table BEEPPATTAB ($BF3E) in 6-byte long "beeper sound
              07884 ;     patterns". 
              07885 ;
              07886 ;     Another table, BEEPFRQTAB ($BF5C), stores the frequencies for the tones
              07887 ;     of each beeper sound pattern, terminated by a marker byte ($FF).
              07888 ;
              07889 ;     BUG (at $BF5C): The pattern frequencies in table BEEPFRQTAB ($BF5C) at
              07890 ;     offset $00 are unused. Suggested Fix: Remove from code.
              07891 ;
              07892 ;     Whenever the program calls subroutine BEEP ($B3A6), that subroutine sets
              07893 ;     up a beeper sound pattern for playing by copying 6 bytes from the pattern
              07894 ;     table BEEPPATTAB ($BF3E) to BEEPFRQIND ($D2)..BEEPFRQSTART ($D7).
              07895 ;     Subroutine SOUND ($B2AB) detects the copied beeper sound pattern and plays
              07896 ;     the encoded tones and pauses.
              07897 ;
              07898 ;     The relevant variables for playing a beeper sound pattern are the
              07899 ;     following (see also figures at BEEPPATTAB ($BF3E)):
              07900 ;
              07901 ;     BEEPFRQIND    ($D2)   = Running index into table BEEPFRQTAB ($BF5C)
              07902 ;     BEEPREPEAT    ($D3)   = Number of times that the beeper sound pattern is
              07903 ;                             repeated - 1
              07904 ;     BEEPTONELIFE  ($D4)   = Lifetime of tone in TICKs - 1
              07905 ;     BEEPPAUSELIFE ($D5)   = Lifetime of pause in TICKs - 1 ($FF -> No pause)
              07906 ;     BEEPPRIORITY  ($D6)   = Beeper sound pattern priority. A playing beeper
              07907 ;                             sound pattern is stopped if a beeper sound pattern
              07908 ;                             of higher priority is about to be played. A value
              07909 ;                             of 0 indicates that no beeper sound pattern is
              07910 ;                             playing at the moment.
              07911 ;     BEEPFRQSTART  ($D7)   = Index to first byte of the beeper sound pattern in
              07912 ;                             table BEEPFRQTAB ($BF5C)
              07913 ;
              07914 ;     BEEPLIFE      ($D8)   = Lifetime of the current tone or pause in TICKs
              07915 ;     BEEPTOGGLE    ($D9)   = Indicates that either a tone (0) or a pause (not
              07916 ;                             0) is currently playing.
              07917 ;
              07918 ; o   NOISE SOUND PATTERNS
              07919 ;
              07920 ;     There are the following noise sound patterns:
              07921 ;
              07922 ;     (1)  PHOTON TORPEDO LAUNCHED
              07923 ;     (2)  SHIP EXPLOSION
              07924 ;     (3)  ZYLON EXPLOSION
              07925 ;
              07926 ;     They are encoded in table NOISEPATTAB ($BF20) in 10-byte long "noise sound
              07927 ;     patterns". 
              07928 ;
              07929 ;     Whenever the program calls subroutine NOISE ($AEA8), that subroutine  sets
              07930 ;     up a noise sound pattern for being played by copying 10 bytes from the
              07931 ;     pattern table NOISEPATTAB ($BF20) to NOISETORPTIM ($DA)..NOISELIFE ($E1)
              07932 ;     and hardware sound registers AUDCTL ($D208) and AUDF3 ($D204).
              07933 ;
              07934 ;     The relevant variables for playing a noise sound pattern are the
              07935 ;     following:
              07936 ;
              07937 ;     NOISETORPTIM  ($DA)   = Timer for PHOTON TORPEDO LAUNCHED noise sound
              07938 ;                             pattern
              07939 ;     NOISEEXPLTIM  ($DB)   = Timer for SHIP EXPLOSION and ZYLON EXPLOSION noise
              07940 ;                             sound patterns
              07941 ;     NOISEAUDC2    ($DC)   = Audio channel 1/2 control shadow register
              07942 ;     NOISEAUDC3    ($DD)   = Audio channel 3   control shadow register
              07943 ;     NOISEAUDF1    ($DE)   = Audio channel 1 frequency shadow register
              07944 ;     NOISEAUDF2    ($DF)   = Audio channel 2 frequency shadow register
              07945 ;     NOISEFRQINC   ($E0)   = Audio channel 1/2 frequency increment
              07946 ;     NOISELIFE     ($E1)   = Noise sound pattern lifetime
              07947 ;
              07948 ;     AUDCTL        ($D208) = POKEY: Audio control
              07949 ;     AUDF3         ($D204) = POKEY: Audio channel 3 frequency audio register
              07950 ;
              07951 ;     There are two more variables that trigger noise effects. They are not part
              07952 ;     of the noise sound pattern table:
              07953 ;
              07954 ;     NOISEZYLONTIM ($E2)  = Timer to trigger the ZYLON EXPLOSION noise sound
              07955 ;                            pattern. It is set in subroutine COLLISION ($AF3D)
              07956 ;                            when the impact of one of our starship's photon
              07957 ;                            torpedoes with a target is imminent. The timer is
              07958 ;                            decremented every TICK. When it reaches a value of
              07959 ;                            0 the ZYLON EXPLOSION noise sound pattern is played
              07960 ;                            in subroutine SOUND ($B2AB). 
              07961 ;     NOISEHITLIFE ($E3)   = Lifetime of a special explosion noise when our
              07962 ;                            starship was hit by a Zylon photon torpedo. It is
              07963 ;                            set in GAMELOOP ($A1F3) to a value of 64 TICKs.
              07964 ;                            When it reaches a value of 0 a special ship
              07965 ;                            explosion noise is played in subroutine SOUND
              07966 ;                            ($B2AB).
              07967 ;
              07968 ; SUBROUTINE DETAILS
              07969 ;
              07970 ; This subroutine executes the following steps:
              07971 ;
              07972 ; (1)  Play beeper sound pattern
              07973 ;
              07974 ;      The playing of a beeper sound pattern is started, continued, or stopped.
              07975 ;
              07976 ; (2)  Play ZYLON EXPLOSION noise sound pattern
              07977 ;
              07978 ;      If the explosion of a target space object is imminent (subroutine
              07979 ;      COLLISION ($AF3D) has set NOISEZYLONTIM ($E2) to the number of game loop
              07980 ;      iterations that will pass until our starship's photon torpedo will hit
              07981 ;      the target), the timer NOISEZYLONTIM ($E2) is decremented every TICK. If
              07982 ;      it reaches a value of 0, then the noise sound pattern ZYLON EXPLOSION is
              07983 ;      played.
              07984 ;
              07985 ; (3)  Play starship's Engines sound
              07986 ;
              07987 ;      If the Engines are louder than the current noise sound pattern then the
              07988 ;      noise sound pattern is terminated and the values for the audio channels
              07989 ;      1..3 are updated: 
              07990 ;
              07991 ;      The velocity of our starship determines the pitch and the volume of the
              07992 ;      Engines: the higher the velocity, the higher the pitch and the volume of
              07993 ;      the Engines. The incremented value of VELOCITYLO ($70) is used as a "base
              07994 ;      value" %abcdefgh.
              07995 ;
              07996 ;      Audio channels 1 and 2 are combined to a 16-bit audio channel 1/2,
              07997 ;      clocked at 1.79 MHz. The inverted bits (represented by an overscore)
              07998 ;      B7..0 of the base value form bits B12..5 of the 16-bit frequency value of
              07999 ;      audio channel 1/2. Bits B7..4 of the base value form bits B3..0 of the
              08000 ;      volume of audio channel 1/2, with noise distortion bit B7 set:
              08001 ;                               ________
              08002 ;      AUDF1/2 ($D202..3) := %000abcdefgh00000
              08003 ;      AUDC2   ($D203)    := %1000abcd
              08004 ;
              08005 ;      Audio channel 3 is also clocked at 1.79 MHz. The inverted bits B7..0 of
              08006 ;      the base value form bits B7..0 of the frequency value of audio channel 3.
              08007 ;      Bits B6..4 of the base value form bits B3..0 of the volume of audio
              08008 ;      channel 3, with noise distortion bit B7 set:
              08009 ;                            ________
              08010 ;      AUDF3   ($D204)    := %abcdefgh
              08011 ;      AUDC3   ($D205)    := %10000bcd
              08012 ;
              08013 ;      Code execution returns at this point.
              08014 ;
              08015 ; (4)  Play ZYLON EXPLOSION or SHIP EXPLOSION noise sound pattern
              08016 ;
              08017 ;      If the ZYLON EXPLOSION or SHIP EXPLOSION noise sound pattern was set up,
              08018 ;      the explosion noise timer NOISEEXPLTIM ($DB) is decremented every TICK.
              08019 ;      It starts either with a value of 4 TICKs with a ZYLON EXPLOSION noise
              08020 ;      sound pattern or with a value of 8 TICKs with a SHIP EXPLOSION noise
              08021 ;      sound pattern, set up in subroutine NOISE ($AEA8). If it reaches a value
              08022 ;      of 0, then the shadow control register of audio channel 1/2 switches to
              08023 ;      "noise distortion" at maximum volume.
              08024 ;
              08025 ; (5)  Play PHOTON TORPEDO LAUNCHED noise sound pattern
              08026 ;
              08027 ;      If the PHOTON TORPEDO LAUNCHED noise sound pattern was set up, the photon
              08028 ;      torpedo noise timer NOISETORPTIM ($DA) is decremented every TICK. It
              08029 ;      starts with a value of 8 TICKs, set in subroutine TRIGGER ($AE29). The
              08030 ;      noise distortion and volume for the shadow control register of audio
              08031 ;      channel 3 is picked from table NOISETORPVOLTAB ($BFEB), the noise
              08032 ;      frequency for audio channel 3 is picked from table NOISETORPFRQTAB
              08033 ;      ($BFF3). If the photon torpedo noise timer reaches a value of 0, then the
              08034 ;      shadow control registers of audio channel 1/2 switch to "tone distortion"
              08035 ;      at maximum volume and a frequency of $0202.
              08036 ;
              08037 ;      NOTE: Using a real-time volume envelope stored in table NOISETORPVOLTAB
              08038 ;      ($BFEB) for a launched photon torpedo results in the distinctive
              08039 ;      "whooshing" photon torpedo sound.
              08040 ;
              08041 ; (6)  Play special ship explosion noise
              08042 ;
              08043 ;      If our starship was hit by a Zylon photon torpedo then NOISEHITLIFE ($E3)
              08044 ;      was set to 64 TICKs in routine GAMELOOP ($A1F3). While this value is
              08045 ;      decremented every TICK, a random frequency value is stored to audio
              08046 ;      channel 3 and the distortion bit of the shadow control register of audio
              08047 ;      channel 3 is randomly toggled.
              08048 ;
              08049 ; (7)  Increase audio channels 1/2 frequency
              08050 ;
              08051 ;      The 16-bit frequency value of audio channels 1/2 (both shadow registers
              08052 ;      and audio registers) is increased every TICK by an increment picked from
              08053 ;      the currently playing noise sound pattern.
              08054 ;
              08055 ; (8)  Mute audio channels gradually
              08056 ;
              08057 ;      Toward the end of a noise sound pattern's lifetime all audio channels
              08058 ;      gradually mute their volume every other TICK until completely silent. 
              08059
              08060 ;*** Play beeper sound pattern *************************************************
B2AB A5D6     08061 SOUND           LDA BEEPPRIORITY        ; Skip if beeper sound pattern not in use
B2AD F037     08062                 BEQ SKIP185             ;
              08063
B2AF C6D8     08064                 DEC BEEPLIFE            ; Decrement beeper lifetime
B2B1 1033     08065                 BPL SKIP185             ; Skip if beeper lifetime still counting down
              08066
B2B3 A5D9     08067                 LDA BEEPTOGGLE          ; Load tone/pause toggle
B2B5 F00A     08068                 BEQ LOOP058             ; Skip if a tone is playing or is to be played
              08069
B2B7 A5D5     08070                 LDA BEEPPAUSELIFE       ; Load pause lifetime
B2B9 3006     08071                 BMI LOOP058             ; Skip if duration = $FF (no pause)
B2BB 85D8     08072                 STA BEEPLIFE            ; Store pause lifetime as beeper lifetime
B2BD A000     08073                 LDY #0                  ; Prep AUDC4 (zero volume)
B2BF F020     08074                 BEQ SKIP184             ; Skip unconditionally
              08075
B2C1 A5D4     08076 LOOP058         LDA BEEPTONELIFE        ; Load tone lifetime
B2C3 85D8     08077                 STA BEEPLIFE            ; Store tone lifetime as beeper lifetime
B2C5 A6D2     08078                 LDX BEEPFRQIND          ; Load frequency index
B2C7 E6D2     08079                 INC BEEPFRQIND          ; Increment frequency index
B2C9 BD5CBF   08080                 LDA BEEPFRQTAB,X        ; Store tone frequency from frequency table in AUDF4
B2CC 8D06D2   08081                 STA AUDF4               ;
B2CF A0A8     08082                 LDY #$A8                ; Prep AUDC4 (tone distortion + medium volume)
B2D1 C9FF     08083                 CMP #$FF                ; Skip if frequency not $FF (there are more tones)
B2D3 D00C     08084                 BNE SKIP184             ;
              08085
B2D5 A5D7     08086                 LDA BEEPFRQSTART        ; Rewind pattern frequency pointer
B2D7 85D2     08087                 STA BEEPFRQIND          ;
B2D9 C6D3     08088                 DEC BEEPREPEAT          ; Decrement sequence counter
B2DB 10E4     08089                 BPL LOOP058             ; Keep playing until sequence counter < 0
              08090
B2DD A000     08091                 LDY #0                  ; Prep AUDC4 with zero volume
B2DF 84D6     08092                 STY BEEPPRIORITY        ; Stop playing beeper sound pattern
              08093
B2E1 8C07D2   08094 SKIP184         STY AUDC4               ; Store in AUDC4
B2E4 84D9     08095                 STY BEEPTOGGLE          ; Store in BEEPTOGGLE
              08096
              08097 ;*** Play ZYLON EXPLOSION noise sound pattern **********************************
B2E6 A5E2     08098 SKIP185         LDA NOISEZYLONTIM       ; Skip if ZYLON EXPLOSION timer not in use
B2E8 F009     08099                 BEQ SKIP186             ;
              08100
B2EA C6E2     08101                 DEC NOISEZYLONTIM       ; Decrement ZYLON EXPLOSION timer
B2EC D005     08102                 BNE SKIP186             ; Skip if ZYLON EXPLOSION timer still counting down
              08103
B2EE A214     08104                 LDX #$14                ; Play noise sound pattern ZYLON EXPLOSION
B2F0 20A8AE   08105                 JSR NOISE               ;
              08106
              08107 ;*** Play our starship's Engines sound *****************************************
B2F3 A670     08108 SKIP186         LDX VELOCITYLO          ; Skip if Engines softer than noise sound pattern
B2F5 8A       08109                 TXA                     ;
B2F6 4A       08110                 LSR A                   ;
B2F7 4A       08111                 LSR A                   ;
B2F8 4A       08112                 LSR A                   ;
B2F9 4A       08113                 LSR A                   ;
B2FA 4A       08114                 LSR A                   ;
B2FB C5E1     08115                 CMP NOISELIFE           ;
B2FD 902C     08116                 BCC SKIP187             ;
              08117
B2FF A900     08118                 LDA #0                  ; Terminate noise sound pattern
B301 85E1     08119                 STA NOISELIFE           ;
              08120
B303 E8       08121                 INX                     ;
B304 8A       08122                 TXA                     ; A := %abcdefgh = VELOCITYLO + 1
B305 49FF     08123                 EOR #$FF                ;           ________
B307 8D04D2   08124                 STA AUDF3               ; AUDF3 := %abcdefgh
              08125
B30A AA       08126                 TAX                     ;                ________
B30B 0A       08127                 ASL A                   ; AUDF2/1 := %000abcdefgh00000
B30C 0A       08128                 ASL A                   ;
B30D 0A       08129                 ASL A                   ;
B30E 0A       08130                 ASL A                   ;
B30F 0A       08131                 ASL A                   ;
B310 8D00D2   08132                 STA AUDF1               ;
B313 8A       08133                 TXA                     ;
B314 4A       08134                 LSR A                   ;
B315 4A       08135                 LSR A                   ;
B316 4A       08136                 LSR A                   ;
B317 8D02D2   08137                 STA AUDF2               ;
              08138
B31A 4A       08139                 LSR A                   ; AUDC2 := %1000abcd
B31B 498F     08140                 EOR #$8F                ; (noise distortion + B7..B4 bits for volume)
B31D 8D03D2   08141                 STA AUDC2               ;
              08142
B320 2987     08143                 AND #$87                ; AUDC3 := %10000bcd
B322 8D05D2   08144                 STA AUDC3               ; (noise distortion + B6..B4 bits for volume)
              08145
B325 A970     08146                 LDA #$70                ; Clock audio channel 1 and 3 @ 1.79 MHz and...
B327 8D08D2   08147                 STA AUDCTL              ; ...combine audio channel 1/2 to 16-bit channel
              08148
B32A 60       08149                 RTS                     ; Return
              08150
              08151 ;*** Play ZYLON EXPLOSION or SHIP EXPLOSION noise ******************************
B32B A5DB     08152 SKIP187         LDA NOISEEXPLTIM        ; Skip if explosion noise timer not in use
B32D F008     08153                 BEQ SKIP188             ;
              08154
B32F C6DB     08155                 DEC NOISEEXPLTIM        ; Decrement explosion noise timer (4 or 8 TICKs long)
B331 D004     08156                 BNE SKIP188             ; Skip if explosion noise timer still counting down
              08157
B333 A98F     08158                 LDA #$8F                ; Shadow register AUDC2 := (noise dist. + max volume)
B335 85DC     08159                 STA NOISEAUDC2          ;
              08160
              08161 ;*** Play PHOTON TORPEDO LAUNCHED noise sound **********************************
B337 A6DA     08162 SKIP188         LDX NOISETORPTIM        ; Skip if photon torpedo noise timer not in use
B339 F01C     08163                 BEQ SKIP190             ;
              08164
B33B C6DA     08165                 DEC NOISETORPTIM        ; Decrement photon torpedo noise timer (8 TICKs long)
B33D D00A     08166                 BNE SKIP189             ; Skip if torpedo noise timer still counting down
              08167
B33F A9AF     08168                 LDA #$AF                ; Shadow register AUDC2 := (tone dist. + max volume)
B341 85DC     08169                 STA NOISEAUDC2          ;
B343 A902     08170                 LDA #$02                ; Set frequency $0202 to AUDF1/2's shadow...
B345 85DE     08171                 STA NOISEAUDF1          ; ...registers
B347 85DF     08172                 STA NOISEAUDF2          ;
              08173
B349 BDEABF   08174 SKIP189         LDA NOISETORPVOLTAB-1,X ; Pick torpedo noise + volume shape (X in 1..8)...
B34C 85DD     08175                 STA NOISEAUDC3          ; ...and store it in AUDC3's shadow register
B34E BDF2BF   08176                 LDA NOISETORPFRQTAB-1,X ; Pick photon torpedo noise frequency (X in 1..8)...
B351 8D04D2   08177                 STA AUDF3               ; ...and store it in AUDF3
B354 8D09D2   08178                 STA STIMER              ; Reset POKEY audio timers
              08179
              08180 ;*** Play special explosion noise when our starship is hit *********************
B357 A5E3     08181 SKIP190         LDA NOISEHITLIFE        ; Skip if special explosion noise not in use
B359 F00E     08182                 BEQ SKIP191             ;
              08183
B35B C6E3     08184                 DEC NOISEHITLIFE        ; Decrement special ship explosion noise lifetime
B35D AD0AD2   08185                 LDA RANDOM              ; Set random frequency to AUDF3
B360 8D04D2   08186                 STA AUDF3               ;
B363 2920     08187                 AND #$20                ; Toggle noise/tone dist. of AUDC3's shadow register
B365 45DD     08188                 EOR NOISEAUDC3          ; ...randomly
B367 85DD     08189                 STA NOISEAUDC3          ;
              08190
              08191 ;*** Increase 16-bit frequency of audio channels 1/2 (shadow registers also) ***
B369 18       08192 SKIP191         CLC                     ; Increase 16-bit frequency value of AUDF1/2...
B36A A5DE     08193                 LDA NOISEAUDF1          ; ...and its shadow register by...
B36C 65E0     08194                 ADC NOISEFRQINC         ; ...noise sound pattern frequency increment
B36E 85DE     08195                 STA NOISEAUDF1          ; AUDF1/2 := NOISEAUDF1/2 := ...
B370 8D00D2   08196                 STA AUDF1               ; ...NOISEAUDF1/2 + NOISEFRQINC
B373 A5DF     08197                 LDA NOISEAUDF2          ;
B375 6900     08198                 ADC #0                  ;
B377 85DF     08199                 STA NOISEAUDF2          ;
B379 8D02D2   08200                 STA AUDF2               ;
              08201
              08202 ;*** Gradually mute audio channels while noise sound pattern expires ***********
B37C A6DC     08203                 LDX NOISEAUDC2          ; Prep AUDC2's shadow register value
B37E A4DD     08204                 LDY NOISEAUDC3          ; Prep AUDC3's shadow register value
              08205
B380 A572     08206                 LDA COUNT8              ; Decrement volumes every other TICK
B382 4A       08207                 LSR A                   ;
B383 901A     08208                 BCC SKIP193             ;
              08209
B385 A5E1     08210                 LDA NOISELIFE           ; Skip if noise sound pattern not in use
B387 F016     08211                 BEQ SKIP193             ;
              08212
B389 C6E1     08213                 DEC NOISELIFE           ; Decrement noise sound pattern lifetime
              08214
B38B C911     08215                 CMP #17                 ; Mute noise sound pattern only in...
B38D B010     08216                 BCS SKIP193             ; ...the last 16 TICKs of its lifetime
              08217
B38F 8A       08218                 TXA                     ; Decrement volume of AUDC2's shadow register
B390 290F     08219                 AND #$0F                ;
B392 F003     08220                 BEQ SKIP192             ;
B394 CA       08221                 DEX                     ;
B395 86DC     08222                 STX NOISEAUDC2          ;
              08223
B397 98       08224 SKIP192         TYA                     ; Decrement volume of AUDC3's shadow register
B398 290F     08225                 AND #$0F                ;
B39A F003     08226                 BEQ SKIP193             ;
B39C 88       08227                 DEY                     ;
B39D 84DD     08228                 STY NOISEAUDC3          ;
              08229
B39F 8E03D2   08230 SKIP193         STX AUDC2               ; Store shadow register values to audio registers
B3A2 8C05D2   08231                 STY AUDC3               ;
              08232
B3A5 60       08233                 RTS                     ; Return
              08234
              08235 ;*******************************************************************************
              08236 ;*                                                                             *
              08237 ;*                                    BEEP                                     *
              08238 ;*                                                                             *
              08239 ;*                          Copy beeper sound pattern                          *
              08240 ;*                                                                             *
              08241 ;*******************************************************************************
              08242
              08243 ; DESCRIPTION
              08244 ;
              08245 ; Copies a 6-byte beeper sound pattern from beeper sound pattern table
              08246 ; BEEPPATTAB ($BF3E) to BEEPFRQIND ($D2)..BEEPFRQSTART ($D7), provided that no
              08247 ; beeper sound pattern with higher priority is currently playing. The beeper
              08248 ; sound pattern will then be automatically played in subroutine SOUND ($B2AB).
              08249 ; See subroutine SOUND ($B2AB) for more information on beeper sound patterns. 
              08250 ;
              08251 ; NOTE: The bytes from table BEEPPATTAB ($BF3E) are copied in reverse order.
              08252 ;
              08253 ; INPUT
              08254 ;
              08255 ;   X = Offset to beeper sound pattern in table BEEPPATTAB ($BF3E). Used values
              08256 ;       are:
              08257 ;     $00 -> HYPERWARP TRANSIT
              08258 ;     $06 -> RED ALERT
              08259 ;     $0C -> ACKNOWLEDGE
              08260 ;     $12 -> DAMAGE REPORT
              08261 ;     $18 -> MESSAGE FROM STARBASE
              08262
B3A6 BD3EBF   08263 BEEP            LDA BEEPPATTAB,X        ; Return if beeper sound pattern of...
B3A9 C5D6     08264                 CMP BEEPPRIORITY        ; ...higher priority is playing
B3AB 900C     08265                 BCC SKIP194             ;
              08266
B3AD A005     08267                 LDY #5                  ; Copy 6-byte beeper sound pattern (in reverse order)
B3AF BD3EBF   08268 LOOP059         LDA BEEPPATTAB,X        ;
B3B2 99D200   08269                 STA BEEPFRQIND,Y        ;
B3B5 E8       08270                 INX                     ;
B3B6 88       08271                 DEY                     ;
B3B7 10F6     08272                 BPL LOOP059             ;
              08273
B3B9 60       08274 SKIP194         RTS                     ; Return
              08275
              08276 ;*******************************************************************************
              08277 ;*                                                                             *
              08278 ;*                                 INITIALIZE                                  *
              08279 ;*                                                                             *
              08280 ;*                          More game initialization                           *
              08281 ;*                                                                             *
              08282 ;*******************************************************************************
              08283
              08284 ; DESCRIPTION
              08285 ;
              08286 ; This subroutine executes the following initialization steps:
              08287 ;
              08288 ; (1)  Set up Display List
              08289 ;
              08290 ;      A Display List is created at DSPLST ($0280). It starts with 2 x 8 = 16
              08291 ;      blank video lines, followed by 90 GRAPHICS7 rows. After a deliberate gap
              08292 ;      in Display List instructions, which will be filled dynamically during the
              08293 ;      game by calls to subroutine MODDLST ($ADF1), it ends with a Display List
              08294 ;      wait-and-jump-back instruction to the start of the Display List at DSPLST
              08295 ;      ($0280).
              08296 ;
              08297 ;      NOTE: The PLAYFIELD color table PFCOLORTAB ($BFA9) is copied to zero-page
              08298 ;      table PF0COLOR ($F2) by loop jamming.
              08299 ;
              08300 ; (2)  Create lookup tables
              08301 ;
              08302 ;      The first lookup table MAPTO80 ($0DE9) maps a byte value of 0..255 to
              08303 ;      0..80. This table is used to map unsigned (absolute) position vector
              08304 ;      components (coordinates) to pixel (or PLAYER) row and column numbers.
              08305 ;
              08306 ;      NOTE: The PLAYFIELD is 160 pixels wide. Pixel column numbers relative the
              08307 ;      horizontal PLAYFIELD center are in -80..79, hence the range of this
              08308 ;      lookup table. Pixel row numbers relative the vertical PLAYFIELD center
              08309 ;      are in -50..49, thus they also fit in the range of this lookup table.
              08310 ;
              08311 ;      The second lookup table MAPTOBCD99 ($0EE9) maps a byte value of 0..255 to
              08312 ;      a BCD-encoded value in 00..99. This table is used to convert byte values
              08313 ;      into decimal 2-digit values displayed by the THETA (in "gradons"), PHI
              08314 ;      (in "gradons"), RANGE (in "centrons"), and VELOCITY (in "metrons per
              08315 ;      second") readouts of the Console Panel Display.
              08316 ;
              08317 ;      The third and fourth lookup tables accelerate drawing of PLAYFIELD space
              08318 ;      objects: In combination they contain the 16-bit start addresses of each
              08319 ;      of the 100 rows of PLAYFIELD memory. The low bytes of the 16-bit
              08320 ;      addresses are stored in table PFMEMROWLO ($0800). The high bytes are
              08321 ;      stored in table PFMEMROWHI ($0864).
              08322 ;
              08323 ;      NOTE: The address increment is 40 (40 bytes = 160 pixels in GRAPHICS7
              08324 ;      mode = 1 PLAYFIELD row of pixels). 
              08325 ;
              08326 ;      NOTE: The PLAYFIELD consists of 90 GRAPHICS7 rows when the Control Panel
              08327 ;      Display is displayed at the bottom. When the Control Panel Display is not
              08328 ;      displayed, for example in demo mode, the PLAYFIELD contains additional
              08329 ;      GRAPHICS7 rows.  
              08330 ;
              08331 ; (3)  Copy Control Panel Display and Galactic Chart Panel Display texts
              08332 ;
              08333 ;      The texts of the Control Panel Display and the Galactic Chart Panel
              08334 ;      Display are copied to their respective locations in memory by loop
              08335 ;      jamming.
              08336 ;
              08337 ; (4)  Initialize Zylon unit movement timer
              08338 ;
              08339 ;      The timer that triggers the movement of Zylon units in the Galactic Chart
              08340 ;      is initialized to a value of 99. See subroutine FLUSHGAMELOOP ($B4E4) for
              08341 ;      more information on Zylon unit movement.
              08342 ;
              08343 ; (5)  Create Galactic Chart
              08344 ;
              08345 ;      The Galactic Chart memory map GCMEMMAP ($08C9) is initialized. It
              08346 ;      represents 16 columns x 8 rows of sectors. Each sector contains one of
              08347 ;      the 4 sector types stored in table SECTORTYPETAB ($BBA6) (starbase, 4
              08348 ;      Zylon ships, 3 Zylon ships, and 2 or 1 Zylon ships), and empty sectors.
              08349 ;      Before distributing the sector types, the initial position of our
              08350 ;      starship is blocked on the Galactic Chart at sector row 4, sector column
              08351 ;      8, so that it will not be inadvertently occupied while other sector types
              08352 ;      are distributed. The number of each of the sector types to be distributed
              08353 ;      is the mission level plus 2. While Zylon units can be placed anywhere,
              08354 ;      starbases are placed neither at the borders of the Galactic Chart nor in
              08355 ;      a sector adjacent to an occupied sector. 
              08356 ;
              08357 ;      After having initialized the Galactic Chart memory map, the top border of
              08358 ;      the Galactic Chart is drawn with characters from the custom character
              08359 ;      set.
              08360 ;
              08361 ;      Finally, the sector in which our starship is located and the arrival and
              08362 ;      departure hyperwarp marker column and row numbers are initialized.
              08363 ;
              08364 ; (6)  Apply a final tweak
              08365 ;
              08366 ;      The last entry of lookup table MAPTOBCD99 ($0EE9) is tweaked to a value
              08367 ;      of CCS.INF * 16 + CCS.SPC. It is used to display an infinity symbol by
              08368 ;      the RANGE readout of the Control Panel Display in subroutine SHOWCOORD
              08369 ;      ($B8A7).
              08370 ;
              08371 ; Code execution continues into subroutine DRAWGC ($B4B9), which draws the
              08372 ; content of the Galactic Chart with characters from the custom character set.
              08373
    =0068     08374 L.MEMPTR1       = $68                   ; 16-bit memory pointer
    =006A     08375 L.MEMPTR2       = $6A                   ; 16-bit memory pointer
    =006A     08376 L.SECTORTYPE    = $6A                   ; Saves sector type. Used values are:
              08377                                         ;   $CF -> Sector contains starbase
              08378                                         ;   $04 -> Sector contains 4 Zylon ships
              08379                                         ;   $03 -> Sector contains 3 Zylon ships
              08380                                         ;   $02 -> Sector contains 2 or 1 Zylon ships
    =006B     08381 L.SECTORCNT     = $6B                   ; Saves number of sectors of the current sector type
              08382
              08383 ;*** Initialize Display List and copy color table ******************************
B3BA A259     08384 INITIALIZE      LDX #89                 ; Set 89(+1) GRAPHICS7 rows from DSPLST+5 on
B3BC A90D     08385 LOOP060         LDA #$0D                ; Prep DL instruction $0D (one row of GRAPHICS7)
B3BE 9D8502   08386                 STA DSPLST+5,X          ; DSPLST+5,X := one row of GRAPHICS7
B3C1 E00A     08387                 CPX #10                 ;
B3C3 B005     08388                 BCS SKIP195             ;
B3C5 BDA9BF   08389                 LDA PFCOLORTAB,X        ; Copy PLAYFIELD color table to zero-page table
B3C8 95F2     08390                 STA PF0COLOR,X          ; (loop jamming)
B3CA CA       08391 SKIP195         DEX                     ;
B3CB 10EF     08392                 BPL LOOP060             ;
              08393
B3CD A970     08394                 LDA #$70                ; DSPLST     := BLK8
B3CF 8D8002   08395                 STA DSPLST              ; DSPLST+1   := BLK8
B3D2 8D8102   08396                 STA DSPLST+1            ;
B3D5 A941     08397                 LDA #$41                ; DSPLST+103 := WAITJMP @ DSPLST
B3D7 8DE702   08398                 STA DSPLST+103          ;
B3DA A980     08399                 LDA #<DSPLST            ;
B3DC 8DE802   08400                 STA DSPLST+104          ;
B3DF A902     08401                 LDA #>DSPLST            ;
B3E1 8DE902   08402                 STA DSPLST+105          ;
              08403
              08404 ;*** Calculate lookup tables ***************************************************
B3E4 A200     08405                 LDX #0                  ; Clear both 16-bit memory pointers
B3E6 8668     08406                 STX L.MEMPTR1           ;
B3E8 8669     08407                 STX L.MEMPTR1+1         ;
B3EA 866A     08408                 STX L.MEMPTR2           ;
B3EC 866B     08409                 STX L.MEMPTR2+1         ;
              08410
              08411 ;*** Calc MAPTO80 map (converts value of $00..$FF to value in 0..80) ***********
B3EE 18       08412 LOOP061         CLC                     ;
B3EF A568     08413                 LDA L.MEMPTR1           ;
B3F1 6951     08414                 ADC #81                 ;
B3F3 8568     08415                 STA L.MEMPTR1           ;
B3F5 A569     08416                 LDA L.MEMPTR1+1         ;
B3F7 9DE90D   08417                 STA MAPTO80,X           ;
B3FA 6900     08418                 ADC #0                  ;
B3FC 8569     08419                 STA L.MEMPTR1+1         ;
              08420
              08421 ;*** Calc MAPTOBCD99 map (converts value of $00..$FF to BCD-value in 00..99) ***
B3FE 18       08422                 CLC                     ;
B3FF A56A     08423                 LDA L.MEMPTR2           ;
B401 6964     08424                 ADC #100                ;
B403 856A     08425                 STA L.MEMPTR2           ;
B405 A56B     08426                 LDA L.MEMPTR2+1         ;
B407 9DE90E   08427                 STA MAPTOBCD99,X        ;
B40A F8       08428                 SED                     ;
B40B 6900     08429                 ADC #0                  ;
B40D D8       08430                 CLD                     ;
B40E 856B     08431                 STA L.MEMPTR2+1         ;
B410 E8       08432                 INX                     ;
B411 D0DB     08433                 BNE LOOP061             ;
              08434
              08435 ;*** Calculate PLAYFIELD memory row addresses, copy Panel Display texts ********
B413 A200     08436                 LDX #<PFMEM             ; Point L.MEMPTR1 to start of PLAYFIELD memory
B415 8668     08437                 STX L.MEMPTR1           ; (X = 0, because PFMEM is at $1000)
B417 A910     08438                 LDA #>PFMEM             ;
B419 8569     08439                 STA L.MEMPTR1+1         ;
              08440
B41B 18       08441 LOOP062         CLC                     ;
B41C A568     08442                 LDA L.MEMPTR1           ;
B41E 9D0008   08443                 STA PFMEMROWLO,X        ; Store 16-bit value of L.MEMPTR1 in PFMEMROWHI/LO
B421 6928     08444                 ADC #40                 ; Add 40 to L.MEMPTR
B423 8568     08445                 STA L.MEMPTR1           ; (40 bytes = 160 pixels = 1 PLAYFIELD row)
B425 A569     08446                 LDA L.MEMPTR1+1         ;
B427 9D6408   08447                 STA PFMEMROWHI,X        ;
B42A 6900     08448                 ADC #0                  ;
B42C 8569     08449                 STA L.MEMPTR1+1         ;
              08450
B42E BD42BB   08451                 LDA PANELTXTTAB,X       ; Copy Control and Galactic Chart Panel Display texts
B431 9D4909   08452                 STA PANELTXT,X          ; (loop jamming)
              08453
B434 E8       08454                 INX                     ;
B435 E064     08455                 CPX #100                ;
B437 90E2     08456                 BCC LOOP062             ; Loop 100 times
              08457
              08458 ;*** Set Zylon unit movement timer *********************************************
B439 CA       08459                 DEX                     ;
B43A 8678     08460                 STX ZYLONUNITTIM        ; Init Zylon unit movement timer to 99 game loops
              08461
              08462 ;*** Create memory map of the Galactic Chart ***********************************
B43C A203     08463                 LDX #3                  ; Loop over all 3(+1) sector types
B43E 8E1109   08464                 STX GCMEMMAP+4*16+8     ; Block our starship's initial position at center of
              08465                                         ; ...Galactic Chart (sector row 4, sector column 8)
              08466
B441 BDA6BB   08467 LOOP063         LDA SECTORTYPETAB,X     ; Prep sector type
B444 856A     08468                 STA L.SECTORTYPE        ;
              08469
B446 A462     08470                 LDY MISSIONLEVEL        ; Number sectors of current type := mission level + 2
B448 C8       08471                 INY                     ;
B449 C8       08472                 INY                     ;
B44A 846B     08473                 STY L.SECTORCNT         ;
              08474
B44C AD0AD2   08475 LOOP064         LDA RANDOM              ; Load random sector 0..127 from GC memory map
B44F 297F     08476                 AND #$7F                ;
B451 A8       08477                 TAY                     ;
B452 B9C908   08478                 LDA GCMEMMAP,Y          ;
B455 D0F5     08479                 BNE LOOP064             ; If sector already occupied, pick another
              08480
B457 A56A     08481                 LDA L.SECTORTYPE        ; Reload sector type
B459 1021     08482                 BPL SKIP196             ; Skip if sector not to be occupied by starbase
              08483
B45B C010     08484                 CPY #$10                ; Place starbase...
B45D 90ED     08485                 BCC LOOP064             ; ...not in first sector row of Galactic Chart
B45F C070     08486                 CPY #$70                ;
B461 B0E9     08487                 BCS LOOP064             ; ...not in last sector row of Galactic Chart
B463 98       08488                 TYA                     ;
B464 290F     08489                 AND #$0F                ;
B466 F0E4     08490                 BEQ LOOP064             ; ...not in first sector column of Galactic Chart
B468 C90F     08491                 CMP #15                 ;
B46A F0E0     08492                 BEQ LOOP064             ; ...not in last sector column of Galactic Chart
B46C B9C808   08493                 LDA GCMEMMAP-1,Y        ; ...not east  of an occupied sector
B46F 19CA08   08494                 ORA GCMEMMAP+1,Y        ; ...not west  of an occupied sector
B472 19D908   08495                 ORA GCMEMMAP+16,Y       ; ...not south of an occupied sector
B475 19B908   08496                 ORA GCMEMMAP-16,Y       ; ...not north of an occupied sector
B478 D0D2     08497                 BNE LOOP064             ;
              08498
B47A A56A     08499                 LDA L.SECTORTYPE        ; Reload sector type
              08500
B47C 99C908   08501 SKIP196         STA GCMEMMAP,Y          ; Store sector type in Galactic Chart memory map
B47F C66B     08502                 DEC L.SECTORCNT         ;
B481 10C9     08503                 BPL LOOP064             ; Next sector
B483 CA       08504                 DEX                     ;
B484 10BB     08505                 BPL LOOP063             ; Next sector type
              08506
              08507 ;*** Clear Galactic Chart and draw top border **********************************
B486 A2B4     08508                 LDX #180                ; Clear Galactic Chart PLAYFIELD
B488 A90A     08509 LOOP065         LDA #CCS.SPC            ;
B48A 9D340D   08510                 STA GCPFMEM-1,X         ;
B48D CA       08511                 DEX                     ;
B48E D0F8     08512                 BNE LOOP065             ;
              08513
B490 A20F     08514                 LDX #15                 ; Draw top border (15(+1) characters)
B492 A918     08515 LOOP066         LDA #CCS.BORDERS        ;
B494 9D370D   08516                 STA GCPFMEM+2,X         ;
B497 CA       08517                 DEX                     ;
B498 10F8     08518                 BPL LOOP066             ;
              08519
B49A A91A     08520                 LDA #CCS.CORNERSW       ; Draw NORTHEAST corner (1 character)
B49C 8D470D   08521                 STA GCPFMEM+18          ;
              08522
B49F A900     08523                 LDA #0                  ; Release starship's position at center of Galactic
B4A1 8D1109   08524                 STA GCMEMMAP+4*16+8     ; ...Chart (sector row 4, sector column 8)
              08525
              08526 ;*** Initialize current sector and hyperwarp marker column and row numbers *****
B4A4 A948     08527                 LDA #$48                ; Place our starship's current sector at
B4A6 8590     08528                 STA CURRSECTOR          ; ...sector row 4, sector column 8
B4A8 A943     08529                 LDA #$43                ; Init departure & arrival hyperwarp marker column
B4AA 858D     08530                 STA WARPDEPRCOLUMN      ;
B4AC 858F     08531                 STA WARPARRVCOLUMN      ;
B4AE A947     08532                 LDA #$47                ; Init departure & arrival hyperwarp marker row
B4B0 858E     08533                 STA WARPARRVROW         ;
B4B2 858C     08534                 STA WARPDEPRROW         ;
              08535
              08536 ;*** Tweak last entry of MAPTOBCD99 ********************************************
B4B4 A9EA     08537                 LDA #CCS.INF*16+CCS.SPC ; Last entry of MAPTOBCD99: 'INFINITY'+'SPACE' char
B4B6 8DE80F   08538                 STA MAPTOBCD99+255      ;
              08539
              08540 ;*******************************************************************************
              08541 ;*                                                                             *
              08542 ;*                                   DRAWGC                                    *
              08543 ;*                                                                             *
              08544 ;*                             Draw Galactic Chart                             *
              08545 ;*                                                                             *
              08546 ;*******************************************************************************
              08547
              08548 ; DESCRIPTION
              08549 ;
              08550 ; Draws the content of the Galactic Chart memory map in GCMEMMAP ($08C9) to the
              08551 ; Galactic Chart PLAYFIELD memory at GCPFMEM ($0D35). 
              08552 ;
              08553 ; NOTE: CPU register X indexes the Galactic Chart memory map GCMEMMAP ($08C9)
              08554 ; (16 x 8 bytes). CPU register Y indexes the Galactic Chart PLAYFIELD memory
              08555 ; GCPFMEM ($0D35) (20 x 9 bytes).
              08556 ;
              08557 ; NOTE: Sectors with 1 or 2 Zylon ships display the same symbol in the Galactic
              08558 ; Chart.
              08559
    =006A     08560 L.GCMEMMAPIND   = $6A                   ; Saves Galactic Chart memory map index
              08561
B4B9 A000     08562 DRAWGC          LDY #0                  ; Clear Galactic Chart PLAYFIELD memory index
B4BB 846A     08563                 STY L.GCMEMMAPIND       ; Clear Galactic Chart memory map index
              08564
B4BD A66A     08565 LOOP067         LDX L.GCMEMMAPIND       ; Load sector of Galactic Chart memory map
B4BF BDC908   08566                 LDA GCMEMMAP,X          ;
B4C2 1002     08567                 BPL SKIP197             ; Skip if not a starbase sector
B4C4 A905     08568                 LDA #5                  ; Prep sector character index for starbase
              08569
B4C6 AA       08570 SKIP197         TAX                     ; Load sector character index
B4C7 BDD1BE   08571                 LDA SECTORCHARTAB,X     ; Load custom character set code from table...
B4CA 994B0D   08572                 STA GCPFMEM+22,Y        ; ...and store it in Galactic Chart PLAYFIELD memory
B4CD C8       08573                 INY                     ; Increment Galactic Chart PLAYFIELD memory index
B4CE E66A     08574                 INC L.GCMEMMAPIND       ; Increment Galactic Chart memory map index
B4D0 A56A     08575                 LDA L.GCMEMMAPIND       ;
B4D2 290F     08576                 AND #$0F                ;
B4D4 D0E7     08577                 BNE LOOP067             ; Next sector column until right border reached
              08578
B4D6 A919     08579                 LDA #CCS.BORDERW        ; Draw right border
B4D8 994B0D   08580                 STA GCPFMEM+22,Y        ;
              08581
B4DB C8       08582                 INY                     ; Adjust Galactic Chart PLAYFIELD memory index
B4DC C8       08583                 INY                     ;
B4DD C8       08584                 INY                     ;
B4DE C8       08585                 INY                     ;
B4DF C0A0     08586                 CPY #$A0                ;
B4E1 90DA     08587                 BCC LOOP067             ; Next sector until bottom-right sector reached
              08588
B4E3 60       08589                 RTS                     ; Return
              08590
              08591 ;*******************************************************************************
              08592 ;*                                                                             *
              08593 ;*                                FLUSHGAMELOOP                                *
              08594 ;*                                                                             *
              08595 ;*         Handle remaining tasks at the end of a game loop iteration          *
              08596 ;*                                                                             *
              08597 ;*******************************************************************************
              08598
              08599 ; DESCRIPTION
              08600 ;
              08601 ; This subroutine handles at the end of a game loop iteration the following
              08602 ; tasks:
              08603 ;
              08604 ; (1)  Increment counters COUNT256 ($76) and COUNT8 ($72).
              08605 ;
              08606 ; (2)  If our starship's energy has dropped below 1000 units then flash a {PINK}
              08607 ;      alert that changes to {DARK GREY BLUE} and back to {PINK} every 128 game
              08608 ;      loop iterations.
              08609 ;
              08610 ; (3)  Set the Shields color and the Control Panel background color every 8 game
              08611 ;      loop iterations:
              08612 ;
              08613 ;      o   If the Shields are up and OK then set the Shields color to {DARK
              08614 ;          GREEN} and the Control Panel background color to {DARK BLUE}.
              08615 ;
              08616 ;      o   If the Shields are up and damaged there is a probability of 78%
              08617 ;          (200:256) that the Shield color is not changed.
              08618 ;
              08619 ;      o   If the Shields are down, damaged, or destroyed then set the Shields
              08620 ;          color to {BLACK}.
              08621 ;
              08622 ;      o   If the Shields are destroyed then set the Control Panel background
              08623 ;          color to {ORANGE}.
              08624 ;
              08625 ; (4)  Decrement the lifetime of our starship's and Zylon photon torpedoes.
              08626 ;
              08627 ; (5)  Decrement the lifetime of an explosion. If the explosion lifetime is less
              08628 ;      than 112 game loop iterations, clear HITBADNESS ($8A) (thus the explosion
              08629 ;      cannot destroy our starship). If the explosion lifetime is less than 24
              08630 ;      (?) game loops decrement the number of explosion fragments. This makes
              08631 ;      explosion fragments disappear gradually toward the end of an explosion.
              08632 ;
              08633 ; (6)  Increment every 40 game loop iterations the stardate clock of the
              08634 ;      Galactic Chart Panel Display.
              08635 ;
              08636 ; (7)  Move Zylon units in the Galactic Chart.
              08637 ;
              08638 ;      Every 50 game loop iterations (or 100 game loop iterations when a
              08639 ;      starbase is surrounded by Zylon units) decrement the score.
              08640 ;
              08641 ; Code execution continues if the program is not in demo mode with the following
              08642 ; steps:
              08643 ;
              08644 ; (1)  Search the Galactic Chart for starbases surrounded by Zylon units.
              08645 ;      Destroy any such starbase: Replace it with a 2-Zylon sector and subtract
              08646 ;      18 points from the score. If the Subspace Radio was not destroyed, then
              08647 ;      flash the title phrase "STARBASE DESTROYED" and play the beeper sound
              08648 ;      pattern MESSAGE FROM STARBASE in subroutine BEEP ($B3A6).
              08649 ;
              08650 ; (2)  Every 8 game loop iterations the Zylon units decide, which starbase to
              08651 ;      hunt: First, 128 randomly picked sectors are searched for a starbase. If
              08652 ;      no starbase was found in this way, the sectors of the Galactic Chart are
              08653 ;      scanned systematically left-to-right, top-to-bottom. If a starbase was
              08654 ;      found then its sector, sector column, and sector row are saved, otherwise
              08655 ;      code execution returns.
              08656 ;
              08657 ; (3)  Now the Zylon units converge toward the sector of the hunted starbase:
              08658 ;      All sectors of the Galactic Chart are scanned. For any sector with a
              08659 ;      Zylon unit that was not moved yet (its sector does not have the temporary
              08660 ;      "already-moved" bit B5 set) its movement probability value is picked from
              08661 ;      table MOVEPROBTAB ($BFBB):
              08662 ;
              08663 ;      +---------------+-------------+----------------+
              08664 ;      |  Sector Type  |  Movement   |   Movement     | 
              08665 ;      |               | Probability |  Probability   |
              08666 ;      |               |    Value    |                |
              08667 ;      +---------------+-------------+----------------+
              08668 ;      | Empty sector  |       0     |   0% (  0:256) | 
              08669 ;      | 1 Zylon ship  |     255     | 100% (255:256) |
              08670 ;      | 2 Zylon ships |     255     | 100% (255:256) | 
              08671 ;      | 3 Zylon ships |     192     |  75% (192:256) | 
              08672 ;      | 4 Zylon ships |      32     |  13% ( 32:256) |
              08673 ;      +---------------+-------------+----------------+
              08674 ;
              08675 ;      If this value is less or equal than a random number in 0..255 then the
              08676 ;      Zylon unit is moved to another sector. A Zylon unit that currently
              08677 ;      occupies the sector of our starship is not moved.
              08678 ;
              08679 ;      BUG (at $B620): The instruction to check the marker bit B5 of the sector
              08680 ;      is CPY #$0A. This works, as sectors containing Zylon units that need to
              08681 ;      be moved have values of 2..4, see table SECTORTYPETAB ($BBA6). Suggested
              08682 ;      fix: Replace CPY #$0A with CPY #$20, which may make the code clearer.
              08683 ;
              08684 ; (4)  For every Zylon unit that is about to be moved, 9 distances ("block
              08685 ;      distances") between the Zylon unit and the starbase are calculated by
              08686 ;      tentatively moving the Zylon unit into each of its 8 adjacent sectors -
              08687 ;      and by moving it not at all. The sector offsets are taken from table
              08688 ;      COMPASSOFFTAB ($BFC0) which stores direction offsets in the following
              08689 ;      order: NORTH, NORTHWEST, WEST, SOUTHWEST, SOUTH, SOUTHEAST, EAST,
              08690 ;      NORTHEAST, CENTER. All 9 distances are stored in 9 consecutive bytes at
              08691 ;      NEWZYLONDIST ($96).
              08692 ;
              08693 ;      NOTE: The last calculated distance is the current distance between Zylon
              08694 ;      unit and starbase.
              08695 ;
              08696 ;      The Zylon unit moves to the first of the 8 adjacent sectors that matches
              08697 ;      the following conditions: 
              08698 ;
              08699 ;      (1)  It is closer to the starbase than the Zylon unit's current sector.
              08700 ;
              08701 ;      (2)  It is located inside the Galactic Chart.
              08702 ;
              08703 ;      (3)  It is empty.
              08704 ;
              08705 ;      (4)  It is not the sector containing our starship.
              08706 ;
              08707 ;      If a suitable new sector was found then the Zylon unit is moved to this
              08708 ;      sector, which is marked with the "already-moved" marker bit B5 in the
              08709 ;      Galactic Chart memory map. This marker bit prevents a Zylon unit that has
              08710 ;      been already moved from being moved again. The old Zylon unit sector is
              08711 ;      cleared. 
              08712 ;
              08713 ;      If no suitable new sector was found then the above distance calculations
              08714 ;      are repeated once again by adding 1 to the current distance between the
              08715 ;      Zylon unit and the starbase. This may provoke a Zylon unit to move that
              08716 ;      would not have moved in the previous set of distance calculations.
              08717 ;
              08718 ;      After having moved all Zylon units the sectors are stripped of the
              08719 ;      "already-moved" marker bit B5.
              08720 ;
              08721 ; (5)  If a starbase has been surrounded then the Zylon unit movement timer is
              08722 ;      reset to 99, buying our starship some time to destroy one of the
              08723 ;      surrounding Zylon units. If the Subspace Radio is not destroyed, then the
              08724 ;      message "STARBASE SURROUNDED" is flashed in the title line and the beeper
              08725 ;      sound pattern MESSAGE FROM STARBASE is played in subroutine BEEP ($B3A6).
              08726
    =006A     08727 L.ISDESTROYED   = $6A                   ; Flags the destruction of a starbase.
              08728                                         ; Used values are:
              08729                                         ;   $00 -> Starbase not destroyed
              08730                                         ;   $02 -> Starbase has been destroyed
    =006A     08731 L.NEWSECTOR     = $6A                   ; Sector to which the Zylon unit is tentatively moved
    =006B     08732 L.ABSDIFFCOL    = $6B                   ; Absolute difference between new Zylon and starbase
              08733                                         ;   column on Galactic Chart in PM pixels
    =006B     08734 L.LOOPCNT2      = $6B                   ; Loop counter. Used values are: 0..1.
    =006A     08735 L.DIRECTIONIND  = $6A                   ; Compass rose direction index.
              08736                                         ; Used values are: 0..7.
              08737
              08738 ;*** Increment counters and flash low-energy alert *****************************
B4E4 E676     08739 FLUSHGAMELOOP   INC COUNT256            ; Increment COUNT256 counter
              08740
B4E6 A290     08741                 LDX #$90                ; Prep DLI background color {DARK GREY BLUE}
B4E8 A576     08742                 LDA COUNT256            ;
B4EA 1009     08743                 BPL SKIP198             ; Skip if counter < 128.
              08744
B4EC AC5509   08745                 LDY ENERGYD1            ; When energy drops below 1000 units...
B4EF C080     08746                 CPY #CCS.COL2!CCS.0     ;
B4F1 D002     08747                 BNE SKIP198             ;
B4F3 A244     08748                 LDX #$44                ; ...prep new DLI background color {PINK}
              08749
B4F5 2903     08750 SKIP198         AND #$03                ; Increment COUNT8
B4F7 8572     08751                 STA COUNT8              ;
B4F9 D01F     08752                 BNE SKIP202             ; Skip setting colors but every 8 game loops
              08753
              08754 ;*** Set Shields and Control Panel background color ****************************
B4FB A47D     08755                 LDY ISSHIELDSON         ; Skip if Shields are off
B4FD F017     08756                 BEQ SKIP201             ;
              08757
B4FF A0A0     08758                 LDY #$A0                ; Prep Shields color {DARK GREEN}
B501 2C9409   08759                 BIT GCSTATSHL           ; Skip if Shields are OK
B504 100B     08760                 BPL SKIP200             ;
B506 7007     08761                 BVS SKIP199             ; Skip if Shields are destroyed
B508 AD0AD2   08762                 LDA RANDOM              ; If Shields are damaged, Shields colors are...
B50B C9C8     08763                 CMP #200                ; ...unchanged with probability of 78% (200:256)
B50D 9007     08764                 BCC SKIP201             ;
              08765
B50F A000     08766 SKIP199         LDY #$00                ; Prep Shields color {BLACK}
B511 98       08767 SKIP200         TYA                     ;
B512 D002     08768                 BNE SKIP201             ;
              08769
B514 A226     08770                 LDX #$26                ; Prep Control Panel background color {ORANGE}
              08771
B516 8481     08772 SKIP201         STY SHIELDSCOLOR        ; Store Shields color
B518 86FB     08773                 STX BGRCOLORDLI         ; Store Control Panel background color
              08774
              08775 ;*** Decrement lifetime of our starship's and Zylon photon torpedoes ***********
B51A A202     08776 SKIP202         LDX #2                  ; Loop over PLAYER2..4
              08777
B51C BD8E0C   08778 LOOP068         LDA PL2SHAPTYPE,X       ; Next PLAYER if not PHOTON TORPEDO (shape type 0)
B51F D006     08779                 BNE SKIP203             ;
              08780
B521 B5EB     08781                 LDA PL2LIFE,X           ; Next PLAYER if this PLAYER not alive
B523 F002     08782                 BEQ SKIP203             ;
              08783
B525 D6EB     08784                 DEC PL2LIFE,X           ; Decrement photon torpedo PLAYER lifetime
              08785
B527 CA       08786 SKIP203         DEX                     ;
B528 10F2     08787                 BPL LOOP068             ; Next PLAYER
              08788
              08789 ;*** Decrement lifetime of explosion *******************************************
B52A A573     08790                 LDA EXPLLIFE            ; Skip if explosion lifetime expired
B52C F016     08791                 BEQ SKIP206             ;
              08792
B52E C673     08793                 DEC EXPLLIFE            ; Decrement explosion lifetime
B530 D004     08794                 BNE SKIP204             ; Skip if explosion lifetime still counting
              08795
B532 A211     08796                 LDX #MAXSPCOBJIND.NL+1  ; Explosion finished,...
B534 8679     08797                 STX MAXSPCOBJIND        ; ...restore normal number of space objects
              08798
B536 C970     08799 SKIP204         CMP #112                ; Skip if explosion lifetime >= 112 game loops
B538 B004     08800                 BCS SKIP205             ;
              08801
B53A A200     08802                 LDX #0                  ; HITBADNESS := NO HIT
B53C 868A     08803                 STX HITBADNESS          ;
              08804
B53E C918     08805 SKIP205         CMP #24                 ; Skip if explosion lifetime >= 24 game loops (?)
B540 B002     08806                 BCS SKIP206             ;
              08807
B542 C679     08808                 DEC MAXSPCOBJIND        ; Decrement number of explosion fragment space objs
              08809
              08810 ;*** Increment stardate clock **************************************************
B544 C674     08811 SKIP206         DEC CLOCKTIM            ; Decrement stardate clock timer
B546 1021     08812                 BPL SKIP209             ; Return if timer is still counting
              08813
B548 A928     08814                 LDA #40                 ; Reset stardate clock timer to 40 game loops
B54A 8574     08815                 STA CLOCKTIM            ;
              08816
B54C A204     08817                 LDX #4                  ; Increment stardate clock of Galactic Chart Panel
B54E FEA309   08818 LOOP069         INC GCSTARDAT,X         ;
B551 BDA309   08819                 LDA GCSTARDAT,X         ;
B554 C9DA     08820                 CMP #[CCS.COL3!ROM.9]+1 ;
B556 900D     08821                 BCC SKIP208             ;
B558 A9D0     08822                 LDA #[CCS.COL3!ROM.0]   ;
B55A 9DA309   08823                 STA GCSTARDAT,X         ;
B55D E003     08824                 CPX #3                  ;
B55F D001     08825                 BNE SKIP207             ;
B561 CA       08826                 DEX                     ;
B562 CA       08827 SKIP207         DEX                     ;
B563 10E9     08828                 BPL LOOP069             ;
              08829
              08830 ;*** Decrement Zylon unit movement timer ***************************************
B565 C678     08831 SKIP208         DEC ZYLONUNITTIM        ; Decrement Zylon unit movement timer
B567 3001     08832                 BMI SKIP210             ; If timer < 0 move Zylon units
              08833
B569 60       08834 SKIP209         RTS                     ; Return
              08835
              08836 ;*** Restore Zylon unit movement timer and decrement score *********************
B56A A931     08837 SKIP210         LDA #49                 ; Reset Zylon unit movement timer to 49
B56C 8578     08838                 STA ZYLONUNITTIM        ;
              08839
B56E A5CB     08840                 LDA SCORE               ; SCORE := SCORE - 1
B570 D002     08841                 BNE SKIP211             ;
B572 C6CC     08842                 DEC SCORE+1             ;
B574 C6CB     08843 SKIP211         DEC SCORE               ;
              08844
B576 A664     08845                 LDX ISDEMOMODE          ; Return if in demo mode
B578 D0EF     08846                 BNE SKIP209             ;
              08847
              08848 ;*** Is starbase surrounded? ***************************************************
B57A 866A     08849                 STX L.ISDESTROYED       ; Init L.ISDESTROYED with 0 (starbase not destroyed)
B57C BDC908   08850 LOOP070         LDA GCMEMMAP,X          ; Loop over all sectors, load sector type
B57F 1019     08851                 BPL SKIP212             ; Skip if not a starbase sector
              08852
B581 20F1B7   08853                 JSR ISSURROUNDED        ; Skip if starbase sector not completely surrounded
B584 F014     08854                 BEQ SKIP212             ;
              08855
              08856 ;*** Starbase is surrounded, destroy starbase **********************************
B586 A902     08857                 LDA #2                  ; Replace starbase sector with 2-Zylon sector
B588 9DC908   08858                 STA GCMEMMAP,X          ;
B58B 856A     08859                 STA L.ISDESTROYED       ; Flag destruction of starbase
              08860
B58D 38       08861                 SEC                     ; SCORE := SCORE - 18
B58E A5CB     08862                 LDA SCORE               ;
B590 E912     08863                 SBC #18                 ;
B592 85CB     08864                 STA SCORE               ;
B594 A5CC     08865                 LDA SCORE+1             ;
B596 E900     08866                 SBC #0                  ;
B598 85CC     08867                 STA SCORE+1             ;
              08868
B59A E8       08869 SKIP212         INX                     ;
B59B 10DF     08870                 BPL LOOP070             ; Next sector
              08871
              08872 ;*** Report starbase destruction ***********************************************
B59D A56A     08873                 LDA L.ISDESTROYED       ; Skip if no starbase has been destroyed
B59F F00F     08874                 BEQ SKIP213             ;
              08875
B5A1 2C9709   08876                 BIT GCSTATRAD           ; Skip notification if Subspace Radio destroyed
B5A4 700A     08877                 BVS SKIP213             ;
              08878
B5A6 A015     08879                 LDY #$15                ; Set title phrase "STARBASE DESTROYED"
B5A8 2023B2   08880                 JSR SETTITLE            ;
              08881
B5AB A218     08882                 LDX #$18                ; Play beeper sound pattern MESSAGE FROM STARBASE
B5AD 20A6B3   08883                 JSR BEEP                ;
              08884
              08885 ;*** Pick new starbase to be hunted by Zylon units *****************************
B5B0 C69F     08886 SKIP213         DEC HUNTTIM             ; Decrement hunting timer
B5B2 3007     08887                 BMI SKIP214             ; If timer < 0 decide which starbase to hunt
              08888
B5B4 A693     08889                 LDX HUNTSECTOR          ; Skip if Zylon units already picked starbase to hunt
B5B6 BDC908   08890                 LDA GCMEMMAP,X          ;
B5B9 301F     08891                 BMI SKIP215             ;
              08892
B5BB A907     08893 SKIP214         LDA #7                  ; Reset hunting timer
B5BD 859F     08894                 STA HUNTTIM             ;
              08895
B5BF A07F     08896                 LDY #127                ; Loop over 127(+1) randomly picked sectors
B5C1 AD0AD2   08897 LOOP071         LDA RANDOM              ;
B5C4 297F     08898                 AND #$7F                ;
B5C6 AA       08899                 TAX                     ;
B5C7 BDC908   08900                 LDA GCMEMMAP,X          ; Skip if starbase sector found
B5CA 300E     08901                 BMI SKIP215             ;
B5CC 88       08902                 DEY                     ;
B5CD 10F2     08903                 BPL LOOP071             ; Next sector
              08904
B5CF A27F     08905                 LDX #127                ; Loop over all sectors of the Galactic Chart
B5D1 BDC908   08906 LOOP072         LDA GCMEMMAP,X          ;
B5D4 3004     08907                 BMI SKIP215             ; Skip if starbase sector found
B5D6 CA       08908                 DEX                     ;
B5D7 10F8     08909                 BPL LOOP072             ; Next sector
              08910
B5D9 60       08911                 RTS                     ; Return (no starbase sector found)
              08912
              08913 ;*** Store coordinates of starbase to be hunted ********************************
B5DA 8693     08914 SKIP215         STX HUNTSECTOR          ; Store hunted starbase sector column and row
B5DC 8A       08915                 TXA                     ;
B5DD 290F     08916                 AND #$0F                ;
B5DF 8594     08917                 STA HUNTSECTCOLUMN      ;
B5E1 8A       08918                 TXA                     ;
B5E2 4A       08919                 LSR A                   ;
B5E3 4A       08920                 LSR A                   ;
B5E4 4A       08921                 LSR A                   ;
B5E5 4A       08922                 LSR A                   ;
B5E6 8595     08923                 STA HUNTSECTROW         ;
              08924
              08925 ;*** Move all Zylon units toward hunted starbase *******************************
B5E8 A2FF     08926                 LDX #$FF                ;
B5EA E8       08927 LOOP073         INX                     ; Loop over all sectors to move Zylon units
B5EB 1030     08928                 BPL SKIP218             ; Jump into loop body below
              08929
              08930 ;*** Strip marker bits from moved Zylon units **********************************
B5ED A200     08931                 LDX #0                  ;
B5EF BDC908   08932 LOOP074         LDA GCMEMMAP,X          ; Loop over all sectors
B5F2 29DF     08933                 AND #$DF                ;
B5F4 9DC908   08934                 STA GCMEMMAP,X          ; Strip marker bit B5 from moved Zylon units
B5F7 E8       08935                 INX                     ;
B5F8 10F5     08936                 BPL LOOP074             ; Next sector
              08937
              08938 ;*** Handle surrounded starbase ************************************************
B5FA 2C9709   08939                 BIT GCSTATRAD           ; Return if Subspace Radio is destroyed
B5FD 701D     08940                 BVS SKIP217             ;
              08941
B5FF A200     08942                 LDX #0                  ; Loop over all sectors
B601 BDC908   08943 LOOP075         LDA GCMEMMAP,X          ;
B604 1013     08944                 BPL SKIP216             ; Skip if not a starbase sector
B606 20F1B7   08945                 JSR ISSURROUNDED        ; Skip if starbase not surrounded
B609 F00E     08946                 BEQ SKIP216             ;
              08947
B60B A963     08948                 LDA #99                 ; Yes, starbase surrounded...
B60D 8578     08949                 STA ZYLONUNITTIM        ; ...set Zylon unit movement timer to 99
              08950
B60F A013     08951                 LDY #$13                ; Set title phrase "STARBASE SURROUNDED"
B611 2023B2   08952                 JSR SETTITLE            ;
              08953
B614 A218     08954                 LDX #$18                ; Play beeper sound pattern MESSAGE FROM STARBASE...
B616 4CA6B3   08955                 JMP BEEP                ; ...and return
              08956
B619 E8       08957 SKIP216         INX                     ;
B61A 10E5     08958                 BPL LOOP075             ; Next sector
              08959
B61C 60       08960 SKIP217         RTS                     ; Return
              08961
              08962 ;*** Move single Zylon unit ****************************************************
B61D BCC908   08963 SKIP218         LDY GCMEMMAP,X          ; X contains current sector
B620 C00A     08964                 CPY #$0A                ; Next sector if it has marker bit B5 set (!)
B622 B0C6     08965                 BCS LOOP073             ;
              08966
B624 AD0AD2   08967                 LDA RANDOM              ; Get random number
B627 D9BBBF   08968                 CMP MOVEPROBTAB,Y       ; Get movement probability
B62A B0BE     08969                 BCS LOOP073             ; Next sector if movement probability < random number
              08970
B62C E490     08971                 CPX CURRSECTOR          ; Next sector if this is our starship's sector
B62E F0BA     08972                 BEQ LOOP073             ;
              08973
              08974 ;*** Compute distance to starbase by moving Zylon unit into 9 directions *******
B630 A008     08975                 LDY #8                  ; Loop over 8(+1) possible directions
B632 18       08976 LOOP076         CLC                     ;
B633 8A       08977                 TXA                     ;
B634 79C0BF   08978                 ADC COMPASSOFFTAB,Y     ; Add direction offset to current sector
B637 856A     08979                 STA L.NEWSECTOR         ; Store new sector
              08980
B639 290F     08981                 AND #$0F                ; Calc distance ("block distance") between...
B63B 38       08982                 SEC                     ; ...starbase sector and tentative new Zylon sector
B63C E594     08983                 SBC HUNTSECTCOLUMN      ;
B63E B004     08984                 BCS SKIP219             ;
B640 49FF     08985                 EOR #$FF                ;
B642 6901     08986                 ADC #1                  ;
B644 856B     08987 SKIP219         STA L.ABSDIFFCOL        ;
B646 A56A     08988                 LDA L.NEWSECTOR         ;
B648 4A       08989                 LSR A                   ;
B649 4A       08990                 LSR A                   ;
B64A 4A       08991                 LSR A                   ;
B64B 4A       08992                 LSR A                   ;
B64C 38       08993                 SEC                     ;
B64D E595     08994                 SBC HUNTSECTROW         ;
B64F B004     08995                 BCS SKIP220             ;
B651 49FF     08996                 EOR #$FF                ;
B653 6901     08997                 ADC #1                  ;
B655 18       08998 SKIP220         CLC                     ;
B656 656B     08999                 ADC L.ABSDIFFCOL        ;
              09000
B658 999600   09001                 STA NEWZYLONDIST,Y      ; Store distance in distance array
B65B 88       09002                 DEY                     ;
B65C 10D4     09003                 BPL LOOP076             ; Next direction
              09004
              09005 ;*** Pick the shortest distance to starbase ************************************
B65E A901     09006                 LDA #1                  ; Loop over compass rose directions twice to...
B660 856B     09007                 STA L.LOOPCNT2          ; ...provoke movement regardless of truncation errors
              09008
B662 A007     09009 LOOP077         LDY #7                  ;
B664 B99600   09010 LOOP078         LDA NEWZYLONDIST,Y      ; Loop over all 7(+1) compass rose directions
B667 C59E     09011                 CMP OLDZYLONDIST        ;
B669 B024     09012                 BCS SKIP222             ; Next direction if new distance > current distance
              09013
B66B 18       09014                 CLC                     ; Calc new Galactic Chart sector for Zylon unit
B66C 8A       09015                 TXA                     ;
B66D 79C0BF   09016                 ADC COMPASSOFFTAB,Y     ;
B670 301D     09017                 BMI SKIP222             ; Next direction if new sector outside Galactic Chart
              09018
B672 846A     09019                 STY L.DIRECTIONIND      ; Save compass rose direction index
B674 A8       09020                 TAY                     ;
B675 B9C908   09021                 LDA GCMEMMAP,Y          ;
B678 D013     09022                 BNE SKIP221             ; Next direction if new sector not empty
              09023
B67A BDC908   09024                 LDA GCMEMMAP,X          ; Preload Zylon sector type to be moved
B67D C490     09025                 CPY CURRSECTOR          ;
B67F F00C     09026                 BEQ SKIP221             ; Next direction if sector is our starship's sector
              09027
B681 0920     09028                 ORA #$20                ; New sector for Zylon unit found!
B683 99C908   09029                 STA GCMEMMAP,Y          ; Temporarily mark that sector with marker bit B5
B686 A900     09030                 LDA #0                  ;
B688 9DC908   09031                 STA GCMEMMAP,X          ; Clear old Zylon unit sector
B68B F00B     09032                 BEQ SKIP223             ; Next sector (unconditional branch)
              09033
B68D A46A     09034 SKIP221         LDY L.DIRECTIONIND      ; Restore compass rose direction index
B68F 88       09035 SKIP222         DEY                     ; Next compass rose direction
B690 10D2     09036                 BPL LOOP078             ;
              09037
B692 E69E     09038                 INC OLDZYLONDIST        ; Increment center distance
B694 C66B     09039                 DEC L.LOOPCNT2          ;
B696 10CA     09040                 BPL LOOP077             ; Loop over all compass rose directions one more time
              09041
B698 4CEAB5   09042 SKIP223         JMP LOOP073             ; Next sector
              09043
              09044 ;*******************************************************************************
              09045 ;*                                                                             *
              09046 ;*                                   ROTATE                                    *
              09047 ;*                                                                             *
              09048 ;*        Rotate position vector component (coordinate) by fixed angle         *
              09049 ;*                                                                             *
              09050 ;*******************************************************************************
              09051
              09052 ; DESCRIPTION
              09053 ;
              09054 ; This subroutine rotates a position vector component (coordinate) of a space
              09055 ; object by a fixed angle around the center of the 3D coordinate system, the
              09056 ; location of our starship. This is used in the Front, Aft, and Long-Range Scan
              09057 ; views to rotate space objects in and out of the view. Although the code is
              09058 ; deceptively short, there is some interesting math involved, so a more detailed
              09059 ; discussion is in order.
              09060 ;
              09061 ; ROTATION MATHEMATICS
              09062 ;
              09063 ; The program uses a left-handed 3D coordinate system with the positive x-axis
              09064 ; pointing to the right, the positive y-axis pointing up, and the positive
              09065 ; z-axis pointing into flight direction.
              09066 ;
              09067 ; A rotation in this coordinate system around the y-axis (horizontal rotation)
              09068 ; can be expressed as 
              09069 ;
              09070 ;     x' :=   cos(ry) * x + sin(ry) * z    (1a)
              09071 ;     z' := - sin(ry) * x + cos(ry) * z    (1b)
              09072 ;
              09073 ; where ry is the clockwise rotation angle around the y-axis, x and z are the
              09074 ; coordinates before the rotation, and the primed coordinates x' and z' the
              09075 ; coordinates after the rotation. The y-coordinate is not changed by the
              09076 ; rotation.
              09077 ;
              09078 ; A rotation in this coordinate system around the x-axis (vertical rotation) can
              09079 ; be expressed as 
              09080 ;
              09081 ;     z' =   cos(rx) * z + sin(rx) * y    (2a)
              09082 ;     y' = - sin(rx) * z + cos(rx) * y    (2b)
              09083 ;
              09084 ; where rx is the clockwise rotation angle around the x-axis, z and y are the
              09085 ; coordinates before the rotation, and the primed coordinates z' and y' the
              09086 ; coordinates after the rotation. The x-coordinate is not changed by the
              09087 ; rotation.
              09088 ;
              09089 ; SUBROUTINE IMPLEMENTATION OVERVIEW
              09090 ;
              09091 ; A single call of this subroutine is able to compute one of the four
              09092 ; expressions (1a)-(2b). To compute all four expressions to get the new set of
              09093 ; coordinates, this subroutine has to be called four times. This is done twice
              09094 ; in pairs in GAMELOOP ($A1F3) at $A391 and $A398, and at $A3AE and $A3B5,
              09095 ; respectively.
              09096 ;
              09097 ; The first pair of calls calculates the new x and z coordinates of a space
              09098 ; object due to a horizontal (left/right) rotation of our starship around the
              09099 ; y-axis according to equations (1a) and (1b).
              09100 ;
              09101 ; The second pair of calls calculates the new y and z coordinates of the same
              09102 ; space object due to a vertical (up/down) rotation around the x-axis according
              09103 ; to equations (2a) and (2b).
              09104 ;
              09105 ; If you look at the code, you may be wondering how this calculation is actually
              09106 ; executed, as there is neither a cos() nor sin() function call. What you'll
              09107 ; actually find implemented are the following calculations:
              09108 ;
              09109 ;     Joystick left                        Joystick right
              09110 ;     ---------------------                ---------------------
              09111 ;     x :=  x      + z / 64    (3a)        x :=  x      - z / 64    (4a)
              09112 ;     z := -x / 64 + z         (3b)        z :=  x / 64 + z         (4b)
              09113 ;
              09114 ;     Joystick down                        Joystick up
              09115 ;     ---------------------                ---------------------
              09116 ;     y :=  y      + z / 64    (5a)        y :=  y      - z / 64    (6a)
              09117 ;     z := -y / 64 + z         (5b)        z :=  y / 64 + z         (6b)
              09118 ;
              09119 ; CORDIC ALGORITHM
              09120 ;
              09121 ; When you compare equations (1a)-(2b) with (3a)-(6b), notice the similarity
              09122 ; between the equations if you substitute
              09123 ;
              09124 ;     sin(ry) -> 1 / 64, 
              09125 ;     cos(ry) -> 1,
              09126 ;     sin(rx) -> 1 / 64, and
              09127 ;     cos(rx) -> 1.
              09128 ;
              09129 ; From sin(ry) = 1 / 64 and sin(rx) = 1 / 64 you can derive that the rotation
              09130 ; angles ry and rx by which the space object is rotated per game loop iteration
              09131 ; have a constant value of 0.89 degrees, as arcsine(1 / 64) = 0.89 degrees.
              09132 ;
              09133 ; What about cos(ry) and cos(rx)? The substitution does not match our derived
              09134 ; angle exactly, because cos(0.89 degrees) = 0.99988 and is not exactly 1.
              09135 ; However, this value is so close to 1 that substituting cos(0.89 degrees) with
              09136 ; 1 is a very good approximation, simplifying calculations significantly.
              09137 ;
              09138 ; Another significant simplification results from the division by 64, because
              09139 ; the actual division operation can be replaced by a much faster bit shift
              09140 ; operation.
              09141 ;
              09142 ; This calculation-friendly way of computing rotations is known as the "CORDIC
              09143 ; (COordinate Rotation DIgital Computer)" algorithm.
              09144 ;
              09145 ; There is one more interesting mathematical subtlety: Did you notice that
              09146 ; equations (1a)-(2b) use a new (primed) pair of variables to store the
              09147 ; resulting coordinates, whereas in equations (3a)-(6b) the value of the first
              09148 ; coordinate of a coordinate pair is overwritten with its new value and this
              09149 ; value is used in the subsequent calculation of the second coordinate? For
              09150 ; example, when the joystick is pushed left, the first call of this subroutine
              09151 ; calculates the new value of x according to equation (3a), overwriting the old
              09152 ; value of x. During the second call to calculate z according to equation (3b),
              09153 ; the new value of x is used instead of the old one. So, why does the rotation
              09154 ; calculation still work? Note, that this value is divided by 64 before it is
              09155 ; added in equation (3b). And this is the trick: By dividing the value by 64 its
              09156 ; contribution is made small enough so that it does not influence the overall
              09157 ; sum significantly.
              09158 ;
              09159 ; SUBROUTINE IMPLEMENTATION DETAILS
              09160 ;
              09161 ; To better understand how this subroutine works, have again a look at equations
              09162 ; (3a)-(6b). If you rearrange the expressions a little their structure is always
              09163 ; of the form
              09164 ;
              09165 ;     TERM2 := TERM2 SIGN TERM3
              09166 ;
              09167 ;     where
              09168 ;
              09169 ;     TERM3 := TERM1 / 64
              09170 ;     SIGN := + or -
              09171 ;
              09172 ; and where TERM1 and TERM2 are position vector components (coordinates). In
              09173 ; fact, this is all this subroutine actually does: It simply adds or subtracts
              09174 ; TERM1 divided by 64 to TERM2. 
              09175 ;
              09176 ; When calling this subroutine the correct indices for the appropriate position
              09177 ; vector components (coordinates) TERM1 and TERM2 are passed in the X and Y
              09178 ; register.
              09179 ;
              09180 ; What about SIGN between TERM2 and TERM3? Have again a look at equations
              09181 ; (3a)-(6b). To compute the two new coordinates after a rotation, the SIGN
              09182 ; toggles from plus to minus and vice versa. The SIGN is initialized by
              09183 ; JOYSTICKDELTA ($6D) before actually calling subroutine ROTATE ($B69B) and is
              09184 ; toggled in every subsequent call of this subroutine. The initial value of SIGN
              09185 ; should be positive (+) if the rotation is clockwise (the joystick is pushed
              09186 ; right or up) and negative if the rotation is counter-clockwise (the joystick
              09187 ; is pushed left or down), respectively. Because SIGN is always toggled you have
              09188 ; to pass the already toggled value with the first call.
              09189 ;
              09190 ; NOTE: Unclear still are three instructions starting at address $B6AD. They
              09191 ; seem to set the two least significant bits of TERM3 in a random fashion. Could
              09192 ; this be some quick hack to avoid messing with lengthy two-complement's
              09193 ; arithmetic here?
              09194 ;
              09195 ; INPUT
              09196 ;
              09197 ;   X = Position vector component index of TERM1. Used values are:
              09198 ;     $00..$30 -> z-component (z-coordinate) of position vector 0..48
              09199 ;     $31..$61 -> x-component (x-coordinate) of position vector 0..48
              09200 ;     $62..$92 -> y-component (y-coordinate) of position vector 0..48
              09201 ;
              09202 ;   Y = Position vector component index of TERM2. Used values are: 
              09203 ;     $00..$30 -> z-component (z-coordinate) of position vector 0..48
              09204 ;     $31..$61 -> x-component (x-coordinate) of position vector 0..48
              09205 ;     $62..$92 -> y-component (y-coordinate) of position vector 0..48
              09206 ;
              09207 ;   JOYSTICKDELTA ($6D) = Initial value of SIGN. Used values are:
              09208 ;     $01 -> (= Positive) Rotate right or up
              09209 ;     $FF -> (= Negative) Rotate left or down
              09210
              09211                                         ; TERM3 is a 24-bit value, represented by 3 bytes as
              09212                                         ; $(sign)(high byte)(low byte)
    =006A     09213 L.TERM3LO       = $6A                   ; TERM3 (high byte), where TERM3 := TERM1 / 64
    =006B     09214 L.TERM3HI       = $6B                   ; TERM3 (low byte),  where TERM3 := TERM1 / 64
    =006C     09215 L.TERM3SIGN     = $6C                   ; TERM3 (sign),      where TERM3 := TERM1 / 64
              09216
B69B BDAD09   09217 ROTATE          LDA ZPOSSIGN,X          ;
B69E 4901     09218                 EOR #$01                ;
B6A0 F002     09219                 BEQ SKIP224             ; Skip if sign of TERM1 is positive
B6A2 A9FF     09220                 LDA #$FF                ;
              09221
B6A4 856B     09222 SKIP224         STA L.TERM3HI           ; If TERM1 pos. -> TERM3 := $0000xx (= TERM1 / 256)
B6A6 856C     09223                 STA L.TERM3SIGN         ; If TERM1 neg. -> TERM3 := $FFFFxx (= TERM1 / 256)
B6A8 BD400A   09224                 LDA ZPOSHI,X            ; where xx := TERM1 (high byte)
B6AB 856A     09225                 STA L.TERM3LO           ;
              09226
B6AD AD0AD2   09227                 LDA RANDOM              ; (?) Hack to avoid messing with two-complement's
B6B0 09BF     09228                 ORA #$BF                ; (?) arithmetic? Provides two least significant
B6B2 5DD30A   09229                 EOR ZPOSLO,X            ; (?) bits B1..0 in TERM3.
              09230
B6B5 0A       09231                 ASL A                   ; TERM3 := TERM * 4 (= TERM1 / 256 * 4 = TERM1 / 64)
B6B6 266A     09232                 ROL L.TERM3LO           ;
B6B8 266B     09233                 ROL L.TERM3HI           ;
B6BA 0A       09234                 ASL A                   ;
B6BB 266A     09235                 ROL L.TERM3LO           ;
B6BD 266B     09236                 ROL L.TERM3HI           ;
              09237
B6BF A56D     09238                 LDA JOYSTICKDELTA       ; Toggle SIGN for next call of ROTATE
B6C1 49FF     09239                 EOR #$FF                ;
B6C3 856D     09240                 STA JOYSTICKDELTA       ;
B6C5 301A     09241                 BMI SKIP225             ; If SIGN negative then subtract, else add TERM3
              09242
              09243 ;*** Addition ******************************************************************
B6C7 18       09244                 CLC                     ; TERM2 := TERM2 + TERM3
B6C8 B9D30A   09245                 LDA ZPOSLO,Y            ; (24-bit addition)
B6CB 656A     09246                 ADC L.TERM3LO           ;
B6CD 99D30A   09247                 STA ZPOSLO,Y            ;
              09248
B6D0 B9400A   09249                 LDA ZPOSHI,Y            ;
B6D3 656B     09250                 ADC L.TERM3HI           ;
B6D5 99400A   09251                 STA ZPOSHI,Y            ;
              09252
B6D8 B9AD09   09253                 LDA ZPOSSIGN,Y          ;
B6DB 656C     09254                 ADC L.TERM3SIGN         ;
B6DD 99AD09   09255                 STA ZPOSSIGN,Y          ;
B6E0 60       09256                 RTS                     ;
              09257
              09258 ;*** Subtraction ***************************************************************
B6E1 38       09259 SKIP225         SEC                     ; TERM2 := TERM2 - TERM3
B6E2 B9D30A   09260                 LDA ZPOSLO,Y            ; (24-bit subtraction)
B6E5 E56A     09261                 SBC L.TERM3LO           ;
B6E7 99D30A   09262                 STA ZPOSLO,Y            ;
              09263
B6EA B9400A   09264                 LDA ZPOSHI,Y            ;
B6ED E56B     09265                 SBC L.TERM3HI           ;
B6EF 99400A   09266                 STA ZPOSHI,Y            ;
              09267
B6F2 B9AD09   09268                 LDA ZPOSSIGN,Y          ;
B6F5 E56C     09269                 SBC L.TERM3SIGN         ;
B6F7 99AD09   09270                 STA ZPOSSIGN,Y          ;
B6FA 60       09271                 RTS                     ;
              09272
              09273 ;*******************************************************************************
              09274 ;*                                                                             *
              09275 ;*                                SCREENCOLUMN                                 *
              09276 ;*                                                                             *
              09277 ;*       Calculate pixel column number from centered pixel column number       *
              09278 ;*                                                                             *
              09279 ;*******************************************************************************
              09280
              09281 ; DESCRIPTION
              09282 ;
              09283 ; Converts a pixel column number relative to the horizontal screen center to a
              09284 ; pixel column number relative to the top-left corner of the screen and stores
              09285 ; the result in table PIXELCOLUMN ($0C2A). The passed relative pixel column
              09286 ; number is always positive. The sign is picked from the corresponding
              09287 ; x-component of the position vector (x-coordinate).
              09288 ;
              09289 ; If the passed relative pixel column number is offscreen horizontally the
              09290 ; calculation is skipped and code execution returns. If the position vector
              09291 ; corresponding to this pixel represents a PLAYFIELD space object (star,
              09292 ; explosion fragments) a new position vector is initialized before code
              09293 ; execution returns. If it represents a PLAYER space object the PLAYER is pushed
              09294 ; offscreen before code execution returns.
              09295 ;
              09296 ; NOTE: The horizontal screen center's pixel column number for PLAYFIELD space
              09297 ; objects has a value of 80 = 160 PLAYFIELD pixels / 2. For PLAYER space objects
              09298 ; it has a value of 125 Player/Missile (PM) pixels (from left to right: 128 PM
              09299 ; pixels to the horizontal screen center - 3 PM pixels relative offset of the
              09300 ; PLAYER shape's horizontal center to its left edge = 125 PM pixels).
              09301 ;
              09302 ; INPUT
              09303 ;
              09304 ;   A = Pixel column number relative to the horizontal screen center, always
              09305 ;       positive. Used values are:
              09306 ;     0..80 -> Regular values, pixel is onscreen
              09307 ;     $FF   -> Pixel is offscreen
              09308 ;   X = Position vector index. Used values are:
              09309 ;     0..4  -> Position vector of a PLAYER space object
              09310 ;     5..48 -> Position vector of a PLAYFIELD space object
              09311
    =006D     09312 L.PIXELCOLUMN   = $6D                   ; Saves relative pixel column number
              09313
B6FB C950     09314 SCREENCOLUMN    CMP #80                 ; If pixel is offscreen (A > 79)...
B6FD B05B     09315                 BCS SKIP233             ; ...return via initializing a new position vector
              09316
B6FF 856D     09317                 STA L.PIXELCOLUMN       ; Save relative pixel column number
B701 A950     09318                 LDA #80                 ; If PLAYFIELD space object -> A := CENTERCOL = 80
B703 E005     09319                 CPX #5                  ; If PLAYER space object    -> A := CENTERCOL = 125
B705 B002     09320                 BCS SKIP226             ;
B707 A97D     09321                 LDA #125                ;
              09322
B709 BCDE09   09323 SKIP226         LDY XPOSSIGN,X          ; Skip if x-coordinate positive
B70C D009     09324                 BNE SKIP227             ;
              09325
B70E 38       09326                 SEC                     ; Pixel in left screen half (x-coordinate negative)
B70F E66D     09327                 INC L.PIXELCOLUMN       ;
B711 E56D     09328                 SBC L.PIXELCOLUMN       ;
B713 9D2A0C   09329                 STA PIXELCOLUMN,X       ; Pixel column := CENTERCOL - (rel. pixel column + 1)
B716 60       09330                 RTS                     ; Return
              09331
B717 18       09332 SKIP227         CLC                     ; Pixel in right screen half (x-coordinate positive)
B718 656D     09333                 ADC L.PIXELCOLUMN       ;
B71A 9D2A0C   09334                 STA PIXELCOLUMN,X       ; Pixel column := CENTERCOL + relative pixel column
B71D 60       09335                 RTS                     ; Return
              09336
              09337 ;*******************************************************************************
              09338 ;*                                                                             *
              09339 ;*                                  SCREENROW                                  *
              09340 ;*                                                                             *
              09341 ;*          Calculate pixel row number from centered pixel row number          *
              09342 ;*                                                                             *
              09343 ;*******************************************************************************
              09344
              09345 ; Converts a pixel row number relative to the vertical screen center to a pixel
              09346 ; row number relative to the top-left corner of the screen and stores the result
              09347 ; in table PIXELROWNEW ($0BF9). The passed relative pixel row number is always
              09348 ; positive. The sign is picked from the corresponding y-component of the
              09349 ; position vector (y-coordinate).
              09350 ;
              09351 ; If the passed relative pixel row number is offscreen vertically the
              09352 ; calculation is skipped and code execution returns. If the position vector
              09353 ; corresponding to this pixel represents a PLAYFIELD space object (star,
              09354 ; explosion fragments) a new position vector is initialized in subroutine
              09355 ; INITPOSVEC ($B764) before code execution returns. If it represents a PLAYER
              09356 ; space object the PLAYER is pushed offscreen before code execution returns.
              09357 ;
              09358 ; NOTE: The vertical screen center's pixel row number for PLAYFIELD space
              09359 ; objects has a value of 50 = 100 PLAYFIELD pixels / 2. For PLAYER space objects
              09360 ; it has a value of 122 Player/Missile (PM) pixels (from top to bottom: 8 PM
              09361 ; pixels to start of Display List + 16 PM pixels to begin of PLAYFIELD + 100 PM
              09362 ; pixels to vertical screen center - 2 PM pixels (?) = 122 PM pixels).
              09363 ;
              09364 ; NOTE: If the position vector corresponding to the pixel represents a PLAYER
              09365 ; space object the passed pixel row number is doubled because 1 PLAYFIELD pixel
              09366 ; has the same height as 2 PM pixels at single-line resolution.
              09367 ;
              09368 ; When in Long-Range Scan view the z-coordinate takes the place of the
              09369 ; y-coordinate of the Front or Aft view. If the Long-Range Scan is damaged the
              09370 ; passed pixel row number is treated randomly as a negative or positive value
              09371 ; (mirror effect).
              09372 ;
              09373 ; INPUT
              09374 ;
              09375 ;   A = Pixel row number relative to the vertical screen center, always
              09376 ;       positive. Used values are:
              09377 ;     0..50 -> Regular values, pixel is onscreen
              09378 ;     $FF   -> Pixel is offscreen
              09379 ;   X = Position vector index. Used values are:
              09380 ;     0..4  -> Position vector of a PLAYER space object
              09381 ;     5..48 -> Position vector of a PLAYFIELD space object
              09382
    =006D     09383 L.PIXELROW      = $6D                   ; Saves relative pixel row number
              09384
B71E C932     09385 SCREENROW       CMP #50                 ; If pixel is offscreen (A > 49)...
B720 B038     09386                 BCS SKIP233             ; ...return via initializing a new position vector
              09387
B722 856D     09388                 STA L.PIXELROW          ; Save relative pixel row number
B724 A932     09389                 LDA #50                 ; If PLAYFIELD space object -> A := CENTERROW = 50
B726 E005     09390                 CPX #5                  ;
B728 B004     09391                 BCS SKIP228             ;
B72A 066D     09392                 ASL L.PIXELROW          ; If PLAYER space object -> Double pixel row number
B72C A97A     09393                 LDA #122                ; If PLAYER space object ->    A := CENTERROW = 122
              09394
B72E 24D0     09395 SKIP228         BIT SHIPVIEW            ; Skip if not in Long-Range Scan view
B730 5013     09396                 BVC SKIP230             ;
              09397
B732 2C9609   09398                 BIT GCSTATLRS           ; Skip if Long-Range Scan OK
B735 1007     09399                 BPL SKIP229             ;
              09400
B737 2C0AD2   09401                 BIT RANDOM              ; Long-Range Scan damaged...
B73A 500E     09402                 BVC SKIP231             ; ...branch randomly to pixel row number calculation
B73C 7015     09403                 BVS SKIP232             ; ...(mirror effect)
              09404
B73E BCAD09   09405 SKIP229         LDY ZPOSSIGN,X          ;
B741 D007     09406                 BNE SKIP231             ; Skip if z-coordinate pos. (Long-Range Scan view)
B743 F00E     09407                 BEQ SKIP232             ; Skip if z-coordinate neg. (Long-Range Scan view)
              09408
B745 BC0F0A   09409 SKIP230         LDY YPOSSIGN,X          ;
B748 F009     09410                 BEQ SKIP232             ; Skip if y-coordinate neg. (Front or Aft view)
              09411
B74A 38       09412 SKIP231         SEC                     ; Pixel in upper screen half (z or y coordinate pos.)
B74B E66D     09413                 INC L.PIXELROW          ;
B74D E56D     09414                 SBC L.PIXELROW          ;
B74F 9DF90B   09415                 STA PIXELROWNEW,X       ; Pixel row  := CENTERROW - (rel. pixel row + 1)
B752 60       09416                 RTS                     ; Return
              09417
B753 18       09418 SKIP232         CLC                     ; Pixel in lower screen half (y or z coordinate neg.)
B754 656D     09419                 ADC L.PIXELROW          ;
B756 9DF90B   09420                 STA PIXELROWNEW,X       ; Pixel row := CENTERROW + relative pixel row
B759 60       09421                 RTS                     ; Return
              09422
B75A E005     09423 SKIP233         CPX #5                  ; Space object is offscreen. If it is a...
B75C B006     09424                 BCS INITPOSVEC          ; ...PLAYFIELD space object -> New position vector
B75E A9FB     09425                 LDA #251                ; ...PLAYER space object    -> Push PLAYER offscreen
B760 9DF90B   09426                 STA PIXELROWNEW,X       ;                              Why a value of 251 (?)
B763 60       09427 SKIP234         RTS                     ; Return
              09428
              09429 ;*******************************************************************************
              09430 ;*                                                                             *
              09431 ;*                                 INITPOSVEC                                  *
              09432 ;*                                                                             *
              09433 ;*                Initialize position vector of a space object                 *
              09434 ;*                                                                             *
              09435 ;*******************************************************************************
              09436
              09437 ; DESCRIPTION
              09438 ;
              09439 ; Initializes the position vector of a space object.
              09440 ;
              09441 ; This subroutine executes the following steps:
              09442 ;
              09443 ; (1)  Set the pixel row and column number to an offscreen value (= 99).
              09444 ;
              09445 ; (2)  If the position vector represents an explosion fragment space object then
              09446 ;      return code execution immediately. This avoids generating new explosion
              09447 ;      fragment space objects. They are separately initialized in subroutine
              09448 ;      COPYPOSVEC ($ACAF), which is called from subroutine INITEXPL ($AC6B).
              09449 ;
              09450 ; (3)  Assign default values (see below) to the position vector components
              09451 ;      (coordinates) depending on our starship's view.
              09452 ;
              09453 ; Code execution continues into subroutine RNDINVXY ($B7BE) where x and y
              09454 ; coordinates are inverted randomly.
              09455 ;
              09456 ; After passing through this and the next subroutine RNDINVXY ($B7BE) the
              09457 ; components of a position vector (coordinates) are assigned to one of the
              09458 ; following values depending on our starship's view:
              09459 ;
              09460 ; o   FRONT VIEW
              09461 ;
              09462 ;     +------------+---------------------------------------+
              09463 ;     | Coordinate |                 Values                |
              09464 ;     +------------+---------------------------------------+
              09465 ;     |     x      |  -4095..+4095 (-($0***)..+$0***) <KM> |
              09466 ;     |     y      |  -4095..+4095 (-($0***)..+$0***) <KM> | 
              09467 ;     |     z      |  +3840..+4095 (          +$0F**) <KM> |
              09468 ;     +------------+---------------------------------------+
              09469 ;
              09470 ; o   AFT VIEW
              09471 ;
              09472 ;     +------------+---------------------------------------+
              09473 ;     | Coordinate |                 Values                |
              09474 ;     +------------+---------------------------------------+ 
              09475 ;     |     x      |  -3840..+3840 (-($0*00)..+$0*00) <KM> |
              09476 ;     |     y      |  -3840..+3840 (-($0*00)..+$0*00) <KM> |
              09477 ;     |     z      |  -3968.. -128 (-($0*80)        ) <KM> |
              09478 ;     +------------+---------------------------------------+ 
              09479 ;     Values of x, y, and z coordinates change in increments of 256.
              09480 ;     Second digit of z-coordinate is -MAX(RNDY,RNDX), where
              09481 ;     RNDY := RND($00..$0F), RNDX := RND($00..$0F).
              09482 ;
              09483 ; o   LONG-RANGE SCAN VIEW
              09484 ;
              09485 ;     +------------+---------------------------------------+
              09486 ;     | Coordinate |                 Values                |
              09487 ;     +------------+---------------------------------------+
              09488 ;     |     x      | -65535..+65535 (-($****)..$****) <KM> |
              09489 ;     |     y      |  -4095..+4095  (-($0***)..$0***) <KM> |
              09490 ;     |     z      | -65535..+65535 (-($****)..$****) <KM> |
              09491 ;     +------------+---------------------------------------+
              09492 ;
              09493 ; INPUT
              09494 ;
              09495 ;   X = Position vector index. Used values are: 0..48.
              09496
    =006A     09497 L.MAXRNDXY      = $6A                   ; Saves MAX(new y-coordinate (high byte), ...
              09498                                         ;  ...new x-coordinate (high byte))
              09499
B764 A963     09500 INITPOSVEC      LDA #99                 ; Init to offscreen pixel row and column numbers
B766 9DF90B   09501                 STA PIXELROWNEW,X       ;
B769 9D2A0C   09502                 STA PIXELCOLUMN,X       ;
              09503
B76C E011     09504                 CPX #17                 ; Return if pos vector is explosion frag space obj
B76E B0F3     09505                 BCS SKIP234             ; This avoids creating new explosion frag space objs
              09506
B770 AD0AD2   09507                 LDA RANDOM              ; RNDY := RND($00..$0F)
B773 290F     09508                 AND #$0F                ;
B775 856A     09509                 STA L.MAXRNDXY          ; Save RNDY
B777 9DA20A   09510                 STA YPOSHI,X            ; y-coordinate (high byte) := RNDY
              09511
B77A AD0AD2   09512                 LDA RANDOM              ; RNDX := RND($00..$0F)
B77D 290F     09513                 AND #$0F                ;
B77F C56A     09514                 CMP L.MAXRNDXY          ;
B781 9002     09515                 BCC SKIP235             ;
B783 856A     09516                 STA L.MAXRNDXY          ; Save MAX(RNDY, RNDX)
B785 9D710A   09517 SKIP235         STA XPOSHI,X            ; x-coordinate (high byte) := RNDX
              09518
B788 A90F     09519                 LDA #$0F                ; z-coordinate (high byte) := $0F
B78A 9D400A   09520                 STA ZPOSHI,X            ;
              09521
B78D A5D0     09522                 LDA SHIPVIEW            ; z-coordinate (sign) := 1 or 0 (Front or Aft view)
B78F 4901     09523                 EOR #$01                ;
B791 2901     09524                 AND #$01                ;
B793 9DAD09   09525                 STA ZPOSSIGN,X          ;
B796 D011     09526                 BNE SKIP236             ; Skip if in Front or Long-Range Scan view
              09527
              09528                                         ; Aft view only:
B798 9D040B   09529                 STA XPOSLO,X            ; x-coordinate (low byte) := 0
B79B 9D350B   09530                 STA YPOSLO,X            ; y-coordinate (low byte) := 0
B79E 38       09531                 SEC                     ; z-coordinate (high byte) := -MAX(RNDY, RNDX)
B79F E56A     09532                 SBC L.MAXRNDXY          ;
B7A1 9D400A   09533                 STA ZPOSHI,X            ;
B7A4 A980     09534                 LDA #$80                ; z-coordinate (low byte) := $80
B7A6 9DD30A   09535                 STA ZPOSLO,X            ;
              09536
B7A9 24D0     09537 SKIP236         BIT SHIPVIEW            ; If not in Long-Range Scan view skip to RNDINVXY
B7AB 5011     09538                 BVC RNDINVXY            ;
              09539
              09540                                         ; Long-Range Scan view only:
B7AD AD0AD2   09541                 LDA RANDOM              ; x-coordinate (high byte) := RND($00..$FF)
B7B0 9D710A   09542                 STA XPOSHI,X            ;
B7B3 AD0AD2   09543                 LDA RANDOM              ; z-coordinate (high byte) := RND($00..$FF)
B7B6 9D400A   09544                 STA ZPOSHI,X            ;
B7B9 2901     09545                 AND #$01                ; Invert z-coordinate randomly
B7BB 9DAD09   09546                 STA ZPOSSIGN,X          ;
              09547
              09548 ;*******************************************************************************
              09549 ;*                                                                             *
              09550 ;*                                  RNDINVXY                                   *
              09551 ;*                                                                             *
              09552 ;*         Randomly invert the x and y components of a position vector         *
              09553 ;*                                                                             *
              09554 ;*******************************************************************************
              09555
              09556 ; DESCRIPTION
              09557 ;
              09558 ; Randomly inverts the x and y components of a position vector (x and y
              09559 ; coordinates). See also subroutine INITPOSVEC ($B764).
              09560 ;
              09561 ; INPUT
              09562 ;
              09563 ;   X = Position vector index. Used values are: 0..48.
              09564
B7BE AD0AD2   09565 RNDINVXY        LDA RANDOM              ; Set sign of y-coordinate randomly
B7C1 2901     09566                 AND #$01                ;
B7C3 9D0F0A   09567                 STA YPOSSIGN,X          ;
B7C6 D00F     09568                 BNE SKIP237             ; Skip if sign positive
              09569
B7C8 38       09570                 SEC                     ; Sign negative -> Calc negative y-coordinate
B7C9 FD350B   09571                 SBC YPOSLO,X            ; (calculate two's-complement of 16-bit value)
B7CC 9D350B   09572                 STA YPOSLO,X            ;
B7CF A900     09573                 LDA #0                  ;
B7D1 FDA20A   09574                 SBC YPOSHI,X            ;
B7D4 9DA20A   09575                 STA YPOSHI,X            ;
              09576
B7D7 AD0AD2   09577 SKIP237         LDA RANDOM              ; Set sign of x-coordinate randomly
B7DA 2901     09578                 AND #$01                ;
B7DC 9DDE09   09579                 STA XPOSSIGN,X          ;
B7DF D00F     09580                 BNE SKIP238             ; Skip if sign positive
              09581
B7E1 38       09582                 SEC                     ; Sign negative -> Calc negative x-coordinate
B7E2 FD040B   09583                 SBC XPOSLO,X            ; (calculate two's-complement of 16-bit value)
B7E5 9D040B   09584                 STA XPOSLO,X            ;
B7E8 A900     09585                 LDA #0                  ;
B7EA FD710A   09586                 SBC XPOSHI,X            ;
B7ED 9D710A   09587                 STA XPOSHI,X            ;
B7F0 60       09588 SKIP238         RTS                     ; Return
              09589
              09590 ;*******************************************************************************
              09591 ;*                                                                             *
              09592 ;*                                ISSURROUNDED                                 *
              09593 ;*                                                                             *
              09594 ;*               Check if a sector is surrounded by Zylon units                *
              09595 ;*                                                                             *
              09596 ;*******************************************************************************
              09597
              09598 ; DESCRIPTION
              09599 ;
              09600 ; Checks if a sector of the Galactic Chart is surrounded by Zylon units in the
              09601 ; adjacent NORTH, EAST, SOUTH, and WEST sectors.
              09602 ;
              09603 ; INPUT
              09604 ;
              09605 ;   X = Sector of Galactic Chart. Used values are: $00..$7F with, for example,
              09606 ;     $00 -> NORTHWEST corner sector
              09607 ;     $0F -> NORTHEAST corner sector
              09608 ;     $70 -> SOUTHWEST corner sector
              09609 ;     $7F -> SOUTHWEST corner sector
              09610 ;
              09611 ; OUTPUT
              09612 ;
              09613 ;   A = Returns if the sector is surrounded by Zylon units in the adjacent
              09614 ;       NORTH, EAST, SOUTH, and WEST sectors.
              09615 ;       0 -> Sector is not surrounded
              09616 ;     > 0 -> Sector is surrounded
              09617
B7F1 BDC808   09618 ISSURROUNDED    LDA GCMEMMAP-1,X        ; Check WEST sector
B7F4 F00D     09619                 BEQ SKIP239             ;
B7F6 BDCA08   09620                 LDA GCMEMMAP+1,X        ; Check EAST sector
B7F9 F008     09621                 BEQ SKIP239             ;
B7FB BDB908   09622                 LDA GCMEMMAP-16,X       ; Check NORTH sector
B7FE F003     09623                 BEQ SKIP239             ;
B800 BDD908   09624                 LDA GCMEMMAP+16,X       ; Check SOUTH sector
B803 60       09625 SKIP239         RTS                     ; Return
              09626
              09627 ;*******************************************************************************
              09628 ;*                                                                             *
              09629 ;*                                  UPDPANEL                                   *
              09630 ;*                                                                             *
              09631 ;*                        Update Control Panel Display                         *
              09632 ;*                                                                             *
              09633 ;*******************************************************************************
              09634
              09635 ; DESCRIPTION
              09636 ;
              09637 ; This subroutine executes the following steps: 
              09638 ;
              09639 ; (1)  Accelerate or decelerate our starship, update the VELOCITY readout
              09640 ;
              09641 ;      If the new velocity value is different from the current one either
              09642 ;      increment or decrement the current velocity value toward the new one.
              09643 ;
              09644 ;      If the Engines are damaged or destroyed (and hyperwarp is not engaged)
              09645 ;      then store a random value (less or equal than the current velocity) as
              09646 ;      the current velocity.
              09647 ;
              09648 ;      Display the updated velocity by the VELOCITY readout of the Control Panel
              09649 ;      Display.
              09650 ;
              09651 ; (2)  Update THETA, PHI, and RANGE readouts
              09652 ;
              09653 ;      If the Attack Computer is working then display the x, y, and z
              09654 ;      coordinates of the currently tracked space object as THETA, PHI, and
              09655 ;      RANGE readout values of the Control Panel Display.
              09656 ;
              09657 ; (3)  Calculate overall energy consumption
              09658 ;
              09659 ;      Add the overall energy consumption per game loop iteration to the energy
              09660 ;      counter. This value is given in energy subunits (256 energy subunits = 1
              09661 ;      energy unit displayed by the 4-digit ENERGY readout of the Console Panel
              09662 ;      Display). It is the total of the following items:
              09663 ;
              09664 ;      (1)  8 energy subunits if the Shields are up
              09665 ;
              09666 ;      (2)  2 energy subunits if the Attack Computer is on
              09667 ;
              09668 ;      (3)  1 energy subunit of the life support system
              09669 ;
              09670 ;      (4)  Our starship's Engines energy drain rate (depending on its velocity)
              09671 ;
              09672 ;      If there is a carryover of the energy counter then decrement the ENERGY
              09673 ;      readout of the Control Panel Display by one energy unit after code
              09674 ;      execution has continued into subroutine DECENERGY ($B86F). 
              09675 ;
              09676 ;      NOTE: The values of ISSHIELDSON ($7D) and ISATTCOMPON ($7E) not only
              09677 ;      indicate if the Shields and the Attack Computer are on. They also store
              09678 ;      the number of energy subunits consumed by these subsystems when they are
              09679 ;      on (2 and 8, respectively).
              09680
              09681 ;*** Accelerate or decelerate our starship *************************************
B804 A670     09682 UPDPANEL        LDX VELOCITYLO          ; Skip if new velocity = current velocity
B806 E471     09683                 CPX NEWVELOCITY         ;
B808 F008     09684                 BEQ SKIP241             ;
              09685
B80A 9004     09686                 BCC SKIP240             ; In/decrement current velocity toward new velocity
B80C C670     09687                 DEC VELOCITYLO          ;
B80E B012     09688                 BCS SKIP242             ;
B810 E670     09689 SKIP240         INC VELOCITYLO          ;
              09690
B812 A5C0     09691 SKIP241         LDA WARPSTATE           ; Skip if hyperwarp engaged
B814 D00C     09692                 BNE SKIP242             ;
              09693
B816 2C9309   09694                 BIT GCSTATENG           ; Skip if Engines are OK
B819 1007     09695                 BPL SKIP242             ;
              09696
B81B A571     09697                 LDA NEWVELOCITY         ; Store RND(0..current velocity) to current velocity
B81D 2D0AD2   09698                 AND RANDOM              ;
B820 8570     09699                 STA VELOCITYLO          ;
              09700
B822 A001     09701 SKIP242         LDY #VELOCD1-PANELTXT-1 ; Update digits of VELOCITY readout
B824 20CDB8   09702                 JSR SHOWDIGITS          ;
              09703
              09704 ;*** Display coordinates of tracked space object of Control Panel Display ******
B827 2C9509   09705                 BIT GCSTATCOM           ; Skip if Attack Computer damaged or destroyed
B82A 3030     09706                 BMI SKIP243             ;
              09707
B82C A931     09708                 LDA #$31                ; Update THETA readout (x-coordinate)
B82E A017     09709                 LDY #THETAC1-PANELTXT   ;
B830 20A7B8   09710                 JSR SHOWCOORD           ;
              09711
B833 A962     09712                 LDA #$62                ; Update PHI readout (y-coordinate)
B835 A01D     09713                 LDY #PHIC1-PANELTXT     ;
B837 20A7B8   09714                 JSR SHOWCOORD           ;
              09715
B83A A900     09716                 LDA #$00                ; Update RANGE readout (z-coordinate)
B83C A023     09717                 LDY #RANGEC1-PANELTXT   ;
B83E 20A7B8   09718                 JSR SHOWCOORD           ;
              09719
B841 AD6E09   09720                 LDA RANGEC1+2           ; Hack to clear RANGE digit 3 when in hyperwarp:
B844 8D6F09   09721                 STA RANGEC1+3           ; Copy RANGE digit 2 to digit 3
B847 C90A     09722                 CMP #CCS.9+1            ; Skip if digit character > '9' (= 'infinity' char)
B849 B011     09723                 BCS SKIP243             ;
              09724
B84B AE5C09   09725                 LDX TRACKDIGIT          ; Get z-coordinate (low byte) of tracked space object
B84E BDD30A   09726                 LDA ZPOSLO,X            ;
B851 4A       09727                 LSR A                   ; ...divide it by 16...
B852 4A       09728                 LSR A                   ;
B853 4A       09729                 LSR A                   ;
B854 4A       09730                 LSR A                   ;
B855 AA       09731                 TAX                     ;
B856 BDE90E   09732                 LDA MAPTOBCD99,X        ; ...map value of $00..$0F to BCD value 0..9
B859 8D6F09   09733                 STA RANGEC1+3           ; ...and store it to RANGE digit 3
              09734
              09735 ;*** Calculate overall energy consumption **************************************
B85C 18       09736 SKIP243         CLC                     ;
B85D A57F     09737                 LDA ENERGYCNT           ; Load energy counter
B85F 657D     09738                 ADC ISSHIELDSON         ; Add 8 energy subunits if Shields on
B861 6580     09739                 ADC DRAINRATE           ; Add our starship's drain rate (in subunits)
B863 657E     09740                 ADC ISATTCOMPON         ; Add 2 energy subunits if Attack Computer on
B865 6901     09741                 ADC #$01                ; Add 1 energy subunit consumed by life support system
B867 C57F     09742                 CMP ENERGYCNT           ;
B869 857F     09743                 STA ENERGYCNT           ;
B86B B039     09744                 BCS SKIP246             ; Return if no energy counter carryover
              09745
B86D A203     09746                 LDX #3                  ; Will decrement third energy digit
              09747
              09748 ;*******************************************************************************
              09749 ;*                                                                             *
              09750 ;*                                  DECENERGY                                  *
              09751 ;*                                                                             *
              09752 ;*                               Decrease energy                               *
              09753 ;*                                                                             *
              09754 ;*******************************************************************************
              09755
              09756 ; DESCRIPTION
              09757 ;
              09758 ; When not in demo mode, subtract energy from the 4-digit ENERGY readout of the
              09759 ; Control Panel Display. If crossing a 100-energy-unit boundary during
              09760 ; subtraction the score is decremented by one unit. If the energy is zero the
              09761 ; game is over.
              09762 ;
              09763 ; INPUT
              09764 ;
              09765 ;   X = ENERGY readout digit to be decremented. Used values are:
              09766 ;     1 -> Subtract 100 units from ENERGY readout
              09767 ;     2 -> Subtract  10 units from ENERGY readout
              09768 ;     3 -> Subtract   1 unit  from ENERGY readout
              09769
              09770 ;*** Display ENERGY readout ****************************************************
B86F 2464     09771 DECENERGY       BIT ISDEMOMODE          ; Return if in demo mode
B871 7033     09772                 BVS SKIP246             ;
              09773
B873 DE5509   09774                 DEC ENERGYD1,X          ; Decrement energy digit character
B876 BD5509   09775                 LDA ENERGYD1,X          ;
B879 C980     09776                 CMP #CCS.COL2!CCS.0     ;
B87B B029     09777                 BCS SKIP246             ; Return if digit character >= '0'
B87D A989     09778                 LDA #CCS.COL2!CCS.9     ;
B87F 9D5509   09779                 STA ENERGYD1,X          ; Store digit character '9'
              09780
              09781 ;*** Decrement score when crossing a 100-energy-unit boundary while subtracting 
B882 E002     09782                 CPX #2                  ; Skip if no crossing of 100-energy-unit boundary
B884 D008     09783                 BNE SKIP245             ;
              09784
B886 A5CB     09785                 LDA SCORE               ; SCORE := SCORE - 1
B888 D002     09786                 BNE SKIP244             ;
B88A C6CC     09787                 DEC SCORE+1             ;
B88C C6CB     09788 SKIP244         DEC SCORE               ;
              09789
B88E CA       09790 SKIP245         DEX                     ;
B88F 10DE     09791                 BPL DECENERGY           ; Next digit
              09792
              09793 ;*** Energy is zero, game over *************************************************
B891 A20A     09794                 LDX #CCS.SPC            ; Clear 4-digit ENERGY readout
B893 8A       09795                 TXA                     ;
B894 A003     09796                 LDY #3                  ;
B896 995509   09797 LOOP079         STA ENERGYD1,Y          ;
B899 88       09798                 DEY                     ;
B89A 10FA     09799                 BPL LOOP079             ;
              09800
B89C 2045B0   09801                 JSR SETVIEW             ; Set Front view
              09802
B89F A031     09803                 LDY #$31                ; Set title phrase "MISSION ABORTED ZERO ENERGY"
B8A1 A204     09804                 LDX #$04                ; Set mission bonus offset
B8A3 200AB1   09805                 JSR GAMEOVER            ; Game over
              09806
B8A6 60       09807 SKIP246         RTS                     ; Return
              09808
              09809 ;*******************************************************************************
              09810 ;*                                                                             *
              09811 ;*                                  SHOWCOORD                                  *
              09812 ;*                                                                             *
              09813 ;*  Display a position vector component (coordinate) in Control Panel Display  *
              09814 ;*                                                                             *
              09815 ;*******************************************************************************
              09816
              09817 ; DESCRIPTION
              09818 ;
              09819 ; Displays a position vector component (coordinate) by one of the THETA, PHI, or
              09820 ; RANGE readouts of the Control Panel Display.
              09821 ;
              09822 ; Write the sign to the Control Panel Display, then map the high byte of the
              09823 ; respective coordinate (x -> THETA, y -> PHI, z -> RANGE) to a BCD-value in
              09824 ; 00..99. Code execution continues into subroutine SHOWDIGITS ($B8CD) where the
              09825 ; digits are actually stored in the Control Panel Display.
              09826 ;
              09827 ; NOTE: If the digits of either the THETA or PHI readout are to be displayed and
              09828 ; the x or y position vector component (high byte) is $FF then tweak the value
              09829 ; to $FE. This avoids accessing table MAPTOBCD99 ($0EE9) with an index of $FF
              09830 ; that would return the special value $EA. This value represents the CCS.INF
              09831 ; ($0E) and CCS.SPC ($0A) characters (see comments in subroutine INITIALIZE
              09832 ; ($B3BA)) that are displayed by the RANGE readout only.
              09833 ;
              09834 ; INPUT
              09835 ;
              09836 ;   A = Position vector component (coordinate) offset. Used values are: 
              09837 ;     $00 -> z-coordinate
              09838 ;     $31 -> x-coordinate
              09839 ;     $62 -> y-coordinate
              09840 ;   Y = Offset into the Control Panel Display memory map. Used values are:
              09841 ;     $17 -> First character (sign) of THETA readout (x-coordinate of tracked
              09842 ;            space object)
              09843 ;     $1D -> First character (sign) of PHI readout   (y-coordinate of tracked
              09844 ;            space object)
              09845 ;     $23 -> First character (sign) of RANGE readout (z-coordinate of tracked
              09846 ;            space object)
              09847
    =006A     09848 L.SIGNCHAR      = $6A                   ; Saves sign character
              09849
B8A7 18       09850 SHOWCOORD       CLC                     ; Add index of tracked space object...
B8A8 6D5C09   09851                 ADC TRACKDIGIT          ; ...to position vector component offset
B8AB AA       09852                 TAX                     ; Save position vector component index
              09853
              09854 ;*** Display sign in Control Panel Display *************************************
B8AC A910     09855                 LDA #CCS.PLUS           ; Save '+' (CCS.PLUS) to sign character
B8AE 856A     09856                 STA L.SIGNCHAR          ;
              09857
B8B0 BDAD09   09858                 LDA ZPOSSIGN,X          ; Prep sign of coordinate
B8B3 4A       09859                 LSR A                   ;
B8B4 BD400A   09860                 LDA ZPOSHI,X            ; Prep coordinate (high byte)
B8B7 B004     09861                 BCS SKIP247             ; Skip if sign is positive
              09862
B8B9 49FF     09863                 EOR #$FF                ; Invert coordinate (high byte)
B8BB C66A     09864                 DEC L.SIGNCHAR          ; Change saved sign character to '-' (CCS.MINUS)
              09865
B8BD AA       09866 SKIP247         TAX                     ; Save coordinate (high byte)
B8BE A56A     09867                 LDA L.SIGNCHAR          ; Store sign character in Control Panel Display
B8C0 994909   09868                 STA PANELTXT,Y          ;
              09869
              09870 ;*** Get RANGE digits **********************************************************
B8C3 98       09871                 TYA                     ; Skip if RANGE is to be displayed
B8C4 2910     09872                 AND #$10                ;
B8C6 F005     09873                 BEQ SHOWDIGITS          ;
              09874
B8C8 E0FF     09875                 CPX #$FF                ; If coordinate (high byte) = $FF decrement value
B8CA D001     09876                 BNE SHOWDIGITS          ; This avoids output of CCS.INFINITY in...
B8CC CA       09877                 DEX                     ; ...THETA and PHI readouts
              09878
              09879 ;*******************************************************************************
              09880 ;*                                                                             *
              09881 ;*                                 SHOWDIGITS                                  *
              09882 ;*                                                                             *
              09883 ;*          Display a value by a readout of the Control Panel Display          *
              09884 ;*                                                                             *
              09885 ;*******************************************************************************
              09886
              09887 ; DESCRIPTION
              09888 ;
              09889 ; Converts a binary value in $00..$FF to a BCD-value in 0..99 and displays it as
              09890 ; a 2-digit number in the Control Panel Display.
              09891 ;
              09892 ; INPUT
              09893 ;
              09894 ;   X = Value to be displayed as a 2-digit BCD-value. Used values are: $00..$FF.
              09895 ;   Y = Offset into the Control Panel Display memory map relative to the first
              09896 ;       character of the Control Panel Display (the 'V' of the VELOCITY
              09897 ;       readout). Used values are: 
              09898 ;     $01 -> Character before first digit of VELOCITY readout
              09899 ;     $17 -> First character (sign) of THETA readout (x-coordinate of tracked
              09900 ;            space object)
              09901 ;     $1D -> First character (sign) of PHI readout   (y-coordinate of tracked
              09902 ;            space object)
              09903 ;     $23 -> First character (sign) of RANGE readout (z-coordinate of tracked
              09904 ;            space object)
              09905
B8CD BDE90E   09906 SHOWDIGITS      LDA MAPTOBCD99,X        ; Map binary value to BCD-value
B8D0 AA       09907                 TAX                     ;
B8D1 290F     09908                 AND #$0F                ;
B8D3 994B09   09909                 STA PANELTXT+2,Y        ; Store 'ones' digit in Control Panel Display
B8D6 8A       09910                 TXA                     ;
B8D7 4A       09911                 LSR A                   ;
B8D8 4A       09912                 LSR A                   ;
B8D9 4A       09913                 LSR A                   ;
B8DA 4A       09914                 LSR A                   ;
B8DB 994A09   09915                 STA PANELTXT+1,Y        ; Store 'tens' digit in Control Panel Display
B8DE 60       09916                 RTS                     ; Return
              09917
              09918 ;*******************************************************************************
              09919 ;*                                                                             *
              09920 ;*                G A M E   D A T A   ( P A R T   2   O F   2 )                *
              09921 ;*                                                                             *
              09922 ;*******************************************************************************
              09923
              09924 ;*** Color register offsets of PLAYER0..4 **************************************
B8DF 00       09925 PLCOLOROFFTAB   .BYTE 0                               ; PLAYER0
B8E0 01       09926                 .BYTE 1                               ; PLAYER1
B8E1 02       09927                 .BYTE 2                               ; PLAYER2
B8E2 03       09928                 .BYTE 3                               ; PLAYER3
B8E3 07       09929                 .BYTE 7                               ; PLAYER4
              09930
              09931 ;*** Shape table 1 (PLAYER2..4) ************************************************
B8E4 00       09932 PLSHAP1TAB      .BYTE $00                             ; ........
B8E5 18       09933                 .BYTE $18                             ; ...##...
B8E6 3C       09934                 .BYTE $3C                             ; ..####..
B8E7 7E       09935                 .BYTE $7E                             ; .######.
B8E8 7E       09936                 .BYTE $7E                             ; .######.
B8E9 76       09937                 .BYTE $76                             ; .###.##.
B8EA F7       09938                 .BYTE $F7                             ; ####.###
B8EB DF       09939                 .BYTE $DF                             ; ##.#####
B8EC DF       09940                 .BYTE $DF                             ; ##.#####
B8ED FF       09941                 .BYTE $FF                             ; ########
B8EE FF       09942                 .BYTE $FF                             ; ########
B8EF F7       09943                 .BYTE $F7                             ; ####.###
B8F0 76       09944                 .BYTE $76                             ; .###.##.
B8F1 7E       09945                 .BYTE $7E                             ; .######.
B8F2 7E       09946                 .BYTE $7E                             ; .######.
B8F3 3C       09947                 .BYTE $3C                             ; ..####..
B8F4 18       09948                 .BYTE $18                             ; ...##...
B8F5 10       09949                 .BYTE $10                             ; ...#....
B8F6 38       09950                 .BYTE $38                             ; ..###...
B8F7 7C       09951                 .BYTE $7C                             ; .#####..
B8F8 7C       09952                 .BYTE $7C                             ; .#####..
B8F9 FE       09953                 .BYTE $FE                             ; #######.
B8FA DE       09954                 .BYTE $DE                             ; ##.####.
B8FB DA       09955                 .BYTE $DA                             ; ##.##.#.
B8FC FA       09956                 .BYTE $FA                             ; #####.#.
B8FD EE       09957                 .BYTE $EE                             ; ###.###.
B8FE EE       09958                 .BYTE $EE                             ; ###.###.
B8FF 7C       09959                 .BYTE $7C                             ; .#####..
B900 7C       09960                 .BYTE $7C                             ; .#####..
B901 38       09961                 .BYTE $38                             ; ..###...
B902 10       09962                 .BYTE $10                             ; ...#....
B903 18       09963                 .BYTE $18                             ; ...##...
B904 3C       09964                 .BYTE $3C                             ; ..####..
B905 3C       09965                 .BYTE $3C                             ; ..####..
B906 7E       09966                 .BYTE $7E                             ; .######.
B907 6E       09967                 .BYTE $6E                             ; .##.###.
B908 7A       09968                 .BYTE $7A                             ; .####.#.
B909 7E       09969                 .BYTE $7E                             ; .######.
B90A 76       09970                 .BYTE $76                             ; .###.##.
B90B 7E       09971                 .BYTE $7E                             ; .######.
B90C 3C       09972                 .BYTE $3C                             ; ..####..
B90D 3C       09973                 .BYTE $3C                             ; ..####..
B90E 18       09974                 .BYTE $18                             ; ...##...
B90F 10       09975                 .BYTE $10                             ; ...#....
B910 38       09976                 .BYTE $38                             ; ..###...
B911 38       09977                 .BYTE $38                             ; ..###...
B912 7C       09978                 .BYTE $7C                             ; .#####..
B913 74       09979                 .BYTE $74                             ; .###.#..
B914 7C       09980                 .BYTE $7C                             ; .#####..
B915 6C       09981                 .BYTE $6C                             ; .##.##..
B916 38       09982                 .BYTE $38                             ; ..###...
B917 38       09983                 .BYTE $38                             ; ..###...
B918 10       09984                 .BYTE $10                             ; ...#....
B919 10       09985                 .BYTE $10                             ; ...#....
B91A 18       09986                 .BYTE $18                             ; ...##...
B91B 3C       09987                 .BYTE $3C                             ; ..####..
B91C 2C       09988                 .BYTE $2C                             ; ..#.##..
B91D 3C       09989                 .BYTE $3C                             ; ..####..
B91E 3C       09990                 .BYTE $3C                             ; ..####..
B91F 18       09991                 .BYTE $18                             ; ...##...
B920 08       09992                 .BYTE $08                             ; ....#...
B921 10       09993                 .BYTE $10                             ; ...#....
B922 38       09994                 .BYTE $38                             ; ..###...
B923 38       09995                 .BYTE $38                             ; ..###...
B924 28       09996                 .BYTE $28                             ; ..#.#...
B925 38       09997                 .BYTE $38                             ; ..###...
B926 10       09998                 .BYTE $10                             ; ...#....
B927 3C       09999                 .BYTE $3C                             ; ..####..
B928 3C       10000                 .BYTE $3C                             ; ..####..
B929 24       10001                 .BYTE $24                             ; ..#..#..
B92A 3C       10002                 .BYTE $3C                             ; ..####..
B92B 7E       10003                 .BYTE $7E                             ; .######.
B92C 7E       10004                 .BYTE $7E                             ; .######.
B92D 7E       10005                 .BYTE $7E                             ; .######.
B92E 5A       10006                 .BYTE $5A                             ; .#.##.#.
B92F FF       10007                 .BYTE $FF                             ; ########
B930 FF       10008                 .BYTE $FF                             ; ########
B931 42       10009                 .BYTE $42                             ; .#....#.
B932 42       10010                 .BYTE $42                             ; .#....#.
B933 42       10011                 .BYTE $42                             ; .#....#.
B934 42       10012                 .BYTE $42                             ; .#....#.
B935 42       10013                 .BYTE $42                             ; .#....#.
B936 42       10014                 .BYTE $42                             ; .#....#.
B937 1C       10015                 .BYTE $1C                             ; ...###..
B938 1C       10016                 .BYTE $1C                             ; ...###..
B939 14       10017                 .BYTE $14                             ; ...#.#..
B93A 3E       10018                 .BYTE $3E                             ; ..#####.
B93B 3E       10019                 .BYTE $3E                             ; ..#####.
B93C 3E       10020                 .BYTE $3E                             ; ..#####.
B93D 2A       10021                 .BYTE $2A                             ; ..#.#.#.
B93E 7F       10022                 .BYTE $7F                             ; .#######
B93F 7F       10023                 .BYTE $7F                             ; .#######
B940 22       10024                 .BYTE $22                             ; ..#...#.
B941 22       10025                 .BYTE $22                             ; ..#...#.
B942 22       10026                 .BYTE $22                             ; ..#...#.
B943 22       10027                 .BYTE $22                             ; ..#...#.
B944 22       10028                 .BYTE $22                             ; ..#...#.
B945 18       10029                 .BYTE $18                             ; ...##...
B946 18       10030                 .BYTE $18                             ; ...##...
B947 3C       10031                 .BYTE $3C                             ; ..####..
B948 3C       10032                 .BYTE $3C                             ; ..####..
B949 3C       10033                 .BYTE $3C                             ; ..####..
B94A 3C       10034                 .BYTE $3C                             ; ..####..
B94B 7E       10035                 .BYTE $7E                             ; .######.
B94C 24       10036                 .BYTE $24                             ; ..#..#..
B94D 24       10037                 .BYTE $24                             ; ..#..#..
B94E 24       10038                 .BYTE $24                             ; ..#..#..
B94F 24       10039                 .BYTE $24                             ; ..#..#..
B950 10       10040                 .BYTE $10                             ; ...#....
B951 10       10041                 .BYTE $10                             ; ...#....
B952 38       10042                 .BYTE $38                             ; ..###...
B953 38       10043                 .BYTE $38                             ; ..###...
B954 38       10044                 .BYTE $38                             ; ..###...
B955 7C       10045                 .BYTE $7C                             ; .#####..
B956 28       10046                 .BYTE $28                             ; ..#.#...
B957 28       10047                 .BYTE $28                             ; ..#.#...
B958 28       10048                 .BYTE $28                             ; ..#.#...
B959 18       10049                 .BYTE $18                             ; ...##...
B95A 18       10050                 .BYTE $18                             ; ...##...
B95B 3C       10051                 .BYTE $3C                             ; ..####..
B95C 18       10052                 .BYTE $18                             ; ...##...
B95D 18       10053                 .BYTE $18                             ; ...##...
B95E 10       10054                 .BYTE $10                             ; ...#....
B95F 10       10055                 .BYTE $10                             ; ...#....
B960 38       10056                 .BYTE $38                             ; ..###...
B961 10       10057                 .BYTE $10                             ; ...#....
B962 18       10058                 .BYTE $18                             ; ...##...
B963 7E       10059                 .BYTE $7E                             ; .######.
B964 FF       10060                 .BYTE $FF                             ; ########
B965 FF       10061                 .BYTE $FF                             ; ########
B966 FF       10062                 .BYTE $FF                             ; ########
B967 FF       10063                 .BYTE $FF                             ; ########
B968 FF       10064                 .BYTE $FF                             ; ########
B969 E7       10065                 .BYTE $E7                             ; ###..###
B96A E7       10066                 .BYTE $E7                             ; ###..###
B96B FF       10067                 .BYTE $FF                             ; ########
B96C FF       10068                 .BYTE $FF                             ; ########
B96D FF       10069                 .BYTE $FF                             ; ########
B96E FF       10070                 .BYTE $FF                             ; ########
B96F FF       10071                 .BYTE $FF                             ; ########
B970 7E       10072                 .BYTE $7E                             ; .######.
B971 7E       10073                 .BYTE $7E                             ; .######.
B972 00       10074                 .BYTE $00                             ; ........
B973 18       10075                 .BYTE $18                             ; ...##...
B974 3C       10076                 .BYTE $3C                             ; ..####..
B975 7E       10077                 .BYTE $7E                             ; .######.
B976 FF       10078                 .BYTE $FF                             ; ########
B977 FF       10079                 .BYTE $FF                             ; ########
B978 FF       10080                 .BYTE $FF                             ; ########
B979 E7       10081                 .BYTE $E7                             ; ###..###
B97A 66       10082                 .BYTE $66                             ; .##..##.
B97B FF       10083                 .BYTE $FF                             ; ########
B97C FF       10084                 .BYTE $FF                             ; ########
B97D FF       10085                 .BYTE $FF                             ; ########
B97E FF       10086                 .BYTE $FF                             ; ########
B97F 7E       10087                 .BYTE $7E                             ; .######.
B980 7E       10088                 .BYTE $7E                             ; .######.
B981 00       10089                 .BYTE $00                             ; ........
B982 18       10090                 .BYTE $18                             ; ...##...
B983 3C       10091                 .BYTE $3C                             ; ..####..
B984 7E       10092                 .BYTE $7E                             ; .######.
B985 FF       10093                 .BYTE $FF                             ; ########
B986 FF       10094                 .BYTE $FF                             ; ########
B987 E7       10095                 .BYTE $E7                             ; ###..###
B988 66       10096                 .BYTE $66                             ; .##..##.
B989 FF       10097                 .BYTE $FF                             ; ########
B98A FF       10098                 .BYTE $FF                             ; ########
B98B FF       10099                 .BYTE $FF                             ; ########
B98C FF       10100                 .BYTE $FF                             ; ########
B98D 3C       10101                 .BYTE $3C                             ; ..####..
B98E 18       10102                 .BYTE $18                             ; ...##...
B98F 3C       10103                 .BYTE $3C                             ; ..####..
B990 FF       10104                 .BYTE $FF                             ; ########
B991 FF       10105                 .BYTE $FF                             ; ########
B992 E7       10106                 .BYTE $E7                             ; ###..###
B993 66       10107                 .BYTE $66                             ; .##..##.
B994 FF       10108                 .BYTE $FF                             ; ########
B995 FF       10109                 .BYTE $FF                             ; ########
B996 7E       10110                 .BYTE $7E                             ; .######.
B997 3C       10111                 .BYTE $3C                             ; ..####..
B998 00       10112                 .BYTE $00                             ; ........
B999 18       10113                 .BYTE $18                             ; ...##...
B99A 3C       10114                 .BYTE $3C                             ; ..####..
B99B FF       10115                 .BYTE $FF                             ; ########
B99C FF       10116                 .BYTE $FF                             ; ########
B99D FF       10117                 .BYTE $FF                             ; ########
B99E 3C       10118                 .BYTE $3C                             ; ..####..
B99F 18       10119                 .BYTE $18                             ; ...##...
B9A0 18       10120                 .BYTE $18                             ; ...##...
B9A1 3C       10121                 .BYTE $3C                             ; ..####..
B9A2 FF       10122                 .BYTE $FF                             ; ########
B9A3 3C       10123                 .BYTE $3C                             ; ..####..
B9A4 18       10124                 .BYTE $18                             ; ...##...
B9A5 28       10125                 .BYTE $28                             ; ..#.#...
B9A6 28       10126                 .BYTE $28                             ; ..#.#...
B9A7 28       10127                 .BYTE $28                             ; ..#.#...
B9A8 28       10128                 .BYTE $28                             ; ..#.#...
B9A9 EE       10129                 .BYTE $EE                             ; ###.###.
B9AA 00       10130                 .BYTE $00                             ; ........
B9AB 00       10131                 .BYTE $00                             ; ........
B9AC EE       10132                 .BYTE $EE                             ; ###.###.
B9AD 28       10133                 .BYTE $28                             ; ..#.#...
B9AE 28       10134                 .BYTE $28                             ; ..#.#...
B9AF 28       10135                 .BYTE $28                             ; ..#.#...
B9B0 28       10136                 .BYTE $28                             ; ..#.#...
              10137
              10138 ;*** Shape table 2 (PLAYER0..1) ************************************************
B9B1 00       10139 PLSHAP2TAB      .BYTE $00                             ; ........
B9B2 81       10140                 .BYTE $81                             ; #......#
B9B3 81       10141                 .BYTE $81                             ; #......#
B9B4 81       10142                 .BYTE $81                             ; #......#
B9B5 81       10143                 .BYTE $81                             ; #......#
B9B6 BD       10144                 .BYTE $BD                             ; #.####.#
B9B7 FF       10145                 .BYTE $FF                             ; ########
B9B8 FF       10146                 .BYTE $FF                             ; ########
B9B9 BD       10147                 .BYTE $BD                             ; #.####.#
B9BA 81       10148                 .BYTE $81                             ; #......#
B9BB 81       10149                 .BYTE $81                             ; #......#
B9BC 81       10150                 .BYTE $81                             ; #......#
B9BD 81       10151                 .BYTE $81                             ; #......#
B9BE 82       10152                 .BYTE $82                             ; #.....#.
B9BF 82       10153                 .BYTE $82                             ; #.....#.
B9C0 BA       10154                 .BYTE $BA                             ; #.###.#.
B9C1 FE       10155                 .BYTE $FE                             ; #######.
B9C2 FE       10156                 .BYTE $FE                             ; #######.
B9C3 BA       10157                 .BYTE $BA                             ; #.###.#.
B9C4 82       10158                 .BYTE $82                             ; #.....#.
B9C5 82       10159                 .BYTE $82                             ; #.....#.
B9C6 42       10160                 .BYTE $42                             ; .#....#.
B9C7 5A       10161                 .BYTE $5A                             ; .#.##.#.
B9C8 7E       10162                 .BYTE $7E                             ; .######.
B9C9 7E       10163                 .BYTE $7E                             ; .######.
B9CA 5A       10164                 .BYTE $5A                             ; .#.##.#.
B9CB 42       10165                 .BYTE $42                             ; .#....#.
B9CC 44       10166                 .BYTE $44                             ; .#...#..
B9CD 54       10167                 .BYTE $54                             ; .#.#.#..
B9CE 7C       10168                 .BYTE $7C                             ; .#####..
B9CF 7C       10169                 .BYTE $7C                             ; .#####..
B9D0 54       10170                 .BYTE $54                             ; .#.#.#..
B9D1 44       10171                 .BYTE $44                             ; .#...#..
B9D2 24       10172                 .BYTE $24                             ; ..#..#..
B9D3 3C       10173                 .BYTE $3C                             ; ..####..
B9D4 3C       10174                 .BYTE $3C                             ; ..####..
B9D5 24       10175                 .BYTE $24                             ; ..#..#..
B9D6 28       10176                 .BYTE $28                             ; ..#.#...
B9D7 38       10177                 .BYTE $38                             ; ..###...
B9D8 38       10178                 .BYTE $38                             ; ..###...
B9D9 28       10179                 .BYTE $28                             ; ..#.#...
B9DA 18       10180                 .BYTE $18                             ; ...##...
B9DB 18       10181                 .BYTE $18                             ; ...##...
B9DC 10       10182                 .BYTE $10                             ; ...#....
B9DD 10       10183                 .BYTE $10                             ; ...#....
B9DE E0       10184                 .BYTE $E0                             ; ###.....
B9DF F8       10185                 .BYTE $F8                             ; #####...
B9E0 F8       10186                 .BYTE $F8                             ; #####...
B9E1 FE       10187                 .BYTE $FE                             ; #######.
B9E2 57       10188                 .BYTE $57                             ; .#.#.###
B9E3 FE       10189                 .BYTE $FE                             ; #######.
B9E4 F8       10190                 .BYTE $F8                             ; #####...
B9E5 F8       10191                 .BYTE $F8                             ; #####...
B9E6 C0       10192                 .BYTE $C0                             ; ##......
B9E7 C0       10193                 .BYTE $C0                             ; ##......
B9E8 F0       10194                 .BYTE $F0                             ; ####....
B9E9 C0       10195                 .BYTE $C0                             ; ##......
B9EA F0       10196                 .BYTE $F0                             ; ####....
B9EB F0       10197                 .BYTE $F0                             ; ####....
B9EC FC       10198                 .BYTE $FC                             ; ######..
B9ED BE       10199                 .BYTE $BE                             ; #.#####.
B9EE FC       10200                 .BYTE $FC                             ; ######..
B9EF F0       10201                 .BYTE $F0                             ; ####....
B9F0 80       10202                 .BYTE $80                             ; #.......
B9F1 80       10203                 .BYTE $80                             ; #.......
B9F2 C0       10204                 .BYTE $C0                             ; ##......
B9F3 C0       10205                 .BYTE $C0                             ; ##......
B9F4 F0       10206                 .BYTE $F0                             ; ####....
B9F5 BC       10207                 .BYTE $BC                             ; #.####..
B9F6 F0       10208                 .BYTE $F0                             ; ####....
B9F7 C0       10209                 .BYTE $C0                             ; ##......
B9F8 07       10210                 .BYTE $07                             ; .....###
B9F9 1F       10211                 .BYTE $1F                             ; ...#####
B9FA 1F       10212                 .BYTE $1F                             ; ...#####
B9FB 7F       10213                 .BYTE $7F                             ; .#######
B9FC EA       10214                 .BYTE $EA                             ; ###.#.#.
B9FD 7F       10215                 .BYTE $7F                             ; .#######
B9FE 1F       10216                 .BYTE $1F                             ; ...#####
B9FF 1F       10217                 .BYTE $1F                             ; ...#####
BA00 03       10218                 .BYTE $03                             ; ......##
BA01 03       10219                 .BYTE $03                             ; ......##
BA02 0F       10220                 .BYTE $0F                             ; ....####
BA03 03       10221                 .BYTE $03                             ; ......##
BA04 0F       10222                 .BYTE $0F                             ; ....####
BA05 0F       10223                 .BYTE $0F                             ; ....####
BA06 3F       10224                 .BYTE $3F                             ; ..######
BA07 7D       10225                 .BYTE $7D                             ; .#####.#
BA08 3F       10226                 .BYTE $3F                             ; ..######
BA09 0F       10227                 .BYTE $0F                             ; ....####
BA0A 01       10228                 .BYTE $01                             ; .......#
BA0B 01       10229                 .BYTE $01                             ; .......#
BA0C 03       10230                 .BYTE $03                             ; ......##
BA0D 03       10231                 .BYTE $03                             ; ......##
BA0E 0F       10232                 .BYTE $0F                             ; ....####
BA0F 3D       10233                 .BYTE $3D                             ; ..####.#
BA10 0F       10234                 .BYTE $0F                             ; ....####
BA11 03       10235                 .BYTE $03                             ; ......##
BA12 18       10236                 .BYTE $18                             ; ...##...
BA13 3C       10237                 .BYTE $3C                             ; ..####..
BA14 7E       10238                 .BYTE $7E                             ; .######.
BA15 7E       10239                 .BYTE $7E                             ; .######.
BA16 DB       10240                 .BYTE $DB                             ; ##.##.##
BA17 C3       10241                 .BYTE $C3                             ; ##....##
BA18 81       10242                 .BYTE $81                             ; #......#
BA19 81       10243                 .BYTE $81                             ; #......#
BA1A 81       10244                 .BYTE $81                             ; #......#
BA1B 10       10245                 .BYTE $10                             ; ...#....
BA1C 38       10246                 .BYTE $38                             ; ..###...
BA1D 7C       10247                 .BYTE $7C                             ; .#####..
BA1E 7C       10248                 .BYTE $7C                             ; .#####..
BA1F D6       10249                 .BYTE $D6                             ; ##.#.##.
BA20 C6       10250                 .BYTE $C6                             ; ##...##.
BA21 82       10251                 .BYTE $82                             ; #.....#.
BA22 82       10252                 .BYTE $82                             ; #.....#.
BA23 18       10253                 .BYTE $18                             ; ...##...
BA24 3C       10254                 .BYTE $3C                             ; ..####..
BA25 3C       10255                 .BYTE $3C                             ; ..####..
BA26 66       10256                 .BYTE $66                             ; .##..##.
BA27 66       10257                 .BYTE $66                             ; .##..##.
BA28 42       10258                 .BYTE $42                             ; .#....#.
BA29 42       10259                 .BYTE $42                             ; .#....#.
BA2A 10       10260                 .BYTE $10                             ; ...#....
BA2B 38       10261                 .BYTE $38                             ; ..###...
BA2C 38       10262                 .BYTE $38                             ; ..###...
BA2D 6C       10263                 .BYTE $6C                             ; .##.##..
BA2E 44       10264                 .BYTE $44                             ; .#...#..
BA2F 44       10265                 .BYTE $44                             ; .#...#..
BA30 18       10266                 .BYTE $18                             ; ...##...
BA31 3C       10267                 .BYTE $3C                             ; ..####..
BA32 24       10268                 .BYTE $24                             ; ..#..#..
BA33 24       10269                 .BYTE $24                             ; ..#..#..
BA34 10       10270                 .BYTE $10                             ; ...#....
BA35 38       10271                 .BYTE $38                             ; ..###...
BA36 28       10272                 .BYTE $28                             ; ..#.#...
BA37 18       10273                 .BYTE $18                             ; ...##...
BA38 3C       10274                 .BYTE $3C                             ; ..####..
BA39 7E       10275                 .BYTE $7E                             ; .######.
BA3A FF       10276                 .BYTE $FF                             ; ########
BA3B 18       10277                 .BYTE $18                             ; ...##...
BA3C 18       10278                 .BYTE $18                             ; ...##...
BA3D FF       10279                 .BYTE $FF                             ; ########
BA3E 7E       10280                 .BYTE $7E                             ; .######.
BA3F 3C       10281                 .BYTE $3C                             ; ..####..
BA40 18       10282                 .BYTE $18                             ; ...##...
BA41 10       10283                 .BYTE $10                             ; ...#....
BA42 38       10284                 .BYTE $38                             ; ..###...
BA43 7C       10285                 .BYTE $7C                             ; .#####..
BA44 FE       10286                 .BYTE $FE                             ; #######.
BA45 38       10287                 .BYTE $38                             ; ..###...
BA46 38       10288                 .BYTE $38                             ; ..###...
BA47 FE       10289                 .BYTE $FE                             ; #######.
BA48 7C       10290                 .BYTE $7C                             ; .#####..
BA49 38       10291                 .BYTE $38                             ; ..###...
BA4A 10       10292                 .BYTE $10                             ; ...#....
BA4B 18       10293                 .BYTE $18                             ; ...##...
BA4C 3C       10294                 .BYTE $3C                             ; ..####..
BA4D 7E       10295                 .BYTE $7E                             ; .######.
BA4E 18       10296                 .BYTE $18                             ; ...##...
BA4F 7E       10297                 .BYTE $7E                             ; .######.
BA50 3C       10298                 .BYTE $3C                             ; ..####..
BA51 18       10299                 .BYTE $18                             ; ...##...
BA52 10       10300                 .BYTE $10                             ; ...#....
BA53 38       10301                 .BYTE $38                             ; ..###...
BA54 7C       10302                 .BYTE $7C                             ; .#####..
BA55 10       10303                 .BYTE $10                             ; ...#....
BA56 7C       10304                 .BYTE $7C                             ; .#####..
BA57 38       10305                 .BYTE $38                             ; ..###...
BA58 10       10306                 .BYTE $10                             ; ...#....
BA59 18       10307                 .BYTE $18                             ; ...##...
BA5A 3C       10308                 .BYTE $3C                             ; ..####..
BA5B 18       10309                 .BYTE $18                             ; ...##...
BA5C 3C       10310                 .BYTE $3C                             ; ..####..
BA5D 18       10311                 .BYTE $18                             ; ...##...
BA5E 10       10312                 .BYTE $10                             ; ...#....
BA5F 38       10313                 .BYTE $38                             ; ..###...
BA60 38       10314                 .BYTE $38                             ; ..###...
BA61 10       10315                 .BYTE $10                             ; ...#....
              10316
              10317 ;*** Display List fragments ****************************************************
              10318 ;
              10319 ; LOCAL VARIABLES
    =1000     10320 PFMEM.C0R0      = PFMEM+0*40                          ; Start address of PLAYFIELD row 0
    =10C8     10321 PFMEM.C0R5      = PFMEM+5*40                          ; Start address of PLAYFIELD row 5
    =12A8     10322 PFMEM.C0R17     = PFMEM+17*40                         ; Start address of PLAYFIELD row 17
              10323
              10324 ;*** Display List fragment for Control Panel Display (bottom text window) ******
BA62 8D       10325 DLSTFRAG        .BYTE $8D                             ; GR7 + DLI
BA63 00       10326                 .BYTE $00                             ; BLK1
BA64 464909   10327                 .BYTE $46,<PANELTXT,>PANELTXT         ; GR1 @ PANELTXT
BA67 20       10328                 .BYTE $20                             ; BLK3
BA68 06       10329                 .BYTE $06                             ; GR1
BA69 00       10330                 .BYTE $00                             ; BLK1
              10331
              10332 ;*** Display List fragment for Galactic Chart view *****************************
BA6A 012EA1   10333 DLSTFRAGGC      .BYTE $01,<DLSTGC,>DLSTGC             ; JMP @ DLSTGC
              10334
              10335 ;*** Display List fragment for Long-Range Scan view ****************************
BA6D 00       10336 DLSTFRAGLRS     .BYTE $00                             ; BLK1
BA6E 00       10337                 .BYTE $00                             ; BLK1
BA6F 46F8A0   10338                 .BYTE $46,<LRSHEADER,>LRSHEADER       ; GR1 @ LRSHEADER
BA72 4DC810   10339                 .BYTE $4D,<PFMEM.C0R5,>PFMEM.C0R5     ; GR7 @ PFMEM.C0R5
              10340
              10341 ;*** Display List fragment for Aft view ****************************************
BA75 00       10342 DLSTFRAGAFT     .BYTE $00                             ; BLK1
BA76 00       10343                 .BYTE $00                             ; BLK1
BA77 4609A1   10344                 .BYTE $46,<AFTHEADER,>AFTHEADER       ; GR1 @ AFTHEADER
BA7A 4DC810   10345                 .BYTE $4D,<PFMEM.C0R5,>PFMEM.C0R5     ; GR7 @ PFMEM.C0R5
              10346
              10347 ;*** Display List fragment for Front view and Title text line ******************
BA7D 4D0010   10348 DLSTFRAGFRONT   .BYTE $4D,<PFMEM.C0R0,>PFMEM.C0R0     ; GR7 @ PFMEM.C0R0
BA80 0D       10349                 .BYTE $0D                             ; GR7
BA81 0D       10350                 .BYTE $0D                             ; GR7
BA82 0D       10351                 .BYTE $0D                             ; GR7
BA83 0D       10352                 .BYTE $0D                             ; GR7
BA84 0D       10353                 .BYTE $0D                             ; GR7
BA85 30       10354                 .BYTE $30                             ; BLK4
BA86 461F0D   10355                 .BYTE $46,<TITLETXT,>TITLETXT         ; GR1 @ TITLETXT
BA89 4DA812   10356                 .BYTE $4D,<PFMEM.C0R17,>PFMEM.C0R17   ; GR7 @ PFMEM.C0R17
              10357
              10358 ;*** Display List fragment offsets relative to DLSTFRAG ************************
BA8C 1B       10359 DLSTFRAGOFFTAB  .BYTE DLSTFRAGFRONT-DLSTFRAG          ; Front view
BA8D 13       10360                 .BYTE DLSTFRAGAFT-DLSTFRAG            ; Aft view
BA8E 0B       10361                 .BYTE DLSTFRAGLRS-DLSTFRAG            ; Long-Range Scan view
BA8F 08       10362                 .BYTE DLSTFRAGGC-DLSTFRAG             ; Galactic Chart view
              10363
              10364 ;*** 1-byte bit patterns for 4 pixels of same color for PLAYFIELD space objects 
BA90 FF       10365 FOURCOLORPIXEL  .BYTE $FF                             ; COLOR3
BA91 FF       10366                 .BYTE $FF                             ; COLOR3
BA92 FF       10367                 .BYTE $FF                             ; COLOR3
BA93 FF       10368                 .BYTE $FF                             ; COLOR3
BA94 AA       10369                 .BYTE $AA                             ; COLOR2
BA95 FF       10370                 .BYTE $FF                             ; COLOR3
BA96 AA       10371                 .BYTE $AA                             ; COLOR2
BA97 FF       10372                 .BYTE $FF                             ; COLOR3
BA98 AA       10373                 .BYTE $AA                             ; COLOR2
BA99 AA       10374                 .BYTE $AA                             ; COLOR2
BA9A AA       10375                 .BYTE $AA                             ; COLOR2
BA9B FF       10376                 .BYTE $FF                             ; COLOR3
BA9C AA       10377                 .BYTE $AA                             ; COLOR2
BA9D AA       10378                 .BYTE $AA                             ; COLOR2
BA9E AA       10379                 .BYTE $AA                             ; COLOR2
BA9F AA       10380                 .BYTE $AA                             ; COLOR2
BAA0 AA       10381                 .BYTE $AA                             ; COLOR2
BAA1 AA       10382                 .BYTE $AA                             ; COLOR2
BAA2 AA       10383                 .BYTE $AA                             ; COLOR2
BAA3 55       10384                 .BYTE $55                             ; COLOR1
BAA4 55       10385                 .BYTE $55                             ; COLOR1
BAA5 AA       10386                 .BYTE $AA                             ; COLOR2
BAA6 55       10387                 .BYTE $55                             ; COLOR1
BAA7 AA       10388                 .BYTE $AA                             ; COLOR2
BAA8 55       10389                 .BYTE $55                             ; COLOR1
BAA9 55       10390                 .BYTE $55                             ; COLOR1
BAAA 55       10391                 .BYTE $55                             ; COLOR1
BAAB AA       10392                 .BYTE $AA                             ; COLOR2
BAAC 55       10393                 .BYTE $55                             ; COLOR1
BAAD 55       10394                 .BYTE $55                             ; COLOR1
BAAE 55       10395                 .BYTE $55                             ; COLOR1
BAAF 55       10396                 .BYTE $55                             ; COLOR1
              10397
              10398 ;*** Masks to filter 1 pixel (2 bits) from 4 pixels (1 byte of PLAYFIELD memory)
BAB0 C0       10399 PIXELMASKTAB    .BYTE $C0                             ; ##......
BAB1 30       10400                 .BYTE $30                             ; ..##....
BAB2 0C       10401                 .BYTE $0C                             ; ....##..
BAB3 03       10402                 .BYTE $03                             ; ......##
              10403
              10404 ;*** Velocity table ************************************************************
BAB4 00       10405 VELOCITYTAB     .BYTE 0                               ; Speed 0 =   0 <KM/H>
BAB5 01       10406                 .BYTE 1                               ; Speed 1 =   1 <KM/H>
BAB6 02       10407                 .BYTE 2                               ; Speed 2 =   2 <KM/H>
BAB7 04       10408                 .BYTE 4                               ; Speed 3 =   4 <KM/H>
BAB8 08       10409                 .BYTE 8                               ; Speed 4 =   8 <KM/H>
BAB9 10       10410                 .BYTE 16                              ; Speed 5 =  16 <KM/H>
BABA 20       10411                 .BYTE 32                              ; Speed 6 =  32 <KM/H>
BABB 40       10412                 .BYTE 64                              ; Speed 7 =  64 <KM/H>
BABC 60       10413                 .BYTE 96                              ; Speed 8 =  96 <KM/H>
BABD 70       10414                 .BYTE 112                             ; Speed 9 = 112 <KM/H>
              10415
              10416 ;*** Keyboard code lookup table ************************************************
BABE F2       10417 KEYTAB          .BYTE $F2                             ; '0'   - Speed 0
BABF DF       10418                 .BYTE $DF                             ; '1'   - Speed 1
BAC0 DE       10419                 .BYTE $DE                             ; '2'   - Speed 2
BAC1 DA       10420                 .BYTE $DA                             ; '3'   - Speed 3
BAC2 D8       10421                 .BYTE $D8                             ; '4'   - Speed 4
BAC3 DD       10422                 .BYTE $DD                             ; '5'   - Speed 5
BAC4 DB       10423                 .BYTE $DB                             ; '6'   - Speed 6
BAC5 F3       10424                 .BYTE $F3                             ; '7'   - Speed 7
BAC6 F5       10425                 .BYTE $F5                             ; '8'   - Speed 8
BAC7 F0       10426                 .BYTE $F0                             ; '9'   - Speed 9
BAC8 F8       10427                 .BYTE $F8                             ; 'F'   - Front view
BAC9 FF       10428                 .BYTE $FF                             ; 'A'   - Aft view
BACA C0       10429                 .BYTE $C0                             ; 'L'   - Long-Range Scan view
BACB FD       10430                 .BYTE $FD                             ; 'G'   - Galactic Chart view
BACC ED       10431                 .BYTE $ED                             ; 'T'   - Tracking on/off
BACD FE       10432                 .BYTE $FE                             ; 'S'   - Shields on/off
BACE D2       10433                 .BYTE $D2                             ; 'C'   - Attack Computer on/off
BACF F9       10434                 .BYTE $F9                             ; 'H'   - Hyperwarp
BAD0 E5       10435                 .BYTE $E5                             ; 'M'   - Manual Target Selector
BAD1 CA       10436                 .BYTE $CA                             ; 'P'   - Pause
BAD2 E7       10437                 .BYTE $E7                             ; 'INV' - Abort Mission
              10438
              10439 ;*** Engines energy drain rates per game loop iteration in energy subunits *****
BAD3 00       10440 DRAINRATETAB    .BYTE 0                               ;
BAD4 04       10441                 .BYTE 4                               ;
BAD5 06       10442                 .BYTE 6                               ;
BAD6 08       10443                 .BYTE 8                               ;
BAD7 0A       10444                 .BYTE 10                              ;
BAD8 0C       10445                 .BYTE 12                              ;
BAD9 0E       10446                 .BYTE 14                              ;
BADA 1E       10447                 .BYTE 30                              ;
BADB 2D       10448                 .BYTE 45                              ;
BADC 3C       10449                 .BYTE 60                              ;
              10450
              10451 ;*** Hyperwarp energy depending on distance ************************************
BADD 0A       10452 WARPENERGYTAB   .BYTE 10                              ; =  100 energy units
BADE 0D       10453                 .BYTE 13                              ; =  130 energy units
BADF 10       10454                 .BYTE 16                              ; =  160 energy units
BAE0 14       10455                 .BYTE 20                              ; =  200 energy units
BAE1 17       10456                 .BYTE 23                              ; =  230 energy units
BAE2 32       10457                 .BYTE 50                              ; =  500 energy units
BAE3 46       10458                 .BYTE 70                              ; =  700 energy units
BAE4 50       10459                 .BYTE 80                              ; =  800 energy units
BAE5 5A       10460                 .BYTE 90                              ; =  900 energy units
BAE6 78       10461                 .BYTE 120                             ; = 1200 energy units
BAE7 7D       10462                 .BYTE 125                             ; = 1250 energy units
BAE8 82       10463                 .BYTE 130                             ; = 1300 energy units
BAE9 87       10464                 .BYTE 135                             ; = 1350 energy units
BAEA 8C       10465                 .BYTE 140                             ; = 1400 energy units
BAEB 9B       10466                 .BYTE 155                             ; = 1550 energy units
BAEC AA       10467                 .BYTE 170                             ; = 1700 energy units
BAED B8       10468                 .BYTE 184                             ; = 1840 energy units
BAEE C8       10469                 .BYTE 200                             ; = 2000 energy units
BAEF D0       10470                 .BYTE 208                             ; = 2080 energy units
BAF0 D8       10471                 .BYTE 216                             ; = 2160 energy units
BAF1 DF       10472                 .BYTE 223                             ; = 2230 energy units
BAF2 E8       10473                 .BYTE 232                             ; = 2320 energy units
BAF3 F1       10474                 .BYTE 241                             ; = 2410 energy units
BAF4 FA       10475                 .BYTE 250                             ; = 2500 energy units
              10476
              10477 ;*** Joystick increments *******************************************************
BAF5 00       10478 STICKINCTAB     .BYTE 0                               ; Centered
BAF6 01       10479                 .BYTE 1                               ; Right or up
BAF7 FF       10480                 .BYTE -1                              ; Left or down
BAF8 00       10481                 .BYTE 0                               ; Centered
              10482
              10483 ;*** 3-byte elements to draw cross hairs and Attack Computer Display ***********
              10484 ;   Byte 1 : Pixel column number of line start
              10485 ;   Byte 2 : Pixel row number of line start
              10486 ;   Byte 3 : B7 = 0 -> Draw line leftward
              10487 ;            B7 = 1 -> Draw line downward
              10488 ;            B6..0  -> Length of line in pixels. Possible values are: 0..127.
              10489 ;
              10490 ;                   #
              10491 ;                   #                              4
              10492 ;                   #                      ##############################
              10493 ;                   #1                     #             #              #
              10494 ;                   #                      #             #11            #
              10495 ;                   #                      #             #              #
              10496 ;                   #                      #5            #    8         #6
              10497 ;                                          #      ###############       #
              10498 ;                                          #      #             #       #
              10499 ;         15                  16           #   7  #             #   10  #
              10500 ; ###############       ###############    ########             #########
              10501 ;                                          #      #12           #       #
              10502 ;                                          #      #             #13     #
              10503 ;                                          #      ###############       #
              10504 ;                   #                      #         9   #              #
              10505 ;                   #                      #             #              #
              10506 ;                   #                      #             #14            #
              10507 ;                   #                      #       3     #              #
              10508 ;                   #2                     ##############################
              10509 ;                   #
              10510 ;                   #
              10511 ;
              10512 ;         Front/Aft Cross Hairs                Attack Computer Display
              10513 ;
              10514 ; LOCAL VARIABLES
    =0080     10515 DOWN            = $80
    =0000     10516 LEFT            = $00
              10517
BAF9 502887   10518 DRAWLINESTAB    .BYTE 80,40,DOWN!7                    ; Line 1
BAFC 503687   10519                 .BYTE 80,54,DOWN!7                    ; Line 2
              10520
BAFF 77461E   10521                 .BYTE 119,70,LEFT!30                  ; Line 3
BB02 77561E   10522                 .BYTE 119,86,LEFT!30                  ; Line 4
BB05 774691   10523                 .BYTE 119,70,DOWN!17                  ; Line 5
BB08 944691   10524                 .BYTE 148,70,DOWN!17                  ; Line 6
BB0B 784E06   10525                 .BYTE 120,78,LEFT!6                   ; Line 7
BB0E 7E4B0F   10526                 .BYTE 126,75,LEFT!15                  ; Line 8
BB11 7E510F   10527                 .BYTE 126,81,LEFT!15                  ; Line 9
BB14 8D4E07   10528                 .BYTE 141,78,LEFT!7                   ; Line 10
BB17 854784   10529                 .BYTE 133,71,DOWN!4                   ; Line 11
BB1A 7E4C85   10530                 .BYTE 126,76,DOWN!5                   ; Line 12
BB1D 8C4C85   10531                 .BYTE 140,76,DOWN!5                   ; Line 13
BB20 855284   10532                 .BYTE 133,82,DOWN!4                   ; Line 14
              10533
BB23 3E320F   10534                 .BYTE 62,50,LEFT!15                   ; Line 15
BB26 54320F   10535                 .BYTE 84,50,LEFT!15                   ; Line 16
BB29 FE       10536                 .BYTE $FE                             ; End marker
              10537
              10538 ;*** 3-byte elements to draw our starship's shape in Long-Range Scan view ******
              10539 ;
              10540 ;   Line  17 18 19 20 21
              10541 ;               ##
              10542 ;               ##
              10543 ;            ## ## ##
              10544 ;         ## ## ## ## ##
              10545 ;         ##    ##    ##
              10546
BB2A 4E3582   10547                 .BYTE 78,53,DOWN!2                    ; Line 17
BB2D 4F3482   10548                 .BYTE 79,52,DOWN!2                    ; Line 18
BB30 503285   10549                 .BYTE 80,50,DOWN!5                    ; Line 19
BB33 513482   10550                 .BYTE 81,52,DOWN!2                    ; Line 20
BB36 523582   10551                 .BYTE 82,53,DOWN!2                    ; Line 21
BB39 FE       10552                 .BYTE $FE                             ; End marker
              10553
              10554 ;*** Initial x and y coordinates of a star during hyperwarp ********************
              10555 ; The following two tables are used to determine the initial x and y coordinates
              10556 ; (high byte) of a star during hyperwarp. An index in 0..3 picks both the x and
              10557 ; y coordinate, thus 4 pairs of coordinates are possible:
              10558 ;
              10559 ; Y           +-------+----------------------------+----------------------------+
              10560 ; ^           | Index |        x-coordinate        |        y-coordinate        |
              10561 ; |           +-------+----------------------------+----------------------------+
              10562 ; |.32.       |   0   | +1024..+1279 (+$04**) <KM> |  +512..+767  (+$02**) <KM> |
              10563 ; |...1       |   1   | +1024..+1279 (+$04**) <KM> |  +768..+1023 (+$03**) <KM> |
              10564 ; |...0       |   2   |  +768..+1023 (+$03**) <KM> | +1024..+1279 (+$04**) <KM> |
              10565 ; |....       |   3   |  +512..+767  (+$02**) <KM> | +1024..+1279 (+$04**) <KM> |
              10566 ; 0----->X    +-------+----------------------------+----------------------------+
              10567
              10568 ;*** Initial x-coordinate (high byte) of star in hyperwarp *********************
BB3A 04       10569 WARPSTARXTAB    .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB3B 04       10570                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB3C 03       10571                 .BYTE $03                             ;  +768..+1023 (+$03**) <KM>
BB3D 02       10572                 .BYTE $02                             ;  +512..+767  (+$02**) <KM>
              10573
              10574 ;*** Initial y-coordinate (high byte) of star in hyperwarp *********************
BB3E 02       10575 WARPSTARYTAB    .BYTE $02                             ;  +512..+767  (+$02**) <KM>
BB3F 03       10576                 .BYTE $03                             ;  +768..+1023 (+$03**) <KM>
BB40 04       10577                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
BB41 04       10578                 .BYTE $04                             ; +1024..+1279 (+$04**) <KM>
              10579
              10580 ;*** Text of Control Panel Display (encoded in custom character set) ***********
              10581 ; Row 1: "V:00 K:00 E:9999 T:0"
              10582 ; Row 2: " O:-00 O:-00 R:-000 "
              10583
BB42 12       10584 PANELTXTTAB     .BYTE CCS.V
BB43 0B       10585                 .BYTE CCS.COLON
BB44 00       10586                 .BYTE CCS.0
BB45 00       10587                 .BYTE CCS.0
BB46 0A       10588                 .BYTE CCS.SPC
BB47 55       10589                 .BYTE CCS.COL1!CCS.K
BB48 4B       10590                 .BYTE CCS.COL1!CCS.COLON
BB49 40       10591                 .BYTE CCS.COL1!CCS.0
BB4A 40       10592                 .BYTE CCS.COL1!CCS.0
BB4B 0A       10593                 .BYTE CCS.SPC
BB4C 8D       10594                 .BYTE CCS.COL2!CCS.E
BB4D 8B       10595                 .BYTE CCS.COL2!CCS.COLON
BB4E 89       10596                 .BYTE CCS.COL2!CCS.9
BB4F 89       10597                 .BYTE CCS.COL2!CCS.9
BB50 89       10598                 .BYTE CCS.COL2!CCS.9
BB51 89       10599                 .BYTE CCS.COL2!CCS.9
BB52 0A       10600                 .BYTE CCS.SPC
BB53 16       10601                 .BYTE CCS.T
BB54 0B       10602                 .BYTE CCS.COLON
BB55 00       10603                 .BYTE CCS.0
              10604
BB56 0A       10605                 .BYTE CCS.SPC
BB57 14       10606                 .BYTE CCS.THETA
BB58 0B       10607                 .BYTE CCS.COLON
BB59 0F       10608                 .BYTE CCS.MINUS
BB5A 00       10609                 .BYTE CCS.0
BB5B 00       10610                 .BYTE CCS.0
BB5C 0A       10611                 .BYTE CCS.SPC
BB5D 51       10612                 .BYTE CCS.COL1!CCS.PHI
BB5E 4B       10613                 .BYTE CCS.COL1!CCS.COLON
BB5F 0F       10614                 .BYTE CCS.MINUS
BB60 00       10615                 .BYTE CCS.0
BB61 00       10616                 .BYTE CCS.0
BB62 0A       10617                 .BYTE CCS.SPC
BB63 93       10618                 .BYTE CCS.COL2!CCS.R
BB64 8B       10619                 .BYTE CCS.COL2!CCS.COLON
BB65 0F       10620                 .BYTE CCS.MINUS
BB66 00       10621                 .BYTE CCS.0
BB67 00       10622                 .BYTE CCS.0
BB68 00       10623                 .BYTE CCS.0
BB69 0A       10624                 .BYTE CCS.SPC
              10625
              10626 ;*** Text of Galactic Chart Panel Display **************************************
              10627 ; Row 1: "WARP ENERGY:   0    "
              10628 ; Row 2: "TARGETS:  DC:PESCLR "
              10629 ; Row 3: "STAR DATE:00.00     "
              10630
BB6A 37       10631                 .BYTE ROM.W
BB6B 21       10632                 .BYTE ROM.A
BB6C 32       10633                 .BYTE ROM.R
BB6D 30       10634                 .BYTE ROM.P
BB6E 00       10635                 .BYTE ROM.SPC
BB6F 25       10636                 .BYTE ROM.E
BB70 2E       10637                 .BYTE ROM.N
BB71 25       10638                 .BYTE ROM.E
BB72 32       10639                 .BYTE ROM.R
BB73 27       10640                 .BYTE ROM.G
BB74 39       10641                 .BYTE ROM.Y
BB75 1A       10642                 .BYTE ROM.COLON
BB76 00       10643                 .BYTE ROM.SPC
BB77 00       10644                 .BYTE ROM.SPC
BB78 00       10645                 .BYTE ROM.SPC
BB79 10       10646                 .BYTE ROM.0
BB7A 00       10647                 .BYTE ROM.SPC
BB7B 00       10648                 .BYTE ROM.SPC
BB7C 00       10649                 .BYTE ROM.SPC
BB7D 00       10650                 .BYTE ROM.SPC
              10651
BB7E B4       10652                 .BYTE CCS.COL2!ROM.T
BB7F A1       10653                 .BYTE CCS.COL2!ROM.A
BB80 B2       10654                 .BYTE CCS.COL2!ROM.R
BB81 A7       10655                 .BYTE CCS.COL2!ROM.G
BB82 A5       10656                 .BYTE CCS.COL2!ROM.E
BB83 B4       10657                 .BYTE CCS.COL2!ROM.T
BB84 B3       10658                 .BYTE CCS.COL2!ROM.S
BB85 9A       10659                 .BYTE CCS.COL2!ROM.COLON
BB86 00       10660                 .BYTE ROM.SPC
BB87 00       10661                 .BYTE ROM.SPC
BB88 24       10662                 .BYTE ROM.D
BB89 23       10663                 .BYTE ROM.C
BB8A 1A       10664                 .BYTE ROM.COLON
BB8B 30       10665                 .BYTE ROM.P
BB8C 25       10666                 .BYTE ROM.E
BB8D 33       10667                 .BYTE ROM.S
BB8E 23       10668                 .BYTE ROM.C
BB8F 2C       10669                 .BYTE ROM.L
BB90 32       10670                 .BYTE ROM.R
BB91 00       10671                 .BYTE ROM.SPC
              10672
BB92 F3       10673                 .BYTE CCS.COL3!ROM.S
BB93 F4       10674                 .BYTE CCS.COL3!ROM.T
BB94 E1       10675                 .BYTE CCS.COL3!ROM.A
BB95 F2       10676                 .BYTE CCS.COL3!ROM.R
BB96 00       10677                 .BYTE ROM.SPC
BB97 E4       10678                 .BYTE CCS.COL3!ROM.D
BB98 E1       10679                 .BYTE CCS.COL3!ROM.A
BB99 F4       10680                 .BYTE CCS.COL3!ROM.T
BB9A E5       10681                 .BYTE CCS.COL3!ROM.E
BB9B DA       10682                 .BYTE CCS.COL3!ROM.COLON
BB9C D0       10683                 .BYTE CCS.COL3!ROM.0
BB9D D0       10684                 .BYTE CCS.COL3!ROM.0
BB9E CE       10685                 .BYTE CCS.COL3!ROM.DOT
BB9F D0       10686                 .BYTE CCS.COL3!ROM.0
BBA0 D0       10687                 .BYTE CCS.COL3!ROM.0
BBA1 00       10688                 .BYTE ROM.SPC
BBA2 00       10689                 .BYTE ROM.SPC
BBA3 00       10690                 .BYTE ROM.SPC
BBA4 00       10691                 .BYTE ROM.SPC
BBA5 00       10692                 .BYTE ROM.SPC
              10693
              10694 ;*** Galactic Chart sector type table ******************************************
BBA6 CF       10695 SECTORTYPETAB   .BYTE $CF                             ; Starbase
BBA7 04       10696                 .BYTE $04                             ; 4 Zylon ships
BBA8 03       10697                 .BYTE $03                             ; 3 Zylon ships
BBA9 02       10698                 .BYTE $02                             ; 1 or 2 Zylon ships
              10699
              10700 ;*** Phrase table **************************************************************
              10701 ; Phrases consist of phrase tokens. These are bytes that encode words, segments
              10702 ; (multiple words that fit into a single line of text), and how they are displayed.
              10703 ;
              10704 ; LOCAL VARIABLES
    =0040     10705 EOP             = $40                                 ; End of phrase
    =0080     10706 EOS             = $80                                 ; End of segment
    =00C0     10707 LONG            = $C0                                 ; Display title phrase for a long time
              10708
              10709                                                       ; Title Phrase Offset, Text
BBAA 00       10710 PHRASETAB       .BYTE $00                             ; (unused)
BBAB 050642   10711                 .BYTE $05,$06,$02!EOP                 ; $01  "ATTACK COMPUTER ON"
BBAE 050643   10712                 .BYTE $05,$06,$03!EOP                 ; $04  "ATTACK COMPUTER OFF"
BBB1 0442     10713                 .BYTE $04,$02!EOP                     ; $07  "SHIELDS ON"
BBB3 0443     10714                 .BYTE $04,$03!EOP                     ; $09  "SHIELDS OFF"
BBB5 060742   10715                 .BYTE $06,$07,$02!EOP                 ; $0B  "COMPUTER TRACKING ON"
BBB8 0743     10716                 .BYTE $07,$03!EOP                     ; $0E  "TRACKING OFF"
BBBA 48       10717                 .BYTE $08!EOP                         ; $10  "WHATS WRONG?"
BBBB 094A     10718                 .BYTE $09,$0A!EOP                     ; $11  "HYPERWARP ENGAGED"
BBBD 0BCD     10719                 .BYTE $0B,$0D!LONG                    ; $13  "STARBASE SURROUNDED"
BBBF 0BCC     10720                 .BYTE $0B,$0C!LONG                    ; $15  "STARBASE DESTROYED"
BBC1 094E     10721                 .BYTE $09,$0E!EOP                     ; $17  "HYPERWARP ABORTED"
BBC3 094F     10722                 .BYTE $09,$0F!EOP                     ; $19  "HYPERWARP COMPLETE"
BBC5 D0       10723                 .BYTE $10!LONG                        ; $1B  "HYPERSPACE"
BBC6 1192     10724                 .BYTE $11,$12!EOS                     ; $1C  "ORBIT ESTABLISHED"
BBC8 56       10725                 .BYTE $16!EOP                         ; $1E  "STANDBY"
BBC9 134E     10726                 .BYTE $13,$0E!EOP                     ; $1F  "DOCKING ABORTED"
BBCB 154F     10727                 .BYTE $15,$0F!EOP                     ; $21  "TRANSFER COMPLETE"
BBCD B8       10728                 .BYTE $38!EOS                         ; $23  " "
BBCE 97       10729                 .BYTE $17!EOS                         ; $24  "STAR FLEET TO"
BBCF 99       10730                 .BYTE $19!EOS                         ; $25  "ALL UNITS"
BBD0 98       10731                 .BYTE $18!EOS                         ; $26  "STAR CRUISER 7"
BBD1 8C       10732                 .BYTE $0C!EOS                         ; $27  "DESTROYED"
BBD2 9D       10733                 .BYTE $1D!EOS                         ; $28  "BY ZYLON FIRE"
BBD3 1E9F     10734                 .BYTE $1E,$1F!EOS                     ; $29  "POSTHUMOUS RANK IS:"
BBD5 FD       10735                 .BYTE $FD                             ; $2B  "<PLACEHOLDER FOR RANK>"
BBD6 25FC     10736                 .BYTE $25,$FC                         ; $2C  "CLASS <PLACEHOLDER FOR CLASS>"
BBD8 78       10737                 .BYTE $38!EOP                         ; $2E  " "
BBD9 9B       10738                 .BYTE $1B!EOS                         ; $2F  "STAR RAIDERS"
BBDA 60       10739                 .BYTE $20!EOP                         ; $30  "COPYRIGHT ATARI 1979"
BBDB B8       10740                 .BYTE $38!EOS                         ; $31  " "
BBDC 97       10741                 .BYTE $17!EOS                         ; $32  "STAR FLEET TO"
BBDD 98       10742                 .BYTE $18!EOS                         ; $33  "STAR CRUISER 7"
BBDE 1A8E     10743                 .BYTE $1A,$0E!EOS                     ; $34  "MISSION ABORTED"
BBE0 1C94     10744                 .BYTE $1C,$14!EOS                     ; $36  "ZERO ENERGY"
BBE2 249F     10745                 .BYTE $24,$1F!EOS                     ; $38  "NEW RANK IS"
BBE4 FD       10746                 .BYTE $FD                             ; $3A  "<PLACEHOLDER FOR RANK>"
BBE5 25FC     10747                 .BYTE $25,$FC                         ; $3B  "CLASS <PLACEHOLDER FOR CLASS>"
BBE7 A7       10748                 .BYTE $27!EOS                         ; $3D  "REPORT TO BASE"
BBE8 68       10749                 .BYTE $28!EOP                         ; $3E  "FOR TRAINING"
BBE9 B8       10750                 .BYTE $38!EOS                         ; $3F  " "
BBEA 97       10751                 .BYTE $17!EOS                         ; $40  "STAR FLEET TO"
BBEB 98       10752                 .BYTE $18!EOS                         ; $41  "STAR CRUISER 7"
BBEC 1A8F     10753                 .BYTE $1A,$0F!EOS                     ; $42  "MISSION COMPLETE"
BBEE 249F     10754                 .BYTE $24,$1F!EOS                     ; $44  "NEW RANK IS:"
BBF0 FD       10755                 .BYTE $FD                             ; $46  "<PLACEHOLDER FOR RANK>"
BBF1 25FC     10756                 .BYTE $25,$FC                         ; $47  "CLASS <PLACEHOLDER FOR CLASS>"
BBF3 66       10757                 .BYTE $26!EOP                         ; $49  "CONGRATULATIONS"
BBF4 2C5A     10758                 .BYTE $2C,$1A!EOP                     ; $4A  "NOVICE MISSION"
BBF6 2E5A     10759                 .BYTE $2E,$1A!EOP                     ; $4C  "PILOT MISSION"
BBF8 315A     10760                 .BYTE $31,$1A!EOP                     ; $4E  "WARRIOR MISSION"
BBFA 335A     10761                 .BYTE $33,$1A!EOP                     ; $50  "COMMANDER MISSION"
BBFC B8       10762                 .BYTE $38!EOS                         ; $52  " "
BBFD 3476     10763                 .BYTE $34,$36!EOP                     ; $53  "DAMAGE CONTROL"
BBFF 37B5     10764                 .BYTE $37,$35!EOS                     ; $55  "PHOTONS DAMAGED"
BC01 78       10765                 .BYTE $38!EOP                         ; $57  " "
BC02 378C     10766                 .BYTE $37,$0C!EOS                     ; $58  "PHOTONS DESTROYED"
BC04 78       10767                 .BYTE $38!EOP                         ; $5A  " "
BC05 23B5     10768                 .BYTE $23,$35!EOS                     ; $5B  "ENGINES DAMAGED"
BC07 78       10769                 .BYTE $38!EOP                         ; $5D  " "
BC08 238C     10770                 .BYTE $23,$0C!EOS                     ; $5E  "ENGINES DESTROYED"
BC0A 78       10771                 .BYTE $38!EOP                         ; $60  " "
BC0B 04B5     10772                 .BYTE $04,$35!EOS                     ; $61  "SHIELDS DAMAGED"
BC0D 78       10773                 .BYTE $38!EOP                         ; $63  " "
BC0E 048C     10774                 .BYTE $04,$0C!EOS                     ; $64  "SHIELDS DESTROYED"
BC10 78       10775                 .BYTE $38!EOP                         ; $66  " "
BC11 06B5     10776                 .BYTE $06,$35!EOS                     ; $67  "COMPUTER DAMAGED"
BC13 78       10777                 .BYTE $38!EOP                         ; $69  " "
BC14 068C     10778                 .BYTE $06,$0C!EOS                     ; $6A  "COMPUTER DESTROYED"
BC16 78       10779                 .BYTE $38!EOP                         ; $6C  " "
BC17 A2       10780                 .BYTE $22!EOS                         ; $6D  "SECTOR SCAN"
BC18 75       10781                 .BYTE $35!EOP                         ; $6E  "DAMAGED"
BC19 A2       10782                 .BYTE $22!EOS                         ; $6F  "SECTOR SCAN"
BC1A 4C       10783                 .BYTE $0C!EOP                         ; $70  "DESTROYED"
BC1B A1       10784                 .BYTE $21!EOS                         ; $71  "SUB-SPACE RADIO"
BC1C 75       10785                 .BYTE $35!EOP                         ; $72  "DAMAGED"
BC1D A1       10786                 .BYTE $21!EOS                         ; $73  "SUB-SPACE RADIO"
BC1E 4C       10787                 .BYTE $0C!EOP                         ; $74  "DESTROYED"
BC1F C1       10788                 .BYTE $01!LONG                        ; $75  "RED ALERT"
BC20 B8       10789                 .BYTE $38!EOS                         ; $76  " "
BC21 97       10790                 .BYTE $17!EOS                         ; $77  "STAR FLEET TO"
BC22 98       10791                 .BYTE $18!EOS                         ; $78  "STAR CRUISER 7"
BC23 1A8E     10792                 .BYTE $1A,$0E!EOS                     ; $79  "MISSION ABORTED"
BC25 249F     10793                 .BYTE $24,$1F!EOS                     ; $7B  "NEW RANK IS:"
BC27 FD       10794                 .BYTE $FD                             ; $7D  "<PLACEHOLDER FOR RANK>"
BC28 25FC     10795                 .BYTE $25,$FC                         ; $7E  "CLASS <PLACEHOLDER FOR CLASS>"
BC2A 66       10796                 .BYTE $26!EOP                         ; $80  "CONGRATULATIONS"
              10797
              10798 ;*** Word table ****************************************************************
              10799 ; Bit B7 of the first byte of a word is the end-of-word marker of the preceding
              10800 ; word
              10801 ;
              10802 ; LOCAL VARIABLES
    =0080     10803 EOW             = $80                                 ; End of word
              10804
BC2B A0202020 10805 WORDTAB         .BYTE EOW!$20,"    RED ALERT"         ; Word $01
BC2F 20524544
BC33 20414C45
BC37 5254    
BC39 CF4E     10806                 .BYTE EOW!'O,"N"                      ; Word $02
BC3B CF4646   10807                 .BYTE EOW!'O,"FF"                     ; Word $03
BC3E D3484945 10808                 .BYTE EOW!'S,"HIELDS"                 ; Word $04
BC42 4C4453  
BC45 C1545441 10809                 .BYTE EOW!'A,"TTACK"                  ; Word $05
BC49 434B    
BC4B C34F4D50 10810                 .BYTE EOW!'C,"OMPUTER"                ; Word $06
BC4F 55544552
BC53 D4524143 10811                 .BYTE EOW!'T,"RACKING"                ; Word $07
BC57 4B494E47
BC5B D7484154 10812                 .BYTE EOW!'W,"HATS WRONG?"            ; Word $08
BC5F 53205752
BC63 4F4E473F
BC67 C8595045 10813                 .BYTE EOW!'H,"YPERWARP"               ; Word $09
BC6B 52574152
BC6F 50      
BC70 C54E4741 10814                 .BYTE EOW!'E,"NGAGED"                 ; Word $0A
BC74 474544  
BC77 D3544152 10815                 .BYTE EOW!'S,"TARBASE"                ; Word $0B
BC7B 42415345
BC7F C4455354 10816                 .BYTE EOW!'D,"ESTROYED"               ; Word $0C
BC83 524F5945
BC87 44      
BC88 D3555252 10817                 .BYTE EOW!'S,"URROUNDED"              ; Word $0D
BC8C 4F554E44
BC90 4544    
BC92 C1424F52 10818                 .BYTE EOW!'A,"BORTED"                 ; Word $0E
BC96 544544  
BC99 C34F4D50 10819                 .BYTE EOW!'C,"OMPLETE"                ; Word $0F
BC9D 4C455445
BCA1 C8595045 10820                 .BYTE EOW!'H,"YPERSPACE"              ; Word $10
BCA5 52535041
BCA9 4345    
BCAB CF524249 10821                 .BYTE EOW!'O,"RBIT"                   ; Word $11
BCAF 54      
BCB0 C5535441 10822                 .BYTE EOW!'E,"STABLISHED"             ; Word $12
BCB4 424C4953
BCB8 484544  
BCBB C44F434B 10823                 .BYTE EOW!'D,"OCKING"                 ; Word $13
BCBF 494E47  
BCC2 C54E4552 10824                 .BYTE EOW!'E,"NERGY"                  ; Word $14
BCC6 4759    
BCC8 D452414E 10825                 .BYTE EOW!'T,"RANSFER"                ; Word $15
BCCC 53464552
BCD0 D354414E 10826                 .BYTE EOW!'S,"TANDBY"                 ; Word $16
BCD4 444259  
BCD7 D3544152 10827                 .BYTE EOW!'S,"TAR FLEET TO"           ; Word $17
BCDB 20464C45
BCDF 45542054
BCE3 4F      
BCE4 D3544152 10828                 .BYTE EOW!'S,"TAR CRUISER 7"          ; Word $18
BCE8 20435255
BCEC 49534552
BCF0 2037    
BCF2 C14C4C20 10829                 .BYTE EOW!'A,"LL UNITS"               ; Word $19
BCF6 554E4954
BCFA 53      
BCFB CD495353 10830                 .BYTE EOW!'M,"ISSION"                 ; Word $1A
BCFF 494F4E  
BD02 A0202020 10831                 .BYTE EOW!$20,"   STAR RAIDERS"       ; Word $1B
BD06 53544152
BD0A 20524149
BD0E 44455253
BD12 DA45524F 10832                 .BYTE EOW!'Z,"ERO"                    ; Word $1C
BD16 C259205A 10833                 .BYTE EOW!'B,"Y ZYLON FIRE"           ; Word $1D
BD1A 594C4F4E
BD1E 20464952
BD22 45      
BD23 D04F5354 10834                 .BYTE EOW!'P,"OSTHUMOUS"              ; Word $1E
BD27 48554D4F
BD2B 5553    
BD2D D2414E4B 10835                 .BYTE EOW!'R,"ANK IS:"                ; Word $1F
BD31 2049533A
BD35 C34F5059 10836                 .BYTE EOW!'C,"OPYRIGHT ATARI 1979"    ; Word $20
BD39 52494748
BD3D 54204154
BD41 41524920
BD45 31393739
BD49 D355422D 10837                 .BYTE EOW!'S,"UB-SPACE RADIO"         ; Word $21
BD4D 53504143
BD51 45205241
BD55 44494F  
BD58 D3454354 10838                 .BYTE EOW!'S,"ECTOR SCAN"             ; Word $22
BD5C 4F522053
BD60 43414E  
BD63 C54E4749 10839                 .BYTE EOW!'E,"NGINES"                 ; Word $23
BD67 4E4553  
BD6A CE4557   10840                 .BYTE EOW!'N,"EW"                     ; Word $24
BD6D C34C4153 10841                 .BYTE EOW!'C,"LASS"                   ; Word $25
BD71 53      
BD72 C34F4E47 10842                 .BYTE EOW!'C,"ONGRATULATIONS"         ; Word $26
BD76 52415455
BD7A 4C415449
BD7E 4F4E53  
BD81 D245504F 10843                 .BYTE EOW!'R,"EPORT TO BASE"          ; Word $27
BD85 52542054
BD89 4F204241
BD8D 5345    
BD8F C64F5220 10844                 .BYTE EOW!'F,"OR TRAINING"            ; Word $28
BD93 54524149
BD97 4E494E47
BD9B C7414C41 10845                 .BYTE EOW!'G,"ALACTIC COOK"           ; Word $29
BD9F 43544943
BDA3 20434F4F
BDA7 4B      
BDA8 C7415242 10846                 .BYTE EOW!'G,"ARBAGE SCOW CAPTAIN"    ; Word $2A
BDAC 41474520
BDB0 53434F57
BDB4 20434150
BDB8 5441494E
BDBC D24F4F4B 10847                 .BYTE EOW!'R,"OOKIE"                  ; Word $2B
BDC0 4945    
BDC2 CE4F5649 10848                 .BYTE EOW!'N,"OVICE"                  ; Word $2C
BDC6 4345    
BDC8 C54E5349 10849                 .BYTE EOW!'E,"NSIGN"                  ; Word $2D
BDCC 474E    
BDCE D0494C4F 10850                 .BYTE EOW!'P,"ILOT"                   ; Word $2E
BDD2 54      
BDD3 C14345   10851                 .BYTE EOW!'A,"CE"                     ; Word $2F
BDD6 CC494555 10852                 .BYTE EOW!'L,"IEUTENANT"              ; Word $30
BDDA 54454E41
BDDE 4E54    
BDE0 D7415252 10853                 .BYTE EOW!'W,"ARRIOR"                 ; Word $31
BDE4 494F52  
BDE7 C3415054 10854                 .BYTE EOW!'C,"APTAIN"                 ; Word $32
BDEB 41494E  
BDEE C34F4D4D 10855                 .BYTE EOW!'C,"OMMANDER"               ; Word $33
BDF2 414E4445
BDF6 52      
BDF7 C4414D41 10856                 .BYTE EOW!'D,"AMAGE"                  ; Word $34
BDFB 4745    
BDFD C4414D41 10857                 .BYTE EOW!'D,"AMAGED"                 ; Word $35
BE01 474544  
BE04 C34F4E54 10858                 .BYTE EOW!'C,"ONTROL"                 ; Word $36
BE08 524F4C  
BE0B D0484F54 10859                 .BYTE EOW!'P,"HOTONS"                 ; Word $37
BE0F 4F4E53  
BE12 A0       10860                 .BYTE EOW!$20                         ; Word $38
BE13 D3544152 10861                 .BYTE EOW!'S,"TAR COMMANDER"          ; Word $39
BE17 20434F4D
BE1B 4D414E44
BE1F 4552    
BE21 80       10862                 .BYTE EOW!$00                         ;
              10863
              10864 ;*** View modes ****************************************************************
BE22 00       10865 VIEWMODETAB     .BYTE $00                             ; Front view
BE23 01       10866                 .BYTE $01                             ; Aft view
BE24 40       10867                 .BYTE $40                             ; Long-Range Scan view
BE25 80       10868                 .BYTE $80                             ; Galactic Chart view
              10869
              10870 ;*** Title phrase offsets of "TRACKING OFF", "SHIELDS OFF", "COMPUTER OFF" *****
BE26 0E       10871 MSGOFFTAB       .BYTE $0E                             ; "TRACKING OFF"
BE27 09       10872                 .BYTE $09                             ; "SHIELDS OFF"
BE28 04       10873                 .BYTE $04                             ; "COMPUTER OFF"
              10874
              10875 ;*** Masks to test if Tracking Computer, Shields, or Attack Computer are on ****
BE29 FF       10876 MSGBITTAB       .BYTE $FF                             ; Mask Tracking Computer
BE2A 08       10877                 .BYTE $08                             ; Mask Shields
BE2B 02       10878                 .BYTE $02                             ; Mask Attack Computer
              10879
              10880 ;*** Title phrase offsets of "COMPUTER TRACKING ON", "SHIELDS ON", "COMPUTER ON"
BE2C 0B       10881 MSGONTAB        .BYTE $0B                             ; "COMPUTER TRACKING ON"
BE2D 07       10882                 .BYTE $07                             ; "SHIELDS ON"
BE2E 01       10883                 .BYTE $01                             ; "COMPUTER ON"
              10884
              10885 ;*** The following two tables encode the PLAYER shapes *************************
              10886 ;
              10887 ; PHOTON TORPEDO (shape type 0, data in shape table PLSHAP1TAB)
              10888 ; Numbers at top indicate the shape table offset of the first and last shape row
              10889 ;
              10890 ; $01..$10  $11..$1E  $1F..$2A  $2B..$34  $35..$3C  $3D..$42  $75..$76  $7A..$7B
              10891 ; ...##...  ...#....  ...##...  ...#....  ...#....  ...#....  ...##...  ...#....
              10892 ; ..####..  ..###...  ..####..  ..###...  ...##...  ..###...  ...##...  ...#....
              10893 ; .######.  .#####..  ..####..  ..###...  ..####..  ..###...
              10894 ; .######.  .#####..  .######.  .#####..  ..#.##..  ..#.#...
              10895 ; .###.##.  #######.  .##.###.  .###.#..  ..####..  ..###...
              10896 ; ####.###  ##.####.  .####.#.  .#####..  ..####..  ...#....
              10897 ; ##.#####  ##.##.#.  .######.  .##.##..  ...##...
              10898 ; ##.#####  #####.#.  .###.##.  ..###...  ....#...
              10899 ; ########  ###.###.  .######.  ..###...
              10900 ; ########  ###.###.  ..####..  ...#....
              10901 ; ####.###  .#####..  ..####..
              10902 ; .###.##.  .#####..  ...##...
              10903 ; .######.  ..###...
              10904 ; .######.  ...#....
              10905 ; ..####..
              10906 ; ...##...
              10907 ;
              10908 ; ZYLON FIGHTER (shape type 1, data in shape table PLSHAP2TAB)
              10909 ; Numbers at top indicate the shape table offset of the first and last shape row
              10910 ;
              10911 ; $01..$0C  $0D..$14  $15..$1A  $1B..$20  $21..$24  $25..$28  $29..$2A  $2B..$2C
              10912 ; #......#  #.....#.  .#....#.  .#...#..  ..#..#..  ..#.#...  ...##...  ...#....
              10913 ; #......#  #.....#.  .#.##.#.  .#.#.#..  ..####..  ..###...  ...##...  ...#....
              10914 ; #......#  #.###.#.  .######.  .#####..  ..####..  ..###...
              10915 ; #......#  #######.  .######.  .#####..  ..#..#..  ..#.#...
              10916 ; #.####.#  #######.  .#.##.#.  .#.#.#..
              10917 ; ########  #.###.#.  .#....#.  .#...#..
              10918 ; ########  #.....#.
              10919 ; #.####.#  #.....#.
              10920 ; #......#
              10921 ; #......#
              10922 ; #......#
              10923 ; #......#
              10924 ;
              10925 ; STARBASE RIGHT (shape type 2, data in shape table PLSHAP2TAB)
              10926 ; Numbers at top indicate the shape table offset of the first and last shape row
              10927 ;
              10928 ; $2D..$36  $38..$40  $41..$46  $36..$38  $36       $00       $00       $00
              10929 ; ###.....  ##......  ##......  ##......  ##......  ........  ........  ........
              10930 ; #####...  ####....  ##......  ####....
              10931 ; #####...  ####....  ####....  ##......
              10932 ; #######.  ######..  #.####..
              10933 ;  #.#.###  #.#####.  ####....
              10934 ; #######.  ######..  ##......
              10935 ; #####...  ####....
              10936 ; #####...  #.......
              10937 ; ##......  #.......
              10938 ; ##......
              10939 ;
              10940 ; STARBASE CENTER (shape type 3, data in shape table PLSHAP1TAB)
              10941 ; Numbers at top indicate the shape table offset of the first and last shape row
              10942 ;
              10943 ; $7E..$8D  $8E..$9C  $9D..$A9  $AA..$B3  $B4..$BB  $BC..$C0  $7B..$7D  $7A..$7B
              10944 ; ...##...  ........  ........  ...##...  ........  ...##...  ...#....  ...#....
              10945 ; .######.  ...##...  ...##...  ..####..  ...##...  ..####..  ..###...  ...#....
              10946 ; ########  ..####..  ..####..  ########  ..####..  ########  ...#....
              10947 ; ########  .######.  .######.  ########  ########  ..####..
              10948 ; ########  ########  ########  ###..###  ########  ...##...
              10949 ; ########  ########  ########  .##..##.  ########
              10950 ; ########  ########  ###..###  ########  ..####..
              10951 ; ###..###  ###..###  .##..##.  ########  ...##...
              10952 ; ###..###  .##..##.  ########  .######.
              10953 ; ########  ########  ########  ..####..
              10954 ; ########  ########  ########
              10955 ; ########  ########  ########
              10956 ; ########  ########  ..####..
              10957 ; ########  .######.
              10958 ; .######.  .######.
              10959 ; .######.
              10960 ;
              10961 ; STARBASE LEFT (shape type 4, data in shape table PLSHAP2TAB)
              10962 ; Numbers at top indicate the shape table offset of the first and last shape row
              10963 ;
              10964 ; $47..$50  $52..$5A  $5B..$60  $50..$52  $50       $00       $00       $00
              10965 ; .....###  ......##  ......##  ......##  ......##  ........  ........  ........
              10966 ; ...#####  ....####  ......##  ....####
              10967 ; ...#####  ....####  ....####  ......##
              10968 ; .#######  ..######  ..####.#
              10969 ; ###.#.#.  .#####.#  ....####
              10970 ; .#######  ..######  ......##
              10971 ; ...#####  ....####
              10972 ; ...#####  .......#
              10973 ; ......##  .......#
              10974 ; ......##
              10975 ;
              10976 ; TRANSFER VESSEL (shape type 5, data in shape table PLSHAP1TAB)
              10977 ; Numbers at top indicate the shape table offset of the first and last shape row
              10978 ;
              10979 ; $43..$52  $53..$60  $61..$6B  $6C..$74  $75..$79  $7A..$7D  $75..$76  $7A..$7B
              10980 ; ..####..  ...###..  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              10981 ; ..####..  ...###..  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              10982 ; ..#..#..  ...#.#..  ..####..  ..###...  ..####..  ..###...
              10983 ; ..####..  ..#####.  ..####..  ..###...  ...##...  ...#....
              10984 ; .######.  ..#####.  ..####..  ..###...  ...##...
              10985 ; .######.  ..#####.  ..####..  .#####..
              10986 ; .######.  ..#.#.#.  .######.  ..#.#...
              10987 ; .#.##.#.  .#######  ..#..#..  ..#.#...
              10988 ; ########  .#######  ..#..#..  ..#.#...
              10989 ; ########  ..#...#.  ..#..#..
              10990 ; .#....#.  ..#...#.  ..#..#..
              10991 ; .#....#.  ..#...#.
              10992 ; .#....#.  ..#...#.
              10993 ; .#....#.  ..#...#.
              10994 ; .#....#.
              10995 ; .#....#.
              10996 ;
              10997 ; METEOR (shape type 6, data in shape table PLSHAP1TAB)
              10998 ; Numbers at top indicate the shape table offset of the first and last shape row
              10999 ;
              11000 ; $01..$10  $11..$1E  $1F..$2A  $2B..$34  $35..$3C  $3D..$42  $75..$76  $7A..$7B
              11001 ; ...##...  ...#....  ...##...  ...#....  ...#....  ...#....  ...##...  ...#....
              11002 ; ..####..  ..###...  ..####..  ..###...  ...##...  ..###...  ...##...  ...#....
              11003 ; .######.  .#####..  ..####..  ..###...  ..####..  ..###...
              11004 ; .######.  .#####..  .######.  .#####..  ..#.##..  ..#.#...
              11005 ; .###.##.  #######.  .##.###.  .###.#..  ..####..  ..###...
              11006 ; ####.###  ##.####.  .####.#.  .#####..  ..####..  ...#....
              11007 ; ##.#####  ##.##.#.  .######.  .##.##..  ...##...
              11008 ; ##.#####  #####.#.  .###.##.  ..###...  ....#...
              11009 ; ########  ###.###.  .######.  ..###...
              11010 ; ########  ###.###.  ..####..  ...#....
              11011 ; ####.###  .#####..  ..####..
              11012 ; .###.##.  .#####..  ...##...
              11013 ; .######.  ..###...
              11014 ; .######.  ...#....
              11015 ; ..####..
              11016 ; ...##...
              11017 ;
              11018 ; ZYLON CRUISER (shape type 7, data in shape table PLSHAP2TAB)
              11019 ; Numbers at top indicate the shape table offset of the first and last shape row
              11020 ;
              11021 ; $61..$69  $6A..$71  $72..$78  $79..$7E  $7F..$82  $83..$85  $29..$2A  $2B..$2C
              11022 ; ...##...  ...#....  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11023 ; ..####..  ..###...  ..####..  ..###...  ..####..  ..###...  ...##...  ...#....
              11024 ; .######.  .#####..  ..####..  ..###...  ..#..#..  ..#.#...
              11025 ; .######.  .#####..  .##..##.  .##.##..  ..#..#..
              11026 ; ##.##.##  ##.#.##.  .##..##.  .#...#..
              11027 ; ##....##  ##...##.  .#....#.  .#...#..
              11028 ; #......#  #.....#.  .#....#.
              11029 ; #......#  #.....#.
              11030 ; #......#
              11031 ;
              11032 ; ZYLON BASESTAR (shape type 8, data in shape table PLSHAP2TAB)
              11033 ; Numbers at top indicate the shape table offset of the first and last shape row
              11034 ;
              11035 ; $86..$8F  $90..$99  $9A..$A0  $A1..$A7  $A8..$AC  $AD..$B0  $29..$2A  $2B..$2C
              11036 ; ...##...  ...#....  ...##...  ...#....  ...##...  ...#....  ...##...  ...#....
              11037 ; ..####..  ..###...  ..####..  ..###...  ..####..  ..###...  ...##...  ...#....
              11038 ; .######.  .#####..  .######.  .#####..  ...##...  ..###...
              11039 ; ########  #######.  ...##...  ...#....  ..####..  ...#....
              11040 ; ...##...  ..###...  .######.  .#####..  ...##...
              11041 ; ...##...  ..###...  ..####..  ..###...
              11042 ; ########  #######.  ...##...  ...#....
              11043 ; .######.  .#####..
              11044 ; ..####..  ..###...
              11045 ; ...##...  ...#....
              11046 ;
              11047 ; HYPERWARP TARGET MARKER (shape type 9, data in shape table PLSHAP1TAB)
              11048 ; Numbers at top indicate the shape table offset of the first and last shape row
              11049 ;
              11050 ; $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $C1..$CC  $75..$76  $C1..$CC
              11051 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ...##...  ..#.#...
              11052 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ...##...  ..#.#...
              11053 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11054 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11055 ; ###.###.  ###.###.  ###.###.  ###.###.  ###.###.  ###.###.            ###.###.
              11056 ; ........  ........  ........  ........  ........  ........            ........
              11057 ; ........  ........  ........  ........  ........  ........            ........
              11058 ; ###.###.  ###.###.  ###.###.  ###.###.  ###.###.  ###.###.            ###.###.
              11059 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11060 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11061 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11062 ; ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...  ..#.#...            ..#.#...
              11063
              11064 ;*** Shape type 0..9 offset table (10 shape cell offsets of shape type...) *****
BE2F 01111F2B 11065 PLSHAPOFFTAB    .BYTE $01,$11,$1F,$2B,$35,$3D,$75,$7A ; ...0 into PLSHAP1TAB
BE33 353D757A
BE37 010D151B 11066                 .BYTE $01,$0D,$15,$1B,$21,$25,$29,$2B ; ...1 into PLSHAP2TAB
BE3B 2125292B
BE3F 2D384136 11067                 .BYTE $2D,$38,$41,$36,$36,$00,$00,$00 ; ...2 into PLSHAP2TAB
BE43 36000000
BE47 7E8E9DAA 11068                 .BYTE $7E,$8E,$9D,$AA,$B4,$BC,$7B,$7A ; ...3 into PLSHAP1TAB
BE4B B4BC7B7A
BE4F 47525B50 11069                 .BYTE $47,$52,$5B,$50,$50,$00,$00,$00 ; ...4 into PLSHAP2TAB
BE53 50000000
BE57 4353616C 11070                 .BYTE $43,$53,$61,$6C,$75,$7A,$75,$7A ; ...5 into PLSHAP1TAB
BE5B 757A757A
BE5F 01111F2B 11071                 .BYTE $01,$11,$1F,$2B,$35,$3D,$75,$7A ; ...6 into PLSHAP1TAB
BE63 353D757A
BE67 616A7279 11072                 .BYTE $61,$6A,$72,$79,$7F,$83,$29,$2B ; ...7 into PLSHAP2TAB
BE6B 7F83292B
BE6F 86909AA1 11073                 .BYTE $86,$90,$9A,$A1,$A8,$AD,$29,$2B ; ...8 into PLSHAP2TAB
BE73 A8AD292B
BE77 C1C1C1C1 11074                 .BYTE $C1,$C1,$C1,$C1,$C1,$C1,$75,$C1 ; ...9 into PLSHAP1TAB
BE7B C1C175C1
              11075
              11076 ;*** Shape type 0..9 height table (10 shape cell heights of shape type...) *****
BE7F 0F0D0B09 11077 PLSHPHEIGHTTAB  .BYTE $0F,$0D,$0B,$09,$07,$05,$01,$01 ; ...0
BE83 07050101
BE87 0B070505 11078                 .BYTE $0B,$07,$05,$05,$03,$03,$01,$01 ; ...1
BE8B 03030101
BE8F 09080502 11079                 .BYTE $09,$08,$05,$02,$00,$00,$00,$00 ; ...2
BE93 00000000
BE97 0F0E0C09 11080                 .BYTE $0F,$0E,$0C,$09,$07,$04,$02,$01 ; ...3
BE9B 07040201
BE9F 09080502 11081                 .BYTE $09,$08,$05,$02,$00,$00,$00,$00 ; ...4
BEA3 00000000
BEA7 0F0D0A08 11082                 .BYTE $0F,$0D,$0A,$08,$04,$03,$01,$01 ; ...5
BEAB 04030101
BEAF 0F0D0B09 11083                 .BYTE $0F,$0D,$0B,$09,$07,$05,$01,$01 ; ...6
BEB3 07050101
BEB7 08070605 11084                 .BYTE $08,$07,$06,$05,$03,$02,$01,$01 ; ...7
BEBB 03020101
BEBF 09090606 11085                 .BYTE $09,$09,$06,$06,$04,$03,$01,$01 ; ...8
BEC3 04030101
BEC7 0B0B0B0B 11086                 .BYTE $0B,$0B,$0B,$0B,$0B,$0B,$01,$0B ; ...9
BECB 0B0B010B
              11087
              11088 ;*** Keyboard codes to switch to Front or Aft view when Tracking Computer is on 
BECF F8       11089 TRACKKEYSTAB    .BYTE $F8                             ; 'F' - Front view
BED0 FF       11090                 .BYTE $FF                             ; 'A' - Aft view
              11091
              11092 ;*** Galactic Chart sector character codes (encoded in custom character set) ***
BED1 0C       11093 SECTORCHARTAB   .BYTE CCS.BORDERSW                    ; Empty sector
BED2 1E       11094                 .BYTE CCS.2ZYLONS                     ; Sector contains 1 Zylon ship
BED3 1E       11095                 .BYTE CCS.2ZYLONS                     ; Sector contains 2 Zylon ships
BED4 1D       11096                 .BYTE CCS.3ZYLONS                     ; Sector contains 3 Zylon ships
BED5 1C       11097                 .BYTE CCS.4ZYLONS                     ; Sector contains 4 Zylon ships
BED6 1B       11098                 .BYTE CCS.STARBASE                    ; Sector contains starbase
              11099
              11100 ;*** Mask to limit veer-off velocity of Hyperwarp Target Marker in hyperwarp ***
BED7 9F       11101 VEERMASKTAB     .BYTE NEG!31                          ;  -31..+31  <KM/H> (unused)
BED8 BF       11102                 .BYTE NEG!63                          ;  -63..+63  <KM/H> PILOT mission
BED9 DF       11103                 .BYTE NEG!95                          ;  -95..+95  <KM/H> WARRIOR mission
BEDA FF       11104                 .BYTE NEG!127                         ; -127..+127 <KM/H> COMMANDER mission
              11105
              11106 ;*** Horizontal PLAYER offsets for PLAYER0..1 (STARBASE LEFT, STARBASE RIGHT) **
BEDB F8       11107 PLSTARBAOFFTAB  .BYTE -8                              ; -8 Player/Missile pixels
BEDC 08       11108                 .BYTE 8                               ; +8 Player/Missile pixels
              11109
              11110 ;*** Mission bonus table *******************************************************
BEDD 50       11111 BONUSTAB        .BYTE 80                              ; Mission complete   NOVICE mission
BEDE 4C       11112                 .BYTE 76                              ; Mission complete   PILOT mission
BEDF 3C       11113                 .BYTE 60                              ; Mission complete   WARRIOR mission
BEE0 6F       11114                 .BYTE 111                             ; Mission complete   COMMANDER mission
              11115
BEE1 3C       11116                 .BYTE 60                              ; Mission aborted    NOVICE mission
BEE2 3C       11117                 .BYTE 60                              ; Mission aborted    PILOT mission
BEE3 32       11118                 .BYTE 50                              ; Mission aborted    WARRIOR mission
BEE4 64       11119                 .BYTE 100                             ; Mission aborted    COMMANDER mission
              11120
BEE5 28       11121                 .BYTE 40                              ; Starship destroyed NOVICE mission
BEE6 32       11122                 .BYTE 50                              ; Starship destroyed PILOT mission
BEE7 28       11123                 .BYTE 40                              ; Starship destroyed WARRIOR mission
BEE8 5A       11124                 .BYTE 90                              ; Starship destroyed COMMANDER mission
              11125
              11126 ;*** Title phrase offsets of scored class rank *********************************
BEE9 A9       11127 RANKTAB         .BYTE $29!EOS                         ; "GALACTIC COOK"
BEEA AA       11128                 .BYTE $2A!EOS                         ; "GARBAGE SCOW CAPTAIN"
BEEB AA       11129                 .BYTE $2A!EOS                         ; "GARBAGE SCOW CAPTAIN"
BEEC AB       11130                 .BYTE $2B!EOS                         ; "ROOKIE"
BEED AB       11131                 .BYTE $2B!EOS                         ; "ROOKIE"
BEEE AC       11132                 .BYTE $2C!EOS                         ; "NOVICE"
BEEF AC       11133                 .BYTE $2C!EOS                         ; "NOVICE"
BEF0 AD       11134                 .BYTE $2D!EOS                         ; "ENSIGN"
BEF1 AD       11135                 .BYTE $2D!EOS                         ; "ENSIGN"
BEF2 AE       11136                 .BYTE $2E!EOS                         ; "PILOT"
BEF3 AE       11137                 .BYTE $2E!EOS                         ; "PILOT"
BEF4 AF       11138                 .BYTE $2F!EOS                         ; "ACE"
BEF5 B0       11139                 .BYTE $30!EOS                         ; "LIEUTENANT"
BEF6 B1       11140                 .BYTE $31!EOS                         ; "WARRIOR"
BEF7 B2       11141                 .BYTE $32!EOS                         ; "CAPTAIN"
BEF8 B3       11142                 .BYTE $33!EOS                         ; "COMMANDER"
BEF9 B3       11143                 .BYTE $33!EOS                         ; "COMMANDER"
BEFA B9       11144                 .BYTE $39!EOS                         ; "STAR COMMANDER"
BEFB B9       11145                 .BYTE $39!EOS                         ; "STAR COMMANDER"
              11146
              11147 ;*** Scored class number table *************************************************
BEFC 95       11148 CLASSTAB        .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFD 95       11149                 .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFE 95       11150                 .BYTE CCS.COL2!ROM.5                  ; Class 5
BEFF 94       11151                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF00 94       11152                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF01 94       11153                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF02 94       11154                 .BYTE CCS.COL2!ROM.4                  ; Class 4
BF03 93       11155                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF04 93       11156                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF05 93       11157                 .BYTE CCS.COL2!ROM.3                  ; Class 3
BF06 92       11158                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF07 92       11159                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF08 92       11160                 .BYTE CCS.COL2!ROM.2                  ; Class 2
BF09 91       11161                 .BYTE CCS.COL2!ROM.1                  ; Class 1
BF0A 91       11162                 .BYTE CCS.COL2!ROM.1                  ; Class 1
BF0B 91       11163                 .BYTE CCS.COL2!ROM.1                  ; Class 1
              11164
              11165 ;*** Title phrase offsets of mission level *************************************
BF0C 4A       11166 MISSIONPHRTAB   .BYTE $4A                             ; "NOVICE MISSION"
BF0D 4C       11167                 .BYTE $4C                             ; "PILOT MISSION"
BF0E 4E       11168                 .BYTE $4E                             ; "WARRIOR MISSION"
BF0F 50       11169                 .BYTE $50                             ; "COMMANDER MISSION"
              11170
              11171 ;*** Damage probability of subsystems depending on mission level ***************
BF10 00       11172 DAMAGEPROBTAB   .BYTE 0                               ;  0% (  0:256) NOVICE mission
BF11 50       11173                 .BYTE 80                              ; 31% ( 80:256) PILOT mission
BF12 B4       11174                 .BYTE 180                             ; 70% (180:256) WARRIOR mission
BF13 FE       11175                 .BYTE 254                             ; 99% (254:256) COMMANDER mission
              11176
              11177 ;*** Title phrase offsets of damaged subsystems ********************************
BF14 55       11178 DAMAGEPHRTAB    .BYTE $55                             ; "PHOTON TORPEDOS DAMAGED"
BF15 5B       11179                 .BYTE $5B                             ; "ENGINES DAMAGED"
BF16 61       11180                 .BYTE $61                             ; "SHIELDS DAMAGED"
BF17 67       11181                 .BYTE $67                             ; "COMPUTER DAMAGED"
BF18 6D       11182                 .BYTE $6D                             ; "LONG RANGE SCAN DAMAGED"
BF19 71       11183                 .BYTE $71                             ; "SUB-SPACE RADIO DAMAGED"
              11184
              11185 ;*** Title phrase offsets of destroyed subsystems ******************************
BF1A 58       11186 DESTROYPHRTAB   .BYTE $58                             ; "PHOTON TORPEDOS DESTROYED"
BF1B 5E       11187                 .BYTE $5E                             ; "ENGINES DESTROYED"
BF1C 64       11188                 .BYTE $64                             ; "SHIELDS DESTROYED"
BF1D 6A       11189                 .BYTE $6A                             ; "COMPUTER DESTROYED"
BF1E 6F       11190                 .BYTE $6F                             ; "LONG RANGE SCAN DESTROYED"
BF1F 73       11191                 .BYTE $73                             ; "SUB-SPACE RADIO DESTROYED"
              11192
              11193 ;*** 3 x 10-byte noise sound patterns (bytes 0..7 stored in reverse order) *****
              11194 ;
              11195 ; (9) AUDCTL        ($D208) POKEY: Audio control
              11196 ; (8) AUDF3         ($D204) POKEY: Audio channel 3 frequency
              11197 ; (7) NOISETORPTIM  ($DA)   Timer for PHOTON TORPEDO LAUNCHED noise sound patterns
              11198 ; (6) NOISEEXPLTIM  ($DB)   Timer for SHIP EXPLOSION and ZYLON EXPLOSION noise sound patterns
              11199 ; (5) NOISEAUDC2    ($DC)   Audio channel 1/2 control shadow register
              11200 ; (4) NOISEAUDC3    ($DD)   Audio channel 3   control shadow register
              11201 ; (3) NOISEAUDF1    ($DE)   Audio channel 1 frequency shadow register
              11202 ; (2) NOISEAUDF2    ($DF)   Audio channel 2 frequency shadow register
              11203 ; (1) NOISEFRQINC   ($E0)   Audio channel 1/2 frequency increment
              11204 ; (0) NOISELIFE     ($E1)   Noise sound pattern lifetime
              11205 ;
              11206 ;                     (0),(1),(2),(3),(4),(5),(6),(7),(8),(9)
BF20 18FF0200 11207 NOISEPATTAB     .BYTE $18,$FF,$02,$00,$8A,$A0,$00,$08,$50,$00; PHOTON TORPEDO LAUNCHED
BF24 8AA00008
BF28 5000    
BF2A 40400103 11208                 .BYTE $40,$40,$01,$03,$88,$AF,$08,$00,$50,$04; SHIP EXPLOSION
BF2E 88AF0800
BF32 5004    
BF34 30400103 11209                 .BYTE $30,$40,$01,$03,$84,$A8,$04,$00,$50,$04; ZYLON EXPLOSION
BF38 84A80400
BF3C 5004    
              11210
              11211 ;*** 5 x 6-byte beeper sound patterns (bytes 0..5 stored in reverse order) *****
              11212 ;
              11213 ; (5) BEEPFRQIND    ($D2) Running index into frequency table BEEPFRQTAB ($BF5C)
              11214 ; (4) BEEPREPEAT    ($D3) Number of times the beeper sound pattern sequence is repeated - 1
              11215 ; (3) BEEPTONELIFE  ($D4) Lifetime of tone in TICKs - 1
              11216 ; (2) BEEPPAUSELIFE ($D5) Lifetime of pause in TICKs - 1 ($FF -> No pause)
              11217 ; (1) BEEPPRIORITY  ($D6) Beeper sound pattern priority. A playing beeper sound pattern is
              11218 ;                         stopped if a beeper sound pattern of higher priority is about to be
              11219 ;                         played. A value of 0 indicates that no beeper sound pattern is
              11220 ;                         playing at the moment.
              11221 ; (0) BEEPFRQSTART  ($D7) Index to first byte of the beeper sound pattern frequency in table
              11222 ;                         BEEPFRQTAB ($BF5C)
              11223 ;
              11224 ; Frequency-over-TICKs diagrams for all beeper sound patterns:
              11225 ;
              11226 ; HYPERWARP TRANSIT
              11227 ;
              11228 ;      FRQ
              11229 ;       |
              11230 ;   $18 |-4--
              11231 ;       |
              11232 ;   $00 |    -3-
              11233 ;       +-------> TICKS
              11234 ;        <13 x >
              11235 ;
              11236 ; RED ALERT
              11237 ;
              11238 ;      FRQ
              11239 ;       |
              11240 ;   $60 |                 --------17-------
              11241 ;       |
              11242 ;   $40 |--------17-------
              11243 ;       |
              11244 ;       +----------------------------------> TICKS
              11245 ;        <-------------- 8 x ------------->
              11246 ;
              11247 ; ACKNOWLEDGE
              11248 ;
              11249 ;      FRQ
              11250 ;       |
              11251 ;   $10 |-3-   -3-   -3-
              11252 ;       |
              11253 ;   $00 |   -3-   -3-   -3-
              11254 ;       +------------------> TICKS
              11255 ;        <------ 1 x ----->
              11256 ;
              11257 ; DAMAGE REPORT (not to scale)
              11258 ;
              11259 ;      FRQ
              11260 ;       |
              11261 ;   $40 |------------33-------------
              11262 ;       |
              11263 ;   $20 |                           ------------33-------------
              11264 ;       |
              11265 ;       +------------------------------------------------------> TICKS
              11266 ;        <------------------------ 3 x ----------------------->
              11267 ;
              11268 ; MESSAGE FROM STARBASE (not to scale)
              11269 ;
              11270 ;      FRQ
              11271 ;       |
              11272 ;   $51 |                                  -----33-----
              11273 ;   $48 |-----33-----
              11274 ;   $40 |                 -----33-----
              11275 ;       |
              11276 ;   $00 |            --9--            --9--            --9--
              11277 ;       +----------------------------------------------------> TICKS
              11278 ;        <---------------------- 1 x ---------------------->
              11279 ;
              11280 ;                     (0),(1),(2),(3),(4),(5)
BF3E 02020203 11281 BEEPPATTAB      .BYTE $02,$02,$02,$03,$0C,$02         ; HYPERWARP TRANSIT
BF42 0C02    
BF44 0403FF10 11282                 .BYTE $04,$03,$FF,$10,$07,$04         ; RED ALERT
BF48 0704    
BF4A 07040202 11283                 .BYTE $07,$04,$02,$02,$00,$07         ; ACKNOWLEDGE
BF4E 0007    
BF50 0B05FF20 11284                 .BYTE $0B,$05,$FF,$20,$02,$0B         ; DAMAGE REPORT
BF54 020B    
BF56 0E060820 11285                 .BYTE $0E,$06,$08,$20,$00,$0E         ; MESSAGE FROM STARBASE
BF5A 000E    
              11286
              11287 ;*** Beeper sound pattern frequency table **************************************
BF5C 10FF     11288 BEEPFRQTAB      .BYTE $10,$FF                         ; (unused) (!)
BF5E 18FF     11289                 .BYTE $18,$FF                         ; HYPERWARP TRANSIT
BF60 4060FF   11290                 .BYTE $40,$60,$FF                     ; RED ALERT
BF63 101010FF 11291                 .BYTE $10,$10,$10,$FF                 ; ACKNOWLEDGE
BF67 4020FF   11292                 .BYTE $40,$20,$FF                     ; DAMAGE REPORT
BF6A 484051FF 11293                 .BYTE $48,$40,$51,$FF                 ; MESSAGE FROM STARBASE
              11294
              11295 ;*** Shape of blip in Attack Computer Display **********************************
BF6E 84       11296 BLIPSHAPTAB     .BYTE $84                             ; #....#..
BF6F B4       11297                 .BYTE $B4                             ; #.##.#..
BF70 FC       11298                 .BYTE $FC                             ; ######..
BF71 B4       11299                 .BYTE $B4                             ; #.##.#..
BF72 84       11300                 .BYTE $84                             ; #....#..
              11301
              11302 ;*** Initial x-coordinate (high byte) of our starship's photon torpedo *********
BF73 FF       11303 BARRELXTAB      .BYTE $FF                             ; Left barrel  = -256 (-$FF00) <KM>
BF74 01       11304                 .BYTE $01                             ; Right barrel = +256 (+$0100) <KM>
              11305
              11306 ;*** Maximum photon torpedo hit z-coordinate (high byte) ***********************
BF75 0C       11307 HITMAXZTAB      .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF76 0C       11308                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF77 0C       11309                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF78 0C       11310                 .BYTE $0C                             ; < 3328 ($0C**) <KM>
BF79 0E       11311                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7A 0E       11312                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7B 0E       11313                 .BYTE $0E                             ; < 3840 ($0E**) <KM>
BF7C 20       11314                 .BYTE $20                             ; < 8448 ($20**) <KM>
              11315
              11316 ;*** Minimum photon torpedo hit z-coordinate (high byte) ***********************
BF7D 00       11317 HITMINZTAB      .BYTE $00                             ; >=    0 ($00**) <KM>
BF7E 00       11318                 .BYTE $00                             ; >=    0 ($00**) <KM>
BF7F 00       11319                 .BYTE $00                             ; >=    0 ($00**) <KM>
BF80 02       11320                 .BYTE $02                             ; >=  512 ($02**) <KM>
BF81 04       11321                 .BYTE $04                             ; >= 1024 ($04**) <KM>
BF82 06       11322                 .BYTE $06                             ; >= 1536 ($06**) <KM>
BF83 08       11323                 .BYTE $08                             ; >= 2048 ($08**) <KM>
BF84 0C       11324                 .BYTE $0C                             ; >= 3072 ($0C**) <KM>
              11325
              11326 ;*** Velocity of homing Zylon photon torpedo ***********************************
BF85 81       11327 ZYLONHOMVELTAB  .BYTE NEG!1                           ;  -1 <KM/H> NOVICE mission
BF86 84       11328                 .BYTE NEG!4                           ;  -4 <KM/H> PILOT mission
BF87 88       11329                 .BYTE NEG!8                           ;  -8 <KM/H> WARRIOR mission
BF88 94       11330                 .BYTE NEG!20                          ; -20 <KM/H> COMMANDER mission
              11331
              11332 ;*** Zylon shape type table ****************************************************
BF89 80       11333 ZYLONSHAPTAB    .BYTE SHAP.ZBASESTAR                  ; ZYLON BASESTAR
BF8A 10       11334                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8B 10       11335                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8C 10       11336                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
BF8D 70       11337                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF8E 70       11338                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF8F 70       11339                 .BYTE SHAP.ZCRUISER                   ; ZYLON CRUISER
BF90 10       11340                 .BYTE SHAP.ZFIGHTER                   ; ZYLON FIGHTER
              11341
              11342 ;*** Zylon flight pattern table ************************************************
BF91 04       11343 ZYLONFLPATTAB   .BYTE 4                               ; Flight pattern 4
BF92 04       11344                 .BYTE 4                               ; Flight pattern 4
BF93 00       11345                 .BYTE 0                               ; Attack Flight Pattern 0
BF94 00       11346                 .BYTE 0                               ; Attack Flight Pattern 0
BF95 00       11347                 .BYTE 0                               ; Attack Flight Pattern 0
BF96 01       11348                 .BYTE 1                               ; Flight pattern 1
BF97 00       11349                 .BYTE 0                               ; Attack Flight Pattern 0
BF98 00       11350                 .BYTE 0                               ; Attack Flight Pattern 0
              11351
              11352 ;*** Zylon velocity table ******************************************************
BF99 3E       11353 ZYLONVELTAB     .BYTE 62                              ; +62 <KM/H>
BF9A 1E       11354                 .BYTE 30                              ; +30 <KM/H>
BF9B 10       11355                 .BYTE 16                              ; +16 <KM/H>
BF9C 08       11356                 .BYTE 8                               ;  +8 <KM/H>
BF9D 04       11357                 .BYTE 4                               ;  +4 <KM/H>
BF9E 02       11358                 .BYTE 2                               ;  +2 <KM/H>
BF9F 01       11359                 .BYTE 1                               ;  +1 <KM/H>
BFA0 00       11360                 .BYTE 0                               ;   0 <KM/H>
BFA1 00       11361                 .BYTE 0                               ;   0 <KM/H>
BFA2 81       11362                 .BYTE NEG!1                           ;  -1 <KM/H>
BFA3 82       11363                 .BYTE NEG!2                           ;  -2 <KM/H>
BFA4 84       11364                 .BYTE NEG!4                           ;  -4 <KM/H>
BFA5 88       11365                 .BYTE NEG!8                           ;  -8 <KM/H>
BFA6 90       11366                 .BYTE NEG!16                          ; -16 <KM/H>
BFA7 9E       11367                 .BYTE NEG!30                          ; -30 <KM/H>
BFA8 BE       11368                 .BYTE NEG!62                          ; -62 <KM/H>
              11369
              11370 ;*** PLAYFIELD colors (including PLAYFIELD colors during DLI) ******************
BFA9 A6       11371 PFCOLORTAB      .BYTE $A6                             ; PF0COLOR    = {GREEN}
BFAA AA       11372                 .BYTE $AA                             ; PF1COLOR    = {LIGHT GREEN}
BFAB AF       11373                 .BYTE $AF                             ; PF2COLOR    = {VERY LIGHT GREEN}
BFAC 00       11374                 .BYTE $00                             ; PF3COLOR    = {BLACK}
BFAD 00       11375                 .BYTE $00                             ; BGRCOLOR    = {BLACK}
BFAE B8       11376                 .BYTE $B8                             ; PF0COLORDLI = {LIGHT MINT}
BFAF 5A       11377                 .BYTE $5A                             ; PF1COLORDLI = {MEDIUM PINK}
BFB0 FC       11378                 .BYTE $FC                             ; PF2COLORDLI = {LIGHT ORANGE}
BFB1 5E       11379                 .BYTE $5E                             ; PF3COLORDLI = {LIGHT PINK}
BFB2 90       11380                 .BYTE $90                             ; BGRCOLORDLI = {DARK BLUE}
              11381
              11382 ;*** Vicinity mask table. Confines coordinates of space objects in sector ******
BFB3 FF       11383 VICINITYMASKTAB .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFB4 FF       11384                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFB5 3F       11385                 .BYTE $3F                             ; <= 16383 ($3F**) <KM>
BFB6 0F       11386                 .BYTE $0F                             ; <=  4095 ($0F**) <KM>
BFB7 3F       11387                 .BYTE $3F                             ; <= 16383 ($3F**) <KM>
BFB8 7F       11388                 .BYTE $7F                             ; <= 32767 ($7F**) <KM>
BFB9 FF       11389                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
BFBA FF       11390                 .BYTE $FF                             ; <= 65535 ($FF**) <KM>
              11391
              11392 ;*** Movement probability of sector types in Galactic Chart ********************
BFBB 00       11393 MOVEPROBTAB     .BYTE 0                               ; Empty sector    0% (  0:256)
BFBC FF       11394                 .BYTE 255                             ; 1 Zylon ship  100% (255:256)
BFBD FF       11395                 .BYTE 255                             ; 2 Zylon ships 100% (255:256)
BFBE C0       11396                 .BYTE 192                             ; 3 Zylon ships  75% (192:256)
BFBF 20       11397                 .BYTE 32                              ; 4 Zylon ships  13% ( 32:256)
              11398
              11399 ;*** Galactic Chart sector offset to adjacent sector ***************************
BFC0 F0       11400 COMPASSOFFTAB   .BYTE -16                             ; NORTH
BFC1 EF       11401                 .BYTE -17                             ; NORTHWEST
BFC2 FF       11402                 .BYTE -1                              ; WEST
BFC3 0F       11403                 .BYTE 15                              ; SOUTHWEST
BFC4 10       11404                 .BYTE 16                              ; SOUTH
BFC5 11       11405                 .BYTE 17                              ; SOUTHEAST
BFC6 01       11406                 .BYTE 1                               ; EAST
BFC7 F1       11407                 .BYTE -15                             ; NORTHEAST
BFC8 00       11408                 .BYTE 0                               ; CENTER
              11409
              11410 ;*** Homing velocities of photon torpedoes 0..1 depending on distance to target 
BFC9 00       11411 HOMVELTAB       .BYTE 0                               ;  +0 <KM/H>
BFCA 08       11412                 .BYTE 8                               ;  +8 <KM/H>
BFCB 10       11413                 .BYTE 16                              ; +16 <KM/H>
BFCC 18       11414                 .BYTE 24                              ; +24 <KM/H>
BFCD 28       11415                 .BYTE 40                              ; +40 <KM/H>
BFCE 30       11416                 .BYTE 48                              ; +48 <KM/H>
BFCF 38       11417                 .BYTE 56                              ; +56 <KM/H>
BFD0 40       11418                 .BYTE 64                              ; +64 <KM/H>
              11419
              11420 ;*** PLAYER shape color table (bits B7..4 of color/brightness) *****************
BFD1 50       11421 PLSHAPCOLORTAB  .BYTE $50                             ; PHOTON TORPEDO          = {PURPLE}
BFD2 00       11422                 .BYTE $00                             ; ZYLON FIGHTER           = {GRAY}
BFD3 20       11423                 .BYTE $20                             ; STARBASE RIGHT          = {ORANGE}
BFD4 20       11424                 .BYTE $20                             ; STARBASE CENTER         = {ORANGE}
BFD5 20       11425                 .BYTE $20                             ; STARBASE LEFT           = {ORANGE}
BFD6 00       11426                 .BYTE $00                             ; TRANSFER VESSEL         = {GRAY}
BFD7 A0       11427                 .BYTE $A0                             ; METEOR                  = {GREEN}
BFD8 00       11428                 .BYTE $00                             ; ZYLON CRUISER           = {GRAY}
BFD9 00       11429                 .BYTE $00                             ; ZYLON BASESTAR          = {GRAY}
BFDA 9F       11430                 .BYTE $9F                             ; HYPERWARP TARGET MARKER = {SKY BLUE}
              11431
              11432 ;*** PLAYER shape brightness table (bits B3..0 of color/brightness) ************
BFDB 0E       11433 PLSHAPBRITTAB   .BYTE $0E                             ; ##############..
BFDC 0E       11434                 .BYTE $0E                             ; ##############..
BFDD 0E       11435                 .BYTE $0E                             ; ##############..
BFDE 0C       11436                 .BYTE $0C                             ; ############....
BFDF 0C       11437                 .BYTE $0C                             ; ############....
BFE0 0C       11438                 .BYTE $0C                             ; ############....
BFE1 0A       11439                 .BYTE $0A                             ; ##########......
BFE2 0A       11440                 .BYTE $0A                             ; ##########......
BFE3 0A       11441                 .BYTE $0A                             ; ##########......
BFE4 08       11442                 .BYTE $08                             ; ########........
BFE5 08       11443                 .BYTE $08                             ; ########........
BFE6 08       11444                 .BYTE $08                             ; ########........
BFE7 06       11445                 .BYTE $06                             ; ######..........
BFE8 06       11446                 .BYTE $06                             ; ######..........
BFE9 04       11447                 .BYTE $04                             ; ####............
BFEA 04       11448                 .BYTE $04                             ; ####............
              11449
              11450 ;*** PHOTON TORPEDO LAUNCHED noise bit and volume (stored in reverse order) ****
BFEB 8A       11451 NOISETORPVOLTAB .BYTE $8A                             ; ##########.....
BFEC 8F       11452                 .BYTE $8F                             ; ###############
BFED 8D       11453                 .BYTE $8D                             ; #############..
BFEE 8B       11454                 .BYTE $8B                             ; ###########....
BFEF 89       11455                 .BYTE $89                             ; #########......
BFF0 87       11456                 .BYTE $87                             ; #######........
BFF1 85       11457                 .BYTE $85                             ; ######.........
BFF2 83       11458                 .BYTE $83                             ; ###............
              11459
              11460 ;*** PHOTON TORPEDO LAUNCHED noise frequency table (stored in reverse order) ***
BFF3 00       11461 NOISETORPFRQTAB .BYTE $00                             ;
BFF4 04       11462                 .BYTE $04                             ;
BFF5 01       11463                 .BYTE $01                             ;
BFF6 04       11464                 .BYTE $04                             ;
BFF7 01       11465                 .BYTE $01                             ;
BFF8 04       11466                 .BYTE $04                             ;
BFF9 01       11467                 .BYTE $01                             ;
BFFA 04       11468                 .BYTE $04                             ;
              11469
BFFB 07       11470                 .BYTE $07                             ; (unused)
              11471
BFFC 00       11472                 .BYTE $00                             ; Always 0 for cartridges
BFFD 80       11473                 .BYTE $80                             ; On SYSTEM RESET jump to INITCOLD via
BFFE 4AA1     11474                 .WORD INITCOLD                        ; Cartridge Initialization Address

SYMBOLS (SORTED BY NAME): 896

 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
=0080  DRAINRATE
 BAD3  DRAINRATETAB
 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
=007E  ISATTCOMPON
=00B8  ISBACKATTACK0
=00B9 ?ISBACKATTACK1
=0064  ISDEMOMODE
=00A3  ISINLOCKON
=007D  ISSHIELDSON
=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
=0000  LEFT
=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
=0010  MAXSPCOBJIND.NL
=0031  MAXSPCOBJNUM
=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
=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
 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
=007A  SAVMAXSPCOBJIND
=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): 896

=0000  CCS.0
=0000  LEFT
=0000  ROM.SPC
=0000 ?SHAP.TORPEDO
=0001 ?CCS.1
=0002 ?CCS.2
=0003 ?CCS.3
=0004 ?CCS.4
=0005 ?CCS.5
=0006 ?CCS.6
=0007 ?CCS.7
=0008 ?CCS.8
=0009  CCS.9
=000A  CCS.SPC
=000B  CCS.COLON
=000C  CCS.BORDERSW
=000D  CCS.E
=000E  CCS.INF
=000E  ROM.DOT
=000F  CCS.MINUS
=0010  CCS.PLUS
=0010  MAXSPCOBJIND.NL
=0010  ROM.0
=0010  SHAP.ZFIGHTER
=0011  CCS.PHI
=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  MAXSPCOBJNUM
=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  SAVMAXSPCOBJIND
=007B  ISSTARBASESECT
=007C  ISTRACKCOMPON
=007D  ISSHIELDSON
=007E  ISATTCOMPON
=007F  ENERGYCNT
=0080  CCS.COL2
=0080  DOWN
=0080  DRAINRATE
=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