General Information #
Author: Greg KnaussLanguage: ACTION!
Compiler/Interpreter: ACTION!
Published: Antic Vol. 6 #10 (02/ 88)
Killer Chess#
Two-player ACTION! shootout#
Killer Chess brings a new frenzy of aggression to the classic game, as you mop up the chessboard without waiting for your opponent to make moves. This type-in program is written in ACTION! and requires the ACTION! language cartridge from Optimized Systems Software, as well as an 8-bit Atari computer with at least 32K memory and a disk drive.
Unless you're a real fanatic or a tournament contender, I'll bet that you don't play much chess anymore. Let's face it, most "regular folks" find chess boring!
But now imagine a revitalized, fast-ACTION! chess-where the players don't take turns.
That's right. . . no turns. Killer Chess players make legal chess moves as fast as they can, deciding on instant strategies that they would have spent dull minutes pondering in a traditional game. Stodgy old chess becomes a fast-gun shootout.
Welcome to Killer Chess, written in ACTION! the fast, powerful programming language from Optimized Systems Software. You and your human opponent will use an Atari 8-bit computer and a pair of joysticks to battle it out in a radical new version of a traditional game
GETTING STARTED #
TYPING IT IN: Insert the ACTION! cartridge into your 8-bit Atari and type in Listing 1, KILLER.ACT Type carefully; because there isn't a TYPO II for ACTION! After you have a copy of the complete program safely saved, go to the monitor by pressing [CONTROL] [SHIFT] [M] and compile the program by typing [C] [RETURN]. When the cursor starts blinking again, type [R] [RETURN] and the title page should appear.MONTHLY DISK USERS: You can play Killer Chess without owning the ACTION! cartridge. Just insert your Antic Monthly Disk into your disk drive, remove all cartridges from your Atari (XL/XE owners should press the [OPTION] key) and turn on your Atari. When the DOS menu appears, just type [L][RETURN], then type KILLER.EXE [RETURN].
When the title screen is seen, press [START] to begin a game. When the game begins, both players will be able to simultaneously move their respective cursors around the board. With joystick 0, player 1 controls the white cursor and white pieces. With joystick 1, player 2 controls the gray cursor and gray pieces.
PLAYING KILLER CHESS #
Simply place the cursor over any piece you want to move and press the joystick button. Now move the cursor over a square that would be a legal move for that piece and press the button again. If the move is illegal, the computer will tell you so -with a rather unpleasant sound- and let you try again. Otherwise the piece will be placed at the new square. If you accidentally pick up a piece and don't want to move it, just replace the cursor over the piece you selected and press the button again. The piece will be dropped.To capture an enemy, simply make a legal move on top of it. The offending piece will be removed from play. You can capture a piece your opponent is "holding". The piece isn't actually moved until it is set down again.
To win, just land one of your characters on top of the opponent's King. To return to the title screen press [START] or wait about 10 seconds.
Killer Chess does not have castling or en passant moves, which are allowed under advanced chess rules but would be too confusing here.
ABOUT THE PROGRAM #
The biggest programming problem in Killer Chess was detecting illegal chess moves. My solution is quite simple and can be applied to any chess program. The method is even fast enough to be used with BASIC.Here's what I did: When a piece is selected, its old position is recorded. Each new position chosen by a player is also recorded. The old position is then subtracted from the new position and stored in a "delta" value, one delta for X and one for Y Delta means how much something changes. So if the new X position is 5 more than the previous one, the Delta X would be five. If the new Y position is 1 less than the old, Delta Y would be -1.
I then used IF statements to determine if the piece was allowed to move to that spot. For instance, a pawn is only allowed to move forward, so I checked to make sure that Delta X is equal to nothing but 1. If the old position was equal to its starting position, I allowed it to move an extra space-because Pawns can move two spaces on their first move.
If the Pawn's new position is on top of an opponent's piece, I allowed for a Delta Y movement of either 1 or -1. Combined with the Delta X, that would result in diagonal movement. Simple, really. It just took a bit of planning to work out the values for the special conditions of each chess piece.
Greg "Maddog" Knauss of Rancho Palos Verdes, California is an indefatigable ACTION! language programmer
; KILLER CHESS
; BY GREG KNAUSS
; (c)1987, ANTIC PUBLISHING
CARD PM,CH
BYTE I,J,K,STK,PLR,LOC,CAP,OK
BYTE ARRAY X(2),Y(2),OX(2),OY(2),
HOLD(2),PAU(2),SND(2),DIS(2)
INT X1,Y1,DX,DY,DUM1,DUM2
PROC CURSOR()
; SHAPE FOR CURSORS
[255 129 129 129 129 129 129 255]
PROC CHRS()
; BOARD EDGE
[ 0 0 0 0 0 0 0 0
0 0 0 0 15 15 15 15
0 0 0 0 0 0 0 0
0 0 0 0 255 255 255 255
0 0 0 0 240 240 240 240
15 15 15 15 15 15 15 15
240 240 240 240 240 240 240 240
15 15 15 15 0 0 0 0
255 255 255 255 0 0 0 0
240 240 240 240 0 0 0 0
; PIECES
0 0 0 56 56 16 124 0
0 84 124 56 56 56 124 0
0 6 60 124 28 28 60 126
0 16 24 108 124 56 16 124
0 214 254 124 56 56 124 254
0 16 56 146 254 124 56 124
; TITLE
0 247 108 112 112 108 246 3
0 62 102 96 96 102 60 0
24 0 56 24 24 24 60 0
224 96 124 102 102 102 247 0
56 24 24 24 24 24 60 0
0 0 60 102 126 96 62 0
0 0 220 102 96 96 240 0
0 0 62 96 60 6 124 0
; "PRESS START"
0 238 170 238 140 138 0 0
0 238 136 206 130 238 0 0
1 225 129 225 33 225 1 0
255 17 123 27 219 27 255 0
255 17 85 17 83 85 255 0
240 16 176 176 176 180 240 0]
PROC SETUP()
GRAPHICS(18) POKE(559,0)
POKE (559,46)
; COLORS
SETBLOCK(706,2,66)
POKE(704,14) POKE(705,8)
POKE(708,10) POKE(710,4)
POKE(709,142) POKE(711,15) ;DO 711
; P/M GRAPHICS
PM=(PEEK(106)-8)*256
POKE(54279,PM/256) POKE(53277,3)
SETBLOCK(53258,2,3) ZERO(PM,1024)
POKE(623,2) PM==+512 K=51
FOR I=32 TO 95 STEP 8 DO
FOR J=0 TO 7 DO POKE(PM+I+J+256,K)
POKE(PM+I+J+384,K) OD K=255-K OD
; REDEFINED CHARACTERS
CH=(PEEK(106)-16)*256
MOVEBLOCK(CH,CHRS,512)
POKE(756,CH/256)
; DRAW BOARD
POSITION(5,1) PRINTD(6,"..........")
FOR I=2 TO 9 DO POSITION(5,I)
PRINTD(6,". .") OD
POSITION(5,10) PRINTD(6,"..........")
POSITION(6,2) PRINTD(6,"+,-./-,+")
POSITION(6,3) PRINTD(6,"********")
POSITION(7,5) PRINTD(6,"......")
POSITION(7,6) PRINTD(6,".....")
POSITION(6,8) PRINTD(6,"********")
POSITION(6,9) PRINTD(6,"+,-./-,+")
POSITION(7,11) PRINTD(6,"......")
POKE(53250,96) POKE(53251,128)
POKE(559,46)
; WAIT FOR [START]
I=0 DO POKE(54282,0) POKE(53273,I)
I==+3 UNTIL PEEK(53279)=6 OD
; DRAW PIECES
POSITION(6,2) PRINTD(6,"+* *+")
POSITION(6,3) PRINTD(6,",* *,")
POSITION(6,4) PRINTD(6,"-* *-")
POSITION(6,5) PRINTD(6,".* *.")
POSITION(6,6) PRINTD(6,"/* */")
POSITION(6,7) PRINTD(6,"-* *-")
POSITION(6,8) PRINTD(6,",* *,")
POSITION(6,9) PRINTD(6,"+* *+")
POSITION(7,11) PRINTD(6," ")
RETURN
PROC MAIN()
; GAME LOOP
DO
SETUP()
X(0)=6 Y(0)=5 X(1)=13 Y(1)=6
HOLD(0)=0 HOLD(1)=0 PAU(0)=0 PAU(1)=0
PLR=1
; PLAYER TURN LOOP
DO
; ALTERNATE PLAYERS
PLR=1-PLR
; RESET THESE FOR EACH TURN
X1=0 Y1=0 POKE(77,0)
IF PAU(PLR)=0 THEN SOUND(PLR,0,0,0)
FI
; MOVE WHICH WAY???
STK=STICK(PLR)
IF STK=14 OR STK=10 OR STK=6 THEN
Y1=-1 FI
IF STK=13 OR STK=9 OR STK=5 THEN Y1=1
FI
IF STK=11 OR STK=10 OR STK=9 THEN
X1=-1 FI
IF STK=7 OR STK=6 OR STK=5 THEN X1=1
FI
; KEEP PLAYER ON BOARD
LOC=LOCATE(X(PLR)+X1,Y(PLR)+Y1)
IF LOC<10 THEN X1=0 Y1=0 FI
; MOVE CURSOR
IF Y1<>0 THEN
ZERO(PM+128*PLR+16+8*Y(PLR),8) FI
X(PLR)==+X1 Y(PLR)==+Y1
POKE(53248+PLR,8*X(PLR)+48)
MOVEBLOCK(PM+128*PLR+16+8*Y(PLR),
CURSOR,8)
; WAIT! HE'S PLACING A PIECE!
IF HOLD(PLR)>0 AND STRIG(PLR)=0 AND
PAU(PLR)=0 THEN CAP=0 OK=0 DX=0 DY=0
; SOMETHING TO CAPTURE!
IF LOC<>32 THEN CAP=1 FI
; FIND DELTA VALUES
DUM1=X(PLR)
DUM2=OX(PLR)
DX=DUM1-DUM2
DUM1=Y(PLR)
DUM2=OY(PLR)
DY=DUM1-DUM2
; FLIP FOR PLAYER 2
IF PLR=1 THEN DX=-DX DY=-DY FI
; IS IT LEGAL???
; PAWN
IF HOLD(PLR)=1 THEN
IF DX=1 AND DY=0 AND CAP=0 THEN
OK=1 FI
IF DX=2 AND DY=0 AND CAP=0 AND
OX(PLR)=7+PLR*5 THEN OK=1 FI
IF DX=1 AND (DY=1 OR DY=-1) AND
CAP=1 THEN OK=1 FI FI
; ROOK
IF HOLD(PLR)=2 THEN
IF (DX<>0 AND DY=0) OR (DX=0 AND
DY<>0) THEN OK=1 FI FI
; KNIGHT
IF HOLD(PLR)=3 THEN
IF (DX=2 AND DY=1) OR (DX=-2 AND
DY=1) THEN OK=1 FI
IF (DX=2 AND DY=-1) OR
(DX=-2 AND DY=-1) THEN OK=1 FI
IF (DX=1 AND DY=2) OR (DX=-1 AND
DY=2) THEN OK=1 FI
IF (DX=1 AND DY=-2) OR
(DX=-1 OR DY=-2) THEN OK=1 FI FI
; BISHOP
IF HOLD(PLR)=4 AND (DX=DY OR DX=-DY)
THEN OK=1 FI
; QUEEN
IF HOLD(PLR)=5 THEN
IF DX=DY OR DX=-DY THEN OK=1 FI
IF (DX<>0 AND DY=0) OR (DX=0 AND
DY<>0) THEN OK=1 FI FI
; KING
IF HOLD(PLR)=6 THEN
IF (DX=1 AND DY=1) OR (DX=0 AND
DY=1) OR (DX=-1 AND DY=1) THEN
OK=1 FI
IF (DX=1 AND DY=0) OR (DX=-1 AND
DY=0) THEN OK=1 FI
IF (DX=1 AND DY=-1) OR (DX=0 AND
DY=-1) OR (DX=-1 AND DY=-1) THEN
OK=1 FI FI
; CAN'T CAPTURE OWN PIECES OR
; BORDER
IF LOC>128*PLR+41 AND
LOC<128*PLR+127 OR LOC<10 THEN OK=0
FI
; DIDN'T MOVE
IF DX=0 AND DY=0 THEN OK=1 FI
; MAKE SURE JUMPS WEREN'T MADE,
; EXCEPT BY KNIGHT
IF HOLD(PLR)<>3 THEN
I=OX(PLR) J=OY(PLR)
X1=0 Y1=0
IF DX<0 THEN X1=-1 FI
IF DX>0 THEN X1=1 FI
IF DY<0 THEN Y1=-1 FI
IF DY>0 THEN Y1=1 FI
IF PLR=1 THEN X1=-X1 Y1=-Y1 FI
IF (DX<-1 OR DX>1) OR (DY<-1 OR
DY>1) THEN
DO
I==+X1 J==+Y1
K=LOCATE(I,J)
IF K<>32 THEN OK=0 FI
UNTIL (I=X(PLR)-X1 AND
J=Y(PLR)-Y1) OR K<10 OD FI FI
; LEGAL MOVE!
IF OK=1 THEN
COLOR=32 PLOT(OX(PLR),OY(PLR))
COLOR=HOLD(PLR)+128*PLR+41
; QUEEN ME!
IF HOLD(PLR)=1 AND
X(PLR)=7*(1-PLR)+6 THEN
COLOR=128*PLR+46 FI
; KILL OTHER PLAYERS HOLD IF THAT'S
; WHAT WAS CAPTURED
IF X(PLR)=OX(1-PLR) AND
Y(PLR)=OY(1-PLR) THEN
HOLD(1-PLR)=0
POSITION(11*(1-PLR)+4,2)
PRINTD(6," ") FI
; WHO'D HE LAND ON??
K=LOCATE(X(PLR),Y(PLR))
; WHOEVER IT WAS, KILL HIM
PLOT(X(PLR),Y(PLR))
COLOR=32 PLOT(11*PLR+4,2)
; A KING DIED!
IF K-128*(1-PLR)-41=6 THEN EXIT FI
HOLD(PLR)=0
SND(PLR)=100*PLR+100 DIS(PLR)=14 FI
; ILLEGAL MOVE...
IF OK=0 THEN SND(PLR)=255
DIS(PLR)=2 FI
PAU(PLR)=5 FI
; PICK UP PIECE
IF HOLD(PLR)=0 AND STRIG(PLR)=0 AND
PAU(PLR)=0 AND LOC<>32 AND
LOC>128*PLR+41 AND LOC<128*PLR+127
THEN
; Grab HOLD
HOLD(PLR)=LOC-128*PLR-41
OX(PLR)=X(PLR) OY(PLR)=Y(PLR)
COLOR=LOC PLOT(11*PLR+4,2)
SND(PLR)=100*PLR+100 DIS(PLR)=10
PAU(PLR)=5 FI
; DELAY
FOR CH=1 TO 2000 DO OD
; PAUSE FOR HUMANS
IF PAU(PLR)>0 THEN PAU(PLR)==-1
SOUND(PLR,SND(PLR),DIS(PLR),
PAU(PLR)*2) FI
; NEXT PLAYER
OD
; VICTORY ROUTINE
SNDRST() ZERO(PM,256) COLOR=32
FOR I=2 TO 9 DO FOR J=6 TO 13 DO
LOC=LOCATE(J,I) IF LOC>128*(1-PLR)
AND LOC<128*(1-PLR)+127 THEN
PLOT(J,I) FI OD OD PLOT(4,2)
PLOT(15,2)
; PAUSE
CH=0 DO CH==+1 FOR I=1 TO 100 DO OD
UNTIL CH=7500 OR PEEK(53279)=6 OD
; START NEW GAME
OD
