6502 MicroChess source. By Lee Davison
[Back]

; MicroChess (c) 1976-2002 Peter Jennings, peterj@benlo.com ; this version for the integrated macroassembler, simulator and debugger for ; 650x microprocessor family by Michal Kowalski http://home.pacbell.net/michal_k/ ; additions and changes by Lee Davison http://members.lycos.co.uk/leeedavison/ ; from suggested ASCII routines in the KIM MicroChess programmers notes ; this version is posted with permission of Peter Jennings, peterj@benlo.com ; display flash during compute move replaced by '?' prompt flash ; piece display changed to display piece at 'to' square after each move ; Simulator I/O base addresse is $F000 ; Simulator window size is 64 columns x 20 rows IO_AREA = $F000 ACIAsimwr = IO_AREA+$01 ACIAsimrd = IO_AREA+$04 DispPosX = IO_AREA+$05 DispPosY = IO_AREA+$06 ; page zero variables BOARD = $50 BK = $60 PIECE = $B0 SQUARE = $B1 SP2 = $B2 SP1 = $B3 INCHEK = $B4 STATE = $B5 MOVEN = $B6 OMOVE = $DC WCAP0 = $DD COUNT = $DE BCAP2 = $DE WCAP2 = $DF BCAP1 = $E0 WCAP1 = $E1 BCAP0 = $E2 MOB = $E3 MAXC = $E4 CC = $E5 PCAP = $E6 BMOB = $E3 BMAXC = $E4 _BCC = $E5 ; was BCC BMAXP = $E6 XMAXC = $E8 WMOB = $EB WMAXC = $EC WCC = $ED WMAXP = $EE PMOB = $EF PMAXC = $F0 PCC = $F1 PCP = $F2 OLDKY = $F3 BESTP = $FB BESTV = $FA BESTM = $F9 DIS1 = $FB DIS2 = $FA DIS3 = $F9 prompt = $FC ; prompt character, '?' or ' ' reverse = $FD ; which way round is the display board *=$1000 ; load into RAM @ $1000 onwards CHESS CLD ; INITIALIZE LDX #$FF ; TWO STACKS TXS LDX #$C8 STX SP2 ; ROUTINES TO LIGHT LED ; DISPLAY AND GET KEY ; FROM KEYBOARD OUT JSR DrawBoard ; draw board LDA #'?' ; prompt character STA prompt ; save it GetKey JSR UpdateDisp ; update prompt & display JSR asciiin ; get key press CMP #'C' ; is it "C" BNE NOSET ; branch if not ; else set up board LDX #$1F ; 32 pieces to do WHSET LDA SETW,X ; FROM STA BOARD,X ; SETW DEX BPL WHSET LDA #$00 ; no reverse STA reverse ; set it LDX #$1B ; *ADDED STX OMOVE ; INITS TO $FF LDA #$CC ; Display CCC BNE CLDSP NOSET CMP #'E' ; [E] BNE NOREV ; REVERSE JSR REVERSE ; BOARD IS LDA reverse ; get reversed flag EOR #$01 ; toggle reverse bit STA reverse ; save flag LDA #$EE ; IS BNE CLDSP NOREV CMP #'P' ; [P] BNE NOGO ; PLAY CHESS JSR GO CLDSP STA DIS1 ; DISPLAY LDA #$00 STA DIS2 ; ACROSS STA DIS3 ; DISPLAY BEQ CHESS NOGO CMP #$0D ; [Enter] BNE NOMV ; MOVE MAN JSR MOVE ; AS ENTERED ; JSR DISP2 ; piece into display JSR DISP3 ; piece into display JMP CHESS ; main loop NOMV ; CMP #'Q' ; [Q] ***Added to allow game exit*** ; BEQ DONE ; quit the game, exit back to system. ; removed from simulator version as no system! JMP INPUT ; process move ;DONE ; JMP $FF00 ; *** MUST set this to YOUR OS starting address ; THE ROUTINE JANUS DIRECTS THE ; ANALYSIS BY DETERMINING WHAT ; SHOULD OCCUR AFTER EACH MOVE ; GENERATED BY GNM JANUS LDX STATE BMI NOCOUNT ; THIS ROUTINE COUNTS OCCURRENCES ; IT DEPENDS UPON STATE TO INDEX ; THE CORRECT COUNTERS COUNTS LDA PIECE BEQ OVER ; IF STATE=8 CPX #$08 ; DO NOT COUNT BNE OVER ; BLK MAX CAP CMP BMAXP ; MOVES FOR BEQ XRT ; WHITE OVER INC MOB,X ; MOBILITY CMP #$01 ; + QUEEN BNE NOQ ; FOR TWO INC MOB,X NOQ BVC NOCAP LDY #$0F ; CALCULATE LDA SQUARE ; POINTS ELOOP CMP BK,Y ; CAPTURED BEQ FOUN ; BY THIS DEY ; MOVE BPL ELOOP FOUN LDA POINTS,Y CMP MAXC,X BCC LESS ; SAVE IF STY PCAP,X ; BEST THIS STA MAXC,X ; STATE LESS CLC PHP ; ADD TO ADC CC,X ; CAPTURE STA CC,X ; COUNTS PLP NOCAP CPX #$04 BEQ ON4 BMI TREE ; (=00 ONLY) XRT RTS ; GENERATE FURTHER MOVES FOR COUNT ; AND ANALYSIS ON4 LDA XMAXC ; SAVE ACTUAL STA WCAP0 ; CAPTURE LDA #$00 ; STATE=0 STA STATE JSR MOVE ; GENERATE JSR REVERSE ; IMMEDIATE JSR GNMZ ; REPLY MOVES JSR REVERSE LDA #$08 ; STATE=8 STA STATE ; GENERATE JSR GNM ; CONTINUATION JSR UMOVE ; MOVES JMP STRATGY ; FINAL EVALUATION NOCOUNT CPX #$F9 BNE TREE ; DETERMINE IF THE KING CAN BE ; TAKEN, USED BY CHKCHK LDA BK ; IS KING CMP SQUARE ; IN CHECK? BNE RETJ ; SET INCHEK=0 LDA #$00 ; IF IT IS STA INCHEK RETJ RTS ; IF A PIECE HAS BEEN CAPTURED BY ; A TRIAL MOVE, GENERATE REPLIES & ; EVALUATE THE EXCHANGE GAIN/LOSS TREE BVC RETJ ; NO CAP LDY #$07 ; (PIECES) LDA SQUARE LOOPX CMP BK,Y BEQ FOUNX DEY BEQ RETJ ; (KING) BPL LOOPX ; SAVE FOUNX LDA POINTS,Y ; BEST CAP CMP BCAP0,X ; AT THIS BCC NOMAX ; LEVEL STA BCAP0,X NOMAX DEC STATE LDA #$FB ; IF STATE=FB CMP STATE ; TIME TO TURN BEQ UPTREE ; AROUND JSR GENRM ; GENERATE FURTHER UPTREE INC STATE ; CAPTURES RTS ; THE PLAYER'S MOVE IS INPUT INPUT SEC ; set for subtract SBC #'0' ; convert ASCII # to binary CMP #$08 ; NOT A LEGAL BCS ERROR ; SQUARE # JSR DISMV JSR DISP2 ; put piece into display ERROR JMP GetKey ; go update move display and wait for next key ; JMP CHESS DISP3 LDA DIS3 ; get position .byte $2C ; make next LDA into BIT xxxx DISP2 LDA DIS2 ; get position LDX #$1F SEARCH CMP BOARD,X ; compare with this piece's position ; LDA BOARD,X ; CMP DIS2 BEQ HERE ; DISPLAY DEX ; PIECE AT BPL SEARCH ; FROM LDX #$BB ; blank square if no matching piece HERE STX DIS1 ; SQUARE STX PIECE RTS ; GENERATE ALL MOVES FOR ONE ; SIDE, CALL JANUS AFTER EACH ; ONE FOR NEXT STE? GNMZ LDX #$10 ; CLEAR GNMX LDA #$00 ; COUNTERS CLEAR STA COUNT,X DEX BPL CLEAR GNM LDA #$10 ; SET UP STA PIECE ; PIECE NEWP DEC PIECE ; NEW PIECE BPL NEX ; ALL DONE? RTS ; #NAME? NEX JSR RESET ; READY LDY PIECE ; GET PIECE LDX #$08 STX MOVEN ; COMMON START CPY #$08 ; WHAT IS IT? BPL PAWN ; PAWN CPY #$06 BPL KNIGHT ; KNIGHT CPY #$04 BPL BISHOP ; BISHOP CPY #$01 BEQ QUEEN ; QUEEN BPL ROOK ; ROOK KING JSR SNGMV ; MUST BE KING! BNE KING ; MOVES BEQ NEWP ; 8 TO 1 QUEEN JSR LINE BNE QUEEN ; MOVES BEQ NEWP ; 8 TO 1 ROOK LDX #$04 STX MOVEN ; MOVES AGNR JSR LINE ; 4 TO 1 BNE AGNR BEQ NEWP BISHOP JSR LINE LDA MOVEN ; MOVES CMP #$04 ; 8 TO 5 BNE BISHOP BEQ NEWP KNIGHT LDX #$10 STX MOVEN ; MOVES AGNN JSR SNGMV ; 16 TO 9 LDA MOVEN CMP #$08 BNE AGNN BEQ NEWP PAWN LDX #$06 STX MOVEN P1 JSR CMOVE ; RIGHT CAP? BVC P2 BMI P2 JSR JANUS ; YES P2 JSR RESET DEC MOVEN ; LEFT CAP? LDA MOVEN CMP #$05 BEQ P1 P3 JSR CMOVE ; AHEAD BVS NEWP ; ILLEGAL BMI NEWP JSR JANUS LDA SQUARE ; GETS TO AND #$F0 ; 3RD RANK? CMP #$20 BEQ P3 ; DO DOUBLE JMP NEWP ; CALCULATE SINGLE STEP MOVES ; FOR K,N SNGMV JSR CMOVE ; CALC MOVE BMI ILL1 ; -IF LEGAL JSR JANUS ; -EVALUATE ILL1 JSR RESET DEC MOVEN RTS ; CALCULATE ALL MOVES DOWN A ; STRAIGHT LINE FOR Q,B,R LINE JSR CMOVE ; CALC MOVE BCC OVL ; NO CHK BVC LINE ; NOCAP OVL BMI ILL ; RETURN PHP JSR JANUS ; EVALUATE POSN PLP BVC LINE ; NOT A CAP ILL JSR RESET ; LINE STOPPED DEC MOVEN ; NEXT DIR RTS ; EXCHANGE SIDES FOR REPLY ; ANALYSIS REVERSE LDX #$0F ETC SEC LDY BK,X ; SUBTRACT LDA #$77 ; POSITION SBC BOARD,X ; FROM 77 STA BK,X STY BOARD,X ; AND SEC LDA #$77 ; EXCHANGE SBC BOARD,X ; PIECES STA BOARD,X DEX BPL ETC RTS ; CMOVE CALCULATES THE TO SQUARE ; USING SQUARE AND THE MOVE ; TABLE FLAGS SET AS FOLLOWS: ; N#NAME? MOVE ; V#NAME? (LEGAL UNLESS IN CR) ; C#NAME? BECAUSE OF CHECK ; [MY &THANKS TO JIM BUTTERFIELD ; WHO WROTE THIS MORE EFFICIENT ; VERSION OF CMOVE) CMOVE LDA SQUARE ; GET SQUARE LDX MOVEN ; MOVE POINTER CLC ADC MOVEX,X ; MOVE LIST STA SQUARE ; NEW POS'N AND #$88 BNE ILLEGAL ; OFF BOARD LDA SQUARE LDX #$20 LOOP DEX ; IS TO BMI NO ; SQUARE CMP BOARD,X ; OCCUPIED? BNE LOOP CPX #$10 ; BY SELF? BMI ILLEGAL LDA #$7F ; MUST BE CAP! ADC #$01 ; SET V FLAG BVS SPX ; (JMP) NO CLV ; NO CAPTURE SPX LDA STATE ; SHOULD WE BMI RETL ; DO THE CMP #$08 ; CHECK CHECK? BPL RETL ; CHKCHK REVERSES SIDES ; AND LOOKS FOR A KING ; CAPTURE TO INDICATE ; ILLEGAL MOVE BECAUSE OF ; CHECK SINCE THIS IS ; TIME CONSUMING, IT IS NOT ; ALWAYS DONE CHKCHK PHA ; STATE #392 PHP LDA #$F9 STA STATE ; GENERATE STA INCHEK ; ALL REPLY JSR MOVE ; MOVES TO JSR REVERSE ; SEE IF KING JSR GNM ; IS IN JSR RUM ; CHECK PLP PLA STA STATE LDA INCHEK BMI RETL ; NO - SAFE SEC ; YES - IN CHK LDA #$FF RTS RETL CLC ; LEGAL LDA #$00 ; RETURN RTS ILLEGAL LDA #$FF CLC ; ILLEGAL CLV ; RETURN RTS ; REPLACE PIECE ON CORRECT SQUARE RESET LDX PIECE ; GET LOGAT LDA BOARD,X ; FOR PIECE STA SQUARE ; FROM BOARD RTS GENRM JSR MOVE ; MAKE MOVE GENR2 JSR REVERSE ; REVERSE BOARD JSR GNM ; GENERATE MOVES RUM JSR REVERSE ; REVERSE BACK ; ROUTINE TO UNMAKE A MOVE MADE BY ; MOVE UMOVE TSX ; UNMAKE MOVE STX SP1 LDX SP2 ; EXCHANGE TXS ; STACKS PLA ; MOVEN STA MOVEN PLA ; CAPTURED STA PIECE ; PIECE TAX PLA ; FROM SQUARE STA BOARD,X PLA ; PIECE TAX PLA ; TO SOUARE STA SQUARE STA BOARD,X JMP STRV ; THIS ROUTINE MOVES PIECE ; TO SQUARE, PARAMETERS ; ARE SAVED IN A STACK TO UNMAKE ; THE MOVE LATER MOVE TSX STX SP1 ; SWITCH LDX SP2 ; STACKS TXS LDA SQUARE PHA ; TO SQUARE TAY LDX #$1F CHECK CMP BOARD,X ; CHECK FOR BEQ TAKE ; CAPTURE DEX BPL CHECK TAKE LDA #$CC STA BOARD,X TXA ; CAPTURED PHA ; PIECE LDX PIECE LDA BOARD,X STY BOARD,X ; FROM PHA ; SQUARE TXA PHA ; PIECE LDA MOVEN PHA ; MOVEN STRV TSX STX SP2 ; SWITCH LDX SP1 ; STACKS TXS ; BACK RTS ; CONTINUATION OF SUB STRATGY ; -CHECKS FOR CHECK OR CHECKMATE ; AND ASSIGNS VALUE TO MOVE CKMATE LDY BMAXC ; CAN BLK CAP CPX POINTS ; MY KING? BNE NOCHEK LDA #$00 ; GULP! BEQ RETV ; DUMB MOVE! NOCHEK LDX BMOB ; IS BLACK BNE RETV ; UNABLE TO LDX WMAXP ; MOVE AND BNE RETV ; KING IN CH? LDA #$FF ; YES! MATE RETV LDX #$04 ; RESTORE STX STATE ; STATE=4 ; THE VALUE OF THE MOVE (IN ACCU) ; IS COMPARED TO THE BEST MOVE AND ; REPLACES IT IF IT IS BETTER PUSH CMP BESTV ; IS THIS BEST BCC RETP ; MOVE SO FAR? BEQ RETP STA BESTV ; YES! LDA PIECE ; SAVE IT STA BESTP LDA SQUARE STA BESTM ; FLASH DISPLAY RETP LDA prompt ; get prompt character EOR #$1F ; toggle between [SPACE] and '?' STA prompt ; save it back JMP UpdateDisp ; update prompt & display ; MAIN PROGRAM TO PLAY CHESS ; PLAY FROM OPENING OR THINK GO LDX OMOVE ; OPENING? BMI NOOPEN ; -NO *ADD CHANGE FROM BPL LDA DIS3 ; -YES WAS CMP OPNING,X ; OPPONENT'S BNE END ; MOVE OK? DEX LDA OPNING,X ; GET NEXT STA DIS1 ; CANNED DEX ; OPENING MOVE LDA OPNING,X STA DIS3 ; DISPLAY IT DEX STX OMOVE ; MOVE IT BNE MV2 ; (JMP) END LDA #$FF ; *ADD - STOP CANNED MOVES STA OMOVE ; FLAG OPENING NOOPEN LDX #$0C ; FINISHED STX STATE ; STATE=C STX BESTV ; CLEAR BESTV LDX #$14 ; GENERATE P JSR GNMX ; MOVES LDX #$04 ; STATE=4 STX STATE ; GENERATE AND JSR GNMZ ; TEST AVAILABLE ; ; MOVES LDX BESTV ; GET BEST MOVE CPX #$0F ; IF NONE BCC MATE ; OH OH! MV2 LDX BESTP ; MOVE LDA BOARD,X ; THE STA BESTV ; BEST STX PIECE ; MOVE LDA BESTM STA SQUARE ; AND DISPLAY JSR MOVE ; IT JSR DISP3 ; piece into display JMP CHESS MATE LDA #$FF ; RESIGN RTS ; OR STALEMATE ; SUBROUTINE TO ENTER THE ; PLAYER'S MOVE DISMV LDX #$04 ; ROTATE DROL ASL DIS3 ; KEY ROL DIS2 ; INTO DEX ; DISPLAY BNE DROL ; ORA DIS3 STA DIS3 STA SQUARE RTS ; THE FOLLOWING SUBROUTINE ASSIGNS ; A VALUE TO THE MOVE UNDER ; CONSIDERATION AND RETURNS IT IN ; THE ACCUMULATOR STRATGY CLC LDA #$80 ADC WMOB ; PARAMETERS ADC WMAXC ; WITH WHEIGHT ADC WCC ; OF O25 ADC WCAP1 ADC WCAP2 SEC SBC PMAXC SBC PCC SBC BCAP0 SBC BCAP1 SBC BCAP2 SBC PMOB SBC BMOB BCS POS ; UNDERFLOW LDA #$00 ; PREVENTION POS LSR CLC ; ************** ADC #$40 ADC WMAXC ; PARAMETERS ADC WCC ; WITH WEIGHT SEC ; OF 05 SBC BMAXC LSR ; ************** CLC ADC #$90 ADC WCAP0 ; PARAMETERS ADC WCAP0 ; WITH WEIGHT ADC WCAP0 ; OF 10 ADC WCAP0 ADC WCAP1 SEC ; [UNDER OR OVER- SBC BMAXC ; FLOW MAY OCCUR SBC BMAXC ; FROM THIS SBC _BCC ; SECTION] SBC _BCC SBC BCAP1 LDX SQUARE ; *************** CPX #$33 BEQ POSN ; POSITION CPX #$34 ; BONUS FOR BEQ POSN ; MOVE TO CPX #$22 ; CENTRE BEQ POSN ; OR CPX #$25 ; OUT OF BEQ POSN ; BACK RANK LDX PIECE BEQ NOPOSN LDY BOARD,X CPY #$10 BPL NOPOSN POSN CLC ADC #$02 NOPOSN JMP CKMATE ; CONTINUE ; most new code from here on ; update move display, do prompt, piece, 'FROM' and 'TO' squares UpdateDisp LDA #$26 ; set cursor X STA DispPosX ; set cursor X LDA #$08 ; set cursor Y STA DispPosY ; set cursor Y LDA prompt ; prompt JSR asciiout ; byte out to display JSR space ; [SPACE] out to display JSR DisPiece ; display piece (from byte in DIS1) JSR space ; [SPACE] out to display LDA DIS2 ; 2nd display byte JSR PSquare ; Print square JSR space ; [SPACE] out to display LDA DIS3 ; 3rd display byte JMP PSquare ; Print square ; draw board on an ASCII character display ; the display in the simulator has cursor ; positioning. Other displays may use escape ; codes to the same ends. DrawBoard JSR Print_c_ ; print copyright LDA #$00 ; set initial position (0,0) is top left STA DispPosX ; set cursor X STA DispPosY ; set cursor Y JSR PColNum ; print column labels JSR Hline ; print horizontal line LDY #$00 ; init board location PNewVert JSR PRowNum ; print row number PVert LDA #'|' ; print vertical edge JSR asciiout ; byte out to display LDX #$1F ; for each piece TYA ; copy square # PPiece CMP BOARD,X ; this piece in this square? BEQ PieceOut ; if so print the piece's color and type DEX ; else try next piece BPL PPiece ; if not done then loop TYA ; copy square # ASL ; shift column LSB into Cb ASL ; ASL ; ASL ; TYA ; copy square # again ADC #$00 ; add column LSB LSR ; result into carry LDA #' ' ; assume white square BCS Iswhite ; branch if white LDA #'#' ; else make square black Iswhite JSR asciiout ; byte out to display JSR asciiout ; byte out to display PNextCol INY ; next column TYA ; get square # AND #$08 ; have we completed the row? BEQ PVert ; if not go do next column LDA #'|' ; yes, put the right edge on JSR asciiout ; byte out to display JSR PRowNum ; print row number JSR CRLF ; print CRLF JSR Hline ; print horizontal line TYA ; copy square # CLC ; clear for add ADC #$08 ; increment to beginning of next row BMI PColNum ; done so go finish board TAY ; else copy new square # BPL PNewVert ; go do next row ; output piece's color & type PieceOut LDA #'W' ; assume white CPX #$10 ; compare with breakpoint (result in Cb) BIT reverse ; test reverse byte BEQ Noflip ; branch if not reverse ; else toggle Cb state ROL ; Cb into D0 EOR #$01 ; toggle bit ROR ; D0 into Cb Noflip BCC NotBlack ; branch if white LDA #'B' ; else make black NotBlack JSR asciiout ; byte out to display TXA ; copy piece AND #$0F ; mask black/white TAX ; back to index LDA P_piece,x ; get current piece 2nd byte JSR asciiout ; byte out to display BNE PNextCol ; branch always ; print " ", line of -'s then [CR][LF] Hline JSR space ; [SPACE] out to display JSR asciiout ; byte out to display (2nd [SPACE]) LDA #'-' ; line of -'s LDX #$19 ; 25 -'s to do HlineL JSR asciiout ; byte out to display DEX ; decrement count BNE HlineL ; loop if not all done ; do newline CRLF LDA #$0D ; [CR] JSR asciiout ; byte out to display LDA #$0A ; [LF] JMP asciiout ; byte out to display & return ; print the column labels PColNum JSR space ; [SPACE] out to display JSR asciiout ; byte out to display (2nd [SPACE]) LDX #$00 ; clear index PNextCNum JSR space ; [SPACE] out to display TXA ; get column number JSR hexout ; A out as hex INX ; next column CPX #$08 ; is it done? BNE PNextCNum ; loop if not BEQ CRLF ; else do newline and return ; print (c) message ; text lines are ... ; Xpos,Ypos,"text",0 ; .. for lines with following lines and ... ; Xpos,Ypos,"text",255 ; for the last line Print_c_ LDX #$FF ; initial -1 Print_c_n INX ; increment index LDA _c_,X ; get cursor X STA DispPosX ; set cursor X INX ; increment index LDA _c_,X ; get cursor Y STA DispPosY ; set cursor Y INX ; increment index Print_c_l LDA _c_,X ; get byte BEQ Print_c_n ; do next line if $00 [EOL] BMI Print_c_e ; exit if $FF [EOT] JSR asciiout ; byte out to display INX ; increment index BNE Print_c_l ; loop Print_c_e RTS ; wait for key asciiin LDA ACIAsimrd ; get chr BEQ asciiin ; no char to get CMP #'a' ; lowe case ASCII BCC asciirts ; skip if not >= AND #$DF ; # and upper case alpha only asciirts RTS PRowNum TYA ; copy row number PSquare AND #$77 ; mask unused bits ; output A as two hex digits hexout PHA ; save for lower digit LSR ; shift upper .. LSR ; .. nibble to .. LSR ; .. lower nibble .. LSR ; .. and clear upper JSR PrintDig ; output hex digit PLA ; get byte back AND #$0F ; clear upper nibble PrintDig SED ; set for hex convert CMP #$0A ; compare with breakpoint ADC #'0' ; add to "0" CLD ; clear again ; byte out to display asciiout STA ACIAsimwr ; byte out to port RTS space LDA #$20 ; [SPACE] BNE asciiout ; print and return ; display piece byte in DIS1 as ASCII string DisPiece LDA DIS1 ; get piece for this move BMI DisSpecial ; branch if not piece AND #$0F ; don't care black or white ASL ; *2 ASL ; *4 ASL ; *8 TAX ; copy index DisString LDY #$08 ; character count DisLoop LDA PieceName,X ; get byte JSR asciiout ; out to display INX ; increment index DEY ; decrement count BNE DisLoop ; loop if not done RTS ; set X for 'special' $CC, $EE and $FF piece codes, else set null DisSpecial CMP #$CC ; compare with reset BNE NotReset ; branch if not reset LDX #PRes-PieceName ; set pointer BNE DisString ; go print it NotReset CMP #$EE ; compare with exchange BNE NotExcg ; branch if not exchange LDX #PExg-PieceName ; set pointer BNE DisString ; go print it NotExcg ; else null CMP #$FF ; compare with check mate BNE NotChkm ; branch if not check mate LDX #PCkm-PieceName ; set pointer BNE DisString ; go print it NotChkm ; else null LDX #PNul-PieceName ; set pointer BNE DisString ; go print it ; text descriptions for the byte in DIS1 PieceName .byte "King " .byte "Queen " .byte "K Rook " .byte "Q Rook " .byte "K Bishop" .byte "Q Bishop" .byte "K Knight" .byte "Q Knight" .byte "K R Pawn" .byte "Q R Pawn" .byte "K N Pawn" .byte "Q N Pawn" .byte "K B Pawn" .byte "Q B Pawn" .byte "Q Pawn " .byte "K Pawn " PRes .byte "Reset " PExg .byte "Exchange" PCkm .byte "Mate" PNul .byte " " ; copyright banner _c_ .byte $24,$01,"+--------------------+",$00 .byte $24,$02,"| MicroChess |",$00 .byte $24,$03,"| (c) 1976-2002 |",$00 .byte $24,$04,"| Peter Jennings |",$00 .byte $24,$05,"| peterj@benlo.com |",$00 .byte $24,$06,"+--------------------+",$FF ; piece character table P_piece .byte "KQCCBBkkPPPPPPPP" ; end of new code ; BLOCK DATA ; *= $1580 ; initial positions SETW .byte $03, $04, $00, $07, $02, $05, $01, $06 .byte $10, $17, $11, $16, $12, $15, $14, $13 .byte $73, $74, $70, $77, $72, $75, $71, $76 .byte $60, $67, $61, $66, $62, $65, $64, $63 MOVEX .byte $00, $F0, $FF, $01, $10, $11, $0F, $EF, $F1 .byte $DF, $E1, $EE, $F2, $12, $0E, $1F, $21 POINTS .byte $0B, $0A, $06, $06, $04, $04, $04, $04 .byte $02, $02, $02, $02, $02, $02, $02, $02 OPNING .byte $99, $25, $0B, $25, $01, $00, $33, $25 .byte $07, $36, $34, $0D, $34, $34, $0E, $52 .byte $25, $0D, $45, $35, $04, $55, $22, $06 .byte $43, $33, $0F, $CC

This version is posted with the permission of Peter Jennings, peterj@benlo.com

e-mail me