--- /dev/null
+/ CHEKMO II
+ZZZ=63
+/AUTHOR JOHN E. COMEAU
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+/ :::::::::::::::::::::::::::::::
+/ : :
+/ : :
+/ : :
+/ : CHEKMO II :
+/ : CHESS PROGRAM 2/74 :
+/ : :
+/ : :
+/ : :
+/ :::::::::::::::::::::::::::::::
+\f
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+
+
+/ FIELD 0 CORE UTILIZATION
+
+/ 0000-0177 CONSTANTS AND POINTERS
+/ 0200-0377 INITIALIZATION
+/ 0400-4777 THE THINKER PART
+/ 5000-6377 INPUT/OUTPUT ROUTINES
+/ 6400-7377 PUSH DOWN LIST AREA
+/ 7400-7577 BOARD & MISC. TABLES
+/ 7600-7777 BINARY LOADER PROGRAM
+\f/SYMBOL DEFINITIONS
+/MISC. SYMBOLS
+PDLS=6400 /BEGINING OF 1000(OCTAL) WORDS RESERVED FOR PUSH DOWN LISTS
+
+/PIECE VALUES DEFINED
+DECIMAL
+KING= 15^32 /15. RELATIVE TO A PAWNS VALUE
+QUEEN= 9^32 /9.0 RELATIVE TO A PAWNS VALUE
+ROOK= 5^32 /5.0 RELATIVE TO A PAWNS VALUE
+BISHOP= 3^32+10 /3.3 RELATIVE TO A PAWNS VALUE
+KNIGHT= 3^32+4 /3.1 RELATIVE TO A PAWNS VALUE
+PAWN= 1^32 /1.0 RELATIVE TO A PAWNS VALUE
+
+OCTAL
+
+/PSEUDO INSTRUCTIONS DEFINED
+PUSH1= JMS I [PUSH01 /PUSH THE AC INTO PUSH DOWN LIST #1
+POP1= JMS I [POP01 /POP THE TOP ENTRY OF PUSH DOWN LIST #1 INTO THE AC
+PRINTO= JMS I [MES /PRINT 6BIT 2CHAR/WORD TEXT AT ADDRESS SPECIFIED IN THE AC
+IPDL1= JMS I [IPDL01 /INITIALIZE PUSH DOWN LIST #1
+PUSH2= JMS I [PUSHIT /PUSH THE CONTENTS OF THE AC INTO PUSH DOWN LIST #2
+POP2= JMS I [POPIT /POP THE TOP ENTRY OF PUSH DOWN LIST #2 INTO THE AC
+IPDL2= JMS I [PDLIN /INITIALIZE PUSH DOWN LIST #2
+SNO= JMS I [RFOFL /SKIP NO OVERFLOW (C(AC)>=0 & C(AC8)=0)
+
+/PDP 8/E IOTS DEFINED
+CAF= 6007
+PSKF=6661
+PCLF=6662
+PSKE=6663
+PSTB=6664
+PCIE=6667
+
+/CONDITIONAL ASSEMBLY DEFINITIONS
+OS8=1 /NO SPECIAL MEANING TO "^C"
+LPTREE=1 /DON'T INCLUDE LINE PRINTER CAPABILITIES
+DEBUG=1 /OPT FOR DYNAMIC ERROR DETECTION
+RANVAL=1 /NOISY EVALUATIONS PLEASE
+
+/DEFAULT ASSEMBLY DEFINITIONS
+IFNDEF OS8 <OS8=0> /NON OS8 SYSTEM
+IFNDEF DEBUG <DEBUG=0> /DEBUG SWITCH CLEARED
+IFNDEF LPTREE <LPTREE=0> /DONT INCLUDE TREE PRINTOUT CAPABILITIES
+IFNDEF RANVAL <RANVAL=1> /INCLUDE A SMIDGEN OF RANDOMNESS IN EVALUATIONS
+\f
+/ABREVIATIONS USED
+
+/ SQR SQUARE
+/ INC INCREMENT
+/ # NUMBER
+/ = EQUALS
+/ - MINUS, NEGATIVE OR TO
+/ & AND
+/ INFO INFORMATION
+/ AC ACCUMULATOR
+/ TEMP TEMPORARY
+/K-SIDE KING SIDE
+/Q-SIDE QUEEN SIDE
+/ LOC LOCATION
+/ CR CARRIAGE RETURN
+/ LF LINE FEED
+/ MSW MOVE SQUARE WORD
+/ MDW MOVE DATA WORD
+/ CHAR CHARACTER
+/ W/ WITH
+/ < LESS THAN
+/ > GREATER THAN
+/ PSW POSITION STATUS WORD
+/ ADDR ADDRESS
+/ PDL PUSH DOWN LIST
+/ PDL#1 PUSH DOWN LIST #1
+/ PDL#2 PUSH DOWN LIST #2
+/ ABS ABSOLUTE
+/ PROM PROMOTION
+/ ARG ARGUMENT
+/ VAL VALUE
+
+\f/ MOVE SQUARE WORD(MSW) FORMAT
+/
+/ -------------------------------------------------------------------------
+/ I I I I I I I I I I I I I
+/ I 0 I 1 I 2 I 3 I 4 I 5 I 6 I 7 I 8 I 9 I 10 I 11 I
+/ I I I I I I I I I I I I I
+/ -------------------------------------------------------------------------
+/ I I I I
+/ -----------------I----------------- -----------------I-----------------
+/
+/ SIXBIT ADDRESS OF THE SIXBIT ADDRESS OF THE
+/ "FROM SQUARE" "TO SQUARE"
+
+
+
+
+
+
+/ MOVE DATA WORD(MDW) FORMAT
+/ -------------------------------------------------------------------------
+/ I I I I I I I I I I I I I
+/ I 0 I 1 I 2 I 3 I 4 I 5 I 6 I 7 I 8 I 9 I 10 I 11 I
+/ I I I I I I I I I I I I I
+/ -------------------------------------------------------------------------
+/ I I I I I I I
+/ I ----I---- ----------------I---------------- -------I-------
+/ I
+/ I UNUSED = THE SIXBIT ADDRESS OF 0 = NORMAL
+/ I ALLWAYS THE "TO SQUARE" IF THE 1 = QUEEN SIDE CASTLING
+/ I EQUALS 0 MOVE IS A 2 SQUARE 2 = KING SIDE CASTLING
+/ I PAWN MOVE 3 = EN PASSANT CAPTURE
+/ I 4 = PAWN PROM. TO KNIGHT
+/ I 5 = PAWN PROM. TO BISHOP
+/ I 6 = PAWN PROM. TO ROOK
+/ I 7 = PAWN PROM. TO QUEEN
+/ I
+/ I
+/ I
+/ I
+/
+/ = 1 IF THIS MOVE
+/ IS A CAPTURE
+\f
+
+*0000
+/INTERRUPT!
+IFRM, 0000
+ JMP I .+1
+ INTHAN /ADDRESS OF THE INTERUPT HANDLER
+REV, ZZZ /LOC 3 HOLDS PROGRAM REVISION #
+ODT4, 0000 /LOCATIONS 4, 5, AND 6 ARE RESERVED FOR DEBUGERS
+ODT5, 0000
+ODT6, 0000
+
+/ ZERO PAGE CONSTANTS
+*11
+RANDOM, 0000
+XR0, 0000
+ITMP0, 0000
+ITMP1, 0000 /AUTO-INCREMENT TEMPORARY STORAGE
+ITMP2, 0000
+CLIST, KBUF-1 /INPUT BUFFER POINTER
+LIST2, 0000
+TEMP, 0000 /TEMPORARY STORAGE LOCATIONS
+TEMP1, 0000 / .
+TEMP2, 0000 / .
+TEMP3, 0000 / .
+TEMP4, 0000 / .
+TMP, 0000 /TEMPORARY STORAGE
+ZOUT, OUT /POINTS TO OUTPUT ROUTINE
+CHAR, 0000 /TEMP. STORAGE PLACE FOR A CHARACTER
+ZCRLF, CRLF /POINTS TO CR-LF PRINTING ROUTINE
+XXXX, 0000 /TEMPORARY STORAGE
+ZBEGIN, BEGIN /POINTS TO INPUT INITIATING ROUTINE
+CNTCHR, 0000 /CHARACTER COUNT
+ISW, 0000 /INPUT SWITCH
+ZGETC, GETC /POINTS TO INPUT BUFFER READING ROUTINE
+PONDIR, 0001 /PAWN DIRECTION CONSTANT
+M1, 0000
+M2, 0000
+M3, 0000
+M4, 0000
+GN1, 0000 /COMMON STORAGE FOR THE MOVE GENERATION ROUTINES
+GN2, 0000 / .
+GN3, 0000 / .
+GN4, 0000 / .
+GNMSW, 0000 / .
+GNMDW, 0000 / .
+FSTRNK, 7777 /-VALUE OF THE FIRST RANK
+ZCHKIO, CHKIO /POINTS TO IO STALL ROUTINE
+WPSW, 0000 /WHITES POSITION STATUS WORD
+BPSW, 0000 /BLACKS POSITION STATUS WORD
+CPSW, 0000 /ADDRESS OF CURRENT POSITION STATUS WORD IS KEPT HERE
+GMAP, 0000
+OMAP, 0000
+TOMAK1, 0000 /MOVE SQUARE WORD HERE
+TOMAK2, 0000 /MOVE DATA WORD HERE
+DIR1, 0000
+DIR2, 0000
+CNTR1, 0000
+WKING, 0000 /ADDRESS OF THE WHITE KING IS STORED HERE
+BKING, 0000 /ADDRESS OF THE BLACK KING IS STORED HERE
+CKING, 0000 /ADRESS OF THE KING BEING TESTED
+TKING, 0000 /TEMP STORAGE FOR KING ADDR
+LSTMV, 0000 /LOCATION WHICH DESCRIBES THE LAST MOVE MADE IF DOUBLE PAWN MOVE
+ZGNMV, GNMV /POINTS TO MOVE GENERATION ROUTINE
+ZMKMV, MKMV /POINTS TO THE MOVE MAKING ROUTINE
+ZUNMV, UNMV /POINTS TO THE MOVE UNMAKING ROUTINE
+ZMAPEC, MAPEC /POINTS TO PIECE MAP ROUTINE
+PW, 0000 /SET = TO TOTAL VALUE OF ALL PIECES ON THE BOARD BY 'MAPEC'
+WHOSE, 0000 /THIS LOC =0 IF IT IS WHITES MOVE, =-1 IF BLACKS
+PCNT, 0000 /USED BY CHKATK =# OF PIECES ATTACKING THE SQUARE
+PVAL, 0000 /USED BY CHKATK =LEAST VALUABLE ATTACKER
+PSQR, 0000 /USED BY CHKATK =ADDRESS OF THE LEAST VALUABLE ATTACKING PIECE
+ZSPLIT, SPLIT /POINTS TO A SUBROUTINE WHICH SPLITS UP A MSW
+ZTSTCH, TSTCHK /POINTS TO CHECK TESTING ROUTINE
+ZFNL, TSTCHK /POINTS TO FINAL LEGAL MOVE VERIFICATION ROUTINE
+GNCNT, 0000 /LOC=NUMBER OF MOVES GENERATED BY GNWMV
+TOADR, 0000
+IOMDW, 0000 /ARGUMENT STORAGE FOR I/O ROUTINES
+IOMSW, 0000 /ARGUMENT STORAGE FOR I/O ROUTINES
+CMSW, 0000 /CHECKMATE SWITCH
+SMSW, 0000 /STALEMATE SWITCH
+COMP, 0000
+ZLOOKA, LOOKA /POINTS TO THE RECURSIVE LOOKAHEAD SUBROUTINE
+UVAL1, 0000
+CVAL1, 3777
+RVAL1, 0000
+MVAL1, 0000 /HOLDS MOBILITY VALUE
+PLY, 0000 /HOLDS CURRENT RECURSION LEVEL OF THE "LOOKA" SUBROUTINE
+DEPTH, 0003 /HOLDS THE MAXIMUM RECURSION LEVEL FOR THE "LOOKA" SUBROUTINE
+RDEPTH, 0000
+BUG, 0000
+RNKKNT, 0000 /TEMP STORAGE FOR BOARD OUTPRINT & BOARD INPUT ROUTINES
+FILKNT, 0
+PIECE, 0
+COLOR, 0
+RNKPTR, 0
+MOBMOD, 0000
+KNGBLK, 0000 /SET BY "GNMV" TO # OF KING MOVES ILLEGAL BECAUSE OF CHECK
+MOB0, 0000
+MOB1, 0000
+CTNEED, 0000
+STRATG, 0000 /HOLDS STRATEGIC VALUE
+PC01, 0000 /POINTER FOR PUSH DOWN LIST #1
+PDLADR, 0000 /POINTER FOR PUSH DOWN LIST #2
+IFNZRO DEBUG<
+ENO, 0000
+ENOB, 0000
+>
+WHOWHI, 0000
+WHOBLK, 0000
+COMTMP, 0000
+BOGUS, 0000
+DOMAP, 0000
+\f*200
+START, IFNZRO LPTREE <
+ TAD (OUT
+ DCA ZOUT /MAKE SURE OUTPUT GOES TO THE TTY
+>
+ JMS I ZCRLF
+ PRINTO; NAME /PRINT "CHEKMO-II"
+ JMS I ZCRLF
+ DCA WHOSE
+ JMS SETBRD /SETUP THE BOARD
+COMPN, DCA WHOWHI /RESET SWITCH FOR THE USER TO PLAY WHITE
+ DCA WHOBLK /RESET SWITCH FOR THE USER TO PLAY BLACK
+COMMAN, IPDL2 /INITIALIZE PUSH DOWN LISTS
+ IPDL1
+ ISZ DOMAP /MAKE SURE A PIECE MAP IS REALY DONE
+ JMS QMATE /TEST FOR SIDE TO MOVE IN CHECKMATE OR STALEMATE
+ TAD WHOSE /GET "WHOSE MOVE" SWITCH
+ SPA CLA /IS IT WHITES OR BLACKS MOVE?
+ JMP BLKMVE /BLACKS
+ PRINTO; MESG23 /PRINT "W. "
+ TAD WHOWHI /GET THE "WHO PLAYS WHITE" SWITCH
+ SZA CLA /DOES THE COMPUTER PLAY ON BEHALF OF WHITE?
+ JMP CMOVE /YES
+USER, PRINTO; MESG24 /PRINT "YOUR MOVE?"
+ JMS I ZBEGIN /SETUP TO ACCEPT A LINE OF INPUT
+ ION /ACCEPT IT ANY TIME NOW
+ JMS I ZCHKIO /WAIT FOR IT TO FINISH
+ JMS I ZGETC /GET 1ST CHAR
+ AND [0077 /ONLY NEED 6 BITS
+ RTL CLL /MOVE THEM TO THE HIGH ORDER 6 BITS
+ RTL /POSITION
+ RTL
+ DCA COMTMP /STORE FOR A WHILE
+ JMS I ZGETC /GET 2ND CHAR
+ AND [0077 /ONLY NEED 6 BITS
+ TAD COMTMP /WE NOW HAVE THE FIRST 2 INPUT CHARS PACKED
+ DCA COMTMP /6BIT STYLE IN 1 WORD
+ TAD (COMLST-2/ADDRESS-2 OF THE COMMAND LIST
+ DCA XR0 /TO AUTO INDEX REGISTER
+NUTHER, ISZ XR0 /INC POINTER TO POINT AT A 6BIT COMMAND IN THE COMMAND LIST
+ TAD I XR0 /GET A LEGAL 6BIT COMMAND
+ SNA /WERE THERE ANY MORE TO GET?
+ JMP UINP /NO. THE USER MUST BE TRYING TO ENTER A MOVE
+ TAD COMTMP /YES. COMPARE WITH THE ONE THE USER JUST INPUTED
+ SZA CLA /IS IT A MATCH?
+ JMP NUTHER /NO. TRY AGAIN
+ TAD I XR0 /YES. GET THE TRANSFER ADDRESS
+ DCA TEMP
+ JMP I TEMP /TRANSFER
+
+COMPW, ISZ WHOWHI /SET SWITCH TO INDICATE THAT WHITE IS PLAYED
+ JMP COMMAN /BY THE COMPUTER
+
+COMPB, ISZ WHOBLK /SET THE SWITCH TO INDICATE THAT BLACK IS PLAYED
+ JMP COMMAN /BY THE COMPUTER
+
+COMBD, JMS DISPLAY /DISPLAY THE BOARD ON THE TELLETYPE
+ JMP COMMAN
+
+COMIP, JMS INPUT /GET THE INPUT OF A POSITION FROM THE TELLETYPE
+ JMP COMPN
+
+UINP, JMS I ZBEGIN /REINIT THE KEYBOARD BUFFER POINTER
+ JMS INMV /WAS A LEGAL MOVE TYPED IN?
+ SKP CLA /NO.
+ JMP COMMAN /YES. IT WAS ALSO MADE BY THE "INMOVE" SUBROUTINE
+ TAD ("? /PRINT A "?"
+ JMS I ZOUT /TO INDICATE THE ERROR
+ JMS I ZCRLF
+ JMP COMMAN /TRY AGAIN
+
+BLKMVE, PRINTO; MESG22 /BRINT "B. "
+ TAD WHOBLK
+ SNA CLA /DOES THE USER PLAY BLACK, OR DOES THE COMPUTER?
+ JMP USER /THE USER
+CMOVE, CLA /COMPUTER NOW MAKES A MOVE
+ TAD (3777 /INITIALIZE SEARCH VALUE TO PREVENT PRUNING AT THE FIRST PLY
+ DCA CVAL1
+ DCA PLY /MAKE SURE PLY # IS 0 BEFORE ENTERING RECURSIVE EVALUATOR
+ IFNZRO LPTREE<
+ TAD (LPTOUT /SWITCH OUTPUT DEVICE TO LINE PRINTER
+ DCA ZOUT
+ JMS I ZCRLF
+ JMS DISPLA /PRINT THE BOARD AT PLY 0
+ JMS TABPLY
+>
+ CMA CLA
+ TAD DEPTH /DO A SHORT "PRE ANALYSIS"
+ SNA /UNLESS WE ARE IN "BLITZ MODE" (DEPTH OF 1)
+ JMP CMOVE1 /WHICH WE ARE
+ IAC
+ DCA RDEPTH /SAVE THE REAL DEPTH
+ IAC
+ DCA DEPTH /SET THE DEPTH TO 1 TEMPORARILY
+ JMS I ZLOOKA /FIND OUT WHICH MOVE LOOKS THE BEST
+ TAD RDEPTH
+ DCA DEPTH /RESTORE THE REAL DEPTH
+CMOVE1, JMS I ZLOOKA /FIGURE OUT WHICH MOVE TO MAKE
+ IFNZRO LPTREE<
+ TAD (OUT /SWITCH OUTPUT DEV. BACK TO TTY
+ DCA ZOUT
+>
+ TAD BESTBL
+ DCA IOMSW
+ TAD BESTBL+1
+ DCA IOMDW
+ TAD BESTBL /GET THE LAST MOVE TO WIN A COMPARE ON PLY #1
+ DCA TOMAK1 /FROM THE TABLE OF BEST MOVES
+ TAD BESTBL+1
+ DCA TOMAK2
+ JMS I ZMKMV /MAKE THE MOVE
+ JMS OUTMV /PRINT OUT THE MOVE JUST MADE
+ JMS GNMVSM /GENERATE MOVES FOR THE SIDE TO MOVE
+ TAD GNCHEK /GET # OF ATTACKS ON THE KING
+ SZA CLA /IS THE SIDE TO MOVE IN CHECK?
+ TAD ("+ /YES. PRINT A "+" TO INDICATE IT
+ JMS I ZOUT
+ JMS I ZCRLF
+ JMP COMMAN
+
+PAGE
+\f/THIS SUBROUTINE GENERATES ALL MOVES FOR A SIDE
+/AND STICKS THEM INTO PDL2.
+/THIS SUBROUTINE IN ADDITION...
+/SETS "GNCNT" TO THE # OF MOVES GENERATED
+/SETS "CMSW" TO A NON-ZERO VALUE IF NO MOVES CAN BE GENERATED BECAUSE OF CHECKMATE
+/SETS "SMSW" TO A NON-ZERO VALUE IF NO MOVES CAN BE GENERATED BECAUSE OF STALEMATE
+/SETS "GNCHEK" TO THE NUMBER OF PIECES ATTACKING THE KING IF THE KING IS IN CHECK
+/SETS "KNGBLK" TO THE NUMBER OF ADJACENT SQUARES THE KING CANNOT MOVE
+/INTO BECAUSE THAT WOULD PUT HIM IN CHECK
+/SETS "MOBMOD" TO THE MOVING SIDES MOBILITY VALUE, BASED ON "GNCNT" AND
+/THE NUMBER OF MOVES THAT ARE ILLEGAL BECAUSE THEY DO NOT
+/GET THE KING OUT OF CHECK, BUT ARE OTHERWISE LEGAL, MINUS
+/50% OF THE TOTAL # OF QUEEN MOVES.
+/IF THIS ROUTINE IS CALLED WITH "BOGUS" SET TO A NON-ZERO VALUE
+/THIS SUBROUTINE WILL NOT PUT ANY MOVES IN PDL#2 OR TRY TO GENERATE
+/EN PASSANT PAWN CAPTURES
+/THIS SUBROUTINE SETS BOGUS TO ZERO BEFORE RETURNING
+GNMV, 0000
+ CLL CLA
+ DCA MOBMOD /INITIALIZE THE MOBMOD COUNTER
+ DCA KNGBLK /INITIALIZE THE BLOCKED KING MOVE COUNTER
+ DCA CMSW /INITIALIZE CHECKMATE SWITCH TO = NO CHECKMATE
+ DCA SMSW /INITIALIZE STALEMATE SWITCH TO = NO STALEMATE
+ DCA QMVCNT /INIT QUEEN MOVE COUNTER
+ TAD CKING /TEST FOR KING IN CHECK
+ DCA TEMP
+ JMS CHKATK /CALL W/AC CLEAR---FIND ALL ATTACKS ON THE KING
+ TAD PCNT /GET # OF ATTACKS
+ DCA GNCHEK /SAVE THE # OF ATTACKS ON THE KING
+ DCA GNCNT /INITIALIZE GENERATION COUNT = 0
+ TAD BOGUS
+ SZA CLA /ARE WE GOING TO BE PUTTING MOVES IN PDL#2?
+ JMP .+3 /NO. NO NEED FOR MARKERS THEN
+ PUSH2 /YES. FIRST THING TO DO IS PUSH 2 BLANK WORDS
+ PUSH2 /TO MARK LIST PLACE
+ TAD CKING /SETUP TO GENERATE KING MOVES
+ DCA CNTR1
+ TAD CNTR1 /SPLIT THE KINGS SQUARES ADDR UP INTO RANK AND FILE #'S
+ AND [0007
+ DCA GN2 /STORE THE FILE #
+ TAD CNTR1
+ RTR
+ RAR
+ AND [0007
+ DCA GN1 /STORE THE RANK #
+ JMS GKM /GENERATE THOSE KING MOVES
+ TAD GNCHEK /GET THE NUMBER OF PIECES PRESENTLY CHECKING THE KING
+ RAR CLL /NO COMMENT
+ SZA CLA /IS THE KING IN DOUBLE CHECK?
+ JMP TSCMSM /YES. NO USE TRYING TO GENERATE MOVES BY OTHER PIECES
+ TAD BOGUS /NO.
+ SNA CLA /IS THIS FOR REAL?
+ JMS GNEP /YES. GENERATE ANY POSIBLE 'EN PASSANT' PAWN CAPTURES NOW
+ TAD GMAP /ADDRESS-1 OF MAP
+ DCA ITMP2 /STORE IT
+NXTSQR, CLL CLA
+ TAD I ITMP2 /GET THE ADDRESS OF THE NEXT PIECE
+ SNA /IS IT REALY A PIECE?
+ JMP TSCMSM /NO. MOVES ARE ALL GENERATED.
+ DCA CNTR1 /YES. STORE ITS ADDRESS
+ IAC
+ DCA CTNEED /INITIALIZE THE CHECK TEST NEED SWITCH
+ TAD CNTR1 /NOW STRIP RANK AND FILE NUMBERS FROM THE ADDRESS
+ AND [0007
+ DCA GN2 /STORE THE FILE NUMBER
+ TAD CNTR1
+ RTR
+ RAR
+ AND [0007
+ DCA GN1 /STORE THE RANK NUMBER
+ TAD I CNTR1 /GET THE VALUE OF THE PIECE ON THE SQUARE
+ JMS CLRFIX
+ TAD [-PAWN
+ SNA /IS IT A PAWN?
+ JMP GPM /YES
+ TAD (PAWN-KNIGHT
+ SNA /IS IT A KNIGHT?
+ JMP GNM /YES
+ TAD (KNIGHT-BISHOP
+ SNA /IS IT A BISHOP?
+ JMP GBM /YES
+ TAD (BISHOP-ROOK
+ SNA /IS IT A ROOK?
+ JMP GRM /YES
+ TAD (ROOK-KING
+ SNA /IS IT A KING?
+ JMP NXTSQR /YES. TRY NEXT PIECE SINCE KING MOVES HAVE ALLREADY BEEN GENERATED
+ TAD (KING-QUEEN
+ SNA /IS IT A QUEEN?
+ JMP GQM /YES
+ HLT /NO. SOMTHINGS WRONG HERE !
+
+QMVCNT, 0000
+GNCHEK, 0000
+
+TSCMSM, TAD QMVCNT /ADD # OF QUEEN MOVES & QUEEN MOVE REJECTS
+ CLL RAR /DIVIDE BY 2
+ TAD QMVCNT
+ CLL RAR /AC WIL EQUAL 3/4 OF THE # OF QUEEN MOVES & REJECTS
+ CIA /SUBTRACT
+ TAD MOBMOD /FROM THE MOBILITY MODIFIER
+ TAD GNCNT /ADD "REAL" MOBILITY IN WITH THE MOBILITY MODIFIER
+ DCA MOBMOD
+ DCA BOGUS
+ TAD GNCNT /GET # OF MOVES GENERATED
+ SZA CLA /ANY?
+ JMP I GNMV /YES: RETURN
+ TAD GNCHEK /NO. ITS EITHER A CHECKMATE OR STALEMATE POSITION
+ SNA /WAS THE KING IN CHECK?
+ ISZ SMSW /NO. SET THE STALEMATE SWITCH
+ DCA CMSW /IF KING WAS IN CHECK (GNCHEK>=1) SET THE CHECKMATE SWITCH
+ JMP I GNMV /RETURN
+
+\fIFNZRO DEBUG<
+/ROUTINE TO ALLOW THE TIMING OF THE "GNMV" SUBROUTINE
+/CALLS IT 4000(OCTAL) TIMES, THEN HALTS
+TIME, IPDL2
+ IPDL1
+ JMS GNWMV
+ ISZ .+2
+ JMP .-4
+ 4000 /# OF ITTERATIONS OF THE TIMING LOOP
+ HLT
+>
+
+/ SNO -- SKIP NO OVERFLOW
+/PSEUDO-INSTRUCTION TO TEST FOR RANK OR FILE OVERFLOW.
+/EFFECTIVLY SKIPS IF NO OVERFLOW. CALL WITH RANK OR FILE
+/NUMBER IN AC. RETURN WITH NUMBER IN AC IF NO OVERFLOW, GARBAGE OTHERWISE
+RFOFL, 0000
+ SPA /LESS THAN ZERO?
+ JMP I RFOFL /YES. RETURN
+ RTR /SHIFT BIT 8 INTO LINK
+ RTR /IF IT'S SET OVERFLOW HAS OCCURED
+ SZL /GREATER THAN 7?
+ JMP I RFOFL /YES. RETURN (WITH A GARBLED ACCUMULATOR)
+ RTL
+ RTL /SHIFT THE WORD BACK TO NORMAL
+ ISZ RFOFL /INC RETURN ADDRESS
+ JMP I RFOFL /RETURN
+PAGE
+\f
+/THIS ROUTINE GENERATES ALL THE MOVES OF A 'STRAIGHT LINE' MOVING
+/PIECE. ITMP0 MUST BE PRESET TO THE ADDRESS-1 OF THE MOVE GENERATION
+/DIRECTION LIST. LCNT MUST BE SET TO MINUS THE NUMBER OF 2-WORD
+/ENTRIES IN THAT LIST
+LINE, CLA
+ TAD I ITMP0 /GET THE VERTICAL DIRECTION
+ DCA DIR1 /SAVE IT
+ TAD I ITMP0 /GET THE HORIZINTAL DIRECTION
+ DCA DIR2 /SAVE THAT ALSO
+ TAD GN1
+ DCA GN3
+ TAD GN2
+ DCA GN4
+LINEM, TAD GN3 /BUILD SQUARE RANK NUMBER
+ TAD DIR1
+ SNO /IS THAT RANK REALY ON THE BOARD?
+ JMP XXOX /NO. IT DOES NOT EXIST
+ DCA GN3
+ TAD DIR2
+ TAD GN4
+ JMS XYZ
+ JMP XXOX
+ TAD I CNTR1 /GET VALUE OF THE MOVING PIECE
+ JMS CLRFIX
+ TAD (-QUEEN
+ SNA CLA /ARE WE TESTING FOR A LEGAL QUEEN MOVE?
+ ISZ QMVCNT /YES. INC QUEEN MOVE COUNTER
+ TAD GNMSW
+ JMS I ZFNL /DO FINAL TEST FOR KING CHECK
+ JMP XOOO /MOVE ILLEGAL: KING IS IN CHECK
+ TAD I TOADR /GET VALUE OF THE 'TO' SQUARE
+ SZA CLA /IS THE MOVE A CAPTURE?
+ STL RAR /YES: SET CAPTURE BIT
+ DCA GNMDW
+ JMS GNSTR /PUSH THE MOVE INTO THE STACK
+XOOO, TAD I TOADR /GET THE VALUE OF THE PIECE ON THE 'TO SQUARE'
+ SNA CLA /WAS THE MOVE A CAPTURE?
+ JMP LINEM /NO. COULD BE MORE MOVES IN THIS DIRECTION
+XXOX, CLA /YES. NO MORE MOVES IN THIS DIRECTION
+ ISZ LCNT /DONE ALL DIRECTIONS?
+ JMP LINE /NO. TRY ANOTHER
+ JMP NXTSQR /YES. DONE WITH THIS PIECE. TRY NEXT
+LCNT, 0000
+
+/ROUTINE TO STORE THE MSW AND MDW IN THE PDL
+GNSTR, 0000
+ ISZ GNCNT /INC GENERATION COUNT
+ CLA
+ TAD BOGUS
+ SZA CLA /SHOULD THESE MOVES GO INTO PDL#2?
+ JMP I GNSTR /NO. DONT PUT ANY THERE!
+ TAD GNMSW /GET MSW
+ PUSH2 /PUSH IT INTO THE LIST
+ TAD GNMDW /GET THE MDW
+ PUSH2 /PUSH IT INTO LIST
+ JMP I GNSTR /RETURN
+
+/SUBROUTINE TO TEST IF THE 'TO' SQUARE IS OCCUPIED BY OWN PIECE
+/IF NOT SKIP FOR RETURN AND BUILD MSW
+XYZ, 0000
+ SNO /DID IT GO OFF THE BOARD?
+ JMP I XYZ /YES: RETURN
+ DCA GN4 /NO: SAVE THIS HALF
+ JMS BLDTO /BUILD 'TO' ADDR
+ TAD I TOADR /GET VALUE OF THE 'TO' SQUARE
+ JMS CLRFIX
+ SMA SZA CLA /OCCUPIED BY OWN PIECE?
+ JMP I XYZ /YES: RETURN
+ JMS BLDMSW /NO: BUILD THE MSW
+ ISZ XYZ /INC RETURN ADDR
+ JMP I XYZ /RETURN
+
+GQM, CLA /GENERATE QUEEN MOVES
+ TAD [-10 /DO ALL DIRECTIONS
+ DCA LCNT
+ TAD (OTRX-1 /DIAGONAL AND ORTHOGONAL
+ DCA ITMP0
+ JMP LINE
+
+GRM, CLA /GENERATE ROOK MOVES
+ TAD (-4 /DO ONLY HALF OF THE DIRECTIONS
+ DCA LCNT
+ TAD (OTR-1 /THE ORTHOGONAL ONES
+ DCA ITMP0
+ JMP LINE
+
+GBM, CLA /GENERATE BISHOP MOVES
+ TAD (-4 /DO ONLY HALF OF THE DIRECTIONS
+ DCA LCNT
+ TAD (OTRX-1 /THE DIAGONAL ONES
+ DCA ITMP0
+ JMP LINE
+
+/SUBROUTINE TO BUILD AN MSW. CALL WITH ADDRESS OF THE 'TO SQUARE' IN LOCATION
+/'TOADR', AND THE LOCATION OF THE 'FROM SQUARE IN LOCATION "CNTR1". RETURN WITH THE
+/NEW MSW IN LOCATION 'GNMSW
+BLDMSW, 0000
+ CLA
+ TAD TOADR
+ AND [0077 /STRIP THE 'TO SQUARE' ADDRESS DOWN INTO 6BIT
+ DCA GNMSW /STORE IT TEMPORARILY
+ TAD CNTR1
+ AND [0077 /DO THE SAME FOR THE 'FROM SQUARE' ADDRESS
+ RTL CLL /BUT INSTEAD OF STORING IT, ROTATE IT INTO BITS 0-5
+ RTL
+ RTL
+ TAD GNMSW /NOW PACK THE 6BIT 'TO SQUARE' ADDRESS IN WITH IT
+ DCA GNMSW /STORE AWAY THE NEW MSW
+ JMP I BLDMSW /RETURN
+
+PUSHIT, 0000 /PUSH ROUTINE
+ DCA I PDLADR /PUT NEW ITEM ON TOP
+ ISZ PDLADR /PUSH
+ JMS OFLOW /TEST FOR LIST OVERLAP
+ JMP I PUSHIT /RETURN
+
+POPIT, 0000 /POP ROUTINE
+ CLA CMA
+ TAD PDLADR /MOVE LIST POINTER DOWN
+ SMA /MAKE SURE LIST DOESN'T GO WILD
+ HLT /IT DID! MANY EXTRA POPS
+ DCA PDLADR
+ TAD I PDLADR /GRAB THE TOP WORD
+ JMP I POPIT /RETURN WITH IT
+
+PUSH01, 0000
+ DCA I PC01 /PUT NEW ITEM ON TOP
+ CMA
+ TAD PC01
+ DCA PC01 /PUSH IT DOWN
+ JMS OFLOW /TEST FOR PDL OVERFLOW
+ JMP I PUSH01 /RETURN
+
+POP01, 0000
+ ISZ PC01 /MOVE THE LIST POINTER DOWN
+ SKP CLA
+ HLT /LOTS OF EXTRA POPS
+ TAD I PC01 /GRAB THE WORD ON TOP
+ JMP I POP01 /RETURN WITH IT
+
+PAGE
+\f/ROUTINE TO GENERATE ALL MOVES OF A KING OR KNIGHT
+/CALLED WITH THE MOVE GENERATION LIST ADDRESS-1 IN AC
+SNGMV, 0000
+ DCA ITMP0 /STORE THE ADDRESS OF THE LIST
+ TAD [7770
+ DCA SCNT /THERE ARE 8 DIRECTIONS
+ DCA GNMDW /INITIALIZE THE MDW
+ TAD GN1
+ TAD I ITMP0
+ SNO /OFF THE BOARD
+ JMP XXXO-1 /YES TRY ANOTHER DIRECTION
+ DCA GN3
+ TAD GN2
+ TAD I ITMP0
+ JMS XYZ
+ JMP XXXO
+ TAD I CNTR1 /GET VALUE OF THE MOVING PIECE
+ JMS CLRFIX
+ TAD (-KING
+ SZA CLA /IS IT A KING?
+ JMP SNGKNT /NO: ITS A KNIGHT
+ TAD GNMSW /YES
+ JMS MMOVE /MAKE THE KING MOVE
+ TAD TOADR
+ DCA TEMP /TEST FOR AN ATTACK ON THE KINGS NEW SQUARE
+ IAC /AND RETURN AFTER THE FIRST ATTACK IS FOUND
+ JMS CHKATK
+ JMS UMOVE /UNMAKE THE MOVE
+ TAD PCNT /NOW WORRY ABOUT LEGAL OR ILLEGAL
+ SNA CLA /WAS THE KING IN CHECK?
+ JMP SNGLGL /NO. MOVE IS LEGAL
+ ISZ KNGBLK /YES. INC BLOCKED KING MOVE COUNTER
+ JMP XXXO /GO TO THE ILLEGAL PLACE
+SNGKNT, TAD GNMSW
+ JMS I ZFNL /DO FINAL CHECK
+ JMP XXXO /KING IS ATTACKED: KNIGHT MOVE NO GOOD
+SNGLGL, TAD I TOADR /GET VALUE OF THE 'TO' SQUARE
+ SZA CLA /IS THE MOVE A CAPTURE?
+ CLA STL RAR /YES: SET CAPTURE BIT
+ TAD GNMDW
+ DCA GNMDW /STORE MDW AGAIN
+ JMS GNSTR /PUSH MOVE INTO LIST
+ SKP
+ ISZ ITMP0 /FAILED ON FIRST LIST ELEMENT. PASS OVER SECOND
+XXXO, CLA
+ ISZ SCNT /TESTED ALL DIRECTIONS?
+ JMP SNGMV+4 /NO. TRY THE NEXT ONE
+ JMP I SNGMV /YES. RETURN
+
+SCNT, 0000 /DIRECTION COUNTER
+
+
+GPM, CLA /GENERATE THE MOVES OF A PAWN
+ DCA GNMDW
+ TAD GN2
+ DCA GN4
+ TAD GN1
+ JMS PST
+ JMP GPM1 /MOVING 1 FORWARD BLOCKED: FORGET 2
+ TAD GN1 /MOVING 1 FORWARD IS NOT BLOCKED. NOW TEST FOR 2
+ TAD FSTRNK
+ SZA CLA
+ JMP GPM1 /NOT THIS PAWNS FIRST MOVE. CAN'T MOVE 2
+ CLA STL RTR
+ DCA GNMDW /SETUP MDW TO INDICATE DOUBLE PAWN MOVE(TEMPORARY INDICATION)
+ TAD GN3
+ JMS PST
+ NOP /MUST BE HERE CAUSE "PST" SUBROUTINE SOMETIMES RETURNS TO ADDRESS+2 OF THE CALLING JMS
+GPM1, CLA /NOW TEST CAPTURES
+ TAD GN1
+ TAD PONDIR
+ DCA GN3
+ IAC
+ TAD GN2
+ DCA GN4
+ TAD GN4
+ AND [7770
+ SZA CLA /CAN IT CAPTURE TO THE HIGH SIDE?
+ JMP .+2 /NO. IT WAS ON THE EDGE OF THE HIGH SIDE
+ JMS CAPTST
+ CLA CMA
+ TAD GN2
+ SPA /CAN IT CAPTURE TO THE LOW SIDE?
+ JMP .+3 /NO. IT WAS ON THE LOW EDGE
+ DCA GN4
+ JMS CAPTST
+ JMP NXTSQR
+\f/FOLLOWING ARE THE MOVE GENERATION DIRECTION LISTS
+OTRX, 1 /BISHOP MOVE DIRECTION LIST
+ -1
+
+ 1
+ 1
+
+ -1
+ -1
+
+ -1
+ 1
+
+OTR, 1 /ROOK MOVE DIRECTION LIST
+ 0
+
+ 0
+ -1
+
+ 0
+ 1
+
+ -1
+ 0
+
+KNLST, 2 /KNIGHT MOVE DIRECTION LIST
+ -1
+
+ 2
+ 1
+
+ 1
+ 2
+
+ -1
+ 2
+
+ -2
+ 1
+
+ -2
+ -1
+
+ -1
+ -2
+
+ 1
+ -2
+
+PAGE
+\f/GENERATE KING MOVES
+GKM, 0000
+ /FIRST TRY CASTLING
+ IAC CLA /SETUP MDW TO INDICATE CASTLING
+ DCA GNMDW
+ TAD PONDIR /BUILD THE ADDRESS OF THE KINGS ORIGINAL SQUARE
+ AND (0070
+ TAD (BOARD+4/KING IS ON FILE E
+ DCA TEMP /STORE THE ADDRESS OF THE KINGS ORIGINAL SQUARE
+ TAD I TEMP /GET THE VALUE OF THE PIECE ON IT
+ JMS CLRFIX
+ TAD (-KING
+ SNA CLA /IS IT A KING?
+ JMP GKM2 /YES
+ TAD I CPSW /NO. MAKE 'CPSW' REFLECT THIS
+ AND [0007 /SAVE BITS 9-11 IN CASE HE IS CASTLED
+ TAD (3000 /SET THE "NO MORE CASTLING" BITS
+ DCA I CPSW /NO MORE CASTLING
+ JMP GKM1 /BUT NORMAL KING MOVES ARE OK. GENERATE THEM NOW
+GKM2, TAD TEMP /CHANGE 'TEMP' TO EQUAL THE ADDRESS OF THE QUEENS ROOK
+ AND [7770 /BY CHANGING THE FILE TO A
+ DCA TEMP /STORE ADDRESS OF QUEENS ROOK
+ TAD I CPSW
+ RTL /MOVE 'QUEEN ROOK BIT' INTO AC0
+ SPA CLA /IF ITS SET THE QUEENS ROOK HAS MOVED
+ JMP CAKR /QUEENS ROOK HAS MOVED ALLREADY: TRY KING SIDE CASTLING
+ TAD I TEMP /GET VALUE OF PIECE ON A1(A8)
+ JMS CLRFIX
+ TAD (-ROOK
+ SNA CLA /IS IT A ROOK?
+ JMP .+5 /YES. CONTINUE
+ TAD (1000 /NO. 'QUEEN ROOK BIT' LIED
+ TAD I CPSW /CHANGE IT TO GIVE A TRUE INDICATION
+ DCA I CPSW /NO MARE CASTLING WITH THE QUEENS ROOK
+ JMP CAKR /AND TRY KING-SIDE CASTLING
+ TAD GNCHEK /FIND OUT IF THE KING IS IN CHECK
+ SZA CLA /IS THE KING IN CHECK
+ JMP CAKR /YES. GO SEE IF THE KINGS ROOK HAS MOVED
+ ISZ TEMP /NO. INC 'TEMP' SO THAT IT EQUALS THE ADDRESS OF B1(B8)
+ TAD I TEMP /GET THE VALUE OF THE SQUARE
+ SZA CLA /IS IT EMPTY?
+ JMP CAKR /NO. TRY KING-SIDE CASTLING
+ ISZ TEMP /INC 'TEMP' SO THAT IT EQUALS THE ADDRESS OF C1(C8)
+ TAD I TEMP /GET THE VALUE OF THE SQUARE
+ SZA CLA /IS IT EMPTY?
+ JMP CAKR /NO. TRY KING-SIDE CASTLING
+ JMS CHKATK /CHECK FOR AN ATTACK ON THAT SQUARE BY AN ENEMY PIECE
+ TAD PCNT /GET # OF ATTACKS
+ SZA CLA /ANY?
+ JMP CAKR /YES. Q-SIDE CASTLING ILLEGAL, TRY K-SIDE
+ ISZ TEMP /INC 'TEMP' TO EQUAL ADDRESS OF D1(D8)
+ TAD I TEMP /GET THE SQUARES VALUE
+ SZA CLA /IS IT OCCUPIED?
+ JMP CAKR /YES. TRY K-SIDE CASTLING INSTEAD
+ JMS CHKATK /CHECK FOR ATTACKS ON SQUARE D1(D8)
+ TAD PCNT /GET # OF ATTACKS
+ SZA CLA /ARE THERE ANY?
+ JMP CAKR /YES. TRY K-SIDE CASTLING
+ TAD PONDIR /NO. QUEEN SIDE CASTLING IS LEGAL!!
+ AND (7070 /BUILD AN MSW FOR QUEEN SIDE CASTLING
+ TAD (0402
+ DCA GNMSW /STORE THE NEW MSW
+ JMS GNSTR /PUSH THE MOVE ONTO PDL2
+CAKR, CLA
+ TAD I CPSW /TRY TO GENERATE A KING SIDE CASTLING MOVE
+ RAL /MOVE 'KING ROOK BIT' OF THE PSW INTO AC0
+ SPA CLA /IS IT SET?
+ JMP GKM1 /YES. KINGS ROOK HAS ALLREADY MOVED
+ TAD TEMP /NO. BUILD ADDRESS OF THE KINGS ROOK
+ AND [7770
+ TAD [0007
+ DCA TEMP
+ TAD I TEMP /GET THE VALUE OF THE PIECE ON H1(H8)
+ JMS CLRFIX
+ TAD (-ROOK
+ SNA CLA /IS IT A ROOK?
+ JMP .+5 /YES CONTINUE
+ CLA STL RTR /NO. 'KING ROOK BIT' LIED: FIX IT
+ TAD I CPSW
+ DCA I CPSW
+ JMP GKM1 /GO TRY PROPER STYLE KING MOVES
+ TAD GNCHEK /TEST FOR KING IN CHECK
+ SZA CLA /IS THEKING IN CHECK?
+ JMP GKM1 /YES. GO TRY REGULAR STYLE KING MOVES
+ TAD TEMP /NO. CONTINUE TRYING FOR KING SIDE CASTLING
+ TAD (-2
+ DCA TEMP /SET 'TEMP' = THE ADDRESS OF SQUARE E1(E8)
+ JMS CAKR1 /TEST TO SEE IF THE SQUARE IS OCUPIED OR ATTACKED
+ ISZ TEMP /NO. INC 'TEMP' TO EQUAL THE ADDRESS OF F1(F8)
+ JMS CAKR1 /TEST THE SQUARE FOR OCCUPATION OR ATTACKS
+ TAD PONDIR /NO. BUILD AN MSW CAUSE KING SIDE CASTLING IS LEGAL!!
+ AND (7070
+ TAD (0406
+ DCA GNMSW
+ ISZ GNMDW /INC MDW SO THAT IT INDICATES KING SIDE CASTLING
+ JMS GNSTR /STORE THE MOVE IN PDL2
+GKM1, CLA
+ TAD (OTRX-1 /NOW GENERATE 'NORMAL' KING MOVES
+ JMS SNGMV
+ JMP I GKM /RETURN
+
+\fCAKR1, 0000
+ TAD I TEMP /GET THE VALUE OF THE SQUARE
+ SZA CLA /IS THERE A PIECE ON IT?
+ JMP GKM1 /YES. MOVE ON TO NORMAL KING MOVES
+ JMS CHKATK /NO. TEST FOR ATTACKS ON THAT SQUARE BY ENEMY PIECES
+ TAD PCNT /GET # OF ATTACKS
+ SZA CLA /ANY?
+ JMP GKM1 /YES.
+ JMP I CAKR1 /RETURN
+
+GNM, CLA /GENERATE KNIGHT MOVES
+ TAD (KNLST-1/GET ADDRESS OF THE KNIGHT MOVE GENERATION LIST
+ JMS SNGMV
+ JMP NXTSQR
+PAGE
+\f/SUBROUTINE TO BUILD A 'TO SQUARE' ADDRESS
+/RETURN WITH ADDRESS IN LOC 'TOADR'
+BLDTO, 0000
+ TAD GN3 /GET RANK # AND ROTATE IT
+ RTL CLL /INTO ITS PROPER PLACE(BITS 6-8)
+ RAL
+ TAD GN4 /ADD IN THE FILE #
+ TAD [BOARD /ADD IN BOARD ADDRESS CONSTANT
+ DCA TOADR /STORE THE ADDRESS
+ JMP I BLDTO /RETURN
+
+
+/SUBROUTINE TO FIX THE COLOR PROBLEM, AND ALLOW ANY SUBROUTINE
+/TO WORK WITH BLACK PIECES AS WELL AS WHITE PIECES
+CLRFIX, 0000
+COLR, HLT /=NOP FOR WHITE, =CIA FOR BLACK
+ JMP I CLRFIX /RETURN
+\f/SUBROUTINE TO GENERATE 'EN PASSANT' PAWN CAPTURES
+/IF PAWNS MYSTERYOUSLY CHANGE COLOR, THIS ROUTINE IS THE LIKLEY SUSPECT
+GNEP, 0000
+ CMA CLA /-1 TO THE AC
+ DCA CTNEED /ALWAYS TEST FOR KING IN CHECK
+ TAD LSTMV /GET SOME INFORMATION ON THE LAST MOVE MADE
+ AND (0770 /ISOLATE THE 'DOUBLE PAWN MOVE' INFO
+ SNA /WAS THE LAST MOVE MADE A DOUBLE PAWN MOVE?
+ JMP I GNEP /NO. 'EN PASSANT' CAPTURES ARE NOT POSIBLE. RETURN
+ RTR CLL /YES. ROTATE THE INFO(6BIT 'TO ADDRESS') INTO BITS 6-11
+ RAR
+ TAD [BOARD /ADD IN BOARD ADDRESS CONSTANT
+ DCA CNTR1 /STORE THE ADDRESS OF THE CAPTURED PAWN
+ TAD CNTR1
+ DCA GNEPTM /STORE THE ADDRESS OF THE CAPTURED PAWN
+ DCA I GNEPTM /TAKE THE PAWN OFF THE BOARD NOW FOR CONVIENIENCE
+ TAD CNTR1 /BUILD A 'TO RANK' THEN A 'TO ADDRESS'
+ RTR CLL /FIRST ROTATE THE OLD 'TO RANK' INTO BITS 9-11
+ RAR
+ AND [0007
+ TAD PONDIR /NEW 'TO RANK' IS 1 MOVE GREATER THAN THE OLD ONE
+ RTL CLL /ROTATE THE 'TO RANK' BACK INTO PLACE AGAIN
+ RAL
+ DCA GNMDW /STORE IT TEMPORARILY
+ TAD CNTR1 /GET THE ADDRESS OF THE PAWN BEING CAPTURED
+ AND (7707 /CLEAR OUT ROOM FOR THE NEW 'TO RANK'
+ TAD GNMDW /ADD THE NEW 'TO RANK' IN
+ DCA TOADR /STORE THE 'TO SQUARE' ADDRESS
+ TAD (4003 /4003 IS THE MDW REPRESENTING AN 'EN PASSANT' CAPTURE
+ DCA GNMDW /STORE THE NEW MDW
+ ISZ CNTR1 /TRY THE ADDJACENT FILE ON THE HIGH SIDE FIRST
+ TAD CNTR1
+ AND [0007
+ SNA CLA /IS THERE REALY A FILE ON THAT SIDE?
+ JMP GNOTF /NO. TRY THE OTHER SIDE
+ TAD I CNTR1 /GET THE VALUE OF THE PIECE ON THE SQUARE
+ JMS CLRFIX
+ TAD [-PAWN
+ SZA CLA /IS IT A PAWN?
+ JMP GNOTF /NO. TRY THE OTHER ADDJACENT FILE
+ JMS BLDMSW /YES. MOVE SEEMS OK. BUILD AN MSW FOR IT
+ TAD GNMSW /LOAD THE MSW INTO THE AC
+ JMS I ZTSTCH /TEST IF THE MOVE IS ILLEGAL BY VIRTUE OF KING IN CHECK
+ SKP /IT IS ILLEGAL DONT STORE IT IN THE PUSH DOWN LIST
+ JMS GNSTR /MOVE IS LEGAL STORE IT IN PDL2
+GNOTF, CLA
+ TAD CNTR1 /GET THE 'FROM SQUARE ADDRESS'
+ TAD (-2 /CHANGE IT TO POINT TO THE ADDJACENT FILE ON THE OTHER SIDE
+ DCA CNTR1
+ TAD GNEPTM /NOW TEST IF THAT FILE REALY EXISTS
+ AND [0007 /IF THE FILE IS 0 WE'RE ON THE EDGE
+ SNA CLA /DOES THE FILE REALY EXIST, OR IS THE PAWN ON THE EDGE OF THE BOARD
+ JMP GNEPDN /DOES NOT EXIST!
+ TAD I CNTR1 /GET THE VALUE OF THE PIECE ON THAT SQUARE
+ JMS CLRFIX
+ TAD [-PAWN
+ SZA CLA /IS IT A PAWN?
+ JMP GNEPDN /NO
+ JMS BLDMSW /YES. BUILD AN MSW
+ TAD GNMSW
+ JMS I ZTSTCH /IS THE KING IN CHECK IF THAT MOVE IS MADE
+ SKP /YES. DONT STORE THE MOVE IN THE PDL
+ JMS GNSTR /NO. STORE THE MOVE IN PDL2
+GNEPDN, TAD [-PAWN
+ JMS CLRFIX
+ DCA I GNEPTM /REPLACE THE PAWN THAT WAS REMOVED EARLIER
+ JMP I GNEP /RETURN
+GNEPTM, 0000 /LOCATION FOR STORAGE OF THE CAPTURED PAWNS ADDRESS
+\f
+/SUBROUTINE TO MAP THE PIECES IF NECCESARY(IF DOMAP=-1).
+/MAP IS IN TWO PARTS, 1 FOR EACH COLOR
+/WHITE MAP STARTS AT LOC 7400. BLACK MAP STARTS AT LOC 7424.
+/MAP FORMAT-- 1 WORD PER PIECE, REPRESENTING THE ADDRESS OF THAT PIECE
+MAPEC, 0000
+ CLA CMA
+ TAD [BOARD /SETUP BOARD ADDRESS
+ DCA ITMP2
+ TAD DOMAP
+ SNA CLA /IS A MAP REALY NECCESARY?
+ JMP I MAPEC /NO. RETURN
+ DCA DOMAP
+ TAD (MAP-1 /YES. SETUP MAP OF WHITES PIECE ADDRESSES
+ DCA ITMP0
+ TAD (MAP+23 /SETUP MAP OF BLACK PIECE ADDRESSES
+ DCA ITMP1
+ TAD (-100 /SETUP COUNT FOR 100(OCTAL) SQUARES ON THE BOARD
+ DCA TEMP4
+ TAD I ITMP2 /GET VALUE OF THE PIECE ON THE SQUARE
+ SZA /IS SQUARE OCCUPIED?
+ JMP MAPOC /YES
+MAPGO, ISZ TEMP4 /FINISHED BOARD YET?
+ JMP .-4 /NO. DO MORE SQUARES
+ DCA I ITMP0 /YES. PUT A 0000 AT THE END OF THE WHITE MAP
+ DCA I ITMP1 /ALSO AT THE END OF THE BLACK MAP
+ JMP I MAPEC /RETURN
+MAPOC, SPA /IS IT WHITE OR BLACK?
+ JMP MAPOCB /ITS BLACK
+ TAD (-KING /ITS WHITE. IS IT A KING?
+ SZA CLA
+ JMP .+3 /NO
+ TAD ITMP2 /YES
+ DCA WKING /STORE ADDRESS OF THE WHITE KING
+ TAD ITMP2
+ DCA I ITMP0 /PUT IT IN THE WHITE MAP WHATEVER IT IS
+ JMP MAPGO
+MAPOCB, TAD (KING /IS IT THE BLACK KING?
+ SZA CLA
+ JMP .+3 /NO. PROCEDE NORMALY
+ TAD ITMP2 /YES, GET ITS ADDRESS
+ DCA BKING /STORE IT
+ TAD ITMP2 /GET THE ADDRESS
+ DCA I ITMP1 /EITHER WAY, PUT IT IN THE BLACK MAP
+\f JMP MAPGO
+PAGE
+\f/SUBROUTINE TO CHECK FOR A 'DOUBLE PAWN MOVE', AND MODIFY THE
+/MDW IF IT IS. ALSO TEST IF A LEGAL PAWN MOVE IS ALSO A PROMOTING MOVE
+/APPROPRIATE ACTION IS TAKEN IF IT IS. IN ANY CASE THIS ROUTINE CALLS
+/'GNSTR' TO STORE MSW & MDW IN PDL2
+PROMCK, 0000
+ CLA
+ TAD GNMDW /GET THE MOVE DATA WORD
+ RTL /ROTATE AC BIT 1 INTO THE LINK
+ SZL CLA /DOES IT SAY 'DOUBLE PAWN MOVE'?
+ JMP PROM1 /YES. SET THE MDW TO SHOW IT
+ TAD GN3 /BUILD THE RANK OF THE PAWN, IF IT WERE TO BE
+ TAD PONDIR /MOVED ONE MORE TIME
+ SNO /IS IT STILL ON THE BOARD?
+ SKP CLA /NO: IT'S A PROMOTIMG MOVE
+ JMP PPLSTR /YES: IT'S NOT A PROMOTING MOVE
+ TAD GNMDW
+ TAD [0004 /SET 'PAWN PROMOTION BIT' (BIT 9) OF THE MDW
+ DCA GNMDW
+ JMS GNSTR /STORE PROMOTION TO KNIGHT MOVE IN PDL2
+ ISZ GNMDW /CHANGE MDW TO INDICATE PROMOTION TO A BISHOP
+ JMS GNSTR /STORE MOVE IN PDL2
+ ISZ GNMDW /CHANGE MDW TO INDICATE PROMOTION TO A ROOK
+ JMS GNSTR /STORE MOVE IN PDL2
+ ISZ GNMDW /CHANGE THE MDW TO INDICATE PROMOTION TO A QUEEN
+PPLSTR, JMS GNSTR /STORE MOVE IN PDL2
+ JMP I PROMCK /RETURN
+PROM1, CLL RTR /CLEAR LINK(BIT 1)AND REROTATE THE MDW BACK INTO POSITION
+ DCA GNMDW /RESTORE THE MDW
+ TAD GNMSW /NOW GET THE MSW
+ AND [0077 /EXTRACT 'TO SQUARE' INFO
+ RTL CLL /ROTATE THE INFO SO THAT IT FITS IN MDW BITS 3-8
+ RAL
+ TAD GNMDW /ADD IT TO THE MDW
+ DCA GNMDW /THERES THE NEW MDW!!!
+ JMP PPLSTR /IF THE PAWN MOVE A DOUBLE MOVE, IT WASN'T QUEENING
+
+/SUBROUTINE TO CHECK FOR LEGAL PAWN CAPTURES
+CAPTST, 0000
+ JMS BLDTO /BUILD THE ADDRESS OF THE 'TO' SQUARE
+ TAD I TOADR /GET THE VALUE OF THE SQUARE
+ JMS CLRFIX
+ SMA CLA /IS IT AN ENEMY PIECE?
+ JMP I CAPTST /YES. CAN ONLY CAPTURE OPPOSING PIECES
+ JMS BLDMSW /NO. CAPTURE SEEMS LEGAL. BUILD AN MSW
+ CLA STL RAR /BUILD AN MDW WHICH INDICATES CASTLING
+ DCA GNMDW
+ TAD GNMSW /FINAL TEST FOR MOVE LEGALITY COMING UP
+ JMS I ZFNL /IS KING IN CHECK?
+ JMP I CAPTST /YES: MOVE ILLEGAL
+ JMS PROMCK /NO: CHECK FOR PROMOTION
+ JMP I CAPTST /RETURN
+
+\fPST, 0000
+ TAD PONDIR
+ DCA GN3
+ JMS BLDTO /BUILD THE 'TO' ADDR
+ TAD I TOADR /GET VALUE OF 'TO' SQUARE
+ SZA CLA /IS THE SQUARE OCCUPIED?
+ JMP I PST /YES, MOVE NO GOOD
+ JMS BLDMSW /NO. PACK IT INTO 12 BITS.
+ TAD GNMSW
+ JMS I ZFNL /IS KING IN CHECK?
+ SKP /YES: MOVE NO GOOD
+ JMS PROMCK /MOVE IS LEGAL. CHECK FOR PAWN PROMOTION
+ ISZ PST /INC RETURN ADDRESS IF "TO" SQUARE WAS NOT OCCUPIED
+ JMP I PST
+
+/TEST FOR LEGAL KNIGHT CAPTURE:
+ISLNM, CLA CLL CMA
+ RAL /AC WILL=-2
+ DCA TOOS
+ TAD M1 /COMPARE RANKS
+ CIA
+ TAD M3
+ SMA
+ CIA
+ IAC
+ SNA
+ JMP .+5
+ IAC
+ SZA CLA
+ JMP BATAK
+ ISZ TOOS
+ TAD M2
+ CIA
+ TAD M4
+ SMA
+ CIA
+ IAC
+ SNA
+ JMP .+5
+ IAC
+ SZA CLA
+ JMP BATAK
+ ISZ TOOS
+ SKP
+ JMP BATAK
+ ISZ TOOS
+ JMP BATAK
+ JMP GATAK
+TOOS, 0000
+ \f
+PDLIN, 0000 /INITIALIZE THE LIST
+ CLA
+ TAD (PDLS
+ DCA PDLADR /INITIALIZE LIST ADDRESS
+ JMP I PDLIN /RETURN
+
+\fIPDL01, 0000 /INITIALIZE PUSH DOWN LIST #1
+ CLA
+ TAD (PDLS+777
+ DCA PC01
+ JMP I IPDL01 /RETURN
+
+/SUBROUTINE TO TEST FOR PUSH DOWN LIST OVERFLOW
+OFLOW, 0000
+ TAD PC01 /GET ADDR OF BOTTOM PDL#1
+ CIA /COMPARE IT WITH
+ TAD PDLADR /THE ADDR OF BOTTOM PDL#2
+ SZA CLA /ARE THEY THE SAME?
+ JMP I OFLOW /NO. RETURN.
+/PUSH DOWN LIST HAS OVERFLOWED!!!!!
+ IFNZRO LPTREE<
+ TAD (OUT
+ DCA ZOUT /MAKE SURE OUTPUT GOES TO THE TTY
+>
+ PRINTO; MESG26 /PRINT "I RESIGN"
+ JMS I ZCRLF
+ HLT
+MESG26, TEXT \I RESIGN\
+
+PAGE
+\f
+/CHECK FOR LEGAL KING MOVE
+ISLKM, CLA
+ TAD M1
+ CIA
+ TAD M3
+ SMA
+ CIA
+ SZA
+ IAC
+ SZA CLA
+ JMP BATAK
+ TAD M2
+ CIA
+ TAD M4
+ SMA
+ CIA
+ SZA
+ IAC
+ SNA CLA
+ JMP GATAK
+ JMP BATAK
+
+/ROUTINE TO CHECK FOR PIECES IN THE MOVE ROW
+ROW, 0000
+ CLA
+ TAD M1
+ CIA
+ TAD M3
+ RAL CLL /GET THE SIGN
+ SZA CLA
+ TAD (10
+ SZL
+ CIA
+ DCA TEMP3
+ TAD M4
+ CIA
+ TAD M2
+ RAL CLL /GET THE SIGN
+ SZA CLA
+ IAC
+ SNL
+ CIA
+ TAD TEMP3
+ DCA TMP
+ TAD TMATK /GET THE SQUARE OF THE ATTACKER
+ DCA TEMP3 /COPY IT SO WE DONT HAVE TO DESTROY THE ORIGINAL
+MIDLIN, TAD TEMP3 /SET TO NEXT SQUARE
+ TAD TMP
+ DCA TEMP3
+ TAD TEMP3 /COMPARE IT WITH THE ATTACKED SQUARE
+ CIA
+ TAD TEMP
+ SNA CLA /ARE THEY THE SAME?
+ JMP I ROW /YES RETURN
+ TAD I TEMP3 /NO. GET THE VALUE OF THE PIECE ON THE SQUARE
+ SNA CLA /IS THE SQUARE EMPTY?
+ JMP MIDLIN /YES- KEEP GOING UNTIL WE FIND ONE THAT ISN'T
+ ISZ ROW /NO. ITS NOT A LEGAL ATTACK--INC RETURN ADDRESS
+ JMP I ROW /RETURN
+
+/CHECK FOR LEGAL BISHOP MOVE
+SUBR1, 0000
+ CLA
+ TAD M1
+ CIA
+ TAD M3
+ SMA
+ CIA
+ DCA TEMP3
+ TAD M2
+ CIA
+ TAD M4
+ SPA
+ CIA
+ TAD TEMP3
+ SZA CLA /ARE BOTH SQUARES ON THE SAME DIAGONAL?
+ JMP I SUBR1 /NO
+ JMS ROW /YES. FIND OUT IF ANY PIECES ARE BLOCKING THAT DIAGONAL
+ ISZ SUBR1 /NONE FOUND -- INC RETURN ADDRESS
+ JMP I SUBR1 /RETURN
+
+/CHECK FOR LEGAL ROOK MOVE
+SUBR2, 0000
+ CLA
+ TAD M1
+ CIA
+ TAD M3
+ SNA CLA
+ JMP .+6 /SAME RANK. FORGET FILE
+ TAD M2
+ CIA
+ TAD M4
+ SZA CLA
+ JMP I SUBR2 /BOTH RANK AND FILE CHANGED?!
+ JMS ROW
+ ISZ SUBR2 /NO PIECES IN THE WAY-- INC RETURN ADDRESS
+ JMP I SUBR2
+
+/CHECK FOR LEGAL QUEEN MOVE
+/GO TO 'GATAK' IF IT IS
+ISLQM, JMS SUBR2 /CHECK FOR A QUEEN MOVE 'ROOK STYLE'
+ SKP /NOT FOUND
+ JMP GATAK /FOUND
+ JMS SUBR1 /IF NOT CHECK FOR BISHOP STYLE QUEEN MOVE
+ JMP BATAK /NIETHER ONE
+ JMP GATAK /FOUND BISHOP STYLE QUEEN MOVE
+
+ISLBM, CLA
+ JMS SUBR1
+ JMP BATAK
+ JMP GATAK
+
+ISLRM, CLA
+ JMS SUBR2
+ JMP BATAK
+ JMP GATAK
+
+PAGE
+
+\f
+/SUBROUTINE TO TEST IF A SQUARE IS ATTACKED BY A PIECE.
+/ALSO FINDS OUT HOW MANY ATTACKERS, AND THE VALUE OF THE LEAST VALUABLE ATTACKER
+/CALL WITH ADDRESS OF SQUARE TO BE TESTED IN LOCATION 'TEMP'
+/ALSO PONDIR AND COLR SET IN REVERSE OF THE ATTACKERS
+/AND THE ATTACKERS PIECE LIST ADDRESS-1 IN LOC 'OMAP'
+/RETURNS WITH NUMBER OF ATTACKERS IN LOC. 'PCNT', THE ADDRESS
+/OF THE LEATST VALUABLE ATTACKER IN LOC "PSQR" AND VALUE OF THE LEAST
+/VALUABLE ATTACKER IN LOC. 'PVAL'
+/IF THE VALUE OF THE LEAST VALUABLE ATTACKER, AND THE # OF ATTACKERS
+/IS NOT IMPORTANT, CALL WITH AC NOT =0
+/RETURN IN THIS CASE IS DIRECTLY AFTER THE FIRST ATTACK IS FOUND
+CHKATK, 0000
+ DCA CKMODE /SET RETURN MODE SWITCH
+ CLA CMA
+ DCA TMATK /INITIALIZE SWITCH ENABLING 1 LOOPBACK IN THE PAWN SECTION
+ DCA PCNT /INITIALIZE PIECE COUNT
+ DCA PVAL /INITIALIZE PIECE VALUE TO 0
+ DCA PSQR /INIT PIECE ADDRESS
+ TAD TEMP /GET SQUARE TO BE CHECKED
+ AND [0007 /EXTRACT THE FILE #
+ DCA M4 /RECORD IT
+ TAD TEMP /GET SQUARE ADDR AGAIN
+ RTR CLL /ROTATE RIGHT 3 BITS SO THAT THE RANK CAN
+ RAR /BE EXTRACTED IN A SIMILAR MANNER
+ AND [0007
+ DCA M3 /STORE RANK #
+ TAD PONDIR /CHECK FOR AN ATTACK BY A PAWN
+ TAD M3
+ SNO /IMPOSIBLE RANK?
+ JMP TAG1 /YES. FORGET PAWN ATTACKS
+ DCA M1 /NO. SAVE THE RANK
+ IAC CLA /NOW BUILD A FILE
+TAG0, TAD M4
+ SNO /IS THAT FILE REALY ON THE BOARD?
+ JMP TAG3 /NO.
+ RTR CLL /YES: PASTE TOGETHER THE ADDRESS OF THIS HYPOTHETICAL PAWN
+ RAR
+ TAD M1
+ RTL
+ RAL
+ TAD [BOARD /ADD IN BOARD ADDRESS CONSTANT
+ DCA TEMP1 /VOLIA! STORE THE ADDRESS
+ TAD I TEMP1 /GET THE VALUE OF THE PIECE AT THAT ADDR
+ JMS CLRFIX
+ TAD (PAWN
+ SZA CLA /PER CHANCE A PAWN?
+ JMP TAG3 /NO: TRY NEXT PIECE
+TAG2, ISZ PCNT /YES. ITS A PAWN ATTACK. INC PIECE COUNT
+ TAD I TEMP1 /SET LOWEST VALUED ATTACKING PIECE VALUE = PAWN
+ DCA PVAL
+ TAD TEMP1 /ALSO SET THE ADDRESS OF THE LOWEST ATTACKING PIECE
+ DCA PSQR /EQUAL TO THE ADDRESS OF THE PAWN
+ TAD CKMODE /TEST FOR 'FAST RETURN' MODE
+ SZA CLA
+ JMP I CHKATK /RETURN NOW
+TAG3, ISZ TMATK /TESTED FOR PAWNS ON BOTH ADJACENT FILES?
+ JMP TAG1 /YES
+ CMA CLA /NO. LOOP BACK FOR THE OTHER FILE
+ JMP TAG0
+TMATK, 0000
+CKMODE, 0000
+TMATK1, 0000
+TAG1, CLA
+ TAD OMAP /GET ADDRESS-1 OF THE ATTACKERS PIECE MAP
+ DCA TOMAK1
+BATAK, ISZ TOMAK1 /INC THE PIECE TABLE ADDRESS
+ TAD I TOMAK1 /GET THE ADDRESS OF THE PIECE
+ SNA /IS IT REALY A PIECE, OR IS THE SQUARE BLANK?
+ JMP I CHKATK /BLANK. TABLE EXAUSTED:RETURN
+ DCA TMATK /NO. SOMTHINGS THERE. STORE ITS ADDRESS
+ TAD TMATK /GET THE ATTACKERS SQR ADDR
+ CIA
+ TAD TEMP /COMPARE WITH THE ATTACKED SQUARS ADDRESS
+ SNA CLA /ARE THEY THE SAME?
+ JMP BATAK /YES.PIECES CANNOT ATTACK THEMSELVES
+ TAD I TMATK
+ JMS CLRFIX
+ TAD (PAWN
+ SNA CLA /IS IT A PAWN?
+ JMP BATAK /YES, DONE PAWNS ALLREADY, TRY NEXT PIECE
+ TAD TMATK /NO GET SQUARE ADDRESS
+ AND [0007 /EXTRACT THE FILE
+ DCA M2 /STORE IT
+ TAD TMATK /GET ADDRESS AGAIN
+ RTR /ROTATE RANK # INTO BITS 9-11
+ RAR
+ AND [0007 /ISOLATE RANK INFO
+ DCA M1 /STORE IT
+ TAD I TMATK /GET THE VALUE OF THE PIECE AGAIN
+ JMS CLRFIX
+ TAD (ROOK /NOW IDENTIFY IT
+ SNA /IS IT A ROOK?
+ JMP ISLRM /YES
+ TAD (-ROOK+BISHOP
+ SNA /IS IT A BISHOP?
+ JMP ISLBM /YES
+ TAD (-BISHOP+KNIGHT
+ SNA /IS IT A KNIGHT?
+ JMP ISLNM /YES
+ TAD (-KNIGHT+KING
+ SNA /IS IT A KING?
+ JMP ISLKM /YES
+ TAD (-KING+QUEEN
+ SNA CLA /IS IT A QUEEN?
+ JMP ISLQM /YES
+ JMP BATAK /NO? WHATEVER WAS THERE MUST HAVE MOVED! PLEASE TO IGNORE.
+
+\f/WE REACH HERE IF AN ATTACK ON THE SQUARE IN QUESTION IS FOUND
+GATAK, ISZ PCNT /INC ATTACK COUNTER
+ TAD CKMODE /TEST FOR FAST RETURN
+ SZA CLA /'FAST RETURN' MODE?
+ JMP I CHKATK /YES. RETURN NOW
+ CMA CLA
+ TAD PCNT
+ SNA CLA /IS THIS THE FIRST ATTACK FOUND?
+ JMP TAG4 /YES. DONT COMPARE
+ TAD I TMATK /NOW COMPARE THE VALUE OF THIS ATTACKING PIECE
+ CIA /WITH THE LOWEST VALUED ATTACKER FOUND SO FAR
+ TAD PVAL
+ JMS CLRFIX
+ SMA CLA /IS THE VALUE OF THIS PIECE LOWER?
+ JMP BATAK /NO
+TAG4, TAD I TMATK /YES. REPLACE THE OLD VALUE WITH THIS ONE
+ DCA PVAL
+ TAD TMATK
+ DCA PSQR
+ JMP BATAK
+
+PAGE
+\f
+/TEST FOR KING IN CHECK BY MOVING A PIECE AND CALLING CHKATK
+/CALL WITH MSW IN AC, AND THE KINGS ADDRESS IN "CKING"
+/RETURN TO THE ADDRESS+1 OF THE CALLING JMS IF THE KING IS IN CHECK
+/RETURN TO THE ADDRESS+2 OF THE CALLING JMS IF THE KING IS NOT IN CHECK
+TSTCHK, 0000
+ DCA MMUMTM /STORE THE MSW FOR THE MOMENT
+ TAD GNCHEK /GET # OF ATTACKS ON THE KING
+ SZA CLA /WAS THE KING IN CHECK?
+ JMP TSTCH1 /YES. DO A COMPLETE TEST FOR KING IN CHECK
+ TAD CTNEED
+ SPA /HAVE WE DETERMINED THAT A CHECK TEST IS NESCESARY?
+ JMP TSTCH1 /YES. DO ONE
+ SNA CLA /NO. HAVE WE DETERMINED THAT IT IS NOT?
+ JMP TSTCH2 /YES. DONT DO ONE THEN
+ DCA CTNEED /NO. DETERMINE THAT NOW
+ TAD CKING
+ DCA TEMP
+ TAD CNTR1
+ DCA TMATK
+ TAD TEMP
+ RTR CLL
+ RAR
+ AND [0007
+ DCA M3
+ TAD TEMP
+ AND [0007
+ DCA M4
+ TAD CNTR1
+ RTR CLL
+ RAR
+ AND [0007
+ DCA M1
+ TAD CNTR1
+ AND [0007
+ DCA M2
+ JMS SUBR1
+ SKP
+ JMP TSTCH1
+ JMS SUBR2
+ JMP TSTCH2
+TSTCH1, CLA CMA
+ DCA CTNEED /SET CHECK TEST NEED SWITCH
+ TAD MMUMTM /GET THE MSW BACK AGAIN
+ JMS MMOVE
+ TAD CKING /ADDRESS TO TEST FOR ATTACK
+ DCA TEMP
+ IAC /RETURN AFTER FIRST ATTACK IS FOUND
+ JMS CHKATK
+ JMS UMOVE /PUT THE PIECE BACK WHERE IT BELONGS
+ TAD PCNT /GET # OF ATTACKS
+ SNA /ANY?
+TSTCH2, ISZ TSTCHK /NO. INC RETURN ADDRESS
+ SNA CLA /I'LL ASK AGAIN: WERE THERE ANY?
+ JMP I TSTCHK /NO. RETURN
+ TAD GNCHEK
+ SZA CLA /WAS IT A CHECK REPLY?
+ ISZ MOBMOD /TALLY ONE MORE ILLEGAL BY VIRTUE OF KING IN CHECK
+ JMP I TSTCHK
+
+\f/SUBROUTINE TO MAKE A SIMPLE TYPE MOVE
+/CALL WITH MSW IN AC
+MMOVE, 0000
+ DCA MMUMT1 /STORE THE MSW
+ TAD MMUMT1
+ JMS I ZSPLIT /SPLIT THE MSW UP INTO 'TO' AND 'FROM' SQUARE ADDRESSES
+ TAD I TEMP1 /GET VALUE OF CAPTURED PIECE
+ DCA MMUMTM /STORE IT
+ TAD I TEMP2 /MOVE THE PIECE
+ DCA I TEMP1 /ONTO ITS NEW SQR
+ DCA I TEMP2 /CLEAR OUT OLD SQR
+ JMP I MMOVE
+
+/SUBROUTINE TO UMMAKE SIMPLE TYPE MOVES
+/AS MADE BY THE MMOVE SUBROUTINE
+UMOVE, 0000
+ CLA
+ TAD MMUMT1 /GET THE MSW
+ JMS I ZSPLIT /SPLIT IT UP INTO 'TO' AND 'FROM' SQUARE ADDRESSES
+ TAD I TEMP1 /GET VALUE OF THE PIECE BEING UNMOVED
+ DCA I TEMP2 /PUT IT BACK ON ITS ORIGINAL SQUARE
+ TAD MMUMTM
+ DCA I TEMP1 /RESTORE CAPTURED PIECE
+ JMP I UMOVE
+MMUMTM, 0000
+MMUMT1, 0000
+
+/SUBROUTINE TO GENERATE ALL MOVES FOR WHITE
+GNWMV, 0000
+ CMA CLA /SETUP FIRST RANK CONSTANT
+ DCA FSTRNK
+ JMS I ZMAPEC /MAP THE PIECES
+ TAD (NOP /SETUP COLOR COMPLIMENTOR
+ DCA COLR
+ IAC /SETUP PAWN DIRECTION CONSTANT
+ DCA PONDIR
+ TAD WKING /SAVE THE ADDRESS OF THE WHITE KING
+ DCA CKING
+ TAD (MAP-1 /SETUP ADDRESS OF WHITE PIECE MAP
+ DCA GMAP
+ TAD (MAP+23 /SETUP ADDRESS OF BLACK PIECE MAP
+ DCA OMAP
+ TAD (WPSW /SETUP CURRENT PSW ADDRESS
+ DCA CPSW
+ JMS I ZGNMV /GENERATE THE MOVES
+ JMP I GNWMV /RETURN
+\f
+
+/SUBROUTINE TO GENERATE ALL MOVES FOR BLACK
+GNBMV, 0000
+ CMA CLA /SETUP THE PAWN DIRECTION CONSTANT
+ DCA PONDIR
+ JMS I ZMAPEC /MAP THE PIECES
+ TAD [CIA /SETUP COLOR COMPLIMENTOR
+ DCA COLR
+ TAD BKING /SAVE THE ADDRESS OF THE BLACK KING
+ DCA CKING
+ TAD (7772 /SETUP FIRST RANK CONSTANT
+ DCA FSTRNK
+ TAD (MAP+23 /SETUP ADDRESS OF BLACK PIECE MAP
+ DCA GMAP
+ TAD (MAP-1 /SETUP ADDRESS OF WHITE PIECE MAP
+ DCA OMAP
+ TAD (BPSW /SETUP POSITION STATUS WORD ADDRESS
+ DCA CPSW
+ JMS I ZGNMV /GENERATE THE MOVES
+ JMP I GNBMV /RETURN
+
+PAGE
+\f
+/SUBROUTINE TO TEST FOR WHITE ATTACKS
+/CALL WITH ADDRESS OF THE SQUARE TO BE TESTED IN AC
+TSTWAT, 0000
+ DCA TEMP
+ TAD [CIA
+ DCA COLR
+ CLA CMA
+ DCA PONDIR
+ TAD (MAP-1 /ADDRESS-1 OF MAP OF ATTACKING PIECES
+ DCA OMAP
+ JMS CHKATK /DO THE TEST
+ JMP I TSTWAT /RETURN
+
+/SUBROUTINE TO TEST FOR BLACK ATTACKS ON ANY SQUARE
+/CALL WITH THE ADDRESS OF THE SQUARE TO BE TESTED IN AC
+TSTBAT, 0000
+ DCA TEMP /STORE ADDRESS OF SQUARE TO BE TESTED
+ TAD (NOP
+ DCA COLR
+ CLA IAC
+ DCA PONDIR
+ TAD (MAP+23 /ADDRESS-1 OF THE BLACK PIECE MAP
+ DCA OMAP
+ JMS CHKATK /DO THE TEST
+ JMP I TSTBAT /RETURN
+
+
+\f
+/SUBROUTINE TO MAKE A MOVE. CALLED WITH MSW IN LOCATION 'TOMAK1'
+/AND MDW IN LOCATION 'TOMAK2'
+MKMV, 0000
+ CLA CLL
+ ISZ DOMAP /SET SWITCH INDICATING THAT A PIECE MAP IS NESSECARY
+ IFNZRO DEBUG<
+ JMS TSTBRD /TEST BOARD
+>
+ TAD TOMAK1
+ PUSH1 /SAVE THE MSW
+ TAD TOMAK1 /GET THE MSW
+ JMS I ZSPLIT /SPLIT THE MSW UP INTO A 'TO' AND A 'FROM' ADDRESSES
+ TAD TOMAK2 /MDW TO AC
+ SMA CLA /IS THE MOVE A CAPTURE?
+ JMP MKMV1 /NO.
+ TAD I TEMP1 /YES. SAVE ITS VALUE IN
+ PUSH1 /THE PUSH DOWN LIST
+ TAD I TEMP1 /GET VAL OF CAPTURED PIECE
+ CIA /SUBTRACT IT FROM THE
+ TAD PW /TOTAL VALUE OF THE BOARD
+ DCA PW
+MKMV1, TAD I TEMP2 /NOW PHYSICALY MOVE THE PIECE
+ DCA I TEMP1 /ONTO ITS NEW SQUARE
+ DCA I TEMP2 /REMOVE THE PIECE FROM ITS OLD SQUARE
+ TAD WPSW /SAVE WHITES POSITION STATUS WORD
+ PUSH1
+ TAD BPSW /SAVE BLACKS POSITION STATUS WORD
+ PUSH1
+ TAD LSTMV
+ PUSH1 /SAVE THE 'LSTMV' INFORMATION
+ TAD TOMAK2 /INSTALL NEW INFORMATION ON THE LAST(THIS) MOVE MADE
+ DCA LSTMV
+ TAD TOMAK2
+ AND [0007
+ SNA /IS THIS ONE OF THE SPECIAL TYPES OF MOVES?
+ JMP MKMVDN /NO. ALL DONE SO RETURN
+ TAD (JMP .+2 /YES. BUILD A 'JMP' TO THE PROPER SPECIAL CASE HANDLER
+ DCA .+1
+ HLT /PUT THE JUMP HERE
+/A JMP TO ONE OF THE FOLLOWING 7 INSTRUCTIONS WAS EXECUTED
+/BY THE PREVIOUS INSTRUCTION
+ JMP MKQSC /MAKE A QUEEN SIDE CASTLING MOVE
+ JMP MKKSC /MAKE A KING SIDE CASTLING MOVE
+ JMP MKEP /EN PASANT
+ TAD (KNIGHT-BISHOP /PROMOTING TO A KNIGHT
+ TAD (BISHOP-ROOK /PROMOTING TO A BISHOP
+ TAD (ROOK-QUEEN /PROMOTING TO A ROOK
+ TAD (QUEEN /PROMOTE TO A QUEEN
+ DCA TEMP3 /STORE ABS VALUE OF THE PROM PIECE
+ TAD I TEMP1 /GET THE VALUE OF THE PROMOTEING PAWN
+ CIA /SUBTRACT IT FROM THE
+ TAD PW /TOTAL VALUE OF THE BOARD
+ DCA PW
+ TAD I TEMP1 /GET THE VAL OF THE MOVING PAWN
+ RAL /LOAD THE SIGN INTO THE LINK
+ CLA
+ TAD TEMP3 /GET ABS VALUE OF PROM PIECE
+ SZL /WAS THE PROMOTING PAWN BLACK?
+ CIA /YES. MAKE THE PROMOTION PIECE BLACK ALSO
+ DCA I TEMP1 /PLACE THE NEW PIECE ON THE BOARD
+ TAD I TEMP1 /ADD THE VALUE OF THE NEW PIECE
+ TAD PW /IN WITH THE TOTAL VALUE
+ DCA PW
+ JMP MKMVDN
+
+MKQSC, TAD TEMP1 /IT'S QUEENS SIDE CASTLING
+ AND [7770
+ DCA TEMP2 /STORE THE ADDR OF QUEENS ROOK BEFORE CASTLING
+ TAD TEMP2
+ TAD (3
+ DCA TEMP1 /STORE ADDRESS OF ROOKS NEW SQUARE
+MKCA1, TAD I TEMP2 /LOAD AC WITH VALUE OF THE ROOK
+ DCA I TEMP1 /PUT THE ROOK DOWN ON ITS NEW SQR
+ DCA I TEMP2 /REMOVE THE ROOK FROM ITS OLD SQR
+ TAD I TEMP1 /GET COLOR OF CASTLING SIDE
+ SPA /IS IT BLACK?
+ ISZ BPSW /YES. SET BIT 11 OF HIS PSW
+ SMA CLA /OR IS IT WHITE?
+ ISZ WPSW /YES. SET BIT 11 OF HIS PSW
+ JMP MKMVDN
+
+MKKSC, TAD TEMP1 /BUILD ADDRESS OF THE
+ IAC /KINGS ROOK
+ DCA TEMP2 /STORE THE ADDR OF KINGS ROOK BEFORE CASTLING
+ TAD (-5 /BUILD THE ADDRESS OF THE ROOKS
+ JMP MKCA1-3 /NEW SQUARE
+
+MKEP, TAD TEMP2 /IT'S AN 'EN PASSANT' CAPTURE
+ AND [7770 /BUILD ADDRESS OF THE PAWN THAT WAS TAKEN
+ DCA TEMP3
+ TAD TEMP1
+ AND [0007
+ TAD TEMP3
+ DCA TEMP3
+ TAD I TEMP3 /SUBTRACT THE PAWNS VALUE
+ CIA /FROM THE TOTAL
+ TAD PW
+ DCA PW
+ DCA I TEMP3 /REMOVE CAPTURED PAWN FROM THE BOARD
+MKMVDN, IFNZRO DEBUG <
+ JMS TSTBRD /TEST BOARD VALUE
+>
+ TAD WHOSE /NOW THAT THE MOVE IS MADE
+ CMA /COMPLIMENT
+ DCA WHOSE /THE "WHOSE MOVE" SWITCH
+ JMP I MKMV /AND RETURN
+
+PAGE
+
+\f
+/SUBROUTINE TO UNMAKE A MOVE MADE BY THE 'MKMV' ROUTINE
+/LIKE THE 'MKMV' SUBROUTINE 'UNMV' IS COLOR INDEPENDENT- USES NO 'CLRFIX'
+UNMV, 0000
+ CLA CLL
+ ISZ DOMAP /SET SWITCH FOR OBSOLETE PIECE MAP
+ IFNZRO DEBUG<
+ JMS TSTBRD /MAKE SURE BOARD VALUE IS OK
+>
+ TAD LSTMV /GET THE MDW FOR THE LAST(THIS) MOVE MADE
+ DCA TOMAK2
+ POP1 /GET THE OLD 'LSTMV' INFO
+ DCA LSTMV /RESTORE IT
+ POP1 /RESTORE BLACKS PSW
+ DCA BPSW
+ POP1 /RESTORE WHITES PSW
+ DCA WPSW
+ TAD TOMAK2 /GET THE MDW FOR THE MOVE
+ SPA CLA /IS IT A CAPTURE?
+ POP1 /YES. GET THE VALUE OF THE CAPTURED PIECE
+ DCA TEMP3 /STORE IT
+ POP1 /GET THE OLD MSW
+ DCA TOMAK1 /STORE THE MSW
+ TAD TOMAK1 /BACK AGAIN
+ JMS I ZSPLIT /UNPACK THE MSW AND BUILD THE 'TO' AND 'FROM' ADDRESSES
+ TAD I TEMP1 /GET THE MOVED PIECE AND
+ IFNZRO DEBUG<
+ SNA /IS IT STILL THERE?
+ HLT /BUG!!!
+>
+ DCA I TEMP2 /PUT IT BACK ON ITS OLD SQUARE
+ TAD TEMP3
+ DCA I TEMP1 /RESTORE THE VALUE OF THE CAPTURED PIECE(OR EMPTY SQUARE)
+ TAD TEMP3 /ADD VAL OF CAPTURED PIECE
+ TAD PW /BACK IN WITH THE TOTAL
+ DCA PW
+ TAD TOMAK2
+ AND [0007
+ SNA /WAS THE MOVE A SPECIAL TYPE?
+ JMP UNMVDN /NO. RETURN
+ TAD (JMP .+2
+ DCA .+1
+ HLT /THE JUMP GOES HERE
+/A JUMP TO ONE OF THE FOLLOWING 7 LOCATIONS WAS
+/EXECUTED BY THE PREVIOUS INSTRUCTION
+ JMP UNQSC /UNMAKE A QUEEN SIDE CASTLING MOVE
+ JMP UNKSC /UNMAKE KING SIDE CASTLING MOVE
+ JMP UNEP /UNMAKE AN EN PASSANT CAPTURE
+ JMP UNQP
+ JMP UNQP
+ JMP UNQP
+UNQP, TAD I TEMP2 /PAWN PROM. MOVE
+ CIA /SUBTRACT PROMOTION VALUE
+ TAD PW /FROM THE TOTAL
+ DCA PW
+ TAD I TEMP2 /GET VALUE OF THE PROMOTION PIECE
+ SMA CLA /WHICH COLOR IS MOVING?
+ TAD (PAWN+PAWN /WHITE IS MOVING.
+ TAD [-PAWN
+ DCA I TEMP2 /RESTORE THE PROMOTION PIECE BACK TO A PAWN
+ TAD I TEMP2 /ADD THE VAL OF THE PAWN
+ TAD PW /IN WITH THE TOTAL VALUE
+ DCA PW
+ JMP UNMVDN
+
+UNKSC, TAD TEMP2 /BUILD ADDR OF ROOKS 'POST CASTLING' SQUARE
+ IAC /BY ADDING +1 TO THE KINGS 'PRE CASTLING' SQUARE ADDRESS
+ DCA TEMP2 /STORE IT
+UNKS1, TAD TEMP2 /BUILD ADDRESS OF THE ROOKS 'PRE CASTLING' SQUARE ADDR
+ TAD (2 /BY ADDING +2 TO ITS 'POST-CASTLING' SQUARE ADDR
+ DCA TEMP1 /STORE ROOKS PRE CASTLING SQUARE ADDRESS
+ TAD I TEMP2 /GET THE ROOKS VALUE
+ DCA I TEMP1 /PLACE THE ROOK BACK ON ITS 'PRE CASTLING' SQUARE
+ DCA I TEMP2 /REMOVE IT FROM ITS 'POST CASTLING SQUARE'
+ JMP UNMVDN
+
+UNQSC, TAD TEMP1 /BUILD THE ADDR OF THE ROOKS 'POST CASTLING SQUARE
+ IAC /BY ADDING +1 TO THE KINGS 'POST CASTLING' SQUARE ADDRESS
+ DCA TEMP2 /STORE IT
+ TAD (-5 /BUILD THE ADDRESS OF THE ROOKS 'PRE CASTLING SQUARE'
+ JMP UNKS1 /SAME AS KING SIDE EXCEPT OVER 5 FILES
+UNEP, TAD TEMP1 /BUILD THE ADDRESS OF THE CAPTURED PAWN
+ AND [0007 /TAKE THE FILE OF THE 'TO SQUARE'
+ DCA TEMP3 /STORE THE TO SQUARE' FILE #
+ TAD TEMP2 /AND EVERYTHING BUT THE FILE #
+ AND [7770 /FROM THE FROM SQUARE ADDRESS
+ TAD TEMP3 /ADD THEN TOGEATHER
+ DCA TEMP3 /STORE
+ TAD I TEMP2 /GET THE VALUE OF THE CAAPTURING PAWN
+ CIA /MAKE THE VALUE THAT OF AN OPOSITE COLORED PAWN
+ DCA I TEMP3 /REPLACE THE PAWN THAT WAS TAKEN 'EN PASSANT'
+ TAD I TEMP3 /ADD PAWNS VALUE
+ TAD PW /IN WITH THE TOTAL
+ DCA PW
+UNMVDN, IFNZRO DEBUG <
+ JMS TSTBRD /VERIFY BOARD VALUE
+>
+ TAD WHOSE /NOW THAT THE MOVE IS UNMADE
+ CMA /COMPLIMENT
+ DCA WHOSE /THE "WHOSE MOVE" SWITCH
+ JMP I UNMV /RETURN
+
+\f/SUBROUTINE TO SPLIT A MSW UP LEAVING THE ADDRESS
+/OF THE 'TO' SQUARE IN LOC 'TEMP1' AND THE ADDRESS OF THE 'FROM'
+/SQUARE IN LOC. 'TEMP2'. CALL WITH MSW IN AC
+SPLIT, 0000
+ DCA TEMP1
+ TAD TEMP1 /FIRST BUILD THE 'FROM' SQUARE ADDRESS
+ RTR CLL
+ RTR
+ RTR
+ AND [0077 /MASK OUT THE GARBAGE IN BITS 0-5
+ TAD [BOARD /ADD IN BOARD ADDRESS CONSTANT
+ DCA TEMP2 /STORE 'FROM' SQUARE ADDRESS
+ TAD TEMP1 /NOW FOR THE 'TO' SQUARE.
+ AND [0077 /MASK OUT BITS 0-5
+ TAD [BOARD /ADD IN BOARD ADDRESS CONSTANT
+ DCA TEMP1 /STORE THE ADDRESS OF THE 'TO' SQUARE
+ JMP I SPLIT /RETURN
+
+/SUBROUTINE TO RETURN THE PLY#-1 IN THE AC.
+/IF THE PLY # IS 8 OR GREATER, 7 IS RETURNED, AND THE LINK IS SET
+/IF PLY # <8 THE LINK IS RETURNED CLEAR
+PLYCHP, 0000
+ CLA STL
+ TAD PLY /GET PLY #
+ TAD [7770 /SUBTRACT 8
+ SMA /IS PLY # 8 OR GREATER ?
+ CLA /YES. PRETEND IT WAS 8
+ TAD [0007 /RESTORE AC VALUE TO PLY#-1
+ JMP I PLYCHP /RETURN
+
+ IFNZRO DEBUG <
+/SUBROUTINE TO GET AN OLD BOARD VALUE FROM PDL#1 AND COMPARE IT WITH THE CURRENT
+/BOARD VALUE. TO VERIFY THE "MKMV" AND "UNMV" SUBROUTINES
+TSTBRD, 0000
+ CLA
+ TAD PW
+ DCA TEMP1
+ JMS BRDVAL /GET CURRENT BOARD VALUE
+ CIA
+ TAD TEMP1
+ SZA CLA /ARE THEY THE SAME?
+ HLT /NO. ERROR SOMEWHERE
+ JMP I TSTBRD /ALL IS WELL
+>
+PAGE
+\f
+
+/SUBROUTINE TO COMPARE THE AC WITH LOCATION 'COMP'
+/RETURN NORMALY IF THEY ARE EQUAL
+/RETURN TO THE ADDRESS+2 OF THE JMS IF THE AC IS LARGER
+/RETURN TO THE ADDRESS+3 OF THE JMS IF 'COMP' IS LARGER
+COMPAR, 0000
+ CIA
+ DCA COMPAC /STORE THE COMPLIMENT OF THE AC
+ TAD COMPAC /COMPARE THE AC WITH 'COMP'
+ TAD COMP
+ SNA CLA /ARE THEY EQUAL?
+ JMP I COMPAR /YES. RETURN NORMALY
+ TAD COMPAC /NO. GET COMPLIMENT OF THE AC AGAIN
+ SPA SNA CLA /WAS THE AC POSITIVE?
+ JMP XXAP /YES. AC WAS POSITIVE
+ TAD COMP /NEGATIVE
+ SMA /IS 'COMP' POSITIVE?
+ JMP XXCL /YES. 'COMP' IS LARGER ALSO
+ TAD COMPAC /NO. BOTH ARE NEGATIVE
+ SPA CLA /BUT WHICH IS THE LARGER?
+ JMP XXAL /THE AC IS THE LARGER
+ JMP XXCL /'COMP' IS THE LARGER
+XXAP, TAD COMP /THE AC WAS POSITIVE
+ SPA /TEST 'COMP' FOR ITS SIGN
+ JMP XXAL /'COMP' IS NEGATIVE, AND THEREFORE LARGER
+ TAD COMPAC
+ SMA CLA
+XXCL, ISZ COMPAR /'COMP' IS LARGER
+XXAL, ISZ COMPAR /AC IS LARGER
+ CLA
+ JMP I COMPAR /RETURN
+COMPAC, 0000
+
+/SUBROUTINE TO TALLY UP THE VALUES OF ALL PIECES ON THE BOARD
+/STORE THE RESULT IN LOC "PW", AND IN THE AC ON RETURN
+BRDVAL, 0000
+ CLA
+ TAD (-100 /INITIALIZE FOR 64 SQUARES
+ DCA TEMP
+ TAD (BOARD-1/ADDRESS-1 OF BOARD
+ DCA ITMP1 /TO AUTO INDEX REG
+ TAD I ITMP1
+ ISZ TEMP /DONE ALL SQUARES?
+ JMP .-2 /NO DO ANNOTHER
+ DCA PW /YES. STORE BOARD VALUE
+ TAD PW /ALSO LOAD INTO AC
+ JMP I BRDVAL /RETURN
+
+PRNCNT, 0000
+
+\fEVAL, 0000
+ CLA
+ IFNZRO RANVAL<
+ TAD I RANDOM /INTRODUCE A RANDOM VARIATION INTO THIS EVALUATION
+ AND (0001 /LET IT BE NO GREATER THAN +1
+>
+ DCA STRATG
+ JMS BREV /DO A BACK RANK EVALUATION
+ JMS COEV /DO A CENTER OCCUPATION EVALUATION
+ JMS CASTEV /EVALUATE CASTLING STATUS
+ TAD PW /ADD THE VALUE OF ALL PIECES ON THE BOARD
+ TAD STRATG /ADD IN STRATEGICAL VALUE
+ JMS LCLRFX /DO A COLOR FIX
+ DCA STRATG /STORE
+ JMS MOBGET /GET MOBILITY VALUE
+ TAD STRATG /ADD IT IN WITH THE TOTAL
+ DCA STRATG /STORE
+/UPCOMING IS A MINI ALPHA BETA PRUNER
+/SINCE THE "HIEP" PART OF THE EVALUATION IS TIME CONSUMING
+/AND IT ONLY SERVES TO MAKE THE EVALUATION RETURNED LESS
+/FAVORABLE FOR THE SIDE TO THAT JUST MOVED, IT IS BOTH
+/WISE AND PROFITABLE TO TRY SAVE TIME THIS WAY
+ TAD STRATG
+ JMS PLYFIX
+ DCA COMP /LOAD SOFTWARE COMPARE REGISTER
+ TAD UVAL1
+ JMS PLYFIX
+ JMS COMPARE/COMPARE VALUES
+ JMP EVAL2 /THEY ARE EQUAL. PRUNE
+ JMP EVAL1 /"HIEP" EVALUATION IS NESSECARY
+ JMP EVAL2 /NO "HIEP" NESSECARY(GOOD)
+EVAL1, JMS HIEP /GET THE CONTROVERSIAL VALUE
+ JMS LCLRFX
+ TAD STRATG
+ JMP I EVAL /RETURN
+
+EVAL2, IFNZRO LPTREE<
+ TAD ("_ /SIGNAL THAT A MINI-PRUNE WAS DONE
+ JMS I ZOUT
+>
+ TAD STRATG /GET VALUE
+ JMP I EVAL /RETURN
+
+\f/SUBROUTINE TO GET THE MOBILITY VALUE FOR THIS POINT IN
+/THE ANALYSIS
+/RETURN WITH VALUE IN THE AC
+MOBGET, 0000
+ CLA
+ TAD MOB0
+ SZA CLA /DO SE HAVE ANY RELIABLE INFORMATION AT HAND ALREADY?
+ JMP MOBGE1 /YES. USE IT
+ ISZ BOGUS /NO. GET SOME NOW
+ TAD GNCNT /SAVE COUNTERS WE ARE ABOUT TO MODIFY
+ PUSH1
+ TAD MOBMOD
+ PUSH1
+ JMS GNBMV /DO A PSEUDO MOVE GENERATION
+ TAD MOBMOD /GET MOBILITY VALUE FOR BLACK
+ DCA MOBGTM /SAVE FOR THE MOMENT
+ ISZ BOGUS
+ JMS GNWMV /DO ANOTHER PSUEDO MOVE GENERATION
+ TAD MOBGTM /SUBTRACT BLACKS MOBILITY VALUE
+ CIA
+ TAD MOBMOD /FROM WHITES
+ JMS LCLRFX
+ DCA MOBGTM /STORE VALUE FOR THE MOMENT
+ POP1 /RESTORE THE COUNTERS THAT WE DESTROYED
+ DCA MOBMOD
+ POP1
+ DCA GNCNT
+ TAD MOBGTM /GET VALUE BACK AGAIN
+ JMP I MOBGET /RETURN
+MOBGE1, TAD MOBMOD /GET MOBILITY VALUE FOR THIS LEVEL
+ SNA /IS THERE ONE FOR THIS LEVEL?
+ TAD MOB0 /NO. USE THE ONE FOR 2 PLYS BACK
+ CIA
+ TAD MOB1
+ CIA
+ JMS PLYFIX
+ JMP I MOBGET /RETURN
+MOBGTM, 0000
+
+PAGE
+\f/THIS IS THE RECURSIVE LOOKAHEAD SUBROUTINE
+/SEARCHES THE GAME TREE "DEPTH" PLYS DEEP. LOACTION "PLY"
+/HOLDS THE CURRENT RECURSION LEVEL, OR DEPTH LEVEL OF THE SEARCH
+/AND MUST BE SET TO = 0, BEFORE THIS ROUTINE IS CALLED FOR THE FIRST TIME
+/SETTING "CVAL1" TO -3777 BEFORE CALLING THIS ROUTINE FOR THE FIRST TIME
+/IS ALSO NICE, TO PREVENT ALPHA-BETA PRUNING AT LEVEL #1
+/THIS ROUTINE ASSUMES THAT THE COMPUTER HAS WHITE, BUT THE "LCLRFX" SUBROUTINE
+/ALLOWS THE COMPUTER TO PLAY BLACK, BY SETING LOCATION "LCLRFX"+1 TO EQUAL
+/A CIA INSTRUCTION
+LOOKA, 0000
+ CLA CLL
+ TAD LOOKA /GET RETURN ADDRESS
+ PUSH1 /SAVE IT IN PDL#1
+ ISZ PLY /INC PLY NUMBER
+ CMA CLA /-1 TO AC
+ TAD PLY
+ SZA CLA /IS THIS THE FIRST PLY?
+ JMP LOOKA1 /NO
+ TAD WHOSE /YES. SETUP "LCLRFX"
+ SMA CLA /WHICH COLOR ARE WE TO LOOK AHEAD ON BEHALF OF?
+ TAD (NOP-CIA/WHITE
+ TAD [CIA /BLACK
+ DCA LCLRFX+1
+ DCA MOBMOD /INITIALIZE MOBILITY VALUES
+ DCA MOB0
+ DCA MOB1
+ DCA ENO /SET EVALUATION COUNTER TO 0
+LOOKA1, TAD UVAL1 /SAVE THE OLD "UPPER LEVEL VALUE"
+ PUSH1 /IN PDL#1
+ TAD CVAL1 /THE OLD "CURRENT LEVEL VALUE"
+ DCA UVAL1 /BECOMES THE NEW "UPPER LEVEL VALUE"
+ TAD PLYFIX+1 /SAVE PLY COMPENSATOR VALUE
+ PUSH1
+ TAD GNCNT /SAVE GENERATION COUNTER
+ PUSH1 /IN PDL#1
+ TAD STRATG /SAVE STRATEGIC VALUE
+ PUSH1
+ DCA GNCNT /CLEAR OUT GENERATION COUNTER, IN CASE NO MOVES ARE GENERATED
+ TAD MOB0 /SAVE MOBILITY OF THE LEVEL 2 ABOVE THIS ONE
+ PUSH1
+ TAD MOB1 /BUMP ALL THE LEVELS BY 1
+ DCA MOB0
+ TAD MOBMOD
+ DCA MOB1
+ DCA MOBMOD /!!!BUG OF AUG 13 FIXED!!!/
+ IFNZRO DEBUG <
+ TAD PDLADR /PUSH A MARKER SO THAT PDL#2 CAN BE VERIFIED
+ PUSH1
+ TAD PC01 /PUSH A MARKER SO THAT PDL#1 CAN BE
+ PUSH1 /VERIFIED TO BE IN LINE
+>
+ TAD PLY /BUILD A NEW PLY COMPENSATOR. FIRST GET PLY #
+ RAR /EVEN/ODD BIT TO LINK
+ SZL CLA /IS PLY # EVEN ?
+ TAD (NOP-CIA/NO. BUILD A NOP INSTRUCTION
+ TAD [CIA
+ DCA PLYFIX+1
+ TAD PLY /PLY # TO AC
+ CIA /COMPARE AGAINST
+ TAD DEPTH /THE MAXIMUM DEPTH
+ SPA CLA /DOES CURRENT PLY# EXCCEDE THE MAX DEPTH #?
+ JMP LEVAL /YES. DO A STATIC EVALUATION OF THE POSITION
+LKFUR, TAD (-3777 /NO. BUILD A STARTING VALUE FOR THIS LEVEL
+ JMS PLYFIX
+ DCA CVAL1 /INITIALIZE VALUE FOR THIS LEVEL
+ JMS GNMVSM /GENERATE THE MOVES OF THE SIDE WHOSE MOVE IT IS
+ TAD CMSW /GIT CHECKMATE SWITCH
+ SZA CLA /IS SIDE TO MOVE IN CHECKMATE?
+ JMP LKCM /YES. DO SOMTHING
+ TAD SMSW /GET STALEMATE SWITCH
+ SZA CLA /IS THE SIDE TO MOVE IN STALEMATE?
+ JMP LKSM /YES. DO SOMTHING
+ JMS PRUNE /ONLY CONSIDER "GOOD" MOVES
+PICK, POP2 /POP A MOVE OUT OF PDL2
+ DCA TOMAK2 /STORE THE MDW
+ POP2
+ SNA /IS IT A MOVE OR THE END OF THE LIST?
+ JMP LKAD /ITS THE END OF THE LIST.
+ DCA TOMAK1 /ITS A MOVE--STORE THE MSW
+IFNZRO LPTREE <
+ TAD TOMAK1
+ DCA IOMSW
+ TAD TOMAK2
+ DCA IOMDW
+ JMS OUTMV /PRINT OUT THE MOVE
+ JMS SPACE /ALSO A SPACE SO THAT THE NEXT TAB STOP IS REACHED
+>
+ JMS I ZMKMV /MAKE THE MOVE
+ JMS I ZLOOKA /PEER FURTHER INTO THE MURKY DEPTHS OF THE GAME TREE
+ IFNZRO LPTREE<
+ JMS I ZCRLF /PRINT A CARRIAGE RETURN
+>
+ JMS I ZUNMV /UNMAKE THE MOVE
+ JMP COMPMV /GO DO A COMPARE
+\f
+/SUBROUTINE TO POP OUT A GROUP OF MOVES FROM PDP#2
+POPOUT, 0000
+ CLA
+ POP2 /OUT MDW
+ POP2 /OUT MSW
+ SZA CLA /IS IT AN MSW OR IS IT THE END OF THE MOVES MARKER?
+ JMP .-3 /IST AN MSW. GO POP OUT ANOTHER MOVE
+ JMP I POPOUT /END. RETURN
+
+/SUBROUTINE TO GENERATE THE MOVES OF THE SIDE WHOSE TURN IT IS TO MOVE
+/AS INDICATED BY THE "WHOSE" SWITCH
+/RETURN WITH THE MOVES IN PDL#2, AND THE AC CLEARED
+GNMVSM, 0000
+ CLA
+ TAD WHOSE /GET "WHOSE MOVE" SWITCH
+ SMA CLA /IS IT WHITES MOVE?
+ JMS GNWMV /YES. GENERATE WHITES MOVES
+ TAD WHOSE
+ SPA CLA /OR IS IT BLACKS MOVE?
+ JMS GNBMV /YES. GENERATE BLACKS MOVES
+ JMP I GNMVSM /RETURN
+PAGE
+
+\fCOMPMV, CLA
+IFNZRO LPTREE <
+ JMS TABPLY /TAB TO COLOMN "PLY"
+ TAD RVAL1
+ JMS OCTOUT
+ TAD CVAL1
+ JMS OCTOUT /PRINT THE VALUE TO BEAT
+>
+ TAD RVAL1 /GET VALUE RETURNED
+ JMS PLYFIX /FIX W/RESPECT TO PLY NUMBER
+ DCA COMP /LOAD SOFTWARE COMPARE REGISTER WITH IT
+ TAD CVAL1 /GET CURRENT VALUE FOR THIS LEVEL
+ JMS PLYFIX /FIX W/RESPECT TO PLY #
+ JMS COMPAR /COMPARE IT WITH THE RETURNED VALUE NOW IN COMPARE REGISTER
+ JMP JMPICK /THEY ARE EQUAL:
+ JMP JMPICK /UNFAVORABLE COMPARE: GO ON TO NEXT MOVE
+RPLACE, TAD RVAL1 /HAIL NEW "BEST MOVE VALUE"
+ DCA CVAL1 /STORE NEW "BEST MOVE VALUE"
+ IFNZRO LPTREE <
+ TAD ("*
+ JMS I ZOUT /THE RETURN MOVE WON INDICATION
+>
+ JMS SETPNT
+ TAD TOMAK1 /MSW
+ DCA I XR0 /INTO "BEST MOVE" TABLE
+ TAD TOMAK2 /MDW
+ DCA I XR0 /INTO THE "BEST MOVE" TABLE
+
+ /COMING UP IS THE "ALPHA BETA PRUNER"
+ /IT CHECKS IF THE NEW "BEST VALUE" FOR THIS LEVEL
+ /IS COMPETITIVE WITH THE "BEST VALUE" ON THE LEVEL ABOVE
+ALPHAB, CLA
+ TAD CVAL1 /GET CURRENT LEVEL VALUE
+ JMS PLYFIX /COMPLIMENT IF THIS IS AN EVEN PLY
+ DCA COMP /LOAD COMPARE REGISTER WITH IT
+ TAD UVAL1 /GET THE VALUE OF THE LEVEL ABOVE
+ JMS PLYFIX
+ JMS COMPAR /COMPARE WITH THE CURRENT LEVEL VALUE IN THE COMPARE REGISTER
+ JMP ALPHAP /EQUAL MEANS PRUNE
+ JMP JMPICK /SORRY. THE VALUE WOULD STILL BE COMPETITIVE ON THE LEVEL ABOVE
+ALPHAP, JMS POPOUT /REMOVE ALL OTHER MOVES ON THIS LEVEL
+ TAD PLY /FOR DEBUG
+ CLA CLL
+ IFNZRO LPTREE<
+ TAD ("!
+ JMS I ZOUT /PRINT INDICATION FOR PRUNE
+>
+ JMP LKAD /YES. GO SET RETURN VALUE
+
+JMPICK, IFNZRO LPTREE <
+ JMS I ZCRLF /CARRIAGE RETURN
+ JMS TABPLY /TAD TO COLOMN # "PLY"
+>
+ CLA
+ JMP PICK
+
+SAVBRD, ROOK
+ KNIGHT
+ BISHOP
+ QUEEN
+ KING
+ BISHOP
+ KNIGHT
+ ROOK
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+BESTBL, ZBLOCK 30 /TABLE TO HOLD THE LAST "BEST MOVE" ON ANY LEVEL
+
+/SUBROUTINE TO SET AUTO-INDEX REG "XRO0" TO POINT TO
+/THE WORD BEFORE THE 2WORD ENTRY IN THE "BESTBL" COROSPONDING WITH THIS PLY
+SETPNT, 0000
+ CLA
+ TAD PLY /GET PLY #
+ CLL RAL /MULT TIMES 2 WORDS IN EACH ENTRY
+ TAD ADCON /ADD IN ADDRESS CONSTANT
+ DCA XR0 /STORE ADDR AS ADVERTISED
+ JMP I SETPNT /RETURN
+ADCON, BESTBL-3
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -ROOK
+ -KNIGHT
+ -BISHOP
+ -QUEEN
+ -KING
+ -BISHOP
+ -KNIGHT
+ -ROOK
+
+PAGE
+\f
+LKAD, CLA /FINISHED GENERATING & EXPLORING MOVES ON THIS LEVEL
+ TAD CVAL1 /SET RETURN VALUE = THIS LEVELS VALUE
+ DCA RVAL1
+ JMP DONE /PREPARE TO RETURN
+
+LKSM, CLA /ITS A STALEMATE!
+ IFNZRO LPTREE<
+ TAD ("=
+ JMS I ZOUT /PRINTOUT STALEMATE INDICATION
+>
+ DCA RVAL1 /SET RETURN VALUE TO TOTALY EVEN GAME ( 0 )
+ JMP LKXM /TAKE SAME RETURN PATH AS A CHECKMATE NOW
+
+/COME HERE TO RETURN FROM THE "LOOKA" SUBROUTINE
+DONE, CLA CMA /-1 TO AC
+ TAD PLY /DECREMENT PLY #
+ DCA PLY
+ TAD UVAL1 /RESTORE VARIOUS DATA TO ITS STATE BEFORE CALLING
+ DCA CVAL1
+ IFNZRO DEBUG <
+ POP1 /POP OUT PDL#1 VERIFIER WORD
+ CIA /SHOULD BE SAME ON EXIT AS WAS ON ENTRY
+ TAD PC01
+ SZA /AFTER COMPLIMENTING, SHOULD BE 0. IS IT?
+ HLT /NO. SURE GLAD I PUT THIS TEST IN!
+ POP1 /DO THE SAME THING FOR PDL#2
+ CIA
+ TAD PDLADR
+ SZA /IS PDL#2 IN LINE?
+ HLT /NO. AMOUNT OFF IS IN THE AC
+>
+ TAD MOB1
+ DCA MOBMOD /RESTORE MOBMOD COUNTER
+ TAD MOB0
+ DCA MOB1
+ POP1
+ DCA MOB0
+ POP1
+ DCA STRATG /RESTORE STRATEGIC VALUE
+ POP1
+ DCA GNCNT /RESTORE OLD MOVE GENERATION COUNTER
+ POP1 /POP OFF OLD PLY COMPENSATOR VALUE
+ DCA PLYFIX+1 /RESTORE IT
+ POP1
+ DCA UVAL1 /RESTORE "UPPER LEVEL VALUE"
+ POP1 /POP OFF RETURN ADDRESS
+ DCA TEMP /RESTORE IT
+ JMP I TEMP /RETURN FROM "LOOKA" SUBROUTINE
+
+\fLKCM, CLA /ITS A CHECKMATE.
+ IFNZRO LPTREE<
+ TAD ("+
+ JMS I ZOUT /PRINT CHECKMATE INDICATION
+>
+ TAD PLY /SUBTRACT PLY # FROM
+ TAD (-3740 /VALUE FOR RETURN VALUE
+ JMS PLYFIX /RETURN VALUE IS POSITIVE IF THIS IS AN EVEN PLY
+ DCA RVAL1
+LKXM, POP2 /POP THE 2 MARKER WORDS OFF OF PDL2
+ POP2 /THAT "GNMV" PUT THERE
+ JMP DONE /READY TO RETURN
+
+/COLOR FIXING SUBROUTINE EXCLUSIVLY FOR THE "LOOKA" SUBROUTINE.
+/FIXES COLOR WITH RESPECT TO PLY EVEN/ODD
+PLYFIX, 0000
+ CIA /=NOP IF PLY IS ODD, OR TO = CIA IF PLY IS EVEN
+ JMP I PLYFIX /RETURN
+
+/GENERAL PURPOSE COLOR FIXING ROUTINE
+/SET "LCLRFX"+1 ONLY ONCE A PROGRAM INITIALIZATION TIME. SET IT TO
+/EQUAL A "NOP" INSTRUCTION IF THE COMPUTER HAS WHITE, SET IT TO A
+/"CIA" INSTRUSTION IF THE COMPUTER HAS BLACK
+LCLRFX, 0000
+ NOP /COMPUTER HAS: WHITE="NOP", BLACK="CIA"
+ JMP I LCLRFX /RETURN
+
+\f/STATIC EVALUATION ROUTINE
+LEVAL, CLA CLL
+ JMS I ZMAPEC /MAP PIECES
+ TAD WHOSE /GET "WHOSE MOVE SWITCH"
+ SMA CLA /IS IT WHITES OR BLACKS?
+ JMP .+4 /WHITES
+ TAD BKING /BLACKS. GET BLACKS KING ADDRESS
+ JMS TSTWAT /FIND OUT IF IT IS ATTACKED
+ JMP .+3
+ TAD WKING /GET WHITES KINGS ADDRESS
+ JMS TSTBAT /FIND OUT IF IT IS ATTACKED
+ TAD PCNT /GET # OF ATTACKERS
+ SZA CLA /IS THE KING IN CHECK?
+ JMP LKFUR /YES. LOOK AHEAD 1 MORE MOVE
+IFNZRO LPTREE <
+ TAD ("#
+ JMS I ZOUT /PRINT EVALUATION INDICATOR
+ ISZ ENO /INC EVALUATION #
+ TAD ENO /FIND OUT IF IT IS OF SPECIAL INTREST
+ CIA /BY TESTING TO SE IF IT IS THE SAME
+ TAD ENOB /AS "ENOB"
+ SNA CLA /IS IT?
+ NOP /YES. A BREAKPOINT FOR ODT MAY BE PLACED HERE
+ TAD ENO /PRINT OUT THE EVALUATION #
+ JMS OCTNFM
+>
+ JMS EVAL /GET AN EVALUATION
+ DCA RVAL1 /SETUP RETURN VALUE
+ JMP DONE /READY TO RETURN
+
+
+/SUBROUTINE TO PRUNE UNDESIRABLE MOVES OUT OF THE TREE BEFORE THEY CREATE
+/HUGE BRANCHES. WHAT TYPES OF MOVES ARE DESIRABLE AND UNDESIRABLE AT ANY GIVEN
+/PLY, IS DETERMINED BY THE TABLE AT LOCATION "PRNPRO"
+/THIS ROUTINE SHOULD SET "PRNCNT" TO THE NUMBER OF MOVES PRUNED
+PRUNE, 0000
+ CLA
+ DCA PRNCNT /INIT PRUNED MOVE COUNTER TO 0
+ TAD GNCHEK /GET # OF CHECKS ON THE KING
+ SZA /IS THE KING IN CHECK?
+ JMP I PRUNE /NO. DONT PRUNE ANY MOVES
+ JMS PLYCHP /GET PLY #
+ TAD (JMP I .+3 /BUILD A JMP I TO THE PROPER PRUNE PROCEDURE
+ DCA .+1 /PUT THE JMP I DOWN SO THAT IT MAY BE EXECUTED
+ HLT /JMP GOES HERE
+
+PRNPRO, PPA /PRUNE PROCEDURE FOR PLY 1
+ PPB /PRUNE PROCEDURE FOR PLY 2
+ PPB /PRUNE PROCEDURE FOR PLY 3
+ PPB /PRUNE PROCEDURE FOR PLY 4
+ PPB /PRUNE PROCEDURE FOR PLY 5
+ PPB /PRUNE PROCEDURE FOR PLY 6
+ PPB /PRUNE PROCEDURE FOR PLY 7
+ PPB /PRUNE PROCEDURE FOR PLY 8 OR GREATER
+
+PPA, JMS BSTOP /COUNT ON A "PRE-ANALYSIS"
+PPZ, JMP I PRUNE /RETURN
+
+PPB, JMS HIEP /FIND OUT THE VALUE OF THE MOST FAVORABLE EN PRISE PIECE CAPTURE
+ SNA CLA /DOES A FAVORABLE ONE EXIST?
+ JMP .+4 /NO. COUNT ON THE ENTRY IN "BESTBL"
+ JMS SETPNT /YES. SETUP POINTER FOR THE INSERTION
+ TAD HIEPMS /OF THE EN PRISE PIECE CAPTURE MSW
+ DCA I XR0 /INTO THE "BESTBL"
+ JMS BSTOP /IF IT EXISTS, BSTOP WILL INSURE THAT IT IS LOOKED AT FIRST
+ JMP I PRUNE /RETURN
+PAGE
+\f/SUBROUTINE TO SCAN THROUGH THE LAST BUNCH OF MOVES IN PDL#2
+/IF A MOVE EXISTS, WHICH HAS THE SAME MSW AS THE LAST "BEST MOVE"
+/ON THIS PLY, THAT MOVE IS SWAPED WITH THE MOVE ON THE TOP OF THE LIST
+BSTOP, 0000
+ JMS SETPNT
+ TAD I XR0
+ CIA
+ DCA TEMP2
+ TAD GNCNT
+ CIA
+ TAD PRNCNT
+ SNA /ANY MOVES TO RUMMAGE THRU?
+ JMP I BSTOP /NO. RETURN
+ DCA TEMP /SETUP COUNT
+ TAD TEMP
+ CLL RAL /MULT TIMES 2 WORDS PER MOVE
+ TAD PDLADR
+ DCA TEMP1
+BSTOP1, TAD I TEMP1 /GET AN MSW
+ IFNZRO DEBUG <
+ SNA /DOES IT LOOK LIKE AN MSW
+ HLT /NOT IF ITS 0 IT DOESNT
+>
+ TAD TEMP2
+ SNA CLA /IS IT A MATCH?
+ JMP BSTOP2 /YES!! GO SWAP IT WITH THE MOVE ON TOP
+ ISZ TEMP1 /BUMP POINTER BY 2 TO POINT TO THE NEXT MSW
+ ISZ TEMP1
+ ISZ TEMP /COMPARED AGAINST ALL MOVES?
+ JMP BSTOP1 /NO. DO ANOTHER
+ JMP I BSTOP /YES. RETURN
+BSTOP2, TAD PDLADR
+ TAD (-2
+ DCA TEMP
+ TAD I TEMP
+ DCA I TEMP1
+ TAD TEMP2
+ CIA
+ DCA I TEMP
+ ISZ TEMP
+ ISZ TEMP1
+ TAD I TEMP1
+ DCA XR0
+ TAD I TEMP
+ DCA I TEMP1
+ TAD XR0
+ DCA I TEMP
+ JMP I BSTOP
+
+
+\f/SUBROUTINE TO EVALUATE THE BACK RANK
+/TO FIND OUT WHAT'S NOT DEVELOPED, AND RETURN A VALUE FOR DEVELOPMENT
+BREV, 0000
+ CLA
+ TAD (NOP
+ DCA BREV2 /SETUP TO DO THE WHITE SIDE FIRST
+ JMS BREV1 /DO AN EVALUATION
+ CIA /NEGATE THE VALUE FOR WHITES SIDE
+ TAD STRATG
+ DCA STRATG
+ TAD [CIA
+ DCA BREV2 /SETUP TO DO THE BLACK SIDE
+ TAD (70 /RANK 8
+ JMS BREV1 /DO THE BLACK EVALUATION
+ TAD STRATG
+ DCA STRATG
+ JMP I BREV /RETURN WITH IT
+
+BREV1, 0000
+ TAD (BOARD-1/CONSTANT FOR BOARD ADDRESS
+ DCA ITMP0
+ DCA TEMP2 /INIT MINOR PIECE COUNTER
+ TAD [7770 /COUNT FOR 10 SQUARES ON THE BACK RANK
+ DCA TEMP1
+ TAD I ITMP0 /GET THE PIECES VALUE
+BREV2, HLT /COMPLIMENT IT IF IT IS BLACK
+ TAD (-KNIGHT
+ SNA /IS IT A KNIGHT?
+ ISZ TEMP2 /YES. INC MINOR PIECE COUNTER
+ TAD (KNIGHT-BISHOP
+ SNA CLA /IS IT A BISHOP?
+ ISZ TEMP2 /YES. INC MINOR PIECE COUNTER
+ ISZ TEMP1 /DONE ALL 8 SQUARES YET?
+ JMP BREV2-1 /NO. GO BACK AND DO ANOTHER
+ TAD TEMP2 /ADD IN # OF MINOR PIECES
+ RAL CLL /MULT TIMES 2
+ RAL CLL /MULT TIMES 2 AGAIN (2*2=4)
+ JMP I BREV1 /RETURN WITH RANK EVALUATION IN THE AC
+/
+/CENTER OCCUPATION EVALUATOR
+COEV, 0000
+ CLA
+ TAD (-4 /SETUP COUNT FOR 4 CENTER SQUARES
+ DCA TEMP1
+ TAD (TAD I COTB /SETUP TO ACCESS ADDRESSES OF THE 4 CENTER SQUARES
+ DCA COEV1
+COEV1, HLT /GET SQUARES VALUE
+ SNA /IS IT OCCUPIED
+ JMP COEV2 /NO. TEST TO SEE IF DONE
+ SMA CLA /IS IT A WHITE PIECE?
+ TAD (10 /VALUE WILL BE +4
+ TAD (-4 /OR -4 IF IT IS BLACK
+ TAD STRATG /ADD TO THE CENTER OCCUPATION VALUE
+ DCA STRATG
+COEV2, ISZ COEV1 /INC INSTRUCTION SO THAT IT REFFRENCES THE NEXT CENTER SQUARE
+ ISZ TEMP1 /DONE ALL 4 SQUARES YET?
+ JMP COEV1 /NO. DO ANOTHER
+ TAD TEMP /YES. GET FINAL VALUE
+ JMP I COEV /AND RETURN
+\f
+/ADDRESSES OF THE 4 CENTER SQUARES
+COTB, BOARD+33
+ BOARD+34
+ BOARD+43
+ BOARD+44
+
+/CASTLING STATUS EVALUATOR
+CASTEV, 0000
+ CLA
+ TAD WPSW
+ RAR /MOVE "CASTLED BIT" INTO LINK
+ SZL CLA /HAS WHITE CASTLED?
+ TAD (10 /YES ADD TO STRATEGIC VALUE
+ TAD STRATG
+ DCA STRATG
+ TAD BPSW
+ RAR /MOVE "CASTLED BIT" TO THE LINK
+ SZL CLA /HAS BLACK CASTLED YET?
+ TAD [7770 /YES. SUBTRACT POINTS FROM THE STRATEGIC VALUE
+ TAD STRATG
+ DCA STRATG
+ JMP I CASTEV /RETURN
+
+PAGE
+\f/SUBROUTINE TO TEST IF A PIECE IS EN PRISE
+/CALL WITH THE ADDRESS OF THE SQUARE TO BE TESTED IN THE AC
+/IF THE PIECE IS EN PRISE, RETURN WITH THE PREDICTED EXCHANGE
+/LOSS IN THE AC, IF NOT 0 IS RETURNED
+/THE ADDRESS OF THE SQUARE IS RETURNED IN "ENPRAD"
+/RETURN WITH ADDR OF ATTACKER IN "ENPSQR"
+/RETURN WITH ADDR OF THE LEAST VALUABLE DEFENDER IN "PSQR"
+/RETURN WITH THE # OF ATTACKERS IN "ENPCNT"
+/RETURN WITH THE # OF DEFENDERS IN "PCNT"
+ENPRIS, 0000
+ DCA ENPRAD /SAVE ADDR OF EN PRIS SQUARE
+ JMS I ZMAPEC /MAKE SURE PIECE MAP IS UP TO DATE
+ TAD I ENPRAD
+ SNA /IS THERE A PIECE ON IT?
+ JMP I ENPRIS /NO. IDIOT! CONSIDER YOURSELF SAVED
+ SMA CLA /YES. IS IT WHITE OR BLACK?
+ JMP ENPRWH /ITS WHITE
+ TAD ENPRAD /BLACK. FIND OUT ABOUT WHITES ATTACKS
+ JMS TSTWAT
+ TAD PVAL
+ DCA ENPVAL /SAVE VALUE OF SMALEST ATTACKER
+ TAD PCNT
+ SNA /ANY ATTACKERS?
+ JMP I ENPRIS /NO.RETURN
+ DCA ENPCNT /SAVE # OF ATTACKERS
+ TAD PSQR
+ DCA ENPSQR /SAVE ADDR OF LEAST VALUABLE ATTACKER
+ TAD ENPRAD /FIND OUT ABOUT DEFENDERS NOW
+ JMS TSTBAT
+ JMP ENPR0 /ALL DONE SETTING UP. GO TO THE BUISINESS PART
+ENPRWH, TAD ENPRAD /FIND OUT ABOUT BLACK ATTACKS
+ JMS TSTBAT
+ TAD PVAL
+ CIA
+ DCA ENPVAL /SAVE VALUE OF LEAST VALUABLE ATTACKER
+ TAD PSQR
+ DCA ENPSQR /SAVE ADDR OF LEAST VALUABLE ATTACKER
+ TAD PCNT
+ SNA /ANY ATTACKERS?
+ JMP I ENPRIS /NO. RETURN
+ DCA ENPCNT /STORE # OF ATTACKERS
+ TAD ENPRAD /FIND OUT ABOUT WHITES DEFENCE
+ JMS TSTWAT
+ TAD PVAL
+ CIA /COMPLIMENT VALUE OF LEAST VALUABLE DEFENDER
+ DCA PVAL
+ENPR0, TAD ENPCNT /GET # OF ATTACKERS
+ CIA
+ TAD PCNT /COMPARE WITH # OF DEFENDERS
+ SMA CLA /MORE ATTACKERS THAN DEFENDERS?
+ JMP ENPR1 /NO.
+ TAD PCNT /# OF DEFENDERS
+ CLL RAR
+ SZA CLA /MORE THAN 1 DEFENDER?
+ JMP ENPR1 /YES. TOO COMPLICATED TO PREDICT THE SWAP ALL THE WAY DOWN
+ SNL CLA /NO. ARE THERE ANY DEFENDERS AT ALL?
+ JMP ENPR2 /NO. ITS EN PRISE ALL RIGHT
+ TAD I ENPRAD /YES. ITS EXACTLY 1 DEFENDER
+ JMS CLRFIX
+ TAD PVAL /ADD VALUE OF DEFENDER PLUS OBJECT
+ TAD ENPVAL /COMPARE WITH THE ATTACKERS VALUE
+ SMA CLA /IS ATTACKER SMALLER THAN DEFENDER PLUS OBJECT?
+ JMP ENPR3 /NO. THE OBJECT IS NOT EN PRISE
+ TAD PVAL /-D
+ TAD ENPVAL /+A
+ SPA SNA CLA /IS DEFENDER SMALLER THAN ATTACKER?
+ JMP ENPR2 /NO. HE WONT CAPTURE BACK THEN
+ TAD PVAL /YES
+ TAD ENPVAL
+ JMS CLRFIX
+ENPR2, TAD I ENPRAD
+ CIA
+ JMP I ENPRIS /RETURN
+ENPR1, CLA
+ TAD I ENPRAD /COMPARE VALUE OF OBJECT
+ JMS CLRFIX
+ TAD ENPVAL /WITH THE VALUE OF THE ATTACKER
+ SMA /IS THE ATTACKERS VALUE SMALLER?
+ENPR3, CLA /NO. PIECE IS NOT EN PRISE
+ CIA
+ JMS CLRFIX
+ JMP I ENPRIS /RETURN
+ENPRAD, 0000
+ENPVAL, 0000
+ENPSQR, 0000
+ENPCNT, 0000
+ IFNZRO DEBUG<
+/TEST OF THE "ENPRIS" ROUTINE
+TESTEP, JMS INPUT
+ JMS I ZMAPEC
+ TAD [BOARD
+ DCA TSTTMP
+ TAD (7700
+ DCA TSTCNT
+TEP2, TAD TSTTMP
+ JMS ENPRIS
+ SNA /IS IT EN PRIS?
+ JMP TEP1 /NO
+ JMS OCTOUT
+ JMS SPACE
+ TAD TSTTMP
+ JMS OUTSQR
+ JMS I ZCRLF
+TEP1, ISZ TSTTMP
+ ISZ TSTCNT
+ JMP TEP2
+ HLT
+ JMP TESTEP
+TSTTMP, 0000
+TSTCNT, 0000
+>
+PAGE
+\f/SUBROUTINE TO RETURN THE EXCHANGE VALUE OF THE HIGHEST EN PRISE
+/PIECE THAT CAN BE TAKEN BY THE SIDE TO MOVE
+/ADDED IN WITH THE VALUE IS A 10 POINT "PENALTY" FOR EACH ADDITIONAL EN PRISE PIECE
+/THAT CAN BE TAKEN
+/THE VALUE IS RETURNED IN SUCH A WAY THAT IT CAN SIMPLY BE ADDED
+/TO THE EVALUATION
+/CALL WITH AC CLEAR TO USE NORMALY
+/THIS ROUTINE CALCULATES WHOSE MOVE IT IS BY EXAMINING LOCATION "WHOSE"
+HIEP, 0000
+ CLA
+ TAD WHOSE
+ SPA CLA /IS IT WHITES MOVE OR BLACKS?
+ TAD (NOP-CIA /BLACKS - SET "HIEPX"=NOP
+ TAD [CIA /WHITES - SET "HIEPX"=CIA
+ DCA HIEPX /SEE
+ DCA HIEPVL /INIT VALUE TO 0
+ DCA HIEPCN /INIT COUNT TO 0
+ JMS I ZMAPEC /MAKE SURE THE PIECE MAP IS UP TO DATE
+ TAD (-12
+ JMS HIEPFX
+ TAD (MAP+12 /BUILD THE ADDR OF THE PIECE MAP(WHICHEVER ONE IT IS)
+ DCA HMAPAD
+HIEP1, CLA
+ TAD I HMAPAD /GET PIECE ADDR
+ ISZ HMAPAD /INC MAP ADDRESS POINTER
+ SNA /DONE ALL PIECES YET?
+ JMP HIEP2 /YES
+ DCA HIEPTM /STORE ADDR FOR THE MOMENT
+ TAD I HIEPTM /GET THE PIECES VALUE
+ JMS HIEPFX
+ TAD (-KING /COMPARE IT WITH THAT OF A KING
+ SNA CLA /IS IT A KING?
+ JMP HIEP1 /YES. KINGS CANT BE SWAPED ANYWAYS
+ TAD HIEPTM /NO. GET THE PIECES ADDR
+ JMS ENPRIS /FIND OUT IF IT IS ENPRIS
+ SNA /IS IT?
+ JMP HIEP1 /NO. TRY THE NEXT ONE
+ DCA HIEPTM /YES. SAVE THE EXCHANGE VALUE
+ ISZ HIEPCN /INC EN PRIS PIECE COUNTER
+ TAD HIEPVL /GET BEST VALUE SO FAR
+ CIA
+ TAD HIEPTM /COMPARE IT WITH THE ONE JUST AQUIRED
+ JMS HIEPFX
+ SMA CLA /IS THE ONE WE JUST GOT BIGGER?
+ JMP HIEP1 /NO. GO TRY ANOTHER PIECE
+ TAD HIEPTM /YES.MAKE THE ONE WE JUST GOT THE NEW VALUE TO BEAT
+ DCA HIEPVL
+ TAD ENPSQR /BUILD MSW FOR THE MOVE TO CAPTURE THIS EN PRISE PIECE
+ AND [0077 /"FROM SQUARE" IS THAT OF THE
+ RTL CLL /LEAST VALUABLE ATTACKER
+ RTL
+ RTL
+ DCA HIEPTM
+ TAD ENPRAD /"TO SQUARE" IS THAT OF THE PIECE ITSELF
+ AND [0077
+ TAD HIEPTM /COMBINE "TO" AND "FROM" 6BIT ADDRESSES
+ DCA HIEPMS /INTO ONE CONVIENIENT MSW
+ JMP HIEP1 /GO TRY ANOTHER PIECE
+HIEP2, CLA CMA
+ TAD HIEPCN /GET # OF EN PRISE PIECES
+ SPA /WERE THERE ANY?
+ CLA /NO
+ CLL RTL
+ RAL /MULT TIMES 8 AND INCLUDE IN THE VALUE RETURNED
+ CIA
+ JMS HIEPFX
+ TAD HIEPVL /GET THE EXCHANGE VALUE
+ JMP I HIEP /RETURN
+
+HIEPFX, 0000
+HIEPX, HLT /NOP,BLACKS MOVE/CIA,WHITES MOVE
+ JMP I HIEPFX
+
+HIEPVL, 0000
+HIEPTM, 0000
+HIEPCN, 0000
+HIEPMS, 0000
+HMAPAD, 0000
+
+
+/SUBROUTINE TO SETUP THE BOARD
+SETBRD, 0000
+ CLA CLL
+ TAD (-100 /IST PUT ALL OF THE PIECES ON THE BOARD
+ DCA TEMP /SETUP A COUNT FOR 64 SQUARES
+ TAD (BOARD-1
+ DCA ITMP0 /BOARD ADDRESS TO AUTO INDEX REG
+ TAD (SAVBRD-1
+ DCA ITMP1 /SAVED BOARD ADDRESS TO AUTO-INDEX REG
+ TAD I ITMP1 /MOVE FROM THE SAVED BOARD AREA
+ DCA I ITMP0 /TO THE WORKING AREA
+ ISZ TEMP /DONE 64 SQUARES YET?
+ JMP .-3 /NO. DO MORE
+ TAD (-40 /NOW CLEAR OUT THE MIDDLE
+ DCA TEMP
+ TAD (BOARD+17
+ DCA ITMP1
+ DCA I ITMP1
+ ISZ TEMP /CLEARED OUT 32 SQUARES YET?
+ JMP .-2 /NO. DO 1 MORE
+ DCA LSTMV
+ DCA WPSW /ENABLE CASTLING BY WHITE
+ DCA BPSW /AND BY BLACK
+ DCA PW /INITIALIZE TOTAL PIECE VALUE
+ JMP I SETBRD /RETURN
+
+COMTM, IAC /TOURNAMENT MODE SETTING
+ IAC
+COMBM, IAC /BLITZ MODE SETTING
+ DCA DEPTH /DEPTH=3 FOR TOURNAMENT MODE, DEPTH=1 FOR BLITZ MODE
+ JMP COMMAN
+
+PAGE
+\f
+/THIS IS THE INTERRUPT HANDLING ROUTINE
+INTHAN, DCA ACHOLD /SAVE ACCUMULATOR
+ RAL /LINK TO AC11
+ DCA LKHOLD /SAVE LINK
+ KSF /KEYBOARD INTERRUPT?
+ HLT /NO. UNEXPLANED INTERRUPT. PRESS START (CLEAR&CONT) TO CLEAR FLAGS
+ KRB /YES. GET THE CHAR
+ SNA /IS IT A NULL CHARACTER ?
+ JMP RTINT /YES. IGNOR IT TOTALY
+ AND (0177 /MAKE SURE BIT 4 IS SET IN
+ TAD (200 /CASE OF A PARITY TTY
+ DCA CHAR /NOW STORE THE CHAR. FOR EASY ACCESS
+ TAD ISW /GET INPUT IN PROGRESS SWITCH
+ SNA CLA /IS IT SET?
+ JMP RTINT /NO. RETURN AND FORGET THAT THIS HAPPENED
+ TAD CHAR /LOAD IT BACK INTO THE AC
+ JMS I ZOUT /ECCO IT
+ TAD CHAR /TEST IF IT IS TO BE IGNORED
+ TAD (-240
+ SNA CLA /IS IT A SPACE ?
+ JMP RTINT /YES. IGNOR IT
+ ISZ CNTCHR /TOO MUCH INPUT?
+ SKP /NO
+ JMP UGO /YES. PRINT "^U", REINITIALIZE, AND TRY AGAIN
+ TAD CHAR /LOAD THE CHAR BACK INTO THE AC AGAIN
+ TAD (-215 /FIND OUT IF IT IS A SPECIAL CHARACTER (CR OR RUBOUT)
+ SNA /IS IT A CR?
+ JMP LINDUN /YES! HE'S DONE TYPING THE INPUT LINE
+ TAD (215-377
+ SNA /IS IT A RUBOUT CHAR?
+ JMP RUBGO /YES. DELETE THE LAST CHAR TYPED
+ TAD (377-225 /NO
+ SNA CLA /IS IT A CONTROL-U?
+ JMP UGO /YES. DELETE A WHOLE LINE
+ TAD CHAR /NO.
+IFNZRO OS8<
+ TAD (-203
+ SNA CLA /IS CHAR A CONTROL-C ?
+ JMP MONITR /YES
+ TAD CHAR /NO. GET ITS VALUE BACK AGAIN
+>
+ DCA I CLIST /STORE THE CHAR. IN THE KEYBOARD BUFFER
+RTINT, TAD LKHOLD /RESTORE THE LINK TO ITS PRE-INTERRUPT STATE
+ CLL RAR
+ TAD ACHOLD /RESTORE ACCUMULATOR
+ RMF /AND THE MEMORY FIELDS
+ ION /WITH INTERRUPT ENABLED,
+ JMP I IFRM /RETURN TO MAIN PROGRAM
+ACHOLD, 0000 /HOLD AC AFTER INTERRUPT
+LKHOLD, 0000 /HOLD LINK AFTER INTERRUPT
+
+LINDUN, DCA I CLIST /MARK THE END OF INPUT WITH A 0000 CHAR. IN BUFFER
+ TAD (KBUF-1 /REINITIALIZE THE KEYBOARD BUFFER
+ DCA CLIST
+ DCA ISW /CLEAR THE INPUT SWITCH
+ JMS I ZCRLF /PRINT A CARRIAGE RETURN-LINE FEED
+ JMP RTINT /RETURN
+
+LNOGO, JMS I ZCRLF /PRINT A CARRIAGE RETURN LINE FEED
+ JMS I ZBEGIN /REINITIALIZE INPUT BUFFER
+ JMP RTINT /RETURN FROM THE LAST INTERRUPT
+
+/IO STALL SUBROUTINE: RETURN WHEN INPUT IS DONE
+CHKIO, 0000
+ CLA
+ TAD ISW /GET THE INPUT SWITCH
+ ISZ RANDOM /INCREMENT THE RANDOM NUMBER
+ SZA CLA /IS INPUT DONE?
+ JMP .-4 /NO: CHECK AGAIN
+ IOF /DONT NEED THIS ANYMORE
+ JMP I CHKIO /YES: RETURN
+
+RUBGO, CLA
+ TAD (KBUF-1
+ CIA
+ TAD CLIST
+ SNA CLA /ARE WE AT THE BEGINING OF A LINE ALLREADY?
+ JMP LNOGO /YES.
+ TAD ("\ /NO. PRINT A "\" CHAR
+ JMS I ZOUT
+ CMA CLA /NOW MOVE BACK THE BUFFER POINTER
+ TAD CLIST
+ DCA CLIST
+ JMP RTINT /RETURN FROM INTERUPT
+
+UGO, CLA
+ PRINTO; MESG21 /PRINT A "^U"
+ JMP LNOGO /GO SETUP FOR A NEW LINE
+
+\f/FOLLOWING IS THE LEGAL COMMAND LIST
+/IT CONSISTS OF A NUMBER OF 2WORD ENTRIES
+/THE 1ST WORD IN EACH ENTRY IS THE 6BIT REPRESENTATION(NEGATED FOR EASY COMPARING)
+/OF A 2 CHARACTER COMMAND
+/THE 2ND WORD CONTAINS THE ADDRESS TO GO TO IF THAT COMMAND IS TYPED
+COMLST, -2027; COMPW /PW - PLAY WHITE
+ -2002; COMPB /PB - PLAY BLACK
+ -2016; COMPN /PN - PLAY NIETHER WHITE OR BLACK
+ -0204; COMBD /BD - DISPLAY THE POSITION
+ -1120; COMIP /IP - INPUT A POSITION
+ -2205; START /RE - RESET (RESIGN)
+ -1526; CMOVE /MV - MOVE
+ -2313; COMSK /SK - SKIP A MOVE
+ -0215; COMBM /BM - BLITZ MODE
+ -2415; COMTM /TM - TOURNAMENT
+ IFNZRO LPTREE <
+ -1424; COMLT /LT - OUTPUT TREE TO LINE PRINTER(LP08)
+>
+ -0000; 0000 /END OF COMMAND LIST
+
+MESG14, TEXT \STALEMATE\
+MESG24, TEXT \YOUR MOVE? \
+
+PAGE
+\f
+/MESSAGE PRINTING SUBROUTINE--CALL WITH ADDR OF MESSAGE IN AC
+/RETURN WITH THE AC CLEAR
+/IF CALLED WITH THE AC IS CLEAR THE ADDRESS OF THE MESSAGE IS TAKEN FROM THE WORD
+/AT THE ADDRESS+1 OF THE CALL TO THIS SUBROUTINE, AND THE RETURN ADDRESS
+/IS THE ADDRESS+2 OF THE CALLING JMS
+MES, 0000
+ SZA /IS THE ADDRESS OF THE MESSAGE IN THE AC?
+ JMP .+3 /YES. DONT BOTHER GETTING IT FROM THE WORD FOLLOWING THE JMS
+ TAD I MES /NO. BOTHER PLEASE
+ ISZ MES /AND INC THE RETURN ADDRESS
+ DCA TEMP /STORE THE ADDRESS OF THE MASSAGE
+MES2, TAD I TEMP /GRAB 2 CHARS. PACKED INTO 1 WORD
+ RTR
+ RTR
+ RTR
+ JMS TYPO /PRINT CHAR IN BITS 0-5
+ TAD I TEMP
+ JMS TYPO /PRINT CHAR IN BITS 6-11
+ ISZ TEMP /NEXT WORD PLEASE
+ JMP MES2
+
+TYPO, 0000
+ AND [0077 /CLEAROUT BITS BELONGING TO THE OTHER CHAR.
+ SNA /IS IT A NULL CHARACTER?
+ JMP I MES /YES: RETURN
+ TAD [-40 /NO. CONVERT IT TO 8 BIT
+ SPA
+ TAD (100
+ TAD (240
+ JMS I ZOUT /NOW PRINT IT
+ JMP I TYPO
+
+/PRINTOUT SUBROUTINE--SINGLE CHARACTER
+OUT, 0000
+ TLS /FIRST PRINT THE CHAR
+ TSF /WAIT FOR THE FLAG TO RETURN
+ JMP .-1 /NOT YET IT HASN'T
+ TCF /CLEAR FLAG TO AVOID TELLEPRINTER INTERUPTS
+ CLA
+ JMP I OUT /RETURN
+
+/CARRIAGE RETURN & LINE FEED SUBROUTINE
+CRLF, 0000
+ CLA
+ TAD (215
+ JMS I ZOUT /PRINT THE CR
+ JMS I ZOUT /AND A NULL
+ TAD (212
+ JMS I ZOUT /PRINT THE LF
+ JMS I ZOUT /PRINT A COUPLE OF NULL FILLER CHARS IN CASE SOMEONE
+ JMS I ZOUT /TRYS TO USE A FANCY VIDEO-SCREEN TERMINAL
+ JMP I CRLF /RETURN
+
+/INITIALIZE INPUT
+BEGIN, 0000
+ CLA IAC
+ DCA ISW /SET THE 'INPUT IN PROGRESS' SWITCH
+ TAD (KBUF-1 /INITIALIZE THE KEYBOARD BUFFER POINTER
+ DCA CLIST
+ TAD (-30
+ DCA CNTCHR /30 CHARACTERS MAXIMUM
+ KCC /REINITIALZE THE KEYBOARD FLAG
+ JMP I BEGIN /RETURN
+
+/GET A CHARACTER FROM THE INPUT BUFFER
+/IGNOR "-" AND ":" CHARACTERS
+GETC, 0000
+ CLA
+ TAD I CLIST /TAKE A CHAR. OUT OF THE BUFFER
+ DCA TEMP /MAKE IT EASILY REACHED
+ TAD TEMP /FIND OUT IF THE CHAR SHOULD BE IGNORED
+ TAD (-"-
+ SNA /IS IT A MINUS SIGN?
+ JMP GETC+1 /YES. IGNOR IT
+ TAD ("--": /NO. TEST FOR A COLON
+ SNA CLA /IS IT A COLON?
+ JMP GETC+1 /YES. IGNOR IT
+ TAD TEMP /NO. LOAD IT BACK INTO AC
+ JMP I GETC /RETURN
+
+/SUBROUTINE TO PRINT A "SIGNED OCTAL" NUMBER
+OCTOUT, 0000
+ DCA TEMP
+ JMS SPACE /PRINT A LEADING SPACE
+ TAD TEMP
+ SPA CLA /IS IT A NEGATIVE #?
+ TAD ("--" /YES PRINT A MINUS SIGN
+ TAD ("
+ JMS I ZOUT
+ TAD TEMP /GET # AGAIN
+ SPA /IS IT NEGATIVE?
+ CIA /YES. MAKE POSITIVE
+ JMS OCTNFM /PRINT IN OCTAL
+ JMP I OCTOUT /RETURN
+
+/SUBROUTINE TO PRINT OUT AN OCTAL NUMBER WITH NO FORMATING
+OCTNFM, 0000
+ RAL /ROTATE INTO POSITION
+ DCA TEMP
+ TAD (-4
+ DCA TEMP1 /SETUP COUNT FOR 4 DIGITS
+OCTMID, TAD TEMP
+ RAL
+ RTL
+ DCA TEMP
+ TAD TEMP
+ AND [0007
+ TAD ("0
+ JMS I ZOUT
+ ISZ TEMP1
+ JMP OCTMID
+ JMP I OCTNFM /RETURN
+
+/SUBROUTINE TO PRINT A SPACE CHARACTER
+SPACE, 0000
+ CLA
+ TAD (240 /LOAD AC WITH SPACE CODE
+ JMS I ZOUT /SEND IT OUT
+ JMP I SPACE /RETURN
+
+IFNZRO OS8 <
+/PRINT A "^C" AND RETURN TO THE OS8 MONITOR
+MONITR, CLA
+ PRINTO; MESG18 /PRINT "^C"
+ CIF CDF 0 /MONITOR IS IN FIELD 0
+ JMP I (7600 /GO TO MONITOR
+>
+
+IFNZRO LPTREE <
+/SUBROUTINE TO TAB OVER TO COLOMN # "PLY"
+TABPLY, 0000
+ CLA
+ TAD PLY /GET PLY #
+ SNA /IS IT ZERO?
+ IAC /YES. DO ONE TAB ANYWAYS
+ CIA
+ DCA CMBCNT /SETUP COLOMN COUNTER
+ PRINTO; MESG19 /PRINT 8 SPACES
+ ISZ CMBCNT /TABBED ENOUGH PLACES YET?
+ JMP .-3 /NO. TAB AGAIN
+ JMP I TABPLY /YES. RETURN
+CMBCNT, 0000
+>
+PAGE
+\f
+/SUBROUTINE TO TRY TO INTERPERT THE CONTENTS OF THE KEYBOARD
+/BUFFER AS A MOVE TYPED IN USING MODIFIED
+/ALGEBREIC NOTATION, TEST THE MOVES LEGALITY, AND MAKE THE
+/MOVE ON THE BOARD
+/IF INPUT IS NOT A LEGAL MOVE RETURN IS TO THE ADDRESS+1
+/OF THE CALLING JMS AND THE AC MAY NOT BE CLEARED
+INMV, 0000
+ CLA
+ DCA IOMSW /INITIALIZE MSW AND MDW
+ DCA IOMDW
+ JMS I ZGETC /GET A CHARACTER
+ JMS ISA2H /IS IT A LETTER "A" TO "H" ?
+ JMP INCA /NO. MOVE MUST BE CASTLING
+ TAD (-301
+ RTL CLL
+ RTL
+ RTL
+ JMS INPAK /STORE THIS CHAR AND GET NEXT
+ JMS IS128 /IS IT A NUMBER "1" TO "8" ?
+ JMP I INMV /NO: BAD INPUT, TAKE ERROR RETURN
+ TAD (-261
+ RTR CLL /ROTATE BITS 9-11 INTO THE 'FROM RANK' POSITION
+ RTR
+ JMS INPAK /PACK IT INTO MSW AND GET NEXT CHAR
+ JMS ISA2H /IS IT A LETTER "A" TO "H" ?
+ JMP I INMV /NO. TAKE ERROR RETURN
+ TAD (-301
+ JMS INPAK
+ JMS IS128 /IS IT A NUMBER "1" TO "8" ?
+ JMP I INMV /NO. TAKE ERROR RETURN
+ TAD (-261
+ RTL CLL /YES. ROTATE BITS 9-11 INTO THE 'TO RANK' POSITION
+ RAL
+ JMS INPAK
+ TAD (-"=
+ SZA CLA /IS IT AN EQUAL SIGN?
+ JMP INMID-1 /NO. INPUT FINISHED, CHECK FOR LEGALITY
+ NOP /YES. HE SAYS IT'S A PAWN PROMOTION
+ JMS I ZGETC /GET THE LETTER OF THE PROMOTION PIECE
+ TAD (-"Q
+ SNA /IS IT A QUEEN?
+ JMP IPPQ /YES
+ TAD ("Q-"R
+ SNA /IS IT A ROOK?
+ JMP IPPR /YES
+ TAD ("R-"B
+ SNA /IS IT A BISHOP?
+ JMP IPPB /YES
+ TAD ("B-"N
+ SNA /IS IT A KNIGHT?
+ JMP IPPN /YES
+ JMP I INMV /NO. NONE OF THE ABOVE. TAKE ERROR RETURN
+IPPQ, IAC
+IPPR, IAC
+IPPB, IAC
+IPPN, TAD (0004
+ DCA IOMDW
+ JMP INMID-1
+
+INCA, TAD (-"O
+ SZA CLA /COULD IT BE CASTLING?
+ JMP I INMV /NO TAKE ERROR RETURN
+ JMS I ZGETC /IT MUST BE CASTLING, GET NEXT CHAR
+ TAD (-"O
+ SZA CLA /IS IT AN "O" ?
+ JMP I INMV /NO. TAKE ERROR RETURN
+ TAD PONDIR /YES. THE MOVE IS CASTLING CALCULATE THE 8TH RANK
+ AND (7070 /AND USE IT TO HELP BUILD AN MSW
+
+ TAD (0406 /KING ALWAYS STARTS FROM FILE 4
+ DCA IOMSW
+ JMS I ZGETC /GET ANOTHER CHAR
+ TAD (-"O /ANOTHER "O" MEANS QUEEN SIDE CASTLING
+ SZA /IS IT QUEENS SIDE?
+ JMP INMID-1 /NO. INPUT DONE. CHECK FOR LEGALITY
+ TAD (-4 /YES. CHANGE 'TO FILE' TO C
+ TAD IOMSW
+ DCA IOMSW
+ JMS GNMVSM /GENERATE THE MOVES OF THE SIDE TO MOVE
+INMID, POP2 /POP OFF AN MDW
+ DCA TOMAK2 /STORE IT
+ POP2 /POP OFF AN MSW
+ SNA /IS IT AN MSW OR THE END OF THE LIST?
+ JMP I INMV /END OF LIST AND MOVE NOT FOUND, TAKE ERROR RETURN
+ CIA
+ TAD IOMSW /COMPARE THE MSW WITH THE ONE HE INPUTED
+ SZA CLA /MATCH?
+ JMP INMID /NO: TRY NEXT
+ TAD IOMSW /YES
+ DCA TOMAK1 /STORE THE MSW
+ TAD IOMDW /GET THE INPUTED MDW
+ SNA CLA /IS IT = 0 ?
+ JMP INMID2 /YES. MOVE IS LEGAL
+ TAD TOMAK2
+ AND [0007 /CLEAR IRRELEVENT BITS
+ CIA
+ TAD IOMDW
+ SZA CLA /DO THE IMPORTANT PARTS OF THE MDW'S MATCH?
+ JMP INMID /NO TRY NEXT MOVE FOR A MATCK
+INMID2, JMS I ZMKMV /MAKE THE MOVE
+ IPDL1 /REINITIALIZE PUSH DOWN LIST #1
+ JMS POPOUT /REINITIALIZE PDL2
+ ISZ INMV /NORMAL RETURN IS TO THE ADDRESS+2 OF THE CALLING JMS
+ JMP I INMV /RETURN
+
+\f/SUBROUTINE USED BY INMV. ADDS NEW COMPONENT TO 'IOMSW'
+/ALSO GETS NEXT CHAR FROM THE BUFFER, AND RETURN WITH ITS VALUE IN THE AC
+INPAK, 0000
+ TAD IOMSW
+ DCA IOMSW
+ JMS I ZGETC
+ JMP I INPAK
+
+MESG18, TEXT \^C\
+MESG15, TEXT \O-O-O\
+NAME, TEXT \CHEKMO-II\
+
+PAGE
+\f/SUBROUTINE TO OUTPUT A MOVE IN MODIFIED ALGEBREIC NOTATION
+/CALL WITH MSW IN 'IOMSW', AND MDW IN 'IOMDW'
+OUTMV, 0000
+ CLA
+ TAD ("
+ DCA IOCH1
+ TAD ("
+ DCA IOCH2
+ TAD IOMDW
+ AND [0007 /BUILD A JUMP
+ TAD (JMP .+3
+ DCA .+1
+ HLT /A JUMP TO ONE OF THE NEXT 8 INSTRUCTIONS IS PLACED HERE
+
+ JMP OUTSTD /STANDARD OUTPUT FOR NORMAL MOVES
+ JMP OUTQCA /QUEEN-SIDE CASTLING
+ JMP OUTKCA /KING-SIDE CASTLING
+ JMP OUTSTD /STANDARD OUTPUT FOR 'EN PASSANT' CAPTURES
+ TAD ("N-"B /PRIMOTE TO A KNIGHT
+ TAD ("B-"R /PROMOTE TO A BISHOP
+ TAD ("R-"Q /PROMOTE TO A ROOK
+ TAD ("Q /PROMOTE TO A QUEEN
+ DCA IOCH2
+ TAD ("= /PRINT AN EQUAL SIGN BEFORE LETTER OF THE PROMOTION PIECE
+ DCA IOCH1
+OUTSTD, CLA /DO STANDARD OUTPUT
+ TAD IOMSW /GET THE MSW FOR THE MOVE TO BE OUTPUT
+ RTR /ROTATE THE 'FROM FILE' BITS INTO AC 9-11
+ RTR
+ RTR
+ JMS OUTSQR /OUTPUT THE "FROM" SQUARE COORDINATES
+ TAD IOMDW /TEST TO SEE IF MOVE IS A CAPTURE
+ SPA CLA /IS IT?
+ TAD (":-"- /YES: OUTPUT A ":" INSTEAD OF A "-"
+ TAD ("- /LOAD AC WITH THE CODE FOR A DASH
+ JMS I ZOUT /OUTPUT IT
+ TAD IOMSW /GET MSW
+ JMS OUTSQR /OUTPUT THE "TO" SQUARE COORDINATES
+ TAD IOCH1 /THIS IS A SPACE UNLESS MOVE IS A PAWN PROMOTION
+ JMS I ZOUT
+ TAD IOCH2 /THIS IS A SPACE UNLESS MOVE IS A PAWN PROMOTION
+ JMS I ZOUT /PRINT THE LAST CHARACTER AND,
+ JMP I OUTMV /RETURN
+
+\f/SUBROUTINE TO OUTPUT THE COORDINATES OF A SQUARE
+/CALL WITH SQUARE # IN AC BITS 6-11
+OUTSQR, 0000
+ DCA IOTMP /SAVE SQR #
+ TAD IOTMP
+ AND [0007 /CLEAR BITS 0-8
+ TAD (301 /OUTPUT FILE AS A CHARACTER "A" TO "H"
+ JMS I ZOUT
+ TAD IOTMP /GET MSW
+ RTR /MOVE RANK INTO BITS 9-11
+ RAR
+ AND [0007
+ TAD (261 /BUILD A CHARACTER "1" TO "8"
+ JMS I ZOUT /OUTPUT IT
+ JMP I OUTSQR /RETURN
+
+OUTKCA, IAC /PASS OVER THE FIRST "O-" OF THE QUEEN SIDE CASTLING MESSAGE
+OUTQCA, TAD (MESG15 /GET ADDRESS OF THE QUEEN SIDE CASTLING MESSAGE
+ PRINTO /TYPE THE MESSAGE
+ JMP I OUTMV /RETURN
+IOCH1, 0000
+IOCH2, 0000
+IOTMP, 0000
+
+/SUBROUTINE TO CHECK FOR A CHARACTER FROM "1" TO "8". SKIP IF IT IS
+/CALL W/CHARACTER IN AC, RETURN SAME WAY
+IS128, 0000
+ TAD (-"1
+ SPA /GREATER OR EQUAL TO "1"?
+ JMP .+4 /NO. DON'T SKIP
+ TAD [7770
+ SPA CLA /LESS THAN "8"?
+ ISZ IS128 /YES. INC RETURN ADDRESS
+ CLA
+ TAD TEMP /LOAD THE CHARACTER BACK INTO THE AC
+ JMP I IS128 /RETURN
+
+\f/SUBROUTINE TO CHECK FOR A CHARACTER FROM "A" TO "H"
+/CALL W/CHARACTER IN AC, RETURN SAME
+/SUBROUTINE EFFECTS A SKIP IF CHAR IS BETWEEN "A" AND "H"
+ISA2H, 0000
+ TAD (-"A
+ SPA /IS IT >= "A" ?
+ JMP .+4 /NO. DONT SKIP
+ TAD [7770
+ SPA CLA /IS IT <= "H" ?
+ ISZ ISA2H /YES. INC RETURN ADDRESS
+ CLA
+ TAD TEMP /GET CHAR BACK
+ JMP I ISA2H /RETURN
+
+/SUBROUTINE TO TEST FOR CHECKMATE OR STALEMATE
+QMATE, 0000
+ JMS GNMVSM /GENERATE THE MOVES OF THE SIDE WHOSE MOVE IT IS
+ JMS POPOUT /DONT NEED THE MOVES JUST THE INFO ON THEM
+ TAD GNCNT /GET # OF MOVES GENERATED
+ SZA CLA /ANY?
+ JMP I QMATE /YES. RETURN
+ TAD CMSW /NO. GET CHECKMATE SWITCH
+ SNA CLA /IS IT SET?
+ TAD (-MESG9+MESG14 /NO. GET ADDR OF STALEMATE MESSAGE
+ TAD (MESG9 /ADD ADDR OF CHECKMATE MESAGE
+ PRINTO /PRINT THE MESSAGE OUT
+ JMS I ZCRLF
+ JMS DISPLA /PRINTOUT THE FINAL POSITION
+ JMP START /START A NEW GAME
+
+
+ IFNZRO LPTREE <
+COMLT, TAD LTSW
+ CMA
+ DCA LTSW
+ JMP COMMAN
+>
+COMSK, TAD WHOSE /COMPLIMENT THE "WHOSE MOVE" SWITCH
+ CMA /SO THAT SOMEONE MISSES A MOVE
+ DCA WHOSE
+ DCA LSTMV /DISABLE EN PASSANT PAWN CAPTURES FOR THE NEXT MOVE
+ JMP COMMAN
+
+PAGE
+\fMESG19, TEXT \ \
+MESG21, TEXT \^U\
+
+IFNZRO LPTREE <
+/SUBROUTINE TO OUTPUT A CHARACTER TO THE LINE PRINTER
+/CALL WITH THE CHAR. IN THE AC, RETURN WITH THE AC CLEARED
+LPTOUT, 0000
+ SNA /TRYING TO PRINT A NULL CHAR ?
+ JMP I LPTOUT /YES. DONT BOTHER, JUST RETURN
+ DCA LPTMP /STORE THE CHAR JUST FOR A MOMENT
+ TAD LTSW /GET TREE PRINTOUT SWITCH
+ SNA CLA /IS IT SET?
+ JMP I LPTOUT /NO. DO NO OUTPUT TO THE LINE PRINTER
+ LAS /READ SWITCHES
+ SMA CLA /SWITCH 0 SET?
+ JMP I LPTOUT /NO. DO NOT OUTPUT TO LINE PRINTER
+ TAD LPTMP /YES.
+ PSKE /ERROR?
+ SKP /NO. CONTINUE
+ JMP .-2 /YES. WAIT FOR THE ERROR TO GO AWAY
+ PSKF /IS THE PRINTER READY TO ACCEPT THE CHAR?
+ JMP .-1 /NO. TEST AGAIN, AND AGAIN
+ PCLF PSTB /YES. PRINT IT
+ CLA /GET READY TO RETURN
+ PCIE /CLEAR LINE PRINTER INTERUPT FLAG
+ JMP I LPTOUT /RETURN
+LPTMP, 0000 /TEMP STORAGE FOR LINE PRINTER ROUTINE
+LTSW, 0000 /TREE PRINTOUT SWITCH
+>
+\f/ CHESSBOARD PRINTER
+
+DISPLAY,0
+ JMS I ZCRLF /PRINT A BLANK LINE
+ TAD (BOARD+70-1
+ DCA RNKPTR /POINT TO TOP RANK
+ TAD [7770
+ DCA RNKKNT /SET UP FOR 8 RANKS
+RNKLUP, TAD RNKPTR
+ DCA XR0 /POINT TO BEFORE LEFTMOST SQUARE IN RANK
+ TAD [7770
+ DCA FILKNT /SET UP FOR 8 SQUARES PER RANK
+ JMP RL1
+RL2, TAD (240
+ JMS I ZOUT
+RL1, DCA COLOR /SET COLOR TO ZERO
+ TAD I XR0 /GET PIECE
+ SNA /IS SQUARE OCCUPIED?
+ JMP EMPTY /NO
+ SPA /YES
+ ISZ COLOR /SET COLOR TO 1 IF BLACK PIECE
+ SPA
+ CIA /TAKE ABSOLUTE VALUE OF PIECE
+ TAD [-PAWN
+ SNA /IS IT A PAWN?
+ JMP DP /YES
+ TAD (PAWN-KNIGHT/NO
+ SNA /IS IT A KNIGHT?
+ JMP DN /YES
+ TAD (KNIGHT-BISHOP/NO
+ SNA /IS IT A BISHOP?
+ JMP DB /YES
+ TAD (BISHOP-ROOK/NO
+ SNA /IS IT A ROOK?
+ JMP DR /YES
+ TAD (ROOK-QUEEN /NO
+ SNA /IS IT HER MAJESTY?
+ JMP DQ /YES
+ TAD (QUEEN-KING /NO
+ SNA CLA /IS IT HIS HIGHNESS?
+ JMP DK /YES
+ TAD ("?-"P /IT'S AN UNKNOWN PIECE
+DP, TAD ("P-"N
+DN, TAD ("N-"B
+DB, TAD ("B-"R
+DR, TAD ("R-"K
+DK, TAD ("K-"Q
+DQ, TAD ("Q
+ DCA PIECE /SAVE PIECE
+ TAD COLOR /WHICH COLOR PIECE IS IT?
+ SZA CLA
+ TAD ("B-"W /BLACK
+ TAD ("W /WHITE
+ JMS I ZOUT /PRINT COLOR OF PIECE
+ TAD PIECE
+ JMS I ZOUT /PRINT NAME OF PIECE
+ JMP NEXT
+EMPTY, TAD XR0
+ RTR
+ RAR
+ AND [0007 /ISOLATE RANK
+ TAD XR0 /ADD IN FILE
+ RAR /PUT PARITY IN LINK
+ SZL CLA /WHITE OR BLACK SQUARE?
+ TAD ("--"* /WHITE
+ TAD ("* /BLACK
+ DCA PIECE
+ TAD PIECE
+ JMS I ZOUT
+ TAD PIECE
+ JMS I ZOUT
+NEXT, ISZ FILKNT /AT END OF RANK?
+ JMP RL2 /NO, GO ON TO NEXT SQUARE
+ JMS I ZCRLF /YES, GO TO NEXT RANK
+ TAD RNKPTR
+ TAD [7770
+ DCA RNKPTR
+ ISZ RNKKNT /WAS THIS THE LAST RANK?
+ JMP RNKLUP /NO, PROCEED TO NEXT RANK
+ JMS I ZCRLF /AN EXTRA CRLF FOR GOOD LUCK
+ JMP I DISPLAY /RETURN
+
+PAGE
+\f
+/CHESS POSITION INPUTTER
+/INPUT A LINE AT A TIME IN FORSYTH NOTATION
+/
+/ POSIBLE ERRORS....
+/ 1? TRYING TO PUT TOO MUCH STUFF ON A RANK
+/ 2? INCOMPLETE RANK SPECIFICATION(NOT ENOUGH STUFF)
+/ 3? UNKNOWN PIECE LETTER
+/ 4? PIECE COLOR NOT "W" OR "B"
+
+INPUT, 0
+ JMS I ZCRLF
+ TAD (BOARD+70-1
+ DCA RNKPTR
+ TAD [7770
+ DCA RNKKNT /SET UP FOR 8 RANKS
+RNLUP, TAD RNKPTR
+ DCA XR0
+ TAD (">
+ JMS I ZOUT /PRINT A ">" TO INDIACTE READYNESS FOR INPUT
+ TAD (7767
+ DCA FILKNT
+ JMS I ZBEGIN /SETUP TO READ A LINE OF INPUT
+ ION /GO !
+ JMS I ZCHKIO
+RL3, JMS I ZGETC /READ A CHARACTER
+ SNA /AT END OF LINE?
+ JMP EOL /YES
+ JMS I (IS128 /IS CHAR A DIGIT?
+ JMP LETTR /NO
+ TAD (-260 /YES, CONVERT TO DIGIT
+ CIA
+ DCA COLOR
+ JMS CHK /TEST FOR TOO ENOUGH STUFF ON THIS RANK ALREADY
+ DCA I XR0
+ ISZ COLOR
+ JMP .-3
+ JMP RL3
+
+LETTR, TAD (-"B
+ SNA /IS IT A BLACK PIECE?
+ JMP BLP /YES
+ TAD ("B-"W
+ SZA CLA /IS IT A WHITE PIECE?
+ JMP ERR4 /NOT "B" OR "W"
+WHP, STA
+BLP, DCA COLOR
+ JMS CHK
+ JMS I ZGETC /GET PIECE NAME
+ TAD (-"B
+ SNA /IS IT A BISHOP?
+ JMP GB /YES
+ TAD ("B-"N /NO
+ SNA /IS IT A KNIGHT?
+ JMP GN /YES
+ TAD ("N-"P /NO
+ SNA /IS IT A PAWN?
+ JMP GP /YES
+ TAD ("P-"R /NO
+ SNA /IS IT A ROOK?
+ JMP GR /YES
+ TAD ("R-"K /NO
+ SNA /IT IT A KING?
+ JMP GK /YES
+ TAD ("K-"Q /NO
+ SNA /IT IT A QUEEN?
+ JMP GQ /YES
+ TAD ("Q-"S /NO
+ SNA CLA /IS IT A SPRINGER?
+ JMP GN /YES, ACCEPT AS KNIGHT
+ JMP ERR3 /UNKNOWN PIECE
+
+GP, TAD (PAWN-KNIGHT
+GN, TAD (KNIGHT-BISHOP
+GB, TAD (BISHOP-ROOK
+GR, TAD (ROOK-QUEEN
+GQ, TAD (QUEEN-KING
+GK, TAD (KING
+ ISZ COLOR /WHICH COLOR
+ CIA /COMPLEMENT VALUE IF BLACK
+ DCA I XR0 /STORE AWAY PIECE
+ JMP RL3 /REITERATE
+
+EOL, ISZ FILKNT /WERE 8 SQUARES INPUTTED?
+ JMP ERR2 /NO, TOO FEW SQUARES
+ TAD RNKPTR
+ TAD [7770
+ DCA RNKPTR /POINT TO NEXT RANK
+ ISZ RNKKNT /WAS THIS LAST RANK?
+ JMP RNLUP /NO
+ DCA BPSW /YES. INITIALIZE POSITION STATUS WORDS
+ DCA WPSW /TO ALLOW CASTLING
+ DCA LSTMV /DISSALLOW EN PASSANT PAWN CAPTURES FOR THE NEXT MOVE
+ JMS BRDVAL /THEN FIGURE OUT ITS VALUE
+/<<DANGER>> THE AC MIGHT NOT EQUAL ZERO NOW!
+ JMS I ZCRLF /LET GUY KNOW HE'S THROUGH
+ JMS DISPLA /PRINT OUT THE BOARD JUST INPUTED
+ JMP I INPUT /RETURN
+
+ERR4, IAC
+ERR3, IAC
+ERR2, IAC
+ERR1, TAD (61
+ JMS I ZOUT
+ TAD ("?
+ JMS I ZOUT
+ JMS I ZCRLF
+ JMP RNLUP
+
+CHK, 0
+ ISZ FILKNT /IS THIS RANK FULL ALREADY?
+ JMP I CHK /NO. KEEP GOING
+ JMP ERR1 /YES. SIGNAL ERROR
+
+MESG9, TEXT \CHECKMATE\
+MESG22, TEXT \B. \
+MESG23, TEXT \W. \
+
+PAGE
+\f*7400
+/TABLE AREA
+
+MAP, ZBLOCK 50 /50 WORDS RESERVED FOR PIECE MAP
+
+KBUF, ZBLOCK 30 /30 WORDS RESERVED FOR THE KEYBOARD BUFFER
+
+/ THE BOARD
+
+BOARD, IFNZRO .&0077<?BOARD MUST OCCUPY 1ST OR 2ND HALF OF A PAGE ?>
+
+
+ ROOK
+ KNIGHT
+ BISHOP
+ QUEEN
+ KING
+ BISHOP
+ KNIGHT
+ ROOK
+
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+ PAWN
+
+ZBLOCK 40
+
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+ -PAWN
+
+ -ROOK
+ -KNIGHT
+ -BISHOP
+ -QUEEN
+ -KING
+ -BISHOP
+ -KNIGHT
+ -ROOK
+
+$&$
+\fSAID FARMER BROWN
+\fWHOSE BALD
+\fON TOP
+\fWISH I COULD
+\fROTATE THE CROP
+\fBURMA SHAVE
+\f
+\fCHEKMO-II WAS WRITTEN, PRODUCED AND DIRECTED BY: JOHN E. COMEAU
+\f
projects / pdp8.git / blobdiff