10 REM CHEKR.ECB
   15 REM ...CHECKERS...Reworked for SOL-20, 6-17-80, R.E.H.
   20 REM ...AUTHOR: ALAN J. SEGAL
   30 REM ...151 SHRUBHOLLOW ROAD    ROSLYN, N.Y.  11576
   40 REM ...CONVERTED TO CDC BASIC:  S. MUELLER
   50 DIM R(50),S(10,10),B$(25)
   60 LET K$="&K": LET J$="&J": PRINT K$;J$;J$
   70 FOR X=1 TO 22: LET B$=B$+CHR(5): NEXT X
   80 PRINT TAB(15);B$
   90 PRINT TAB(15);B$(1,3);"    CHECKERS    ";B$(1,3)
  100 PRINT TAB(15);B$;J$
  110 PRINT "   This program will play CHECKERS. The computor"
  120 PRINT "is X and you are O. The computor will move first."
  130 PRINT J$;"#CAUTION#"
  140 PRINT "DO NOT TRY TO DOUBLE JUMP.   You will get the"
  150 PRINT "chance.  The squares are in the form (X,Y)"
  160 PRINT "and thus (1,1) is the lower left.": PRINT
  170 DATA -1,-1,1,1,1,1
  180 READ G,L,X1,X2,Y1,Y2
  190 DATA 1,0,1,0,0,0,-1,0
  200 DATA 0,1,0,0,0,-1,0,-1
  210 FOR X=1 TO 8
  220   IF X/2=INT(X/2) THEN  RESTORE 200 ELSE  RESTORE 190
  230   FOR Y=1 TO 8: READ S(X,Y): NEXT Y
  240 NEXT X
  250 PRINT "WAIT FOR THE COMPUTER TO MOVE."
  260 LET L=-1*L
  270 FOR X=1 TO 8
  280   FOR Y=1 TO 8
  290     IF S(X,Y)=0 THEN 370
  300     IF G>0 THEN 320
  310     IF S(X,Y)>0 THEN 370 ELSE 330
  320     IF S(X,Y)<0 THEN 370
  330     IF ABS(S(X,Y))<>1 THEN 350
  340     GOSUB 450
  350     IF ABS(S(X,Y))<>2 THEN 370
  360     GOSUB 610
  370     IF X<>8 THEN 400
  380     IF L=1 THEN 400
  390     RETURN
  400   NEXT Y
  410 NEXT X
  420 PRINT
  430 GOSUB 1060
  440 GOTO 260
  450 FOR A=-1 TO 1 STEP 2: REM ...Regular moves
  460   LET U=X+A
  470   LET V=Y+G
  480   IF U<1 OR U>8 THEN 590
  490   IF V<1 OR V>8 THEN 590
  500   IF S(U,V)=0 THEN  GOSUB 820 ELSE 520
  510   GOTO 590
  520   IF S(U,V)=G THEN 590
  530   IF S(U,V)=2*G THEN 590
  540   LET U=U+A
  550   LET V=V+G
  560   IF U<1 OR U>8 THEN 590
  570   IF V<1 OR V>8 THEN 590
  580   IF S(U,V)=0 THEN  GOSUB 820
  590 NEXT A
  600 RETURN
  610 REM ...KING MOVES
  620 FOR A=-1 TO 1 STEP 2
  630   FOR B=-1 TO 1 STEP 2
  640     LET U=X+A
  650     LET V=Y+B
  660     IF U<1 OR U>8 THEN 780
  670     IF V<1 OR V>8 THEN 780
  680     IF S(U,V)<>1 THEN 780
  690     GOSUB 820
  700     GOTO 780
  710     IF S(U,V)=G THEN 780
  720     IF S(U,V)=2*G THEN 780
  730     LET U=U+A
  740     LET V=V+B
  750     IF U<1 OR U>8 THEN 780
  760     IF V<1 OR V>8 THEN 780
  770     IF S(U,V)=1 THEN  GOSUB 820
  780   NEXT B
  790 NEXT A
  800 RETURN
  810 GOTO 1450
  820 REM ...SUBROUTINE...
  830 LET P=P+1
  840 IF P=K THEN 1150
  850 IF V<>(4.5+(3.5*G)) THEN 870
  860 LET Q=Q+2
  870 IF X<>(4.5-(3.5*G)) THEN 890
  880 LET Q=Q-2
  890 REM ...
  900 IF U<>1 THEN 920
  910 LET Q=Q+1
  920 IF U<>8 THEN 940
  930 LET Q=Q+1
  940 FOR C=-1 TO 1 STEP 2
  950   IF U+C<1 OR V+G<1 THEN 1020
  960   IF S(U+C,V+G)<1 THEN 1010
  970   LET Q=Q-1
  980   IF U-C<1 OR V-G<1 THEN 1020
  990   IF S(U-C,V-G)<>1 THEN 1010
 1000   LET Q=Q-1
 1010   REM ...THIS WAS EVALUATION
 1020 NEXT C
 1030 LET R(P)=Q
 1040 LET Q=0
 1050 RETURN
 1060 IF P=0 THEN 1910
 1070 FOR J=10 TO -10 STEP -1
 1080   FOR F=1 TO P
 1090     IF R(F)=J THEN  EXIT 1120
 1100   NEXT F
 1110 NEXT J
 1120 LET K=F+P
 1130 GOSUB 260
 1140 RETURN
 1150 PRINT K$;"  I'll move from (";X;",";Y;
 1160 PRINT " ) to (";U;",";V;" )"
 1170 LET F=0: LET K=0: LET P=0
 1180 IF V<>(4.5+(3.5*G)) THEN 1210
 1190 LET S(U,V)=2*G: PRINT "... and get a KING."
 1200 GOTO 1220
 1210 LET S(U,V)=S(X,Y)
 1220 LET S(X,Y)=0
 1230 IF ABS(X-U)<>2 THEN 1250
 1240 LET S((X+U)/2,(Y+V)/2)=0
 1250 GOSUB 1420
 1260 RETURN
 1270 LET J9=0: REM ..."Extra jumps" Subroutine
 1280 FOR X=-1 TO 1 STEP 2
 1290   FOR Y=1 TO -1 STEP -2
 1300     IF A+X<1 OR A+X>8 THEN 1390
 1310     IF B+X<1 OR B+X>8 THEN 1390
 1320     IF S(A,B)=1 AND Y=-1 THEN 1390
 1330     IF S(A+X,B+Y)>=0 THEN 1390
 1340     LET X2=A+(X*2): LET Y2=B+(Y*2)
 1350     IF X2<1 OR X2>8 THEN 1390
 1360     IF Y2<1 OR Y2>8 THEN 1390
 1370     IF S(X2,Y2)=0 THEN  LET J9=1 ELSE 1390
 1380     LET X3=A: LET Y3=B
 1390   NEXT Y
 1400 NEXT X
 1410 RETURN
 1420 PRINT : REM ...DISPLAY the BOARD
 1430 PRINT "       1 2 3 4 5 6 7 8"
 1440 PRINT "     ";B$(1,19)
 1450 FOR Y=8 TO 1 STEP -1
 1460   PRINT Y;"   ";B$(1,1);" ";
 1470   FOR X=1 TO 8
 1480     LET I=2*X+4
 1490     ON S(X,Y)+3 GOTO 1500,1510,1520,1530,1540
 1500     PRINT TAB(I);"X*";: GOTO 1550
 1510     PRINT TAB(I);"X";: GOTO 1550
 1520     PRINT TAB(I);".";: GOTO 1550
 1530     PRINT TAB(I);"O";: GOTO 1550
 1540     PRINT TAB(I);"O*";
 1550   NEXT X
 1560   PRINT " ";B$(1,1)
 1570 NEXT Y
 1580 PRINT "     ";B$(1,19);J$
 1590 IF J9=1 THEN  PRINT "You have another jump from ";X3;Y3
 1600 IF J9=-1 THEN  PRINT "I have another jump."
 1610 INPUT "From ---=>",E,H
 1620 LET X=E: LET Y=H
 1630 IF S(X,Y)<>0 THEN 1660
 1640 PRINT
 1650 GOTO 1610
 1660 INPUT " to  ---=>",A,B
 1670 LET X=A: LET Y=B
 1680 IF S(X,Y)=0 THEN 1720
 1690 PRINT "THAT SPACE IS ALREADY OCCUPIED."
 1700 PRINT
 1710 GOTO 1420
 1720 IF J9=0 THEN 1770
 1730 IF E=X3 AND H=Y3 THEN 1770 ELSE  PRINT "&K"
 1740 PRINT "You must continue with the piece at ";X3;Y3
 1750 PRINT : GOTO 1420
 1760 IF J9=0 THEN 1770
 1770 LET S(A,B)=S(E,H): LET J9=0
 1780 LET S(E,H)=0
 1790 LET T=(4.5-(3.5*G))
 1800 IF ABS(E-A)<>2 THEN 1830
 1810 LET S((E+A)/2,(H+B)/2)=0
 1820 GOSUB 1270
 1830 IF B<>T THEN 1850
 1840 LET S(A,B)=-2*G: PRINT "You get a KING."
 1850 IF J9>0 THEN 1420
 1860 FOR X=8 TO 8
 1870   FOR Y=8 TO 8
 1880     RETURN
 1890   NEXT Y
 1900 NEXT X
 1910 PRINT J$;"VERY GOOD ... YOU WIN."
 1920 END