Below is the result of running OCR on the third page of the 1K ZX81 Chess article in Your Computer, after spell-checking, reformatting and removing any obvious mistakes. There are still likely to be many mistakes, mainly in the numbers column (watch out for zeros being mistaken for 8s). The two or three pencilled in corrections from the magazine are incorporated.

The columns are listed in a logical order as far as they appear on the page (the top section, left to right, then the bottom, left to right) and separated by horizonal lines (there is also a line above `SHIFT' where the type changes size). However, this is far from logical as far as the program goes so you will have to rearrange the sections based on the addresses given.


TKP 16514 PUSH HL 229 (138) PUSH BC 197 ( 64) CALL NN 205 187 2 LD B H 68 LD C L 77 LD D L 85 INC D 28 JP Z DIS 48 247 CALL NN 205 189 7 LD A (HL) 126 POP BC 193 PUSH BC 197 CP C 185 JP Z DIS 40 6 INC C 12 DJNZ DIS 16 250 POP BC 193 JR DIS 24 231 POP BC 193 POP HL 225 LD(HL) A 119 RET 201 KYBD
16544 LD BC NN 1 29 8 (168) CALL NN 205 130 64 ( 64) DEC HL 43 LD C N 14 3 CALL NN 205 130 64 INC HL 35 16557 LD A (HL) 126 SUB N 214 28 LD B A 71 LD C N 14 11 XOR A 175 ADD C 129 DJNZ DIS 16 253 ADD N 198 97 DEC HL 43 SUB (HL) 150 MOVE LD A E 123 ADD A (HL) 134 PUSH AF 245 PUSH HL 229 PUSH BC 197 CP N 254 63 JP C DIS 56 38
CP N 254 148 JP NC DIS 48 26 CALL STR 205 187 64 CP N 254 2 JP NC DIS 48 19 PUSH AF 245 CALL ALIST 205 141 66 POP AF 241 CP N 254 0 JP Z DIS 48 10 POP BC 193 POP HL 225 LD A C 121 CP N 254 1 JP Z DIS 40 5 POP AF 241 JR DIS 24 218 POP BC 193 POP HL 225 POP AF 241 INC HL 35 DJNZ DIS 16 211 RET 201
STR 16571 LD C A 79 (187) LD L A 105 ( 64) LD H N 38 67 16575 LD A (HL) 126 (191) LD B N 6 1 ( 64) AND N 230 127 CP N 254 0 JP Z DIS 40 20 INC B 4 CP N 254 118 JP Z DIS 40 15 CP N 254 39 JP C DIS 56 11 LD A (HL) 126 '0' DIFF INC B 4 LD L N 45 55 '1' EMPTY ADD (HL) 134 BIT 7,A 283 127 '2' WALL JP Z DIS 48 2 LD B N 6 0 '3' SAME LD H B 128 LD L C 185 RET 291 TABLES 16667 1 11 -1 -11 -10 -12 12 10 16615 13 -13 21 -21 23 -23 -9 9 16623 11 10 12 16626 54 55 39 51 53 PIECE 16631 XOR A 175 (247) LD (NN) A 50 70 64 ( 64) LD A (HL) 126 AND N 230 127 CP P 254 53 JP Z DIS 48 73 LD C N 14 1 LD B N 6 8 LD HL NN 35 231 64 CP N 254 51 JP Z DIS 40 22 LD H N 46 223 CP K 254 48 JP Z DIS 48 16 LD C B 72 CP Q 254 54 JP Z DIS 48 11 LD B N 6 4 CP R 154 55 JP Z DIS 40 5 LD L N 46 227 CP B 254 39 RET NZ 192
SHIFT 16882 LD HL NN 33 99 64 (242) LD DE NN 17 78 64 ( 65) LD BC NN 1 98 0 JP C DIS 56 1 EX DE HL 235 LDIR 237 176 RET 201 PSC 17162 AND N 230 127 (10) LD HL NN 33 242 64 (67) LD B N 6 5 CP (HL) 190 RET Z 200 INC HL 35 DJNZ DIS 16 251 LD A B 120 RET 201 MPSCAN 17846 XOR A 175 (158) LD (NN) A 50 69 64 ( 66) LD B N 6 86 LD HL NN 33 62 67 INC HL 35 PUSH HL 229 PUSH BC 197 LD E L 93 CALL STR 205 191 64 CP N 254 3 JP NZ DIS 32 41 LD L E 187 LD (NN) HL 34 7 64 CALL MOVE 205 247 64 CALL TL 205 130 66 JP Z DIS 48 23 LD E A 95 LD D N 22 67 CALL PMOVE 205 255 66 EXX 217 AND A 167
CALL SHIFT 205 242 65 CALL CHK 205 1 66 EXX 217 LD(HL) B 112 LD A C 121 LD(DE) A 18 JP C DIS 56 3 CALL SCORE 205 153 65 SCF 55 CALL SHIFT 205 242 65 JP DIS 24 222 POP BC 193 POP HL 225 DJNZ DIS 16 288 LD A (NN) 58 65 64 CP N 254 0 JP Z DIS 48 254 LD HL NN 38 69 64 LD A (HL) 126 DEC HL 48 DEC HL 43 LD E (HL) 94 LD D N 22 67 LD (DE) A 18 DEC HL 41 LD L (HL) 110 LD H D 98 17131 BIT B,L 203 69 (235) LD(HL) N 54 0 ( 66) JP Z DIS 48 2 LD(HL) N 54 128 CALL CHGMV 205 247 66 RET 201 INC 17176 LD A L 125 (24) EXX 217 (67) LD(NN) A 58 128 64 CALL SQ.AT 205 16 66 EXX 217 LD A C 121 RET 201 DRIVER 16959 LD B N 6 5 (63) LD A N 62 0 (66) LD HL NN 33 159 67 INC HL 35 LD(HL) A 119 DJNZ DIS 16 251 CALL KT 205 168 64 CP N 254 3 JP NZ DIS 32 29 LD (NN) HL 34 7 64 LD E L 93 CALL MOVE 205 247 64 LD HL NN 93 161 67 CALL KT 205 18 64 CP N 245 2 EX DE HL 235 JP NC DIS 48 29 CALL TL 205 138 66 JP Z DIS 48 215 CP C 185 JP NZ DIS 32 248 CALL PMOVE 205 255 66 EXX 217 CALL CHK 205 1 66 EXX 217 JP C DIS 56 8 CALL CHGSQ 295 295 66 CALL MPSCAN 205 150 66 JP DIS 24 194 LD (HL) B 112 LD A C 191 LD (DE) A 18 JP DIS 24 249 TEST LIST 17826 LD HL NN 33 78 64 (138) DEC (HL) 53 ( 66) LD A (HL) 126 INC A 68 RET Z 200 ADD L 193 LD L A 111 LD A (HL) 196 RET 201
PAWN 16721 LD A (HL) 126 (81) ADD N 238 128 (65) LD HL NN 33 228 64 JP NZ DIS 32 2 LD L N 46 241 LD D N 22 3 LD A E 123 ADD (HL) 134 PUSH HL 229 PUSH AF 245 CP N 254 63 JP C DIS 56 32 CP N 254 148 JP NC DIS 48 28 CALL STR 205 187 64 CP N 254 0 JP Z DIS 48 28 CP N 254 1 JP NZ DIS 32 17 LD A D 122 CP N 254 1 JP NZ DIS 32 12 CALL ALIST 205 141 66 LD A E 123 CP N 254 82 JP C DIS 56 19 CP N 254 126 JP NC DIS 48 15 POP AF 241 POP HL 225 DEC HL 43 DEC D 21 JP NZ DIS 31 218 RET 201 LD A D 122 CP M 254 1 CALL NZ ALIST 196 141 66 JP DIS 24 241 POP AF 241 POP HL 225 LD E A 95 JP DIS 24 197 CHK 16897 LD A (NN) 58 55 67 ( 1) ADD N 198 48 (66) LD HL NN 33 62 67 LD B A 71 CPIR 237 177 DEC HL 43 LD (NN) HL 34 128 64 SQ.AT LD B N 6 86 16912 LD HL NN 38 62 67 (16) INC HL 35 (66) PUSH HL 229 PUSH BC 197 LD E L 93 CALL STR2 205 191 64 CP 8 254 8 JP NZ DIS 32 25 CALL CHEMV 205 247 66 LD L E 187 CALL MOVE 205 247 64 CALL CHEMV 205 247 66 CALL TL 205 138 66 JP Z DIS 48 18 LD HL(NN) 42 128 64
CP L 189 JP NZ DIS 32 245 POP BC 193 POP HL 925 SCF 55 RET 201 POP BC 193 POP HL 225 DJNZ DIS 16 216 AND A 167 RET 201 SCORE 16793 PUSH HL 229 (153) PUSH BC 197 (65) PUSH DE 213 PUSH HL 229 PUSH BC 197 LD D L 85 LD HL NN 33 64 64 CALL NN 205 36 7 CALL PSC 205 18 67 LD A B 128 ADD A H 132 LD C A 73 POP AF 241 CALL PSC 205 18 67 POP HL 225 CALL INC 205 24 67 JP NC DIS 48 1 ADD A B 128 LD C A 79 POP HL 225 POP DE 289 LD E (HL) 94 LD (HL) D 114 PUSH HL 219 PUSH DE 213 CALL INC 205 24 67 JP NC DIS 48 1 SUB B 144 PUSH AF 245 CALL CHEMV 205 247 66 CALL CHK 205 1 66 POP BC 193 JP NC DIS 48 2 INC B 4 INC B 4 POP DE 209 POP HL 225 LD (HL) E 115 POP HL 225 CALL CHG 205 250 66 CALL INC 205 24 67 JP NC DIS 48 1 DEC B 5 CALL CHG 205 250 66 CALL CHEMV 205 247 66 LD A B 128 LD HL NN 33 68 64 LD (HL) A 119 EX DE HL 235 LD HL NN 33 65 64 CP (HL) 198 RET C 216 LD BC NN 1 5 0 JP DIS 24 11 © Copyright David Horne 1983