Hello World: ORG 1000H CO EQU 0x03FA START: LXI H,MSG PRINT: MOV A,M ORA A JZ DONE MOV C,A CALL CO INX H JMP PRINT DONE: RET MSG: DB 'Hellorld!',0 END :10100000 2111 107E B7CA 1010 4FCD FA03 23C3 0310 | 6D (<-this last byte is the checksum) :0B101000 C948 656C 6C6F [20 57 6F] 726C 6421 00 | B5 :00000001 FF H e l l o [ W o ] r l d ! \0 WORKS Mandelbrot generator (C) ChatGPT ORG 0x1000 CO EQU 0x03FA ; ============================================================ ; Mandelbrot for Intel 8080 / MCS-80 KIT ; ; Display: 79 x 23 characters ; ; Fixed point: ; 128 = 1.0 ; ; Program: 1000H onwards ; Stack: 1300H-13FFH -- NEVER TOUCHED BY PROGRAM DATA ; Work: 3000H-33FFH ; ; Exit: RET ; ============================================================ ; ------------------------------------------------------------ ; Parameter block (this is for easier user access so you can just change those with the ML monitor) ; so the machine doesn't have to render the same image again and again at retrocomputing events ; ------------------------------------------------------------ CENTER_X EQU 0x3000 CENTER_Y EQU 0x3002 STEP_X EQU 0x3004 STEP_Y EQU 0x3006 ITER_MAX EQU 0x3008 ; ------------------------------------------------------------ ; Working storage ; ------------------------------------------------------------ TOP_Y EQU 0x3009 CUR_X EQU 0x300B CUR_Y EQU 0x300D Z_X EQU 0x300F Z_Y EQU 0x3011 OLD_X EQU 0x3013 OLD_Y EQU 0x3015 X2 EQU 0x3017 Y2 EQU 0x3019 ITER EQU 0x301B COLS EQU 0x301C ROWS EQU 0x301D SIGN EQU 0x301E MUL_A EQU 0x301F MUL_B EQU 0x3021 ; ============================================================ ; PROGRAM ; ============================================================ START: ; ------------------------------------------------------------ ; Calculate TOP_Y = CENTER_Y - 11 * STEP_Y ; ------------------------------------------------------------ LHLD CENTER_Y SHLD TOP_Y MVI B,11 TOP_Y_LOOP: LHLD TOP_Y XCHG LHLD STEP_Y MOV A,E SUB L MOV E,A MOV A,D SBB H MOV D,A XCHG SHLD TOP_Y DCR B JNZ TOP_Y_LOOP ; ------------------------------------------------------------ ; Start at top row ; ------------------------------------------------------------ LHLD TOP_Y SHLD CUR_Y MVI A,23 STA ROWS ; ============================================================ ; ROW LOOP ; ============================================================ ROW_LOOP: ; ------------------------------------------------------------ ; CUR_X = CENTER_X - 40 * STEP_X ; ------------------------------------------------------------ LHLD CENTER_X SHLD CUR_X MVI B,40 X_START_LOOP: LHLD CUR_X XCHG LHLD STEP_X MOV A,E SUB L MOV E,A MOV A,D SBB H MOV D,A XCHG SHLD CUR_X DCR B JNZ X_START_LOOP ; ------------------------------------------------------------ ; 79 columns ; ------------------------------------------------------------ MVI A,79 STA COLS COLUMN_LOOP: CALL MANDEL_POINT ; ------------------------------------------------------------ ; Map iteration count to density. ; ; 0 -> 0 ; 1..2 -> 1 ; 3..4 -> 2 ; ... ; 13..14 -> 7 ; 15+ -> 7 ; ------------------------------------------------------------ CPI 15 JC DENSITY_LOW MVI A,7 JMP DENSITY_INDEX DENSITY_LOW: INR A RRC ANI 0x07 DENSITY_INDEX: MOV E,A MVI D,0 LXI H,DENSITY DAD D MOV C,M CALL CO ; ------------------------------------------------------------ ; CUR_X += STEP_X ; ------------------------------------------------------------ LHLD CUR_X XCHG LHLD STEP_X DAD D SHLD CUR_X LDA COLS DCR A STA COLS JNZ COLUMN_LOOP ; ------------------------------------------------------------ ; Newline ; ------------------------------------------------------------ MVI C,0x0D CALL CO MVI C,0x0A CALL CO ; ------------------------------------------------------------ ; CUR_Y += STEP_Y ; ------------------------------------------------------------ LHLD CUR_Y XCHG LHLD STEP_Y DAD D SHLD CUR_Y LDA ROWS DCR A STA ROWS JNZ ROW_LOOP RET ; ============================================================ ; MANDEL_POINT ; ; Calculate: ; ; z = z*z + c ; ; starting with z = 0. ; ; Returns A = iteration count. ; ; A = ITER_MAX means the point survived. ; ============================================================ MANDEL_POINT: LXI H,0 SHLD Z_X SHLD Z_Y XRA A STA ITER ITERATE: ; ------------------------------------------------------------ ; Preserve the old Z values. ; ------------------------------------------------------------ LHLD Z_X SHLD OLD_X LHLD Z_Y SHLD OLD_Y ; ------------------------------------------------------------ ; If |X| >= 256, escape. ; ; Allowed values: ; 0000H..00FFH = 0..255 ; FF01H..FFFFH = -255..-1 ; ; FF00H is -256 and must escape too. ; ------------------------------------------------------------ LHLD OLD_X MOV A,H CPI 0x00 JZ X_OK CPI 0xFF JNZ ESCAPED MOV A,L ORA A JZ ESCAPED X_OK: ; ------------------------------------------------------------ ; Same test for Y. ; ------------------------------------------------------------ LHLD OLD_Y MOV A,H CPI 0x00 JZ Y_OK CPI 0xFF JNZ ESCAPED MOV A,L ORA A JZ ESCAPED Y_OK: ; ------------------------------------------------------------ ; X2 = OLD_X * OLD_X ; ------------------------------------------------------------ LHLD OLD_X XCHG LHLD OLD_X CALL SMUL SHLD X2 ; ------------------------------------------------------------ ; Y2 = OLD_Y * OLD_Y ; ------------------------------------------------------------ LHLD OLD_Y XCHG LHLD OLD_Y CALL SMUL SHLD Y2 ; ------------------------------------------------------------ ; Escape if X2 + Y2 >= 4. ; ; With 128 = 1.0: ; ; 4 * 128 * 128 = 65536 ; ; Carry from the 16-bit addition means >= 4. ; ------------------------------------------------------------ LHLD X2 XCHG LHLD Y2 DAD D JC ESCAPED ; ------------------------------------------------------------ ; Convert squares to fixed-point: ; ; raw square / 128 ; ------------------------------------------------------------ LHLD X2 CALL SHR7 SHLD X2 LHLD Y2 CALL SHR7 SHLD Y2 ; ============================================================ ; New X: ; ; X = X2 - Y2 + CUR_X ; ============================================================ LHLD Y2 XCHG LHLD X2 MOV A,L SUB E MOV L,A MOV A,H SBB D MOV H,A ; HL = X2 - Y2 XCHG LHLD CUR_X DAD D SHLD Z_X ; ============================================================ ; New Y: ; ; Y = 2 * OLD_X * OLD_Y + CUR_Y ; ; Raw product is shifted right 6: ; ; (X * Y * 128 * 128) / 64 ; = X * Y * 256 ; ; which represents 2*X*Y at scale 128. ; ============================================================ LHLD OLD_X XCHG LHLD OLD_Y CALL SMUL CALL ASR6 XCHG LHLD CUR_Y DAD D SHLD Z_Y ; ------------------------------------------------------------ ; ITER++ ; ------------------------------------------------------------ LDA ITER INR A STA ITER MOV B,A LDA ITER_MAX CMP B JNZ ITERATE ; Survived all iterations. LDA ITER RET ESCAPED: LDA ITER RET ; ============================================================ ; SMUL ; ; Signed 16-bit multiply. ; ; Input: ; HL = signed value ; DE = signed value ; ; The caller must ensure: ; - Both operands are in -255..+255. ; - The signed product fits in 16 bits. ; ; Output: ; HL = signed product ; ============================================================ SMUL: SHLD MUL_A XCHG SHLD MUL_B ; ------------------------------------------------------------ ; Determine sign of result. ; ------------------------------------------------------------ XRA A STA SIGN LHLD MUL_A MOV A,H ANI 0x80 JZ A_POSITIVE MVI A,1 STA SIGN CALL ABS_HL SHLD MUL_A A_POSITIVE: LHLD MUL_B MOV A,H ANI 0x80 JZ B_POSITIVE LDA SIGN XRI 1 STA SIGN CALL ABS_HL SHLD MUL_B B_POSITIVE: ; ------------------------------------------------------------ ; Low bytes are now the unsigned operands. ; ------------------------------------------------------------ LHLD MUL_A MOV B,L LHLD MUL_B MOV C,L CALL MUL8 ; ------------------------------------------------------------ ; Apply sign. ; ------------------------------------------------------------ LDA SIGN ORA A RZ MOV A,L CMA MOV L,A MOV A,H CMA MOV H,A INX H RET ; ============================================================ ; ABS_HL ; ; Absolute value of signed 16-bit HL. ; ============================================================ ABS_HL: MOV A,H ANI 0x80 RZ MOV A,L CMA MOV L,A MOV A,H CMA MOV H,A INX H RET ; ============================================================ ; MUL8 ; ; Unsigned 8 x 8 -> 16 bit. ; ; Input: ; B = multiplicand ; C = multiplier ; ; Output: ; HL = product ; ============================================================ MUL8: LXI H,0 MOV E,B MVI D,0 MVI B,8 MUL_LOOP: MOV A,C ANI 1 JZ MUL_NO_ADD DAD D MUL_NO_ADD: ; ------------------------------------------------------------ ; DE <<= 1 ; ; Clear carry before shifting E, then propagate E's high ; bit into D. ; ------------------------------------------------------------ XRA A MOV A,E RAL MOV E,A MOV A,D RAL MOV D,A ; ------------------------------------------------------------ ; Examine the next multiplier bit. ; ; RRC is intentional: over eight iterations, each original ; bit of C reaches bit 0 exactly once. ; ------------------------------------------------------------ MOV A,C RRC MOV C,A DCR B JNZ MUL_LOOP RET ; ============================================================ ; SHR7 ; ; Logical right shift HL by 7. ; ; Used only on positive squares. ; ============================================================ SHR7: MVI B,7 SHR7_LOOP: XRA A MOV A,H RAR MOV H,A MOV A,L RAR MOV L,A DCR B JNZ SHR7_LOOP RET ; ============================================================ ; ASR6 ; ; Arithmetic right shift signed HL by 6. ; ============================================================ ASR6: CALL ASR1 CALL ASR1 CALL ASR1 CALL ASR1 CALL ASR1 CALL ASR1 RET ; ============================================================ ; ASR1 ; ; Arithmetic right shift signed HL by one. ; ============================================================ ASR1: MOV A,H ANI 0x80 JZ ASR_POS STC JMP ASR_DO ASR_POS: XRA A ASR_DO: MOV A,H RAR MOV H,A MOV A,L RAR MOV L,A RET ; ============================================================ ; ASCII density LUT ; ; 8 entries, from empty to dense. ; ============================================================ DENSITY: DB ' .-=+*#@' ; ============================================================ ; TEST ROUTINES ; ; These can be started using the monitor's G command. ; ; Results are stored at 3100H onwards. ; The parameter and working storage at 3000H-3022H are ; otherwise unchanged by the test wrappers, except that ; the point tests deliberately set CUR_X, CUR_Y and ITER_MAX. ; ============================================================ ORG 0x1210 ; ------------------------------------------------------------ ; TEST_MUL8_SMALL ; ; 13 * 17 = 221 = 00DDH ; ; Result: 3100H-3101H = DD 00 ; THIS TEST HANGS ON MY MACHINE. But it does write the correct result to memory. ; and all the other tests work! And yes I checked, 120A is C9 which is RET. ; ------------------------------------------------------------ TEST_MUL8_SMALL: MVI B,13 MVI C,17 CALL MUL8 SHLD 0x3100 RET ; ------------------------------------------------------------ ; TEST_MUL8_LARGE ; ; 255 * 255 = 65025 = FE01H ; ; Result: 3102H-3103H = 01 FE ; ------------------------------------------------------------ TEST_MUL8_LARGE: MVI B,255 MVI C,255 CALL MUL8 SHLD 0x3102 RET ; ------------------------------------------------------------ ; TEST_SMUL_NEGPOS ; ; -3 * 5 = -15 = FFF1H ; ; Result: 3104H-3105H = F1 FF ; ------------------------------------------------------------ TEST_SMUL_NEGPOS: LXI H,0xFFFD LXI D,0x0005 CALL SMUL SHLD 0x3104 RET ; ------------------------------------------------------------ ; TEST_SMUL_NEGNEG ; ; -3 * -5 = 15 = 000FH ; ; Result: 3106H-3107H = 0F 00 ; ------------------------------------------------------------ TEST_SMUL_NEGNEG: LXI H,0xFFFD LXI D,0xFFFB CALL SMUL SHLD 0x3106 RET ; ------------------------------------------------------------ ; TEST_SHR7 ; ; 8000H >> 7 = 0100H ; ; Result: 3108H-3109H = 00 01 ; ------------------------------------------------------------ TEST_SHR7: LXI H,0x8000 CALL SHR7 SHLD 0x3108 RET ; ------------------------------------------------------------ ; TEST_ASR6 ; ; -128 >> 6 = -2 = FFFEH ; ; Result: 310AH-310BH = FE FF ; ------------------------------------------------------------ TEST_ASR6: LXI H,0xFF80 CALL ASR6 SHLD 0x310A RET ; ------------------------------------------------------------ ; TEST_POINT_ZERO ; ; c = 0 + 0i ; Expected: 16 iterations ; ; Result: 310CH = 10 ; ------------------------------------------------------------ TEST_POINT_ZERO: LXI H,0 SHLD CUR_X SHLD CUR_Y MVI A,16 STA ITER_MAX CALL MANDEL_POINT STA 0x310C RET ; ------------------------------------------------------------ ; TEST_POINT_NEG1 ; ; c = -1 + 0i ; Expected: 16 iterations ; ; Result: 310DH = 10 ; ------------------------------------------------------------ TEST_POINT_NEG1: LXI H,0xFF80 SHLD CUR_X LXI H,0 SHLD CUR_Y MVI A,16 STA ITER_MAX CALL MANDEL_POINT STA 0x310D RET ; ------------------------------------------------------------ ; TEST_POINT_POS1 ; ; c = +1 + 0i ; Expected: 2 iterations ; ; Result: 310EH = 02 ; ------------------------------------------------------------ TEST_POINT_POS1: LXI H,0x0080 SHLD CUR_X LXI H,0 SHLD CUR_Y MVI A,16 STA ITER_MAX CALL MANDEL_POINT STA 0x310E RET ; ------------------------------------------------------------ ; TEST_POINT_POS2 ; ; c = +2 + 0i ; Expected: 1 iteration ; ; Result: 310FH = 01 ; ------------------------------------------------------------ TEST_POINT_POS2: LXI H,0x0100 SHLD CUR_X LXI H,0 SHLD CUR_Y MVI A,16 STA ITER_MAX CALL MANDEL_POINT STA 0x310F RET ; ------------------------------------------------------------ ; TEST_POINT_NEG2 ; ; c = -2 + 0i ; Expected: 1 iteration ; ; Result: 3110H = 01 ; ; Specifically tests the -256 component boundary. ; ------------------------------------------------------------ TEST_POINT_NEG2: LXI H,0xFF00 SHLD CUR_X LXI H,0 SHLD CUR_Y MVI A,16 STA ITER_MAX CALL MANDEL_POINT STA 0x3110 RET ; ============================================================ ; DEFAULT PARAMETERS ; ; 128 = 1.0 ; ; CENTER_X = -0.5 ; CENTER_Y = 0 ; ; STEP_X = 4/128 = 0.03125 ; STEP_Y = 10/128 = 0.078125 ; ; ITER_MAX = 16 ; ============================================================ ORG 0x3000 DW 0xFFC0 ; CENTER_X = -64 DW 0x0000 ; CENTER_Y = 0 DW 0x0004 ; STEP_X = 4 DW 0x000A ; STEP_Y = 10 DB 16 ; ITER_MAX END If you have an MCS-80, you can just paste this into a terminal. I1000 2A0230220930060B2A0930EB2A06307B$ I1010 955F7A9C57EB22093005C208102A0930$ I1020 220D303E17321D302A0030220B300628$ I1030 2A0B30EB2A04307B955F7A9C57EB220B$ I1040 3005C230103E4F321C30CD9B10FE0FDA$ I1050 57103E07C35B103C0FE6075F160021FD$ I1060 11194ECDFA032A0B30EB2A043019220B$ I1070 303A1C303D321C30C24A100E0DCDFA03$ I1080 0E0ACDFA032A0D30EB2A063019220D30$ I1090 3A1D303D321D30C22810C9210000220F$ I10A0 30221130AF321B302A0F302213302A11$ I10B0 302215302A13307CFE00CAC710FEFFC2$ I10C0 4E117DB7CA4E112A15307CFE00CADA10$ I10D0 FEFFC24E117DB7CA4E112A1330EB2A13$ I10E0 30CD52112217302A1530EB2A1530CD52$ I10F0 112219302A1730EB2A193019DA4E112A$ I1100 1730CDCA112217302A1930CDCA112219$ I1110 302A1930EB2A17307D936F7C9A67EB2A$ I1120 0B3019220F302A1330EB2A1530CD5211$ I1130 CDD811EB2A0D30192211303A1B303C32$ I1140 1B30473A0830B8C2A8103A1B30C93A1B$ I1150 30C9221F30EB222130AF321E302A1F30$ I1160 7CE680CA71113E01321E30CDA011221F$ I1170 302A21307CE680CA88113A1E30EE0132$ I1180 1E30CDA0112221302A1F30452A21304D$ I1190 CDAC113A1E30B7C87D2F6F7C2F6723C9$ I11A0 7CE680C87D2F6F7C2F6723C921000058$ I11B0 1600060879E601CABB1119AF7B175F7A$ I11C0 1757790F4F05C2B411C90607AF7C1F67$ I11D0 7D1F6F05C2CC11C9CDEB11CDEB11CDEB$ I11E0 11CDEB11CDEB11CDEB11C97CE680CAF5$ I11F0 1137C3F611AF7C1F677D1F6FC9202E2D$ I1200 3D2B2A2340$ I3000 C0FF000004000A0010$