Programs
Here are some programs for the SAP-1 using the original instruction set from Ben Eater.
Multiply
Multiplies x by y and outputs the product. Does not handle overflow. Must reset 13 and 14 between executions.
Source: Ben Eater’s video
LDA 14 SUB 12 JC 6 LDA 13 OUT HLT STA 14 LDA 13 ADD 15 STA 13 JMP 0 - 1 product x y
00011110 00111100 01110110 00011101 11100000 11110000 01001110 00011101 00101111 01001101 01100000 00000000 00000001 00000000 00000000 00000000
Division
Divides x by y and outputs the quotient. Must reset 13 and 14 between executions. Infinite loop if dividing by 0.
LDA 14 SUB 15 JC 6 LDA 13 OUT HLT STA 14 LDA 13 ADD 12 STA 13 JMP 0 - 1 0 x y
00011110 00111111 01110110 00011101 11100000 11110000 01001110 00011101 00101100 01001101 01100000 00000000 00000001 00000000 00000000 00000000
Fibonacci
Fibonacci sequence algorithm. Loops after it overflows.
LDI 1 STA 14 LDI 0 STA 15 OUT LDA 14 ADD 15 JC 0 STA 14 OUT LDA 15 ADD 14 JC 0 JMP 3 x y
01010001 01001110 01010000 01001111 11100000 00011110 00101111 01110000 01001110 11100000 00011111 00101110 01110000 01100011 00000000 00000000
Add / Subtract loop
A simple program to test conditional jumps. Increments by x until carry, then decrements by x until 0. Repeat.
LDI 0 ADD 15 JC 5 OUT JMP 1 SUB 15 JZ 1 OUT JMP 5 - - - - - - x
01010000 00101111 01110101 11100000 01100001 00111111 10000001 11100000 01100101 00000000 00000000 00000000 00000000 00000000 00000000 XXXXXXXX
4 20 69
Simple program that outputs 4 then 20 then 69. Something to keep the kids entertained.
LDI 4 OUT ADD 14 OUT ADD 15 OUT JMP 0 - - - - - - - 16 49
01010100 11100000 00101110 11100000 00101111 11100000 01100000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00010000 00110001