CPU in a Weekend

2022 January 25

I made a toy 12-bit 8 ISA CPU.

4 bit op-code, 8 bit address, 8 bit ALU.

Implements LDA (load accumulator with value at address), STA (store accumulator at address), ADD (accumulator + register b), SUB (accumulator - register b), MBA (move accumulator to register b), JMP (jump to address), JZ (jump to address if zero flag set), HLT (halt), with op-codes 0001 to 0111 and 1111, respectively.

You can write your own program, load it into the RAM, and press the start button to watch magic happen.

Examples:

0b000000000000 0b000000001010 0b000100000001 0b010100000000 0b000100000000 0b001100000000 0b001000000000 0b010110000100 0b111111111111

0x0: 0 0x1: 5 0x2: LDA 1 0x3: MBA 0x4: LDA 0 0x5: ADD 0x6: STA 0 0x7: JMP 4 0x8: HLT

0b000100001011 0b010100000000 0b000100001100 0b010000000000 0b011100000110 0b011000000011 0b000100001100 0b010000000000 0b011100001010 0b011000000111 0b111111111111 0b000000000001 0b000000000011

0x0: LDA 11 0x1: MBA 0x2: LDA 12 0x3: SUB 0x4: JZ 6 0x5: JMP 3 0x6: LDA 8 0x7: SUB 0x8: JZ 10 0x9: JMP 7 0xa: HLT 0xb: 1 0xc: 3