Fun with Logisim Modeling a basic 8-bit CPU largely from discrete logic. I'm not following any specific architecture, but drawing inspiration from the likes of Z80, 6502, 6800, etc. It has two registers, Accumulator/A and B; 8-bit Program Counter and Address bus; and currently two flags, Zero and Carry (though neither is used yet). So far, the ALU is functional with Add, Subtract, And, Or, Xor, and Not. I've also got three load/store operations: LD A->B LD B->A LD Imm->A I need to add more of the standard load/store operations, branch/jump, and shift/rotate. It's ... a mess, but it can run a basic program to load values and add them together (or use any of the ALU functions). For a first attempt thrown together in a few hours with no real planning, I'm impressed with how it's gone thus far.