This page shows a list of all ALU instructions.
How the ALU works
ALU opcodes encode instructions which compute a function between Offset registers R and O, and then place the result into the R register. There are sixteen such instructions. The function index is encoded in the low-order four bits of the opcode.
- CLR Set R to zero
- IDO Identity O
- OCR Ones' complement of R
- OCO Ones' complement of O
- SLR Shift left R
- SLO Shift left O
- SRR Shift right (logical) R
- SRO Shift right (logical) O
- AND Bitwise AND between R and O
- IOR Bitwise inclusive OR between R and O
- EOR Bitwise exclusive OR between R and O
- ADD 8-bit Addition result of R plus O
- CAR Carry bit of addition result of R plus O, zero or one
- RLO Logical flag (TRUE=255, FALSE=0) R less than O
- REO Logical flag (TRUE=255, FALSE=0) R equals O
- RGO Logical flag (TRUE=255, FALSE=0) R greater than O