PDP-8

AND the memory operand with AC (primary opcode)

Two's complement ADD to AC with carry in L (primary opcode)

increment memory operand and skip next instruction if result is zero (primary opcode)

deposit accumulator into memory operand and clear AC (primary opcode)

Jump to subroutine (storing return address in first word of subroutine) (primary opcode)

jump jump jump jump jump (primary opcode)

Input/Output Transfer (primary opcode)

microcode operations (primary opcode)

clear accumulator (group 1 / group 2 / group 3 microcode)

clear L bit (group 1 microcode)

complement accumulator (group 1 microcode)

complement L bit (group 1 microcode)

increment accumulator (group 1 microcode)

rotate right (group 1 microcode)

rotate left (group 1 microcode)

rotate right twice (group 1 microcode)

rotate left twice (group 1 microcode)

byte swap 6-bit bytes (group 1 microcode / 8/e and up)

Skip on AC (OR group) (group 2 microcode)

Skip on AC equal to zero (OR group) (group 2 microcode)

Skip on L equal to zero (OR group) (group 2 microcode)

Logically OR front panel switches into AC (group 2 microcode)

Halt (group 2 microcode)

Skip unconditionally (AND group) (group 2 microcode)

Skip on AC >= 0 (AND group) (group 2 microcode)

Skip on AC != 0 (AND group) (group 2 microcode)

Ski-p on L == 0 (AND groupO (group 2 microcode)

Multiplier quotient with AC (logical or MQ into AC) (group 3 microcode)

Step counter load into AC (group 3 microcode)

Multiplier quotient Load (transfer AC to MQ and clear AC) (group 3 microcode)

CLA + MQL clears both AC and MQ (group 3 microcode)

Extened arithmetic element (not an opcode)

Multiplier / Quotient register (EAE required)

Step Counter Load (immediate word follows / 8/I and above) into EAE step counter to control loop counts for hardware-accelerated shift/multiply/divide

Multiply (EAE required)

Divide (EAE required)

Normalize (EAE required)

Shift-left (immediate word follows (EAE required)

Arithmetic shift right (EAE required)

Logical shift right (EAE required)

abbreviation of CMA and IAC to two's complement AC

No operation (group 1 microcode with no instructions)