<programming> (Or "op code") The part or parts of a machine
language instruction which determines what kind of action the
computer should take, e.g. add, jump, load, store. In any
particular instruction set certain fixed bit positions
within the instruction word contain the op code, others give
parameters such as the addresses or registers involved.
For example, in a 32-bit instruction the most significant
eight bits might be the op code giving 256 possible
operations.
For some instruction sets, certain values in the fixed bit
positions may select a group of operations and the exact
operation may depend on other bits within instruction word or
subsequent words.
When programming in assembly language, the op code is
represented by a readable name called an instruction
mnemonic.
(1997-02-14)
Nearby terms:
operational semantics « operational test and evaluation « operational testing « operation code » operations support technician » operator » Operator Control Language
