operation code (redirected from order code)

operation code

The part of a machine instruction that tells the computer what to do, such as input, add or branch. The operation code is the verb; the operands are the nouns.

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operation code [‚äp·ə′rā·shən ‚kōd]

(computer science)

A field or portion of a digital computer instruction that indicates which action is to be performed by the computer. Also known as command code.

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(programming)

operation code - (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.