operation code

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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.

operation code

(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.

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.
References in periodicals archive ?
For each binary, one text file was generated, which contain the frequency of opcodes in the corresponding binary file.
Examples of error conditions are: not recognizing an opcode, insufficient entries in the stack for an instruction, and receiving a return instruction when the virtual machine does not think it is in a subroutine.
const or var) or the position, pos, of the opcode as seen in the Code_Pattern section of Figure 2.
The PowerPC Architecture maintains the same basic programming model and instruction opcode assignments as the POWER architecture.
The toolkit can handle opcode tables in row-major or column-major form.
OpCode If a branch checks an integer for less than zero, less than or equal to zero, or equal to a constant, predict the branch on false condition.
9) Nine more 6-bit opcode remain for other expansion.
No opcode exists that corresponds to the ORI, but the results in the registers are correct.
The ALU +] opcode is used, which independently adds the upper and lower bytes in the two 16-bit words, and also restricts each result to the limits 0 and 255.
Instructions are 2, 4, 6, or 8 bytes long, with their length, address mode, and opcode specified in the first two bytes for efficient decoding.