Machine code |
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General concepts |
Instructions |
In computing, an opcode (abbreviated from operation code)[1][2] is an enumerated value that specifies the operation to be performed. Opcodes are employed in hardware devices such as arithmetic logic units (ALUs) and central processing units (CPUs) as well as in some software instruction sets. In ALUs the opcode is directly applied to circuitry via an input signal bus, whereas in CPUs, the opcode is the portion of a machine language instruction that specifies the operation to be performed.