Opcode
part of a machine instruction
In computing, an opcode (abbreviated from operation code) is an enumerated value that specifies the operation to be performed. Opcodes are employed in hardware devices such as arithmetic logic units (ALUs), central processing units (CPUs), and software instruction sets. In ALUs, the opcode is directly applied to circuitry via an input signal bus. In contrast, in CPUs, the opcode is the portion of a machine language instruction that specifies the operation to be performed.
CPUs
Opcodes are found in the machine language instructions of CPUs as well as in some abstract computing machines. In CPUs, an opcode may be referred to as an instruction machine code, instruction code, instruction syllable, instruction parcel, or opstring. For any particular processor (which may be a general CPU or a more specialized processing unit), the opcodes are defined by the processor's instruction set architecture (ISA). They can be described using an opcode table. The types of operations may include arithmetic, data copying, logical operations, program control, and special instructions (e.g., CPUID).
In addition to the opcode, many instructions specify the data (known as operands) the operation will act upon, although some instructions may have implicit operands or none.
“Opcode” enters the record as part of a machine instruction. Crown Archives preserves that source wording while asking what Opcode, part and machine can confirm, complicate or overturn.
Why this record matters
“Opcode” is worth following because a concise public description often conceals a longer documentary argument. Here, Opcode, part and machine provides the most credible route into that argument.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Jul 7, 2026. The linked authority identifier is Q766483. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Opcode” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.