microcode

IPA/ˈmaɪkrəʊkəʊd/
KK[mˈaɪkrokˌod]IPA/ˈmaɪkrəʊkəʊd/

microcode — noun

1. a set of very basic, hard-wired instructions kept inside a computer chip that te

1.nounC2
Definition

a set of very basic, hard-wired instructions kept inside a computer chip that tells the chip how to carry out each step of a higher-level program.

Example

Kenji spent two weeks rewriting the microcode for the lab's new graphics processor.

common verb: rewrite/update the microcode

A faulty patch to the microcode caused half of the office computers to freeze on Monday morning.

collocation: patch / update the microcode

Common collocations
  • rewrite the microcode
  • patch the microcode
  • update the microcode
  • ship with microcode
  • load microcode into the processor
Synonyms
  • firmware

    broader — any low-level software baked into a device; microcode is one specific kind that lives inside a CPU

  • microinstructions

    the individual steps that together make up the microcode; near-synonym in academic writing

Usage Note

Uncountable; takes singular verb agreement and no article in generic statements (e.g. 'microcode runs below the OS', not 'a microcode'). Frequent verbs: write, patch, update, ship, run.

Common Mistakes

Intel released three new microcodes last year.
Intel released three new microcode updates last year.
microcode is uncountable; count the updates or patches, not the microcode itself.

Word family

Synonym discussion

Sense: noun/1

All three describe instructions kept very close to the hardware, but they sit at different layers. **Microcode** is the lowest of the three: it lives inside the processor chip itself and tells the chip how to perform each machine instruction by triggering tiny circuit operations. **Firmware** is broader — any small program permanently stored in a device's memory, such as the code that runs a router, a printer, or a hard drive's controller; microcode is one special kind of firmware. **Machine code** sits one level above microcode: it is the stream of binary instructions that the CPU reads from a normal program, and each of those instructions is then carried out by microcode under the hood. In practice, a software engineer writes machine code (through a compiler), a device maker ships firmware, and only chip designers at companies like Intel or AMD ever touch the microcode.

microcode ↗firmware ↗machine code

Common collocations

Nouns

  • microcode update
  • microcode patch
  • microcode layer

Phrases

  • a microcode update
  • load microcode
  • ship with microcode

Prepositions

  • microcode for [a chip]
  • microcode in [the processor]

Etymology

GreekLatinEnglish

Coined in 1951 by the British computer scientist Maurice Wilkes from the prefix 'micro-' (Greek mikros, 'small') plus 'code' in the computing sense of a set of instructions. Wilkes proposed that the very basic steps of a processor could themselves be written as a tiny program stored inside the CPU, rather than being fixed in the wiring — hence 'micro' (smaller and lower than ordinary program code).