instruction register


(IR) The part of a central processing unit (CPU) control unit that holds the machine instruction currently being executed. The CPU's fetch-execute cycle loads instructions from memory into the instruction register. The IR in turn drives the instruction decoding logic that determines what operation teh CPU should perform on what data.

Modern processors have an instruction pipeline to minimise the time the control unit is waiting for instructions and data to be fetched from memory. This may distrubute the job of the IR over several registers in the pipeline.

Last updated: 2018-08-31

Nearby terms:

instruction prefetchinstruction registerinstruction scheduling

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