functional unit

In computer engineering, an execution unit is a part of a CPU that performs the operations and calculations called for by the program. It may have its own internal control sequence unit (not to be confused with the CPUs main control unit), some registers, and other internal units such as a sub-ALU or FPU, or some smaller, more specific components.
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An entity of hardware, software, or both, capable of accomplishing a specified purpose.

A subsystem of the central processing unit of a computer. E.g. arithmetic and logic unit, memory address register, barrel shifter, register file.
(1995-02-10)