Functional unit

A functional unit may in turn have sub-systems of its own, containing smaller functional units, and so on.

For example, an aircraft may contain a navigation system, containing a gyroscope as a functional unit, which in turn may contain an embedded micro-computer[?], which in turn contains a microprocessor, which in turn contains an arithmetic and logic unit, which is made out of logic gates, which is made out of transistors.

See also: configuration

In computer engineering, the term "functional unit" often refers specifically to an execution unit.