In computer engineering, an execution unit is a part of a CPU that performs the operations and calculations called for by the program. It often has its own control unit, registers, and other electronics, such as an arithmetic and logic unit or floating point unit, or some smaller, more specific component.
It is commonplace for modern CPUs to have multiple parallel execution units, referred to as scalar or superscalar design. The simplest arrangement is to use one, the bus manager, to manage the memory interface, and the others to perform calculations. Additionally, modern CPUs execution units are usually pipelined.