In computer engineering, an execution unit (E-unit or EU) is a part of the

central processing unit A central processing unit (CPU), also called a central processor, main processor or just Processor (computing), processor, is the electronic circuitry that executes Instruction (computing), instructions comprising a computer program. The CPU per ...

(CPU) that performs the operations and calculations as instructed by the

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...

. It may have its own internal control sequence unit (not to be confused with the CPU's main

control unit The control unit (CU) is a component of a computer's central processing unit (CPU) that directs the operation of the processor. A CU typically uses a binary decoder to convert coded instructions into timing and control signals that direct the op ...

), some

register Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), th ...

s, and other internal units such as an arithmetic logic unit (ALU),

address generation unit The address generation unit (AGU), sometimes also called address computation unit (ACU), is an execution unit inside central processing units (CPUs) that calculates addresses used by the CPU to access main memory. By having address calculations ...

(AGU), floating-point unit (FPU), load-store unit (LSU),

branch execution unit A branch, sometimes called a ramus in botany, is a woody structural member connected to the central trunk of a tree (or sometimes a shrub). Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually ...

(BEU) or some smaller and more specific components."Execution Unit" discussion from the University of Massachusetts Amherst
archived on the

Wayback Machine The Wayback Machine is a digital archive of the World Wide Web founded by the Internet Archive, a nonprofit based in San Francisco, California. Created in 1996 and launched to the public in 2001, it allows the user to go "back in time" and see ...

It is common for modern CPUs to have multiple parallel functional units within its execution units, which is referred to as superscalar design. The simplest arrangement is to use a single bus manager unit to manage the memory interface, and the others to perform calculations. Additionally, modern CPUs' execution units are usually pipelined.

References

Central processing unit Computer arithmetic {{Comp-eng-stub