central processing unit

architecture, processor (CPU, processor) The part of a

computer which controls all the other parts. Designs vary

widely but, in general, the CPU consists of the controlunit, the arithmetic and logic unit (ALU) and memory

(registers, cache, RAM and ROM) as well as various

temporary buffers and other logic.

The control unit fetches instructions from memory and decodes

them to produce signals which control the other part of the

computer. This may cause it to transfer data between memory

and ALU or to activate peripherals to perform input or

output.

A parallel computer has several CPUs which may share other

resources such as memory and peripherals.

The term "processor" has to some extent replaced "CPU", though

RAM and ROM are not normally considered as part of a

processor. This is particularly true of common modern

microprocessors though there have been microprocessors which

include RAM and/or ROM on the same integrated circuit.

The CPU Info Center lists many kinds of CPU.

(1998-10-21)