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Central processing unit

(Redirected from CPU)

The central processing unit (CPU) is the part of a computer that interprets and carries out the instructions contained in the software. In most CPUs, this task is divided between a control unit that directs program flow and one or more execution units that perform operations on data. Almost always, a collection of registers is included to hold operands and intermediate results.

When every part of a CPU is on a single physical integrated circuit, it is called a microprocessor. Practically all CPUs manufacturered today are microprocessors.

The term CPU is often used vaguely to include other centrally important parts of a computer such as caches and input/output controllers, especially when those functions are on the same microprocessor chip as the CPU.


Manufacturers of desktop computers often erroneously describe the entire personal computer (the system unit or sometimes white box including the computer case and the computer hardware it contains) as the CPU. Rather, the CPU, as a functional unit, is that part of the computer which actually executes the instructions (add, subtract, shift, fetch, etc.).

A family of CPU designs is often referred to as a CPU architecture.

1 See also


Notable CPU architectures include:

Emerging new CPU architectures include:

Historically important CPUs have been:

Types of CPUs

The above processor architectures could also be characterized by their CPU design like register size. Today most desktop computers and laser printers have 32-bit processors; 64-bit processors are being phased in. Smaller devices like mobile phones, PDAs, or portable video game devices may have 16 or 8-bit processors. Embedded systems such as microwave ovens, calculators, computer keyboards, and infrared remote controls typically have 8-bit or 4-bit processors.

See also

Last updated: 10-24-2004 05:10:45