Central processing unit

The Central Processing Unit (or 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.

The term CPU is often used vaguely to include other centrally important parts of a computer such as caches and input/output controllers, especially in computers with modern microprocessor chips that include several of these functions in one physical integrated circuit.

Manufacturers and retailers of desktop computers often erroneously describe the computer case and its contents as the CPU.

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

Notable CPU architectures include:

Intel's x86 architecture
IBM's System/370 architecture
DEC's PDP-11 architecture
Motorola's 68000 architecture
Sun Microsystems's SPARC architecture
MIPS Computer Systems Inc.'s MIPS architecture
HP's PA-RISC architecture
DEC's Alpha architecture
The Apple Computer/IBM/Motorola alliance's PowerPC architecture
ARM's StrongARM architecture
SuperH's SuperH architecture

Emerging new CPU architectures include:

Intel's Itanium architecture
AMD's x86-64 architecture