Central processing unit
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.
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 which is misleading.
A family of CPU designs is often referred to as a CPU architecture.
Notable CPU architectures include:
Emerging new CPU architectures include:
Historically important CPUs have been:
The above processor architectures could also be characterized by their CPU design
size. Today most desktop computers have 32-bit
processors are being phased in. Smaller devices like mobile phones, PDAs, or portable video game
devices may have 16 or 8-bit