The central processing unit (CPU) is the part of a computer that interprets and carries out the instructions contained in the software.
Overview
Most CPUs divide the tasks of interpreting and carrying out the instructions between:
- A control unit that directs program flow and
- One or more execution units that perform operations on data.
Almost always, a CPU includes a collection of registers to hold operands and intermediate results.
When every part of a CPU sits on a single physical integrated circuit, one calls it a microprocessor. Practically all CPUs manufactured today class as microprocessors.
The term "CPU" often refers—imprecisely—to other centrally important parts of a computer, such as caches and input/output controllers, especially when those functions exist on the same microprocessor chip as the CPU. With the arrival of multi-core chips, the term CPU can either mean the physical chip (see the picture) mounted on the motherboard, or it can mean the core within the chip.
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, consists of that part of the computer which actually executes the instructions (add, subtract, shift, fetch, etc.).
A family of CPU designs can class as a CPU architecture.
Types of CPUs
Many processor architectures can also be characterized by their CPU design, like register size. Today most desktop computers and laser printers have 32-bit processors; with 64-bit processors becoming more widespread. 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.
Several major CPU manufacturers have begun to push the idea of using multiple-core processors in personal desktop computers.
Notable CPU architectures
Embedded CPU architectures
Microcomputer/PC CPU architectures
Workstation/Server CPU architectures
Mini/MidRange/Mainframe CPU architectures
Emerging CPU architectures
Historically important CPUs
See also
External links
