Alternatively referred to as the brain of the computer, processor, central processor, or microprocessor, the CPU (pronounced as C-P-U) was first developed at Intel with the help of Ted Hoff in the early 1970's and is short for Central Processing Unit. The computer CPU is responsible for handling all instructions it receives from hardware and software running on the computer.

Note: Many new computer users may improperly call their computer and sometimes their monitor the CPU. When referring to your computer or monitor it is proper to refer to them as either the "computer" or "monitor" and not a CPU.

In the picture below, is an example of what the top and bottom of an Intel Pentium processor looks like. The processor is placed and secured into a compatible CPU socket found on the motherboard, and because of the heat it produces it is covered with a heat sink to help keep it cool and running smoothly.

Computer CPU (Central Processing Unit)

As can be seen by the above picture, the CPU chip is usually in the shape of a square or rectangle and has one notched corner to help place the chip into the computer properly. On the bottom of the chip are hundreds of connector pins that plug into each of the corresponding holes on the socket. Today, most CPU's resemble the picture shown above; however, Intel and AMD have also experimented with slot processors that were much larger and slid into a slot on the motherboard. Also, over the years there have been dozens of different types of sockets on motherboards, each socket only supports so many different processors, and each has its own pin layout.

Components of the CPU

In the CPU, the primary components are the ALU (Arithmetic Logic Unit) that performs mathematical, logical, and decision operations and the CU (Control Unit) that directs all of the processors operations.

Machine cycle

Over the history of computer processors, the speed (clock speed) and capabilities of the processor have dramatically improved. For example, the first microprocessor was the Intel 4004 that was released November 15, 1971 and had 2,300 transistors and performed 60,000 operations per second. The Intel Pentium Processor shown on this page has 3,300,000 transistors and performs around 188,000,000 instructions per second.

Types of CPUs

There are two main types of CPUs found in computers today: 32-bit and 64-bit. In addition to this, CPUs can be broken down into types based on the manufacturer and version as well.

Below is a list of the more common types of CPUs for home or business computers, in chronological order of release by manufacturer.

Note: There are multiple versions for some of these CPU types.

AMD processors

Athlon XP

Athlon 64
Mobile Athlon 64
Athlon XP-M
Athlon 64 FX

Turion 64
Athlon 64 X2
Turion 64 X2
Phenom FX
Phenom X4

Phenom X3
Athlon 6-series
Athlon 4-series
Athlon X2
Phenom II

Athlon II
E2 series
A4 series
A6 series
A8 series
A10 series

Intel processors

Pentium w/ MMX
Pentium Pro
Pentium II

Pentium III
Pentium M
Celeron M

Pentium 4
Mobile Pentium 4-M
Pentium D

Pentium Extreme Edition
Core Duo
Core 2 Duo

Core i3
Core i5
Core i7

The AMD Opteron series and Intel Xeon series are two common types of CPUs for servers and some workstation computers.

Some mobile devices, like smartphones and tablets, use ARM CPUs. These CPUs are smaller in size, require less power and generate less heat.

Related pages

Also see: Coprocessor, CPU socket, Dual-core, Logic chip, Motherboard, Parallel processing, CPU terms, Register