8-bit
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{{dablink|This article is about 8-bit in computer architecture. For the era of computer gaming commonly referred to as "8-bit", see [[History of video game consoles (third generation)]]. For music in the 8-bit style, see [[8-bit (music)]]. For the sprite comic, see [[8-Bit Theater]]}}
{{N-bit|8|(1 octet)}}
Eight-bit CPUs normally use an 8-bit data bus and a [[16-bit]] address bus which means that their [[address space]] is limited to 64 [[KB]]s. This is not a "natural law", however, so there are exceptions.
The first widely adopted 8-bit [[microprocessor]] was the [[Intel 8080]], being used in many [[smart card]]s{{Fact|date=January 2008}} and hobbyist computers of the late 1970s and early 1980s, often running the [[CP/M]] [[operating system]]. The [[Zilog Z80]] (compatible with the 8080) and the [[Motorola 6800]] were also used in similar computers. The Z80 and the [[MOS Technology 6502]] 8-bit CPUs were widely used in [[home computer]]s and [[game console]]s of the 70s and 80s. Many 8-bit CPUs or [[microcontroller]]s are the basis of today's ubiquitous [[embedded systems]].
There are 2<sup>8</sup> (256) possible values for 8 bits.(in binary)
About 55% of all CPUs sold in the world are 8-bit microcontrollers or [[microprocessor]]s. {{Fact|date=April 2007}}
==Why 8 bits?==
[[4-bit]] microprocessors were developed in the early 1970s starting with the [[Intel 4004]]. Intel swiftly followed with 8-bit processors, and most competitors to Intel started with 8-bits. Performance and memory limitations meant that 4-bit processors fell out of more demanding applications quickly (4-bit processors are still [[mass-produced]] however).
==List of 8-bit CPUs==
A [[CPU]] can be classified on the basis of the [[data]] it can access in a single [[Instruction (computer science)|operation]]. An 8-bit processor can access 8 bits of data in a single operation, as opposed to a [[16-bit]] processor, which can access 16 bits of data in a single operation.
''Examples of 8-bit processors (very incomplete):''
* [[Intel 8008]]
* [[Intel 8080]] (''8008 source compatible'')
* [[Intel 8085]] (''8080 binary compatible'')
* [[Intel 8051]] (''Harward architecture'')
* [[Zilog Z80]] (''8080 binary compatible'')
* [[Zilog Z180]] (''Z80 binary compatible'')
* [[Zilog Z8]]
* [[Zilog eZ80]] (''Z80 binary compatible'')
* [[Motorola 6800]]
* [[Motorola 6809]] (''partially 6800 compatible'')
* [[MOS Technology 6502]]
* [[Microchip PIC10]][http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2060]
* [[Microchip PIC12]][http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2553¶m=en027589]
* [[Microchip PIC16]][http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2553¶m=en027586]
* [[Microchip PIC18]][http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2042¶m=en020453],[http://en.wikipedia.org/wiki/PIC_microcontroller]
* [[Atmel AVR]] family microcontrollers
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