8-bit

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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

Processors
4-bit	8-bit	12-bit	16-bit	18-bit	24-bit	31-bit	32-bit	36-bit	48-bit	64-bit	128-bit
Applications
8-bit			16-bit			31-bit	32-bit			64-bit
Data Sizes
4-bit	8-bit		16-bit				32-bit			64-bit	128-bit
nibble byte octet word dword qword

In computer architecture, 8-bit integers, memory addresses, or other data units are those that are at most 8 bits (1 octet) wide. Also, 8-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 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 KBs. 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 cards^{[citation needed]} 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 computers and game consoles of the 70s and 80s. Many 8-bit CPUs or microcontrollers are the basis of today's ubiquitous embedded systems.

There are 2⁸ (256) possible values for 8 bits.(in binary)

About 55% of all CPUs sold in the world are 8-bit microcontrollers or microprocessors.^{[citation needed]}

[edit] 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).

[edit] List of 8-bit CPUs

A CPU can be classified on the basis of the data it can access in a single 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):