The term x86 refers to a family of instruction set architectures based on the Intel 8086 CPU. The 8086 was launched in 1978 as a fully 16-bit extension of Intel's early 8-bit based microprocessors and also introduced segmentation to overcome the 16-bit addressing barrier of earlier chips. The term x86 derived from the fact that early successors to the 8086 also had names ending in "86". Many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility. The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA, and many others.
The term is not synonymous with IBM PC compatibility as this implies a multitude of other hardware; embedded systems as well as computers used x86 chips before the PC-compatible market started, some of them before the IBM PC itself.
As the term became common after the introduction of the 80386, it usually implies binary compatibility with the 32-bit instruction set of the 80386. This may sometimes be emphasized as x86-32 to distinguish it either from the original 16-bit "x86-16" or from the 64-bit x86-64. Although most x86 processors used in new personal computers and servers have 64-bit capabilities, to avoid compatibility problems with older computers or systems, the term x86-64 (or x64) is often used to denote 64-bit software, with the term x86 implying only 32-bit.
Although the 8086 was primarily developed for embedded systems and small single-user computers, largely as a response to the successful 8080-compatible Zilog Z80, the x86 line soon grew in features and processing power. Today, x86 is ubiquitous in both stationary and portable personal computers and has replaced midrange computers and RISC-based processors in a majority of servers and workstations as well. A large amount of software, including operating systems (OSs) such as DOS, Windows, Linux, BSD, Solaris, and Mac OS X supports x86-based hardware.
Modern x86 is relatively uncommon in embedded systems however, and small low power applications (using tiny batteries) and low-cost microprocessor markets, such as home appliances and toys, lack any significant x86 presence. Simpler 16-bit x86 chips are more common here, although VIA C7, VIA Nano, AMD's Geode, Athlon Neo, and Intel Atom are examples of 32- and 64-bit designs used in parts of these segments.
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