X86

x86 is the instruction set architecture (ISA) for the Intel 8086 and 8088 chips, 16-bit microprocessors first produced in 1978 The 8088 chip was used in the very first incarnation of an IBM compatible PC introduced by IBM in 1983.

The x86 instruction set achieved historic status due to a remarkable decision, made jointly by the designers of the original IBM compatible PC. They decided to maintain backward compatibility in both software and hardware, and to maintain it indefinitely, Thus, all subsequent "Intel" processor chips in the 86-styled family would always execute the original x86 instructions.

This agreement would later have a profound impact on the Personal Computer industry, and came to be known as the "WinTel" agreement.

Furthermore, this joint decision meant that any program which ran on the original Microsoft DOS operating system, whose hardware platform was always guaranteed to be x86, continued to execute successfully on later versions of Microsoft operating systems.

This decision to maintain backward compatibility of hardware and software laid the groundwork for the subsequent success of the x86 family of microprocessors, and the IBM compatible PCs which contain them.