X86 assembly language

x86 assembly language is a family of backward-compatible assembly languages, which provide some level of compatibility all the way back to the Intel 8008 introduced in April 1972. x86 assembly languages are used to produce object code for the x86 class of processors. Like all assembly languages, it uses short mnemonics to represent the fundamental instructions that the CPU in a computer can understand and follow. Compilers sometimes produce assembly code as an intermediate step when translating a high level program into machine code. Regarded as a programming language, assembly coding is machine-specific and low level. Assembly languages are more typically used for detailed and time critical applications such as small real-time embedded systems or operating system kernels and device drivers.

The Intel 8086 and 8088 were the first CPUs to have an instruction set that is now commonly referred to as x86. These 16-bit CPUs were an evolution of the previous generation of 8-bit CPUs such as the 8080, inheriting many characteristics and instructions, extended for the 16-bit era. The 8086 and 8088 both used a 20-bit address bus and 16-bit internal registers but while the 8086 had a 16-bit data bus, the 8088, intended as a low cost option for embedded applications and small computers, had an 8-bit data bus. The x86 assembly language covers the many different versions of CPUs that followed: from Intel, the 80186, 80188, 80286, 80386, 80486, Pentium, Pentium Pro, and so on, as well as non-Intel CPUs from AMD and Cyrix such as the 5x86 and K6 processors and the NEC V20 (although these mostly Intel-compatible CPUs add instructions which might not strictly be considered part of the x86 assembly language, much as the instructions that Zilog added to the Z80 to form its superset of the Intel 8080 instruction set would not be considered part of the i8080 assembly language.) (AMD also manufactured Intel 8086-family CPUs prior to the 80386 under a second-source contract, as did some other semiconductor manufacturers.) The term x86 applies to any CPU which can run the original assembly language. (Usually it will run at least some of the extensions too.)

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