Instruction Set - x86 (AMD, Intel)

Cpu Moore Law Transistor


x86 is the name of an instruction set that originated at Intel.

The x86 instruction set architecture has evolved over time by:

The term x86 is derived from the fact that many of Intel's early processors that implemented this instruction set had names ending in 86. See processor


The first CPU created with this ISA was the Intel 8086 in 1978.

Microprocessor Year Processor Word Size (Bit) Address Bus Word Size (Bit) Data Bus Word Size (Bit) Clock Speed (MHz) New Features
8086/87* 1978 16 20 20 5 to 10 Real Mode
8088 1979 16 20 8 5 to 10
80186/87* 1982 16 20 20 6 to 25
80286/87* 1984 16 24 16 6 to 25 Protected Mode
80386 1985
80486 1989
Pentium 1993
Pentium 1993

87 is the floating point co-processor of the 86


Every version has full backwards compatibility with its previous version.

Version ISA Name CPU
16-bit IA-16 x86 Intel 8086 (1978) - 80286 CPUs
32 bit wiki/IA-32 x86-32 or i386 wiki/intel_80386
64 bit wiki/x86-64 AMD64 almost identical to Intel 64 (EM64T, IA-32e)


  • the pattern 10100000 means add two numbers,
  • the pattern 000000101 means halt a computer

More, see wiki/X86_instruction_listings

Documentation / Reference

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