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) |
More, see wiki/X86_instruction_listings