x86

x86
Designer	Intel, AMD
Bits	16-bit, 32-bit an 64-bit
Introduced	1978 (16-bit), 1985 (32-bit), 2003 (64-bit)
Design	CISC
Teep	Register-memory
Encodin	Variable (1 tae 15 bytes)
Brainchin	Status register
Endianness	Little
Page size	8086–i286: None; i386, i486: 4 KB pages; P5 Pentium: addit 4 MB pages; (Legacy PAE: 4 KB→2 MB); x86-64: addit 1 GB pages
Extensions	x87, IA-32, MMX, SSE, SSE2, x86-64, SSE3, SSSE3, SSE4, SSE5, AVX
Appen	Pairtly. For some advanced featurs, x86 mey require license frae Intel; x86-64 mey require an addeetional license frae AMD. The 80486 processor haes been on the mercat for mair nor 20 years an so cannot be subject tae patent claims. The pre-586 subset o the x86 airchitectur is tharefore fully open.
Registers
General purpose	16-bit: six semi-dedicatit registers, BP an SP are nae general-purpose; 32-bit: aicht GPRs, includin EBP an ESP; 64-bit: 16 GPRs, includin RBP an RSP;
Floatin pynt	16-bit: optional separate x87 FPU; 32-bit: optional separate or integratit x87 FPU, integratit SSE2 units in later processors; 64-bit: integratit x87 an SSE2 units;

x86 is a faimily o backward compatible instruction set airchitecturs^[a] based on the Intel 8086 CPU an its Intel 8088 variant.

Notes

↑ Unlik the microairchitectur (an speceefic electronic an phesical implementation) uised for a speceefic microprocessor design

↑ Pryce, Dave (11 Mey 1989). "80486 32-bit CPU breaks new ground in chip density and operating performance. (Intel Corp.) (product announcement) EDN" (Press release).