X86

x86
Designer	Intel, AMD
Bits	16-bit, 32-bit and 64-bit
Introduced	1978 (16-bit), 1985 (32-bit), 2003 (64-bit)
Design	CISC
Type	Register–memory
Encoding	Variable (1 to 15 bytes)
Branching	Condition code
Endianness	Little
Page size	8086–i286: None; i386, i486: 4 KB pages; P5 Pentium: added 4 MB pages; (Legacy PAE: 4 KB→2 MB); x86-64: added 1 GB pages
Extensions	x87, IA-32, x86-64, x86-S, MMX, 3DNow!, SSE, MCA, ACPI, SSE2, NX bit, SMT, SSE3, SSSE3, SSE4, SSE4.2, AES-NI, CLMUL, RDRAND, SHA, MPX, SME, SGX, XOP, F16C, ADX, BMI, FMA, AVX, AVX2, AVX-VNNI, AVX512, AVX10, VT-x, VT-d, AMD-V, AMD-Vi, TSX, ASF, TXT, APX
Open	Partly. For some advanced features, x86 may require license from Intel; x86-64 may require an additional license from AMD. The Pentium Pro processor (and NetBurst) has been on the market for more than 21 years and so cannot be subject to patent claims. The i686 subset of the x86 architecture is therefore fully open.
Registers
General-purpose	16-bit: 6 semi-dedicated registers, BP and SP are not general-purpose; 32-bit: 8 GPRs, including EBP and ESP; 64-bit: 16 GPRs, including RBP and RSP;
Floating point	16-bit: optional separate x87 FPU; 32-bit: optional separate or integrated x87 FPU, integrated SSE units in later processors; 64-bit: integrated x87 and SSE2 units, later implementations extended to AVX2 and AVX512;

x86 (also known as 80x86^[2] or the 8086 family^[3]) is a family of complex instruction set computer (CISC) instruction set architectures^[a] initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introduced in 1978 as a fully 16-bit extension of Intel's 8-bit 8080 microprocessor, with memory segmentation as a solution for addressing more memory than can be covered by a plain 16-bit address. The term "x86" came into being because the names of several successors to Intel's 8086 processor end in "86", including the 80186, 80286, 80386 and 80486 processors. Colloquially, their names were "186", "286", "386" and "486".

The term is not synonymous with IBM PC compatibility, as this implies a multitude of other computer hardware. Embedded systems and general-purpose computers used x86 chips before the PC-compatible market started,^[b] some of them before the IBM PC (1981) debut.

As of June 2022^[update], most desktop and laptop computers sold are based on the x86 architecture family,^[4] while mobile categories such as smartphones or tablets are dominated by ARM. At the high end, x86 continues to dominate computation-intensive workstation and cloud computing segments.^[5] The fastest supercomputer in the TOP500 list for June 2022 was the first exascale system, Frontier,^[6] built using AMD Epyc CPUs based on the x86 ISA; it broke the 1 exaFLOPS barrier in May 2022.^[7]

^ Pryce, Dave (May 11, 1989). "80486 32-bit CPU breaks new ground in chip density and operating performance. (Intel Corp.) (product announcement) EDN" (Press release).
^ Rao, P.V.S. (2009). Computer System Architecture. Prentice-Hall of India. p. 402 (Section 19.1, The x86 family of processors). ISBN 978-81-203-3594-3.
^ Mhatre, Swapneel Chandrakant (2012). Microprocessors and Interfacing Techniques: For S. E. (Computer Engineering) Semester II of University of Pune. Jaico Publishing House. ISBN 978-81-8495-325-1.
^ Alcorn, Paul (February 9, 2022). "AMD Sets All-Time CPU Market Share Record as Intel Gains in Desktop and Notebook PCs". Tom's Hardware.
^ Brandon, Jonathan (April 15, 2015). "The cloud beyond x86: How old architectures are making a comeback". ICloud PE. Business Cloud News. Archived from the original on August 19, 2021. Retrieved November 23, 2020. Despite the dominance of x86 in the datacentre it is difficult to ignore the noise vendors have been making over the past couple of years around non-x86 architectures like ARM...
^ "June 2022". TOP500.
^ Larabel, Michael (May 30, 2022). "AMD-Powered Frontier Supercomputer Tops Top500 At 1.1 Exaflops, Tops Green500 Too". Phoronix. Retrieved June 1, 2022.

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

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

[2] Rao, P.V.S. (2009). Computer System Architecture. Prentice-Hall of India. p. 402 (Section 19.1, The x86 family of processors). ISBN 978-81-203-3594-3.

[3] Mhatre, Swapneel Chandrakant (2012). Microprocessors and Interfacing Techniques: For S. E. (Computer Engineering) Semester II of University of Pune. Jaico Publishing House. ISBN 978-81-8495-325-1.

[6] Alcorn, Paul (February 9, 2022). "AMD Sets All-Time CPU Market Share Record as Intel Gains in Desktop and Notebook PCs". Tom's Hardware.

[7] Brandon, Jonathan (April 15, 2015). "The cloud beyond x86: How old architectures are making a comeback". ICloud PE. Business Cloud News. Archived from the original on August 19, 2021. Retrieved November 23, 2020. Despite the dominance of x86 in the datacentre it is difficult to ignore the noise vendors have been making over the past couple of years around non-x86 architectures like ARM...

[8] "June 2022". TOP500.

[9] Larabel, Michael (May 30, 2022). "AMD-Powered Frontier Supercomputer Tops Top500 At 1.1 Exaflops, Tops Green500 Too". Phoronix. Retrieved June 1, 2022.

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