X86


x86
DesignerIntel, AMD
Bits16-bit, 32-bit and 64-bit
Introduced1978 (16-bit), 1985 (32-bit), 2003 (64-bit)
DesignCISC
TypeRegister–memory
EncodingVariable (1 to 15 bytes)
BranchingCondition code
EndiannessLittle
Page size8086i286: None
i386, i486: 4 KB pages
P5 Pentium: added 4 MB pages
(Legacy PAE: 4 KB→2 MB)
x86-64: added 1 GB pages
Extensionsx87, IA-32, x86-64, 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, VT-x, VT-d, AMD-V, AMD-Vi, TSX, ASF, TXT
OpenPartly. For some advanced features, x86 may require license from Intel; x86-64 may require an additional license from AMD. The 80486 processor has been on the market for more than 30 years[1] and so cannot be subject to patent claims. The pre-586 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
The x86 architectures were based on the Intel 8086 microprocessor chip, initially released in 1978.
Intel Core 2 Duo, an example of an x86-compatible, 64-bit multicore processor
AMD Athlon (early version), a technically different but fully compatible x86 implementation

x86 is a family of 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.

Many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility.[b] The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA Technologies and many other companies; there are also open implementations, such as the Zet SoC platform (currently inactive).[2] Nevertheless, of those, only Intel, AMD, VIA Technologies, and DM&P Electronics hold x86 architectural licenses, and from these, only the first two are actively producing modern 64-bit designs.

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,[c] some of them before the IBM PC (1981) debut.

As of 2021, most desktop computers, laptops and game consoles (with the exception of the Nintendo Switch[3][4]) sold are based on the x86 architecture,[citation needed] while mobile categories such as smartphones or tablets are dominated by ARM; at the high end, x86 continues to dominate compute-intensive workstation and cloud computing segments,[5] while the fastest supercomputer is ARM-based, and the top 4 are no longer x86-based. [3]

  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. ^ "Zet: The x86 (IA-32) open implementation: Overview". OpenCores. November 4, 2013. Retrieved January 5, 2014.
  3. ^ a b "Consolidated Financial Highlights - Q2 FY2022" (PDF). Nintendo. November 4, 2021. Retrieved November 13, 2021.
  4. ^ "Global unit sales of current generation video game consoles from 2008 to 2020". Statista. Retrieved November 13, 2021.
  5. ^ Brandon, Jonathan (April 15, 2015). "The cloud beyond x86: How old architectures are making a comeback". ICloud PE. Business Cloud News. 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...


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