IA-32

This article is about the 32-bit version of the Intel x86 instruction set architecture. For the x86 instruction set architecture in general, see x86.

IA-32 (short for "Intel Architecture, 32-bit", commonly called i386[1][2])[3] is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the 80386 microprocessor in 1985. IA-32 is the first incarnation of x86 that supports 32-bit computing;[4] as a result, the "IA-32" term may be used as a metonym to refer to all x86 versions that support 32-bit computing.[5][6]

Within various programming language directives, IA-32 is still sometimes referred to as the "i386" architecture. In some other contexts, certain iterations of the IA-32 ISA are sometimes labelled i486, i586 and i686, referring to the instruction supersets offered by the 80486, the P5 and the P6 microarchitectures respectively. These updates offered numerous additions alongside the base IA-32 set including floating-point capabilities and the MMX extensions.

Intel was historically the largest manufacturer of IA-32 processors, with the second biggest supplier having been AMD. During the 1990s, VIA, Transmeta and other chip manufacturers also produced IA-32 compatible processors (e.g. WinChip). In the modern era, Intel still produced IA-32 processors under the Intel Quark microcontroller platform until 2019; however, since the 2000s, the majority of manufacturers (Intel included) moved almost exclusively to implementing CPUs based on the 64-bit variant of x86, x86-64. x86-64, by specification, offers legacy operating modes that operate on the IA-32 ISA for backwards compatibility. Even given the contemporary prevalence of x86-64, as of today, IA-32 protected mode versions of many modern operating systems are still maintained, e.g. Microsoft Windows (until Windows 10),[7] Windows Server (until Windows Server 2008)[8] and the Debian Linux distribution.[9] In spite of IA-32's name (and causing some potential confusion), the 64-bit evolution of x86 that originated out of AMD would not be known as "IA-64", that name instead belonging to Intel's Itanium architecture.

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  4. ^ "Intel 64 and IA-32 Architectures Software Developer's Manual". Intel Corporation. September 2014. p. 31. Archived from the original on January 26, 2012. Retrieved December 19, 2014. The Intel386 processor was the first 32-bit processor in the IA-32 architecture family. It introduced 32-bit registers for use both to hold operands and for addressing.
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  7. ^ "Windows 10 System Requirements & Specifications | Microsoft". www.microsoft.com. Archived from the original on May 1, 2018. Retrieved August 20, 2018.
  8. ^ Scott M. Fulton, III (May 16, 2007). "Windows Server 2008 'The Last 32-bit Operating System'". BetaNews. Archived from the original on April 1, 2023. Retrieved April 1, 2023.
  9. ^ "Debian GNU/Linux on x86 Machines". Archived from the original on April 28, 2019. Retrieved August 20, 2020.