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{{N-bit|32|(4 [[Octet (computing)|octets]])}}  32-bit [[Microcomputer|microcomputer]]s are computers in which 32-bit [[Engineering:Microprocessor|microprocessor]]s are the norm.

==Range for storing integers==
A 32-bit register can store 2<sup>32</sup> different values. The range of [[Integer|integer]] values that can be stored in 32 bits depends on the [[Integer (computer science)#Value and representation|integer representation]] used. With the two most common representations, the range is 0 through 4,294,967,295 (2<sup>32</sup> − 1) for representation as an ([[Signedness|unsigned]]) [[Binary number|binary number]], and −2,147,483,648 (−2<sup>31</sup>) through 2,147,483,647 (2<sup>31</sup> − 1) for representation as [[Two's complement|two's complement]].

One important consequence is that a processor with 32-bit [[Memory address|memory address]]es can directly access at most 4&nbsp;[[Gibibyte|GiB]] of [[Byte addressing|byte-addressable]] memory (though in practice the limit may be lower).

==Technical history==
Memory, as well as other digital [[Physics:Electronic circuit|circuits]] and wiring, was expensive during the first decades of 32-bit architectures (the 1960s to the 1980s).<ref>{{cite book|last1=Patterson|first1=David|last2=Ditzel|first2=David|title=Readings in Computer Architecture|date=2000|publisher=Academic Press|location=San Diego|isbn=9781558605398|page=136}}</ref> Older 32-bit processor families (or simpler, cheaper variants thereof) could therefore have many compromises and limitations in order to cut costs. This could be a 16-bit [[Arithmetic logic unit|ALU]], for instance, or external (or internal) buses narrower than 32 bits, limiting memory size or demanding more cycles for instruction fetch, execution or write back.

Despite this, such processors could be labeled "32-bit," since they still had 32-bit registers and instructions able to manipulate 32-bit quantities. For example, the original [[Engineering:Motorola 68000|Motorola 68000]] had a 16-bit data ALU and a 16-bit external data bus, but had 32-bit registers and a 32-bit based instruction set. Such designs were sometimes referred to as "16/32-bit".<ref>{{cite web|title=68000 users manual|url=https://www.nxp.com/files/archives/doc/ref_manual/M68000PRM.pdf}}</ref>

However, the opposite is often true for newer 32-bit designs. For example, the [[Engineering:Pentium Pro|Pentium Pro]] processor is a 32-bit machine, with 32-bit registers and instructions that manipulate 32-bit quantities, but the external address bus is 36 bits wide, giving a larger address space than 4&nbsp;GB, and the external data bus is 64 bits wide, primarily in order to permit a more efficient prefetch of instructions and data.<ref>{{cite journal|last=Gwennap|first=Linley|date=16 February 1995|url=http://www.eecg.toronto.edu/~moshovos/ACA05/read/ppro1.pdf|title=Intel’s P6 Uses Decoupled Superscalar Design|publisher=Microprocessor Report|accessdate=3 December 2012}}</ref>

==Architectures==
Prominent 32-bit instruction set architectures used in general-purpose computing include the IBM System/360 and IBM System/370 (which had [[24-bit|24-bit]] addressing) and the System/370-XA, ESA/370, and ESA/390 (which had [[31-bit|31-bit]] addressing), the [[Company:Digital Equipment Corporation|DEC]] [[VAX]], the [[NS320xx]], the Motorola 68000 family (the first two models of which had 24-bit addressing), the [[Company:Intel|Intel]] [[IA-32]] 32-bit version of the [[X86|x86]] architecture, and the 32-bit versions of the [[ARM architecture|ARM]],<ref>{{cite web|title=ARM architecture overview|url=https://web.eecs.umich.edu/~prabal/teaching/eecs373-f10/readings/ARM_Architecture_Overview.pdf}}</ref> [[SPARC]], [[MIPS architecture|MIPS]], [[PowerPC]] and [[PA-RISC]] architectures.  32-bit instruction set architectures used for embedded computing include the 68000 family and ColdFire, x86, ARM, MIPS, PowerPC, and [[Engineering:Infineon TriCore|Infineon TriCore]] architectures.

== {{anchor|32-bit application}} Applications==
On the x86 architecture, a 32-bit application normally means [[Software|software]] that typically (not necessarily) uses the 32-bit linear [[Address space|address space]] (or [[Flat memory model|flat memory model]]) possible with the 80386 and later chips. In this context, the term came about because [[Engineering:DOS|DOS]], [[Software:Microsoft Windows|Microsoft Windows]] and OS/2<ref>''There were also variants of UNIX for the 80286''.</ref> were originally written for the [[Engineering:Intel 8088|8088/8086]] or [[Engineering:Intel 80286|80286]], [[16-bit|16-bit]] microprocessors with a segmented address space where programs had to switch between segments to reach more than 64 [[Kilobyte|kilobyte]]s of [[Object file|code]] or data. As this is quite time-consuming in comparison to other machine operations, the performance may suffer. Furthermore, [[Computer programming|programming]] with segments tend to become complicated; special ''far'' and ''near'' keywords or ''memory models'' had to be used (with care), not only in [[Assembly language|assembly language]] but also in high level languages such as Pascal, compiled [[BASIC]], [[Fortran]], [[C (programming language)|C]], etc.

The 80386 and its successors fully support the 16-bit segments of the 80286 but also segments for 32-bit address offsets (using the new 32-bit width of the main registers). If the [[Base address|base address]] of all 32-bit segments is set to 0, and segment registers are not used explicitly, the segmentation can be forgotten and the processor appears as having a simple linear 32-bit address space. [[Operating system]]s like Windows or OS/2 provide the possibility to run 16-bit (segmented) programs as well as 32-bit programs. The former possibility exists for [[Backward compatibility|backward compatibility]] and the latter is usually meant to be used for new [[Software engineering|software development]].

==Images==

In digital images/pictures, 32-bit usually refers to [[RGBA color space]]; that is, 24-bit truecolor images with an additional 8-bit alpha channel. Other image formats also specify 32 bits per pixel, such as [[RGBE image format|RGBE]].

In digital images, 32-bit sometimes refers to [[High-dynamic-range imaging|high-dynamic-range imaging]] (HDR) formats that use 32 bits per channel, a total of 96 bits per pixel. 32-bit-per-channel images are used to represent values brighter than what [[SRGB|sRGB]] color space allows (brighter than white); these values can then be used to more accurately retain bright highlights when either lowering the exposure of the image or when it is seen through a dark filter or dull reflection.

For example, a reflection in an oil slick is only a fraction of that seen in a mirror surface. HDR imagery allows for the reflection of highlights that can still be seen as bright white areas, instead of dull [[Grey|grey]] shapes.

==File formats==
A 32-bit file format is a [[Binary file|binary file]] [[File format|format]] for which each elementary information is defined on 32 bits (or 4 [[Byte|byte]]s). An example of such a format is the [[Windows Metafile|Enhanced Metafile Format]].

==See also==
* [[16-bit|16-bit]]
* 64-bit
* History of video games (32-bit era)
* Word (data type)
* [[Physical Address Extension]] (PAE)

==References==
{{Reflist}}
* {{FOLDOC}}

==External links==
* [http://computer.howstuffworks.com/bytes.htm HOW Stuff Works "How Bits and Bytes work"]
* [http://www.lockergnome.com/windows/2009/01/07/32-bit-vs-64-bit-windows/ Ken Colburn on LockerGnome.com: ''32-Bit Vs. 64-Bit Windows'']

{{CPU technologies}}

[[Category:Data unit]]

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