Microprocessor: Difference between revisions

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{{Short description|Computer processor contained on an integrated-circuit chip}}

{{Use dmy dates|date=June 2022}}

{{EngvarB|date=June 2022}}[[File:C4004 two lines.jpg|thumb|upright=0.9|4-bit [[Intel 4004]] (1971) ]]

[[File:TIMotorola TMS1000NLLXC6800A 1.jpg|thumb|upright=0.9|Texas Instruments8-bit [[TexasMotorola Instruments TMS1000|TMS10006800]] (1974)]]

[[File:C4004Intel twoC8086 lines1.jpg|thumb|upright=0.9|16-bit [[Intel 40048086]] (1978)]]

[[File:MotorolaKL XC6800AIBM 1PowerPC 601.jpg|thumb|upright=0.9|32-bit [[MotorolaPowerPC 6800601]] (MC68001993)]]

[[File:Scan des AMD Ryzen Threadripper 7970X 20240407 075.jpg|thumb|[[64-bit]], 32-core (64-threads), AMD Ryzen Threadripper 7970X based on [[x86-64]] [[Zen 4]] (2023)]]A '''microprocessor''' is a [[computer]] [[processor (computing)|processor]] for which the data processing logic and control is included on a single [[integrated circuit]] (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's [[central processing unit]] (CPU). The IC is capable of interpreting and executing program instructions and performing arithmetic operations.<ref>{{cite web |last=Orion |first=Veritas |date=2024-08-23 |title=What distinguishes a microprocessor from a microcontroller? |url=https://www.ampheo.com/blog/microprocessor-vs-microcontroller-comparison |website=Ampheo Electronics |publisher=Orion Veritas}}</ref> The microprocessor is a multipurpose, [[Clock signal|clock]]-driven, [[Processor register|register]]-based, [[digital integrated circuit]] that accepts [[binary code|binary]] data as input, processes it according to [[instruction (computing)|instruction]]s stored in its [[computer memory|memory]], and provides results (also in binary form) as output. Microprocessors contain both [[combinational logic]] and [[sequential logic|sequential digital logic]], and operate on numbers and symbols represented in the [[binary number]] system.

[[File:Scan des AMD Ryzen Threadripper 7970X 20240407 075.jpg|thumb|A modern [[64-bit computing|64-bit]] [[x86-64]] processor (AMD Ryzen Threadripper 7970X, based on [[Zen 4]], 2023)]]

[[File:AMD Ryzen 7 1800X.jpg|thumb|AMD Ryzen 7 1800X (2017, based on [[Zen (microarchitecture)|Zen]]) processor in an [[socket AM4|AM4]] socket on a motherboard]]

The integration of a whole CPU onto a single or a few integrated circuits using [[Very-Large-Scale Integration]] (VLSI) greatly reduced the cost of processing power. Integrated circuit processors are produced in large numbers by highly automated [[metal–oxide–semiconductor]] (MOS) [[semiconductor device fabrication|fabrication processes]], resulting in a relatively low [[unit price]]. Single-chip processors increase reliability because there are fewer electrical connections that can fail. As [[Processor design|microprocessor designs]] improve, the cost of manufacturing a chip (with smaller components built on a semiconductor chip the same size) generally stays the same, according to [[Rock's law]].

A '''microprocessor''' is a [[computer]] [[processor (computing)|processor]] for which the data processing logic and control is included on a single [[integrated circuit]] (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's [[central processing unit]] (CPU). The IC is capable of interpreting and executing program instructions and performing arithmetic operations.<ref>{{cite web |last=Orion |first=Veritas |date=2024-08-23 |title=What distinguishes a microprocessor from a microcontroller? |url=https://www.ampheo.com/blog/microprocessor-vs-microcontroller-comparison |website=Ampheo Electronics |publisher=Orion Veritas}}</ref> The microprocessor is a multipurpose, [[Clock signal|clock]]-driven, [[Processor register|register]]-based, [[digital integrated circuit]] that accepts [[binary code|binary]] data as input, processes it according to [[instruction (computing)|instruction]]s stored in its [[computer memory|memory]], and provides results (also in binary form) as output. Microprocessors contain both [[combinational logic]] and [[sequential logic|sequential digital logic]], and operate on numbers and symbols represented in the [[binary number]] system.

Before microprocessors, small computers had been built using racks of [[circuit board]]s with many [[medium-scale integration|medium-]] and [[small-scale integration|small-scale integrated circuits]],. These were typically of the [[Transistor–transistor logic|TTL]] type. Microprocessors combined this into one or a few [[large-scale integration|large-scale]] ICs. While there is disagreement over who deserves credit for the invention of the microprocessor, the first commercially available microprocessor was the [[Intel 4004]], designed by [[Federico Faggin]] and introduced in 1971.<ref name = "IEEE">{{cite web | url=https://spectrum.ieee.org/the-surprising-story-of-the-first-microprocessors | title=The Surprising Story of the First Microprocessors | date=30 August 2016 | access-date=4 October 2022 | archive-date=4 October 2022 | archive-url=https://web.archive.org/web/20221004011825/https://spectrum.ieee.org/the-surprising-story-of-the-first-microprocessors | url-status=live }}</ref>

The integration of a whole CPU onto a single or a few integrated circuits using [[Very-Large-Scale Integration]] (VLSI) greatly reduced the cost of processing power. Integrated circuit processors are produced in large numbers by highly automated [[metal–oxide–semiconductor]] (MOS) [[semiconductor device fabrication|fabrication processes]], resulting in a relatively low [[unit price]]. Single-chip processors increase reliability because there are fewer electrical connections that can fail. As [[Processor design|microprocessor designs]] improve, the cost of manufacturing a chip (with smaller components built on a semiconductor chip the same size) generally stays the same according to [[Rock's law]].

Continued increases in microprocessor capacity have since rendered other forms of computers almost completely obsolete (see [[history of computing hardware]]), with one or more microprocessors used in everything from the smallest [[embedded system]]s and [[handheld device]]s to the largest [[Mainframe computer|mainframe]]s and [[supercomputer]]s.

Before microprocessors, small computers had been built using racks of [[circuit board]]s with many [[medium-scale integration|medium-]] and [[small-scale integration|small-scale integrated circuits]], typically of [[Transistor–transistor logic|TTL]] type. Microprocessors combined this into one or a few [[large-scale integration|large-scale]] ICs. While there is disagreement over who deserves credit for the invention of the microprocessor, the first commercially available microprocessor was the [[Intel 4004]], designed by [[Federico Faggin]] and introduced in 1971.<ref name = "IEEE">{{cite web | url=https://spectrum.ieee.org/the-surprising-story-of-the-first-microprocessors | title=The Surprising Story of the First Microprocessors | date=30 August 2016 | access-date=4 October 2022 | archive-date=4 October 2022 | archive-url=https://web.archive.org/web/20221004011825/https://spectrum.ieee.org/the-surprising-story-of-the-first-microprocessors | url-status=live }}</ref>

A microprocessor is distinct from a [[microcontroller]] including a [[system on a chip]].<ref name="Warnes 2003 pp. 443–477">{{cite book | last=Warnes | first=Lionel | title=Electronic and Electrical Engineering | chapter=Microprocessors and microcontrollers | publisher=Macmillan Education UK | publication-place=London | date=2003 | isbn=978-0-333-99040-7 | doi=10.1007/978-0-230-21633-4_23 | pages=443–477 | quote=microprocessor is not a stand-alone computer, since it lacks memory and input/output control. These are the missing parts that the microcontroller supplies, making it more nearly a complete computer on a chip.}}</ref><ref name="Morris 1985 p.">{{cite book | last=Morris | first=Noel M. | title=Microelectronic and Microprocessor-based Systems | publisher=Macmillan Education UK | publication-place=London | date=1985 | isbn=978-0-333-36190-0 | doi=10.1007/978-1-349-06978-1 | page=16 | quote=A microprocessor itself is incapable of performing calculations and requires a support system in order to do so. The CPU support system includes a storage system in which not only the operating instructions but also the data (operands) are stored.}}</ref> A microprocessor is related but distinct from a [[digital signal processor]], a specialized microprocessor chip, with its architecture optimized for the operational needs of [[digital signal processing]].<ref>{{cite book |editor-last1=Yovits |editor-first1=Marshall C. |last1=Dyer |first1=Stephen A. |last2=Harms |first2=Brian K. |chapter=Digital Signal Processing |title=Advances in Computers |date=1993-08-13 |volume=37 |pages=59{{hyphen}}118 |publisher=[[Academic Press]] |doi=10.1016/S0065-2458(08)60403-9 |isbn=978-0120121373 |issn=0065-2458 |lccn=59015761 |chapter-url=https://books.google.com/books?id=vL-bB7GALAwC&pg=PA104 |ol=OL10070096M |oclc=858439915 |df=dmy-all}}</ref>{{rp|pages=104{{hyphen}}107}}<ref name="Liptak">{{cite book |last=Liptak |first=B. G. |title=Process Control and Optimization |series=Instrument Engineers' Handbook |edition=4th |year=2006 |volume=2 |pages=11–12 |publisher=CRC Press |isbn=978-0849310812 |url=https://books.google.com/books?id=TxKynbyaIAMC&pg=PA11 |via=[[Google Books]]}}</ref>

Continued increases in microprocessor capacity have since rendered other forms of computers almost completely obsolete (see [[history of computing hardware]]), with one or more microprocessors used in everything from the smallest [[embedded system]]s and [[handheld device]]s to the largest [[Mainframe computer|mainframe]]s and [[supercomputer]]s.

==Structure==

A microprocessor is distinct from a [[microcontroller]] including a [[system on a chip]].<ref name="Warnes 2003 pp. 443–477">{{cite book | last=Warnes | first=Lionel | title=Electronic and Electrical Engineering | chapter=Microprocessors and microcontrollers | publisher=Macmillan Education UK | publication-place=London | date=2003 | isbn=978-0-333-99040-7 | doi=10.1007/978-0-230-21633-4_23 | pages=443–477 | quote=microprocessor is not a stand-alone computer, since it lacks memory and input/output control. These are the missing parts that the microcontroller supplies, making it more nearly a complete computer on a chip.}}</ref><ref name="Morris 1985 p.">{{cite book | last=Morris | first=Noel M. | title=Microelectronic and Microprocessor-based Systems | publisher=Macmillan Education UK | publication-place=London | date=1985 | isbn=978-0-333-36190-0 | doi=10.1007/978-1-349-06978-1 | page=16 | quote=A microprocessor itself is incapable of performing calculations and requires a support system in order to do so. The CPU support system includes a storage system in which not only the operating instructions but also the data (operands) are stored.}}</ref> A microprocessor is related but distinct from a [[digital signal processor]], a specialized microprocessor chip, with its architecture optimized for the operational needs of [[digital signal processing]].<ref>{{cite book |editor-last1=Yovits |editor-first1=Marshall C. |last1=Dyer |first1=Stephen A. |last2=Harms |first2=Brian K. |chapter=Digital Signal Processing |title=Advances in Computers |date=1993-08-13 |volume=37 |pages=59{{hyphen}}118 |publisher=[[Academic Press]] |doi=10.1016/S0065-2458(08)60403-9 |isbn=978-0120121373 |issn=0065-2458 |lccn=59015761 |chapter-url=https://books.google.com/books?id=vL-bB7GALAwC&pg=PA104 |ol=OL10070096M |oclc=858439915 |df=dmy-all}}</ref>{{rp|pages=104{{hyphen}}107}}<ref name="Liptak">{{cite book |last=Liptak |first=B. G. |title=Process Control and Optimization |series=Instrument Engineers' Handbook |edition=4th |year=2006 |volume=2 |pages=11–12 |publisher=CRC Press |isbn=978-0849310812 |url=https://books.google.com/books?id=TxKynbyaIAMC&pg=PA11 |via=[[Google Books]]}}</ref>

[[File:Z80 arch.svg|thumb|upright=1.7|AThe block diagram of the[[Computer architecture|architecture]] of the [[Zilog Z80|Z80]] microprocessor, showing(1976) theinternally uses an 8-bit [[Arithmetic logic unit|arithmetic and logic section]], and [[Processor register|register]] file, [[controlbut logic]]accesses section,external andmemory [[Datausing buffer|buffer]]s to external16-bit [[Memory address|addressaddresses]] and data lines]]

==Struct Area==

[[File:Z80 arch.svg|thumb|upright=1.7|A block diagram of the architecture of the [[Zilog Z80|Z80]] microprocessor, showing the [[Arithmetic logic unit|arithmetic and logic section]], [[Processor register|register]] file, [[control logic]] section, and [[Data buffer|buffer]]s to external [[Memory address|address]] and data lines]]

The complexity of an integrated circuit is bounded by physical limitations on the number of [[transistors]] that can be put onto one chip, the number of package terminations that can connect the processor to other parts of the system, the number of interconnections it is possible to make on the chip, and the heat that the chip can [[Thermal management (electronics)|dissipate]]. Advancing technology makes more complex and powerful chips feasible to manufacture.

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A minimal hypothetical microprocessor might include only an [[arithmetic logic unit]] (ALU), and a [[control logic]] section. The ALU performs addition, subtraction, and operations such as AND or OR. Each operation of the ALU sets one or more [[Bit field|flag]]s in a [[status register]], which indicate the results of the last operation (zero value, negative number, [[Integer overflow|overflow]], or others). The control logic retrieves instruction codes from memory and initiates the sequence of operations required for the ALU to carry out the instruction. A single [[operation code]] might affect many individual data paths, registers, and other elements of the processor.

As integrated circuit technology advanced, it was feasible to manufacture more and more complex processors on a single chip. The size of data objects became larger; allowing more transistors on a chip allowed [[Word (computer architecture)|word]] sizes to increase from [[4-bit computing|4-]] and [[8-bit computing|8-bit]] words up to today's [[64-bit computing|64-bit]] words. Additional features were added to the processor architecture; more on-chip registers sped up programs, and complex instructions could be used to make more compact programs. [[Floating-point arithmetic]], for example, was often not available on 8-bit microprocessors, but had to be carried out in [[software]]. Integration of the [[floating-point unit]], first as a separate integrated circuit and then as part of the same microprocessor chip, sped up floating-point calculations.

Occasionally, physical limitations of integrated circuits made such practices as a [[Bit slicing|bit slice]] approach necessary. Instead of processing all of a long word on one integrated circuit, multiple circuits [[parallel computing|in parallel]] processed subsets of each word. While this required extra logic to handle, for example, carry and overflow within each slice, the result was a system that could handle, for example, [[32-bit computing|32-bit]] words using integrated circuits with a capacity for only four&nbsp;bits each.

The ability to put large numbers of transistors on one chip makes it feasible to integrate memory on the same die as the processor. This [[CPU cache]] has the advantage of faster access than off-chip memory and increases the processing speed of the system for many applications. Processor [[Clock rate|clock frequency]] has increased more rapidly than external memory speed, so [[Cache (computing)|cache memory]] is necessary if the processor is not to be delayed by slower external memory.

The design of some processors has become complicated enough to be difficult to fully [[Integrated circuit testing|test]], and this has caused problems at large cloud providers.<ref>{{Cite web |url=https://www.theregister.com/2021/06/04/google_chip_flaws/ |title=FYI: Today's computer chips are so advanced, they are more 'mercurial' than precise – and here's the proof |access-date=13 February 2024 |archive-date=13 February 2024 |archive-url=https://web.archive.org/web/20240213173804/https://www.theregister.com/2021/06/04/google_chip_flaws/ |url-status=live }}</ref>

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* A [[digital signal processor]] (DSP) is specialized for [[signal processing]].

* [[Graphics processing unit]]s (GPUs) are processors designed primarily for [[Realreal-time computer graphics|realtime rendering]] of images.

* Other specialized units exist for [[video processing]] and [[vision processing unit|machine vision]]. (See: [[Hardware acceleration]].)

* [[Microcontroller]]s in [[embedded system]]s and [[Peripheral|peripheral device]]s.

* [[System on a chip|Systems on chip]] (SoCs) often integrate one or more microprocessor and microcontroller cores with other components such as [[radio modemsmodem]]s, and are used in smartphones and tablet computers.

===Speed and power considerations===

Microprocessors can be selected for differing applications based on their word size, which is a measure of their complexity. Longer word sizes allow each [[Clock signal|clock cycle]] of a processor to carry out more computation, but correspond to physically larger integrated circuit dies with higher standby and operating [[Electric energy consumption|power consumption]].<ref name="cmicrotek">CMicrotek.

[[File:Intel i9-9900K.jpg|thumb|Intel Core i9-9900K (2018, based on [[Coffee Lake]])]]

[http://cmicrotek.com/wordpress_159256135/?p=22 "8-bit vs 32-bit Micros"] {{webarchive|url=https://web.archive.org/web/20140714123158/http://cmicrotek.com/wordpress_159256135/?p=22 |date=2014-07-14 }}.</ref> 4-, 8- or 12-bit processors are widely integrated into microcontrollers operating embedded systems. Where a system is expected to handle larger volumes of data or require a more flexible [[user interface]], 16-, 32- or 64-bit processors are used. An 8- or [[16-bit computing|16-bit]] processor may be selected over a 32-bit processor for [[system on a chip]] or microcontroller applications that require extremely [[low-power electronics]], or are part of a [[mixed-signal integrated circuit]] with noise-sensitive on-chip [[Analogue electronics|analog electronics]] such as high-resolution analog to digital converters, or both.

Microprocessors can be selected for differing applications based on their word size, which is a measure of their complexity. Longer word sizes allow each [[Clock signal|clock cycle]] of a processor to carry out more computation, but correspond to physically larger integrated circuit dies with higher standby and operating [[Electric energy consumption|power consumption]].<ref name="cmicrotek">CMicrotek.

[http://cmicrotek.com/wordpress_159256135/?p=22 "8-bit vs 32-bit Micros"] {{webarchive|url=https://web.archive.org/web/20140714123158/http://cmicrotek.com/wordpress_159256135/?p=22 |date=2014-07-14 }}.</ref> 4-, 8- or 12-bit processors are widely integrated into microcontrollers operating embedded systems. Where a system is expected to handle larger volumes of data or require a more flexible [[user interface]], 16-, 32- or 64-bit processors are used. An 8- or [[16-bit computing|16-bit]] processor may be selected over a 32-bit processor for [[system on a chip]] or microcontroller applications that require extremely [[low-power electronics]], or are part of a [[mixed-signal integrated circuit]] with noise-sensitive on-chip [[Analogue electronics|analog electronics]] such as high-resolution analog to digital converters, or both.

Some people say that running 32-bit arithmetic on an 8-bit chip could end up using more power, as the chip must execute software with multiple instructions.<ref>{{cite web|title=Managing the Impact of Increasing Microprocessor Power Consumption|url=http://www.ruf.rice.edu/~mobile/elec518/readings/Intel/gunther01power.pdf|website=[[Rice University]]|access-date=October 1, 2015|url-status=live|archive-url=https://web.archive.org/web/20151003085353/http://www.ruf.rice.edu/~mobile/elec518/readings/Intel/gunther01power.pdf|archive-date=October 3, 2015}}</ref>

However, others say that modern 8-bit chips are always more power-efficient than 32-bit chips when running equivalent software routines.<ref name="freeman" >Wayne Freeman.

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==History==

{{See also|Microprocessor chronology}}

The advent of low-cost [[computers]] on [[integrated circuits]] has transformed [[modern society]]. General-purpose microprocessors in [[personal computer]]s are used for computation, text editing, [[multimedia|multimedia display]], and communication over the [[Internet]]. Many more microprocessors are part of [[embedded system]]s, providing digital control over myriad objects from appliances to automobiles to [[cellular phone]]s and industrial [[process control]]. Microprocessors perform binary operations based on [[Boolean algebra|Boolean logic]], named after [[George Boole]]. The ability to operate computer systems using Boolean Logic was first proven in a 1938 thesis by master's student [[Claude Shannon]], who later went on to become a professor. Shannon is considered "The Father of Information Theory". In 1951 [[Microprogramming]] was invented by [[Maurice Wilkes]] at the [[ University of Cambridge]], UK, from the realisation that the central processor could be controlled by a specialised program in a dedicated [[ROM]].<ref>{{Cite journal | last1 = Wilkes | first1 = M. V. | title = The Growth of Interest in Microprogramming: A Literature Survey | doi = 10.1145/356551.356553 | journal = ACM Computing Surveys | volume = 1 | issue = 3 | pages = 139–145 | year = 1969 | s2cid = 10673679 | doi-access = free }}</ref> Wilkes is also credited with the idea of symbolic labels, macros and subroutine libraries.<ref>{{cite web |title=Sir Maurice Wilkes, The Father Of Computing, Dies |website=Silicon UK |date=3 December 2010 |url=https://www.silicon.co.uk/workspace/sir-maurice-wilkes-the-father-of-computing-dies-aged-97-14967|access-date=28 November 2023}}</ref>

Following the development of [[MOS integrated circuit]] chips in the early 1960s, MOS chips reached higher [[transistor density]] and lower manufacturing costs than [[bipolar junction transistor|bipolar]] [[integrated circuits]] by 1964. MOS chips further increased in complexity at a rate predicted by [[Moore's law]], leading to [[large-scale integration]] (LSI) with hundreds of [[transistors]] on a single MOS chip by the late 1960s. The application of MOS LSI chips to [[computing]] was the basis for the first microprocessors, as engineers began recognizing that a complete [[computer processor]] could be contained on several MOS LSI chips.<ref name="ieee">{{cite journal|last1=Shirriff|first1=Ken|date=30 August 2016|title=The Surprising Story of the First Microprocessors|url=https://spectrum.ieee.org/the-surprising-story-of-the-first-microprocessors|journal=[[IEEE Spectrum]]|publisher=[[Institute of Electrical and Electronics Engineers]]|volume=53|issue=9|pages=48–54|doi=10.1109/MSPEC.2016.7551353|access-date=13 October 2019|s2cid=32003640|url-access=subscription|url-status=live|archive-url=https://web.archive.org/web/20171124080014/http://spectrum.ieee.org/tech-history/silicon-revolution/the-surprising-story-of-the-first-microprocessors|archive-date=2017-11-24}}</ref> Designers in the late 1960s were striving to integrate the [[central processing unit]] (CPU) functions of a computer onto a handful of MOS LSI chips, called microprocessor unit (MPU) chipsets.

While there is disagreement over who invented the microprocessor,<ref name = "IEEE" /><ref>{{Cite web |last=Laws |first=David |date=2018-09-20 |title=Who Invented the Microprocessor? |url=https://computerhistory.org/blog/who-invented-the-microprocessor/ |access-date=2024-01-19 |website=Computer History Museum |language=en |archive-date=19 January 2024 |archive-url=https://web.archive.org/web/20240119023250/https://computerhistory.org/blog/who-invented-the-microprocessor/ |url-status=live }}</ref> the first commercially available microprocessor was the [[Intel 4004]], released as a single MOS LSI chip in 1971.<ref>{{cite web |title=1971: Microprocessor Integrates CPU Function onto a Single Chip |website=The Silicon Engine |url=https://www.computerhistory.org/siliconengine/microprocessor-integrates-cpu-function-onto-a-single-chip/ |publisher=[[Computer History Museum]] |access-date=22 July 2019 |archive-date=12 August 2021 |archive-url=https://web.archive.org/web/20210812104243/https://www.computerhistory.org/siliconengine/microprocessor-integrates-cpu-function-onto-a-single-chip/ |url-status=live }}</ref> The single-chip microprocessor was made possible with the development of MOS [[silicon-gate]] technology (SGT).<ref name="silicon-gate">{{Cite web|url=https://www.computerhistory.org/siliconengine/silicon-gate-technology-developed-for-ics/|title=1968: Silicon Gate Technology Developed for ICs {{!}} The Silicon Engine {{!}} Computer History Museum|website=www.computerhistory.org|access-date=2019-10-24|archive-date=29 July 2020|archive-url=https://web.archive.org/web/20200729145834/https://www.computerhistory.org/siliconengine/silicon-gate-technology-developed-for-ics/|url-status=live}}</ref> The earliest MOS transistors had [[aluminium]] [[metal gate]]s, which Italian physicist [[Federico Faggin]] replaced with [[silicon]] [[self-aligned gate]]s to develop the first silicon-gate MOS chip at [[Fairchild Semiconductor]] in 1968.<ref name="silicon-gate"/> Faggin later joined [[Intel]] and used his silicon-gate MOS technology to develop the 4004, along with [[Marcian Hoff]], [[Stanley Mazor]] and [[Masatoshi Shima]] in 1971.<ref>{{Cite web|url=https://www.computerhistory.org/siliconengine/microprocessor-integrates-cpu-function-onto-a-single-chip/|title=1971: Microprocessor Integrates CPU Function onto a Single Chip {{!}} The Silicon Engine {{!}} Computer History Museum|website=www.computerhistory.org|access-date=2019-10-24|archive-date=12 August 2021|archive-url=https://web.archive.org/web/20210812104243/https://www.computerhistory.org/siliconengine/microprocessor-integrates-cpu-function-onto-a-single-chip/|url-status=live}}</ref> The 4004 was designed for [[Busicom]], which had earlier proposed a multi-chip design in 1969, before Faggin's team at Intel changed it into a new single-chip design. Intel introduced the first commercial microprocessor, theThe [[4-bit computing|4-bit]] Intel 4004, in 1971. It was soon followed by the 8-bit microprocessor [[Intel 8008]] in 1972. The MP944 chipset used in the [[F-14 CADC|F-14 Central Air Data Computer]] in 1970 has also been cited as an early microprocessor, but was not known to the public until declassified in 1998.

Other [[embedded system|embedded]] uses of 4-bit and 8-bit microprocessors, such as [[computer terminal|terminal]]s, [[computer printer|printer]]s, various kinds of [[automation]] etc., followed soon after. Affordable 8-bit microprocessors with [[16-bit computing|16-bit]] addressing also led to the first general-purpose [[microcomputer]]s from the mid-1970s on.

The first use of the term "microprocessor" is attributed to [[Viatron|Viatron Computer Systems]]<ref>[http://bitsavers.org/pdf/viatron/ViatronSystem21Brochure.pdf Viatron Computer Systems. "System 21 is Now!"] {{webarchive|url=https://web.archive.org/web/20110321143159/http://www.bitsavers.org/pdf/viatron/ViatronSystem21Brochure.pdf |date=2011-03-21 }} (PDF).</ref> describing the custom integrated circuit used in their System 21 small computer system announced in 1968.

Since the early 1970s, the increase in capacity of microprocessors has followed [[Moore's law]]; this originally suggested that the number of components that can be fitted onto a chip doubles every year. With present technology, it is actually every two years,<ref>{{citeCite FTP journal|last=Moore |first=Gordon |title=Cramming more components onto integrated circuits |journal=Electronics |volume=38 |issue=8 |date=19 April 1965 |url=ftp://download.intel.com/museum/Moores_Law/Articles-Press_Releases/Gordon_Moore_1965_Article.pdf |access-date=2009-12-23 |url-status=dead |archive-urlserver=https://web.archive.org/web/20080218224945/http://download.intel.com/museum/Moores_Law/Articles-Press_Releases/Gordon_Moore_1965_Article.pdf |archive-date=18 February 2008Electronics }}</ref> {{Obsolete source|date=August 2019}} and as a result Moore later changed the period to two years.<ref>{{cite journalweb |title=Excerpts from A Conversation with Gordon Moore: Moore's Law |publisher=Intel |year=2005 |url=ftp://download.intel.com/museum/Moores_Law/Video-Transcripts/Excepts_A_Conversation_with_Gordon_Moore.pdf |access-date=2009-12-23 |url-status=dead |archive-url=https://web.archive.org/web/2012102906005020080218225540/http://download.intel.com/museum/Moores_Law/Video-Transcripts/Excepts_A_Conversation_with_Gordon_Moore.pdf |archive-date=20122008-1002-2918 |url-status=dead |access-date=2009-12-23 }}</ref>

===First projects===

These projects delivered a microprocessor at about the same time: [[Garrett AiResearch]]'s [[Central Air Data Computer]] (CADC) (1970), [[Texas Instruments]]' TMS 1802NC (September 1971) and [[Intel]]'s [[Intel 4004|4004]] (November 1971, based on an earlier 1969 [[Busicom]] design). Arguably, [[Four-Phase Systems AL1]] microprocessor was also delivered in 1969.

====Four-Phase Systems AL1 (1969)====

The [[Four-Phase Systems AL1]] was an 8-bit [[bit slice]] chip containing eight registers and an ALU.<ref>{{cite book | page=121 | chapter=When is a Microprocessor not a Microprocessor? The Industrial Construction of Semiconductor Innovation | author=Basset, Ross | title=Exposing Electronics | editor=Finn, Bernard | publisher=Michigan State University Press | year=2003 | isbn=978-0-87013-658-0 | chapter-url=https://books.google.com/books?id=rsRJTiu1h9MC | url-status=live | archive-url=https://web.archive.org/web/20140330235547/http://books.google.com/books?id=rsRJTiu1h9MC | archive-date=2014-03-30 }}</ref><!-- UK ed. same page scheme--> It was designed by [[Lee Boysel]] in 1969.<ref>{{cite web | url=http://www.computerhistory.org/semiconductor/timeline/1971-MPU.html | publisher=Computer History Museum | website=The Silicon Engine | title=1971 - Microprocessor Integrates CPU Function onto a Single Chip | access-date=2010-07-25 | url-status=live | archive-url=https://web.archive.org/web/20100608102128/http://www.computerhistory.org/semiconductor/timeline/1971-MPU.html | archive-date=2010-06-08 }}</ref><ref>{{cite web | url=http://home.comcast.net/~gordonepeterson2/schaller_dissertation_2004.pdf | title=Technological Innovation in the Semiconductor Industry: A Case Study of the International Technology Roadmap for Semiconductors | author=Shaller, Robert R. | date=15 April 2004 | publisher=George Mason University | access-date=2010-07-25 | archive-url=https://web.archive.org/web/20061219012629/http://home.comcast.net/~gordonepeterson2/schaller_dissertation_2004.pdf | archive-date=2006-12-19 | url-status=live }}</ref><ref>{{cite web | url=http://www-sul.stanford.edu/depts/hasrg/histsci/silicongenesis/moore-ntb.html | title=Interview with Gordon E. Moore | date=3 March 1995 | ___location=Los Altos Hills, California | author=RW | publisher=Stanford University | website=[[LAIR]] History of Science and Technology Collections | url-status=live | archive-url=https://web.archive.org/web/20120204045916/http://www-sul.stanford.edu/depts/hasrg/histsci/silicongenesis/moore-ntb.html | archive-date=4 February 2012 }}</ref> At the time, it formed part of a nine-chip, 24-bit CPU with three AL1s. It was later called a microprocessor when, in response to 1990s litigation by [[Texas Instruments]], Boysel constructed a demonstration system where a single AL1 with a 1969 datestamp formed part of a courtroom demonstration computer system, together with RAM, ROM, and an input-output device.<ref>Bassett 2003. pp. 115, 122.</ref> The AL1 wasn't sold individually, but was part of the System IV/70 announced in September 1970 and first delivered in February 1972.<ref name=":0">{{Cite web| title=Four-Phase System IV Series | url=https://bitsavers.trailing-edge.com/pdf/datapro/datapro_reports_70s-90s/Four_Phase/M11-435-10_7908_Four-Phase_System_IV.pdf | archive-url=https://web.archive.org/web/20241231053554/https://bitsavers.trailing-edge.com/pdf/datapro/datapro_reports_70s-90s/Four_Phase/M11-435-10_7908_Four-Phase_System_IV.pdf | archive-date=2024-12-31}}</ref>

====Garrett AiResearch CADC (1970)====

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{{Further|F-14 CADC}}

In 1968, [[Garrett AiResearch]] (who employed designers [[Ray Holt (computer scientist)|Ray Holt]] and Steve Geller) was invited to produce a digital computer to compete with [[electromechanical]] systems then under development for the main flight control computer in the [[US Navy]]'s new [[F-14 Tomcat]] fighter. The design was complete by 1970, and used a [[MOSFET|MOS]]-based chipset as the core CPU. The design was significantly (approximately 20 times) smaller and much more reliable than the mechanical systems it competed against and was used in all of the early Tomcat models. This system contained "a 20-bit, [[Pipeline (computing)|pipelined]], [[Parallel computing|parallel]] [[multiprocessor|multi-microprocessor]]". The Navy refused to allow publication of the design until 1997. Released in 1998, the documentation on the [[Central Air Data Computer|CADC]], and the [[MP944]] chipset, are well known. Ray Holt's autobiographical story of this design and development is presented in the book: The Accidental Engineer.<ref>{{Cite web|url=https://firstmicroprocessor.com/|archiveurl=https://web.archive.org/web/20140106143912/http://www.firstmicroprocessor.com/|url-status=dead|title=First Microprocessor|archivedate=January 6, 2014|website=First Microprocessor &#124; 50th Anniversary of the Microprocessor 2020}}</ref><ref>{{cite web | title=World's First Microprocessor Chip Set | last=Holt | first=Ray M. | url=http://www.firstmicroprocessor.com | publisher=Ray M. Holt website | archive-date=January 6, 2014 | access-date=2010-07-25 | url-status=live | archive-url=https://web.archive.org/web/20140106143912/http://www.firstmicroprocessor.com/ }}</ref>

[[Ray Holt]] graduated from [[California State Polytechnic University, Pomona]] in 1968, and began his computer design career with the CADC.<ref>{{Cite magazine |last=Fallon |first=Sarah |title=The Secret History of the First Microprocessor, the F-14, and Me |url=https://www.wired.com/story/secret-history-of-the-first-microprocessor-f-14/ |access-date=2024-01-21 |magazine=Wired |language=en-US |issn=1059-1028 |archive-date=18 January 2024 |archive-url=https://web.archive.org/web/20240118132936/https://www.wired.com/story/secret-history-of-the-first-microprocessor-f-14/ |url-status=live }}</ref> From its inception, it was shrouded in secrecy until 1998 when at Holt's request, the US Navy allowed the documents into the public ___domain. Holt has claimed that no one has compared this microprocessor with those that came later.<ref>{{cite speech | title=Lecture: Microprocessor Design and Development for the US Navy F14 FighterJet | last=Holt | first=Ray | date=27 September 2001 | ___location=Room 8220, Wean Hall, Carnegie Mellon University, Pittsburgh, PA, US | url=http://www.pdl.cmu.edu/SDI/2001/092701.html | access-date=2010-07-25 | url-status=live | archive-url=https://web.archive.org/web/20111001020654/http://www.pdl.cmu.edu/SDI/2001/092701.html | archive-date=1 October 2011 }}</ref> According to Parab et al. (2007), {{Blockquote|text=The scientific papers and literature published around 1971 reveal that the MP944 digital processor used for the F-14 Tomcat aircraft of the US Navy qualifies as the first microprocessor. Although interesting, it was not a single-chip processor, as was not the Intel 4004{{snd}}they both were more like a set of parallel building blocks you could use to make a general-purpose form. It contains a CPU, [[Random-access memory|RAM]], [[Read-only memory|ROM]], and two other support chips like the Intel 4004. It was made from the same [[PMOS logic|P-channel]] technology, operated at [[United States Military Standard|military specifications]] and had larger chips{{snd}}an excellent computer engineering design by any standards. Its design indicates a major advance over Intel, and two year earlier. It actually worked and was flying in the F-14 when the Intel 4004 was announced. It indicates that today's industry theme of converging [[Digital signal processor|DSP]]-[[microcontroller]] architectures was started in 1971.<ref>{{cite book | title=Exploring C for Microcontrollers: A Hands on Approach | last1=Parab | first1=Jivan S. | last2=Shelake | first2=Vinod G. | last3=Kamat | first3=Rajanish K. | last4=Naik | first4=Gourish M. | publisher=Springer | page=4 | year=2007 | isbn=978-1-4020-6067-0 | url=http://ee.sharif.edu/~sakhtar3/books/Exploring%20C%20for%20Microcontrollers.pdf | access-date=2010-07-25 | url-status=live | archive-url=https://web.archive.org/web/20110720043756/http://ee.sharif.edu/~sakhtar3/books/Exploring%20C%20for%20Microcontrollers.pdf | archive-date=2011-07-20 }}</ref>}} This convergence of DSP and microcontroller architectures is known as a [[digital signal controller]].<ref>{{cite book|editor=Yovits, M. C.|author1=Dyer, S. A.|author2=Harms, B. K.|chapter=Digital Signal Processing|title=Advances in Computers|year=1993|volume=37|pages=104–107|publisher=Academic Press|doi=10.1016/S0065-2458(08)60403-9|isbn=9780120121373|chapter-url=https://books.google.com/books?id=vL-bB7GALAwC&pg=PA104|url-status=live|archive-url=https://web.archive.org/web/20161229031814/https://books.google.com/books?id=vL-bB7GALAwC&pg=PA104|archive-date=2016-12-29}}</ref>

====Gilbert Hyatt (1970) ====

In 1990, American engineer Gilbert Hyatt was awarded U.S. Patent No. 4,942,516,<ref>{{Cite patent|country=US|number=4942516|title=Single chip integrated circuit computer architecture|gdate=1990-07-17|invent1=Hyatt|inventor1-first=Gilbert P|url=https://patents.google.com/patent/US4942516A}} {{Webarchive|url=https://web.archive.org/web/20120525061939/http://www.google.com/patents/about?id=cNcbAAAAEBAJ |date=25 May 2012 }}</ref> which was based on a 16-bit serial computer he built at his [[Northridge, California]], home in 1969 from boards of bipolar chips after quitting his job at [[Teledyne]] in 1968;<ref name = "IEEE" /><ref name= "LAT" /> though the patent had been submitted in December 1970 and prior to [[Texas Instruments]]' filings for the TMX 1795 and TMS 0100, Hyatt's invention was never manufactured.<ref name ="LAT"/><ref>{{cite news | url=https://www.nytimes.com/1996/06/20/business/for-texas-instruments-some-bragging-rights.html | title=For Texas Instruments, Some Bragging Rights | newspaper=The New York Times | date=20 June 1996 | last1=Markoff | first1=John | access-date=4 October 2022 | archive-date=28 September 2022 | archive-url=https://web.archive.org/web/20220928210935/https://www.nytimes.com/1996/06/20/business/for-texas-instruments-some-bragging-rights.html | url-status=live }}</ref><ref>{{cite web | url=https://www.pcmag.com/news/the-birth-of-the-microprocessor | title=The Birth of the Microprocessor | date=16 December 2014 | access-date=4 October 2022 | archive-date=4 October 2022 | archive-url=https://web.archive.org/web/20221004020435/https://www.pcmag.com/news/the-birth-of-the-microprocessor | url-status=live }}</ref> This nonetheless led to claims that Hyatt was the inventor of the microprocessor and the payment of substantial royalties through a [[Philips N.V.]] subsidiary,<ref>{{cite web | url=https://www.latimes.com/archives/la-xpm-1991-11-07-fi-1581-story.html | title=Microprocessor Patent Holder Signs Contract : Invention: La Palma inventor signs with Dutch electronics giant, the first company to accord validity to his patent | website=[[Los Angeles Times]] | date=7 November 1991 | access-date=4 October 2022 | archive-date=4 October 2022 | archive-url=https://web.archive.org/web/20221004023903/https://www.latimes.com/archives/la-xpm-1991-11-07-fi-1581-story.html | url-status=live }}</ref> until Texas Instruments prevailed in a complex legal battle in 1996, when the U.S. Patent Office overturned key parts of the patent, while allowing Hyatt to keep it.<ref name = "IEEE" /><ref>{{cite web | url=https://lasvegassun.com/news/2014/dec/21/inventors-fight-recognition-ongoing-not-all-consum/ | title=Inventor's fight for recognition ongoing but not all-consuming - Las Vegas Sun Newspaper | date=21 December 2014 | access-date=4 October 2022 | archive-date=20 October 2022 | archive-url=https://web.archive.org/web/20221020013849/https://lasvegassun.com/news/2014/dec/21/inventors-fight-recognition-ongoing-not-all-consum/ | url-status=live }}</ref> Hyatt said in a 1990 ''Los Angeles Times'' article that his invention would have been created had his prospective investors backed him, and that the venture investors leaked details of his chip to the industry, though he did not elaborate with evidence to support this claim.<ref name ="LAT">{{cite web | url=https://www.latimes.com/archives/la-xpm-1990-10-21-fi-4400-story.html | title=Chip Designer's 20-Year Quest : Computers: Gilbert Hyatt's solitary battle to patent the microprocessor appears to have paid off, if it can withstand legal challenges. Here's his story | website=[[Los Angeles Times]] | date=21 October 1990 | access-date=4 October 2022 | archive-date=4 October 2022 | archive-url=https://web.archive.org/web/20221004020434/https://www.latimes.com/archives/la-xpm-1990-10-21-fi-4400-story.html | url-status=live }}</ref> In the same article, ''The Chip'' author [[T.R. Reid]] was quoted as saying that historians may ultimately place Hyatt as a co-inventor of the microprocessor, in the way that Intel's Noyce and TI's Kilby share credit for the invention of the chip in 1958: "Kilby got the idea first, but Noyce made it practical. The legal ruling finally favored Noyce, but they are considered co-inventors. The same could happen here."<ref name = "LAT"/> Hyatt would go on to fight a decades-long legal battle with the state of California over alleged unpaid taxes on his patent's windfall after 1990, which would culminate in a landmark Supreme Court case addressing states' [[sovereign immunity]] in ''[[Franchise Tax Board of California v. Hyatt (2019)]]''.

====Texas Instruments TMX 1795 (1970–1971)====

Along with Intel (who developed the [[Intel 8008|8008]]), Texas Instruments developed in 1970&ndash;1971 a one-chip CPU replacement for the [[Datapoint 2200]] terminal, the TMX 1795 (later TMC 1795.). Like theIntel's later [[8008]], it was rejected by customer Datapoint. According to Gary Boone, the TMX 1795 never reached production. Still it reached a working prototype state at 1971 February 24, therefore it is the world's first 8-bit microprocessor.<ref name="righto_com">{{cite web | url=https://www.righto.com/2015/05/the-texas-instruments-tmx-1795-first.html | title=The Texas Instruments TMX 1795: The (Almost) first, forgotten microprocessor }}</ref> Since it was built to the same specification, its instruction set was very similar to the Intel 8008.<ref name="genie">{{cite book |first1=Frederick |last1=Seitz |first2=Norman G. |last2=Einspruch |chapter=19. The 1970s and the Microprocessor § Texas Instruments |title=Electronic Genie: The Tangled History of Silicon |publisher=University of Illinois Press |date=1998 |isbn=0252023838 |pages=228–9 |chapter-url=https://books.google.com/books?id=IT90cDPh54wC&pg=PA229 |access-date=14 August 2022 |archive-date=19 February 2023 |archive-url=https://web.archive.org/web/20230219195307/https://books.google.com/books?id=IT90cDPh54wC&pg=PA229 |url-status=live }}</ref><ref name="shirriff">{{cite journal |first=Ken |last=Shirriff |title=The Surprising Story of the First Microprocessors |journal=IEEE Spectrum |volume=53 |issue=9 |pages=48–54 |date=2016 |doi=10.1109/MSPEC.2016.7551353 |s2cid=32003640 |url=https://ieeexplore.ieee.org/document/7551353 |access-date=14 August 2022 |archive-date=14 August 2022 |archive-url=https://web.archive.org/web/20220814014410/https://ieeexplore.ieee.org/document/7551353 |url-status=live }}</ref>

====Texas Instruments TMS 1802NC (1971)====

The TMS1802NC was, announced September 17, 1971, was the first microcontroller and at launch implemented a four-function calculator. The TMS1802NC, despite its designation, was not part of the [[TMS 1000]] series; it was later redesignated as part of the TMS 0100 series, which was used in the TI Datamath calculator. AlthoughIt was marketed as a calculator-on-a-chip, theand TMS1802NC wasalso "fully programmable", includingbut onthis theprogramming had to done during manufacturing. Its chip integrated a CPU with an 11-bit instruction word, 3520 bits (320 instructions) of ROM and 182 bits of RAM.<ref name="genie" /><ref>U.S. Patent no. 4,074,351 (TMS1802NC.)</ref><ref name="shirriff" /><ref>[https://web.archive.org/web/20060218021723/http://www.ti.com/corp/docs/company/history/calcchip.shtml "STANDARD CALCULATOR ON A CHIP ANNOUNCED BY TEXAS INSTRUMENTS"], press release. TI, Sep. 19, 1971. Originally on ti.com but now archived at archive.org.</ref>

====Pico/General Instrument (1971)====

[[File:GI250 PICO1 die photo.jpg|thumb|upright=1.2|The PICO1/GI250 chip introduced in 1971: It was designed by Pico Electronics (Glenrothes, Scotland) and manufactured by General Instrument of Hicksville NY.]]

In 1971, Pico Electronics<ref>{{cite web | title=Microprocessor History: Foundations in Glenrothes, Scotland | last=McGonigal | first=James | date=20 September 2006 | url=http://www.spingal.plus.com/micro | website=McGonigal personal website | access-date=2009-12-23 | url-status=dead | archive-url=https://web.archive.org/web/20110720142104/http://www.spingal.plus.com/micro/ | archive-date=20 July 2011 }}</ref> and [[General Instrument]] (GI) introduced their first collaboration in ICs, a complete single-chip calculator IC for the Monroe/[[Litton Industries|Litton]] Royal Digital III calculator. This chip could also arguably lay claim to be one of the first microprocessors or microcontrollers having [[Read-only memory|ROM]], [[Random-access memory|RAM]] and a [[RISC]] instruction set on-chip. The layout for the four layers of the [[PMOS logic|PMOS]] process was hand drawn at x500 scale on mylar film, a significant task at the time given the complexity of the chip.

Pico was a spinout by five GI design engineers whose vision was to create single-chip calculator ICs. They had significant previous design experience on multiple calculator chipsets with both GI and [[Elliott Automation|Marconi-Elliott]].<ref>{{cite web | title=ANITA at its Zenith | website=Bell Punch Company and the ANITA calculators | first=Nigel | last=Tout | url=http://anita-calculators.info/html/anita_at_its_zenith.html | access-date=2010-07-25 | url-status=live | archive-url=https://web.archive.org/web/20100811034328/http://anita-calculators.info/html/anita_at_its_zenith.html | archive-date=2010-08-11 }}</ref> The key team members had originally been tasked by [[Elliott Automation]] to create an 8-bit computer in MOS and had helped establish a MOS Research Laboratory in [[Glenrothes]], Scotland in 1967.

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====Intel 4004 (1971) ====

{{Main|Intel 4004}}

[[File:C4004 (Intel).jpg|thumb|TheIntel's first microprocessor, the [[Intel 4004|4004]], with cover removed (left) and as actually used (right)]]

[[File:Intel_4004_ad.jpg|thumb|Intel advertisement in [[Electronic News]] magazine from 1971 emphasizing the 4004's affordability, compactness, ease of programming, and flexibility.]]

The [[Intel 4004]] is often (falsely) regarded as the first true microprocessor built on a single chip,<ref>{{cite web | title=The Microcomputer Revolution | first=Pamela E. | last=Mack | date=30 November 2005 | url=http://www.clemson.edu/caah/history/FacultyPages/PamMack/lec122/micro.htm | access-date=2009-12-23 | url-status=live | archive-url=https://web.archive.org/web/20100114160413/http://www.clemson.edu/caah/history/FacultyPages/PamMack/lec122/micro.htm | archive-date=14 January 2010 }}</ref><ref>{{cite journalweb | title=History in the Computing Curriculum | url=http://www.hofstra.edu/pdf/CompHist_9812tla6.PDF | access-date=2009-12-23 | url-status=dead | archive-url=https://web.archive.org/web/20110719211222/http://www.hofstra.edu/pdf/CompHist_9812tla6.PDF | archive-date=2011-07-19 }}</ref> priced at {{US$|60|1971|round=-1}}.<ref>{{cite web |first=Peter |last=Bright |title=The 40th birthday of—maybe—the first microprocessor, the Intel 4004 |publisher=arstechnica.com |date=November 15, 2011 |url=https://arstechnica.com/business/2011/11/the-40th-birthday-ofmaybethe-first-microprocessor/ |url-status=live |archive-url=https://web.archive.org/web/20170106233202/http://arstechnica.com/business/2011/11/the-40th-birthday-ofmaybethe-first-microprocessor/ |archive-date=January 6, 2017 }}</ref> The claim of being the first is definitely false, as the earlier TMS1802NC was also a true microprocessor built on a single chip and the same applies for the - prototype only - 8-bit TMX 1795.<ref name="righto_com" /> The first known advertisement for the 4004 is dated November 15, 1971, and appeared in ''[[Electronic News]]''.<ref>{{citationCite neededweb|dateurl=https://www.intel.la/content/www/xl/es/history/museum-story-of-intel-4004.html#:~:text=April1971:%20Era%20of%20integrated%20electronics,wide%20variety%20of%20electronic%20devices.|title=intel's 2023first microprocessor|access-date=2025-02-05}}</ref> The microprocessor was designed by a team consisting of Italian engineer [[Federico Faggin]], American engineers [[Marcian Hoff]] and [[Stanley Mazor]], and Japanese engineer [[Masatoshi Shima]].<ref>{{cite journal | title=The History of the 4004 | last1=Faggin | first1=Federico | last2=Hoff | first2=Marcian E. Jr. | last3=Mazor | first3=Stanley | last4=Shima | first4=Masatoshi | journal=IEEE Micro | date=December 1996 | volume=16 | issue=6 | pages=10–20 | doi=10.1109/40.546561 }}</ref>

The project that produced the 4004 originated in 1969, when [[Busicom]], a Japanese calculator manufacturer, asked Intel to build a chipset for high-performance [[desktop calculator]]s. Busicom's original design called for a programmable chip set consisting of seven different chips. Three of the chips were to make a special-purpose CPU with its program stored in ROM and its data stored in shift register read-write memory. [[Ted Hoff]], the Intel engineer assigned to evaluate the project, believed the Busicom design could be simplified by using dynamic RAM storage for data, rather than shift register memory, and a more traditional general-purpose CPU architecture. Hoff came up with a four-chip architectural proposal: a ROM chip for storing the programs, a dynamic RAM chip for storing data, a simple [[input/output|I/O]] device, and a 4-bit central processing unit (CPU). Although not a chip designer, he felt the CPU could be integrated into a single chip, but as he lacked the technical know-how the idea remained just a wish for the time being.

[[File:Intel 4004.jpg|thumb|First microprocessor by Intel, the 4004]]

While the architecture and specifications of the MCS-4 came from the interaction of Hoff with [[Stanley Mazor]], a software engineer reporting to him, and with Busicom engineer [[Masatoshi Shima]], during 1969, Mazor and Hoff moved on to other projects. In April 1970, Intel hired Italian engineer [[Federico Faggin]] as project leader, a move that ultimately made the single-chip CPU final design a reality (Shima meanwhile designed the Busicom calculator firmware and assisted Faggin during the first six months of the implementation). Faggin, who originally developed the [[silicon gate]] technology (SGT) in 1968 at [[Fairchild Semiconductor]]<ref>{{cite conference | title=Insulated Gate Field Effect Transistor Integrated Circuits with Silicon Gates | last1=Faggin | first1=F. | last2=Klein | first2=T. | last3=Vadasz | first3=L. | conference=International Electronic Devices Meeting | publisher=IEEE Electron Devices Group | date=23 October 1968 | url=http://www.intel4004.com/images/iedm_covart.jpg | format=JPEG image | access-date=2009-12-23 | url-status=live | archive-url=https://web.archive.org/web/20100219143313/http://www.intel4004.com/images/iedm_covart.jpg | archive-date=19 February 2010 }}</ref> and designed the world's first commercial integrated circuit using SGT, the Fairchild 3708, had the correct background to lead the project into what would become the first commercial general purpose microprocessor. Since SGT was his very own invention, Faggin also used it to create his new methodology for [[random logic]] design that made it possible to implement a single-chip CPU with the proper speed, power dissipation and cost. The manager of Intel's MOS Design Department was [[Leslie L. Vadász]] at the time of the MCS-4 development but Vadász's attention was completely focused on the mainstream business of semiconductor memories so he left the leadership and the management of the MCS-4 project to Faggin, who was ultimately responsible for leading the 4004 project to its realization. Production units of the 4004 were first delivered to Busicom in March 1971 and shipped to other customers in late 1971.{{citation needed|date=March 2014}}

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{{More citations needed|section and the sections below|date=June 2011}}

The [[Intel 4004]] was followed in 1972 by the [[Intel 8008]], intel's first [[8-bit computing|8-bit]] microprocessor.<ref>{{Cite web|title=Intel Microprocessor Quick Reference Guide - Year|url=https://www.intel.com/pressroom/kits/quickrefyr.htm|access-date=2021-09-21|website=www.intel.com|archive-date=6 October 2021|archive-url=https://web.archive.org/web/20211006020846/https://www.intel.com/pressroom/kits/quickrefyr.htm|url-status=live}}</ref> The 8008 was not, however, an extension of the 4004 design, but instead the culmination of a separate design project at Intel, arising from a contract with [[Datapoint|Computer Terminals Corporation]], of San Antonio TX, for a chip for a terminal they were designing,<ref name="mit-comp-history">{{cite book | last = Ceruzzi | first = Paul E. | title = A History of Modern Computing | edition = 2nd | date = May 2003 | publisher = MIT Press | isbn = 978-0-262-53203-7 | pages = [https://archive.org/details/historyofmodernc00ceru_0/page/220 220–221] | url = https://archive.org/details/historyofmodernc00ceru_0/page/220 }}</ref> the [[Datapoint 2200]]—fundamental aspects of the design came not from Intel but from CTC. In 1968, CTC's Vic Poor and Harry Pyle developed the original design for the [[instruction set]] and operation of the processor. In 1969, CTC contracted two companies, [[Intel]] and [[Texas Instruments]], to make a single-chip implementation, known as the CTC 1201.<ref name="forgotten-history">{{cite magazine |url=http://www.computerworld.com/s/article/9111341/Forgotten_PC_history_The_true_origins_of_the_personal_computer |title=Forgotten history: the true origins of the PC |first=Lamont |last=Wood |date=August 2008 |magazine=Computerworld |archive-url=https://web.archive.org/web/20220606084706/http://www.computerworld.com/s/article/print/9111341/Forgotten_PC_history_The_true_origins_of_the_personal_computer?taxonomyName=Hardware&taxonomyId=12 |archive-date=2022-06-06 |access-date=2011-01-07 |url-status=dead }}</ref> In late 1970 or early 1971, TI dropped out being unable to make a reliable part. In 1970, with Intel yet to deliver the part, CTC opted to use their own implementation in the Datapoint 2200, using traditional TTL logic instead (thus the first machine to run "8008 code" was not in fact a microprocessor at all and was delivered a year earlier). Intel's version of the 1201 microprocessor arrived in late 1971, but was too late, slow, and required a number of additional support chips. CTC had no interest in using it. CTC had originally contracted Intel for the chip, and would have owed them {{US$|50,000|1971}} for their design work.<ref name="forgotten-history"/> To avoid paying for a chip they did not want (and could not use), CTC released Intel from their contract and allowed them free use of the design.<ref name="forgotten-history"/> Intel marketed it as the 8008 in April, 1972, as the world's first 8-bit microprocessor. It was the basis for the famous "[[Mark-8]]" computer kit advertised in the magazine ''[[Radio-Electronics]]'' in 1974. This processor had an 8-bit data bus and a 14-bit address bus.<ref>Intel 8008 data sheet.</ref>

The 8008 was the precursor to the successful [[Intel 8080]] (1974), which offered improved performance over the 8008 and required fewer support chips. Federico Faggin conceived and designed it using high voltage N channel MOS. The [[Zilog Z80]] (1976) was also a Faggin design, using low voltage N channel with depletion load and derivative Intel 8-bit processors: all designed with the methodology Faggin created for the 4004. [[Motorola]] released the competing [[Motorola 6800|6800]] in August 1974, and the similar [[MOS Technology 6502]] was released in 1975 (both designed largely by the same people). The 6502 family rivaled the Z80 in popularity during the 1980s.

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A low overall cost, little packaging, simple [[computer bus]] requirements, and sometimes the integration of extra circuitry (e.g. the Z80's built-in [[memory refresh]] circuitry) allowed the [[home computer]] "revolution" to accelerate sharply in the early 1980s. This delivered such inexpensive machines as the Sinclair [[ZX81]], which sold for {{US$|99|1981}}. A variation of the 6502, the [[MOS Technology 6510]] was used in the [[Commodore 64]] and yet another variant, the 8502, powered the [[Commodore 128]].

[[Western Design Center|The Western Design Center, Inc]] (WDC) introduced the CMOS [[WDC 65C02]] in 1982 and licensed the design to several firms. It was used as the CPU in the [[Apple IIe]] and [[Apple IIc|IIc]] personal computers as well as in medical implantable grade [[pacemaker]]s and [[defibrillator]]s, automotive, industrial and consumer devices. WDC pioneered the licensing of microprocessor designs, later followed by [[Arm (company)Holdings|ARM]] (32-bit) and other microprocessor [[intellectual property]] (IP) providers in the 1990s.

Motorola introduced the [[Motorola 6809|MC6809]] in 1978. It was an ambitious and well thought-through 8-bit design that was [[source-code compatibility|source compatible]] with the [[Motorola 6800|6800]], and implemented using purely [[electrical wiring|hard-wired]] logic (subsequent 16-bit microprocessors typically used [[microcode]] to some extent, as [[complex instruction set computer|CISC]] design requirements were becoming too complex for pure hard-wired logic).

Another early 8-bit microprocessor was the [[Signetics 2650]], which enjoyed a brief surge of interest due to its innovative and powerful [[instruction set architecture]].

A seminal microprocessor in the world of spaceflight was [[Radio Corporation of America|RCA]]'s [[RCA 1802]] (aka CDP1802, RCA COSMAC) (introduced in 1976), which was used on board the ''[[Galileo (spacecraft)|Galileo]]'' probe to Jupiter (launched 1989, arrived 1995). RCA COSMAC was the first to implement [[CMOS]] technology. The CDP1802 was used because it could be run at very [[low-power electronics|low power]], and because a variant was available fabricated using a special production process, [[silicon on sapphire]] (SOS), which provided much better protection against [[cosmic radiation]] and [[electrostatic discharge]] than that of any other processor of the era. Thus, the SOS version of the 1802 was said to be the first [[radiation-hardened]] microprocessor.

The RCA 1802 had a [[static logic (digital logic)|static design]], meaning that the [[clock frequency]] could be made arbitrarily low, or even stopped. This let the [[Galileo (spacecraft)|''Galileo'' spacecraft]] use minimum electric power for long uneventful stretches of a voyage. Timers or sensors would awaken the processor in time for important tasks, such as navigation updates, attitude control, data acquisition, and radio communication. Current versions of the Western Design Center 65C02 and 65C816 also have [[static core]]s, and thus retain data even when the clock is completely halted.

===12-bit designs===

The [[Intersil 6100]] family consisted of a [[12-bit computing|12-bit]] microprocessor (the 6100) and a range of peripheral support and memory ICs. The microprocessor recognised the DEC [[PDP-8]] [[minicomputer]] instruction set. As such it was sometimes referred to as the '''CMOS-PDP8'''. Since it was also produced by Harris Corporation, it was also known as the '''Harris HM-6100'''. By virtue of its CMOS technology and associated benefits, the 6100 was being incorporated into some military designs until the early 1980s.

===16-bit designs===

{{x86 processor modes}}

The first multi-chip [[16-bit computing|16-bit]] microprocessor was the [[National Semiconductor]] [[IMP-16]], introduced in early 1973. An 8-bit version of the chipset was introduced in 1974 as the IMP-8.

Other early multi-chip 16-bit microprocessors include the [[MCP-1600]] that [[Digital Equipment Corporation|Digital Equipment Corporation (DEC)]] used in the [[LSI-11]] OEM board set and the packaged [[PDP-11|PDP-11/03]] [[minicomputer]]—and the [[Fairchild Semiconductor]] MicroFlame 9440, both introduced in 1975–76. In late 1974, National introduced the first 16-bit single-chip microprocessor, the [[National Semiconductor PACE]],<ref>{{cite web | url=https://www.cpu-world.com/CPUs/PACE/index.html | title=National Semiconductor PACE CPU family | access-date=25 November 2022 | archive-date=25 November 2022 | archive-url=https://web.archive.org/web/20221125202308/https://www.cpu-world.com/CPUs/PACE/index.html | url-status=live }}</ref> which was later followed by an [[NMOS logic|NMOS]] version, the [[INS8900]].

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Next in list is the [[General Instrument CP1600]], released in February 1975,<ref>{{Cite web |last=EDN Staff |date=2000-01-01 |title=General Instrument's microprocessor aimed at minicomputer market |url=https://www.edn.com/general-instruments-microprocessor-aimed-at-minicomputer-market/ |access-date=2023-01-01 |website=EDN |language=en-US |archive-date=25 November 2022 |archive-url=https://web.archive.org/web/20221125201445/https://www.edn.com/general-instruments-microprocessor-aimed-at-minicomputer-market/ |url-status=live }}</ref> which was used mainly in the [[Intellivision]] console.

Another early single-chip 16-bit microprocessor was TI's [[Texas Instruments TMS9900|TMS 9900]], which was also compatible with their [[TI-990]] line of minicomputers. The 9900 was used in the TI 990/4 minicomputer, the [[TI-99/4A]] home computer, and the TM990 line of OEM microcomputer boards. The chip was packaged in a large ceramic 64-pin [[Dual in-line package|DIP package]], while most 8-bit microprocessors such as the Intel 8080 used the more common, smaller, and less expensive plastic 40-pin DIP. A follow-on chip, the TMS 9980, was designed to compete with the Intel 8080, had the full TI 990 16-bit instruction set, used a plastic 40-pin package, moved data 8&nbsp;bits at a time, but could only address 16&nbsp;[[Kilobyte|KB]]. A third chip, the TMS 9995, was a new design. The family later expanded to include the 99105 and 99110.

The [[Western Design Center]] (WDC) introduced the CMOS [[WDC 65816/65802|65816]] 16-bit upgrade of the WDC CMOS [[WDC 65C02|65C02]] in 1984. The 65816 16-bit microprocessor was the core of the [[Apple IIGS]] and later the [[Super Nintendo Entertainment System]], making it one of the most popular 16-bit designs of all time.

Intel "upsized" their 8080 design into the 16-bit [[Intel 8086]], the first member of the [[x86]] family, which powers most modern [[IBM PC compatible|PC]] type computers. [[Intel]] introduced the 8086 as a cost-effective way of porting software from the 8080 lines, and succeeded in winning much business on that premise. The [[Intel 8088|8088]], a version of the 8086 that used an 8-bit external data bus, was the microprocessor in the first [[IBM PC]]. Intel then released the [[Intel 80186|80186]] and [[Intel 80188|80188]], the [[Intel 80286|80286]] and, in 1985, the 32-bit [[Intel 80386|80386]], cementing their PC market dominance with the processor family's backwards compatibility. The 80186 and 80188 were essentially versions of the 8086 and 8088, enhanced with some onboard peripherals and a few new instructions. Although Intel's 80186 and 80188 were not used in IBM PC type designs,{{dubious|Intel 80186 and IBM PC-style computers|date=November 2016}} second source versions from NEC, the [[NEC V20|V20]] and V30 frequently were. The 8086 and successors had an innovative but limited method of [[memory segmentation]], while the 80286 introduced a full-featured segmented [[memory management unit]] (MMU). The 80386 introduced a flat 32-bit memory model with paged memory management.

The 16-bit Intel x86 processors up to and including the 80386 do not include [[Floating-point unit|floating-point units (FPUs)]]. Intel introduced the [[Intel 8087|8087]], [[Intel 80187|80187]], [[Intel 80287|80287]] and [[Intel 80387|80387]] math coprocessors to add hardware floating-point and transcendental function capabilities to the 8086 through 80386 CPUs. The 8087 works with the 8086/8088 and 80186/80188,<ref>Intel 8087 datasheet, pg. 1</ref> the 80187 works with the 80186 but not the 80188,<ref>The 80187 only has a 16-bit data bus because it used the 80387SX core.</ref> the 80287 works with the 80286 and the 80387 works with the 80386. The combination of an x86 CPU and an x87 coprocessor forms a single multi-chip microprocessor; the two chips are programmed as a unit using a single integrated instruction set.<ref>"Essentially, the 80C187 can be treated as an additional resource or an extension to the CPU. The 80C186 CPU together with an 80C187 can be used as a single unified system." Intel 80C187 datasheet, p. 3, November 1992 (Order Number: 270640-004).</ref> The 8087 and 80187 coprocessors are connected in parallel with the data and address buses of their parent processor and directly execute instructions intended for them. The 80287 and 80387 coprocessors are interfaced to the CPU through I/O ports in the CPU's address space, this is transparent to the program, which does not need to know about or access these I/O ports directly; the program accesses the coprocessor and its registers through normal instruction opcodes.

===32-bit designs===

[[File:80486DX2 200x.png|thumb|Upper interconnect layers on an [[Intel 80486]]DX2 die]]

16-bit designs had only been on the market briefly when [[32-bit computing|32-bit]] implementations started to appear.

The most significant of the 32-bit designs is the [[Motorola 68000|Motorola MC68000]], introduced in 1979. The 68k, as it was widely known, had 32-bit registers in its programming model but used 16-bit internal data paths, three 16-bit Arithmetic Logic Units, and a 16-bit external data bus (to reduce pin count), and externally supported only 24-bit addresses (internally it worked with full 32&nbsp;bit addresses). In [[PC-based IBM-compatible mainframes]] the MC68000 internal microcode was modified to emulate the 32-bit System/370 IBM mainframe.<ref>{{cite web |url=https://priorart.ip.com/IPCOM/000059679 |title=Implementation of IBM System 370 Via Co-Microprocessors/The Co-Processor Interface on priorart.ip.com |publisher=priorart.ip.com |date=1986-01-01 |access-date=2020-07-23 |archive-date=11 December 2015 |archive-url=https://web.archive.org/web/20151211060121/http://priorart.ip.com/IPCOM/000059679 |url-status=live }}</ref> Motorola generally described it as a 16-bit processor. The combination of high performance, large (16&nbsp;[[megabyte]]s or 2²⁴&nbsp;bytes) memory space and fairly low cost made it the most popular [[CPU design]] of its class. The [[Apple Lisa]] and [[Macintosh 128K|Macintosh]] designs made use of the 68000, as did other designs in the mid-1980s, including the [[Atari ST]] and [[Amiga]].

The world's first single-chip fully 32-bit microprocessor, with 32-bit data paths, 32-bit buses, and 32-bit addresses, was the [[AT&T Corporation|AT&T]] [[Bell Labs]] [[Bellmac 32|BELLMAC-32A]], with first samples in 1980, and general production in 1982.<ref>{{cite web|title=Shoji, M. Bibliography|url=http://cm.bell-labs.com/cm/cs/bib/shoji.bib|date=7 October 1998<!-- page info -->|publisher=Bell Laboratories|access-date=2009-12-23|url-status=dead|archive-url=https://web.archive.org/web/20081016070217/http://cm.bell-labs.com/cm/cs/bib/shoji.bib|archive-date=16 October 2008}}</ref><ref>{{cite web|title=Timeline: 1982–1984|website=Physical Sciences & Communications at Bell Labs|publisher=Bell Labs, Alcatel-Lucent|url=http://www.bell-labs.com/org/physicalsciences/timeline/span23.html |archive-url=https://web.archive.org/web/20110514025934/http://www.bell-labs.com/org/physicalsciences/timeline/span23.html |archive-date=2011-05-14 |date=17 January 2001 |access-date=2009-12-23}}</ref> After the [[Bell System divestiture|divestiture of AT&T]] in 1984, it was renamed the WE 32000 (WE for [[Western Electric]]), and had two follow-on generations, the WE 32100 and WE 32200. These microprocessors were used in the AT&T 3B5 and 3B15 minicomputers; in the 3B2, the world's first desktop super microcomputer; in the "Companion", the world's first 32-bit [[laptop]] computer; and in "Alexander", the world's first book-sized super microcomputer, featuring ROM-pack memory cartridges similar to today's gaming consoles. All these systems ran the [[UNIX System V]] operating system.

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The first commercial, single chip, fully 32-bit microprocessor available on the market was the [[HP FOCUS]].

Intel's first 32-bit microprocessor was the [[Intel iAPX 432|iAPX 432]], which was introduced in 1981, but was not a commercial success. It had an advanced [[Capability-based security|capability-based]] [[Object (computer science)|object-oriented]] architecture, but poor performance compared to contemporary architectures such as Intel's own 80286 (introduced 1982), which was almost four times as fast on typical benchmark tests. However, the results for the iAPX432 was partly due to a rushed and therefore suboptimal [[Ada (programming language)|Ada]] [[compiler]].{{citation needed|date=April 2011}}

Motorola's success with the 68000 led to the [[Motorola 68010|MC68010]], which added [[virtual memory]] support. The [[Motorola 68020|MC68020]], introduced in 1984 added full 32-bit data and address buses. The 68020 became hugely popular in the [[Unix]] supermicrocomputer market, and many small companies (e.g., [[Altos Computer Systems|Altos]], [[UNOS (operating system)|Charles River Data Systems]], [[Cromemco]]) produced desktop-size systems. The [[Motorola 68030|MC68030]] was introduced next, improving upon the previous design by integrating the MMU into the chip. The continued success led to the [[Motorola 68040|MC68040]], which included an [[floating-point unit|FPU]] for better math performance. The 68050 failed to achieve its performance goals and was not released, and the follow-up [[Motorola 68060|MC68060]] was released into a market saturated by much faster RISC designs. The 68k family faded from use in the early 1990s.

Other large companies designed the 68020 and follow-ons into embedded equipment. At one point, there were more 68020s in embedded equipment than there were [[Intel]] Pentiums in PCs.<ref>{{cite web|title=MCore: Does Motorola Need Another Processor Family?|last=Turley|first=Jim|website=Embedded Systems Design|publisher=TechInsights (United Business Media)|url=http://www.embedded.com/98/9807sr.htm|date=July 1998|archive-url=https://web.archive.org/web/19980702003323/http://www.embedded.com/98/9807sr.htm |archive-date=1998-07-02|access-date=2009-12-23}}</ref> The [[Motorola ColdFire|ColdFire]] processor cores are derivatives of the 68020.

During this time (early to mid-1980s), [[National Semiconductor]] introduced a very similar 16-bit pinout, 32-bit internal microprocessor called the NS 16032 (later renamed 32016), the full 32-bit version named the [[NS320xx|NS 32032]]. Later, National Semiconductor produced the [[NS320xx|NS 32132]], which allowed two CPUs to reside on the same memory bus with built in arbitration. The NS32016/32 outperformed the MC68000/10, but the NS32332—which arrived at approximately the same time as the MC68020—did not have enough performance. The third generation chip, the NS32532, was different. It had about double the performance of the MC68030, which was released around the same time. The appearance of RISC processors like the AM29000 and MC88000 (now both dead) influenced the architecture of the final core, the NS32764. Technically advanced—with a superscalar RISC core, 64-bit bus, and internally overclocked—it could still execute Series 32000 instructions through real-time translation.

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| doi=10.1016/j.respol.2007.11.006| s2cid = 73520408

}}

</ref> This is a [[RISC]] processor design, which has since come to dominate the 32-bit [[embedded systems]] processor space due in large part to its power efficiency, its licensing model, and its wide selection of system development tools. Semiconductor manufacturers generally license cores and integrate them into their own [[system on a chip]] products; only a few such vendors such as Apple are licensed to modify the ARM cores or create their own. Most [[cell phones]] include an ARM processor, as do a wide variety of other products. There are microcontroller-oriented ARM cores without virtual memory support, as well as [[symmetric multiprocessor system|symmetric multiprocessor]] (SMP) applications processors with virtual memory.

From 1993 to 2003, the 32-bit [[x86]] architectures became increasingly dominant in [[desktop computer|desktop]], [[laptop]], and server markets, and these microprocessors became faster and more capable. Intel had licensed early versions of the architecture to other companies, but declined to license the Pentium, so [[AMD]] and [[Cyrix]] built later versions of the architecture based on their own designs. During this span, these processors increased in complexity (transistor count) and capability (instructions/second) by at least three orders of magnitude. Intel's Pentium line is probably the most famous and recognizable 32-bit processor model, at least with the public at broad.

===64-bit designs in personal computers===

While [[64-bit computing|64-bit]] microprocessor designs have been in use in several markets since the early 1990s (including the [[Nintendo 64]] [[gaming console]] in 1996), the early 2000s saw the introduction of 64-bit microprocessors targeted at the PC market.

With AMD's introduction of a 64-bit architecture backwards-compatible with x86, [[x86-64]] (also called '''AMD64'''), in September 2003, followed by Intel's near fully compatible 64-bit extensions (first called IA-32e or EM64T, later renamed '''Intel 64'''), the 64-bit desktop era began. Both versions can run 32-bit legacy applications without any performance penalty as well as new 64-bit software. With operating systems [[Windows XP Professional x64 Edition|Windows XP x64]], [[Windows Vista]] x64, [[Windows 7]] x64, [[Linux]], [[BSD]], and [[macOS]] that run 64-bit natively, the software is also geared to fully utilize the capabilities of such processors. The move to 64&nbsp;bits is more than just an increase in register size from the IA-32 as it also doubles the number of general-purpose registers.

The move to 64&nbsp;bits by [[PowerPC]] had been intended since the architecture's design in the early 90s and was not a major cause of incompatibility. Existing integer registers are extended as are all related data pathways, but, as was the case with IA-32, both floating-point and vector units had been operating at or above 64&nbsp;bits for several years. Unlike what happened when IA-32 was extended to x86-64, no new general purpose registers were added in 64-bit PowerPC, so any performance gained when using the 64-bit mode for applications making no use of the larger address space is minimal.{{citation needed|date=June 2013}}

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In the mid-1980s to early 1990s, a crop of new high-performance reduced instruction set computer ([[RISC]]) microprocessors appeared, influenced by discrete RISC-like CPU designs such as the [[IBM 801]] and others. RISC microprocessors were initially used in special-purpose machines and [[Unix]] [[workstation]]s, but then gained wide acceptance in other roles.

The first commercial RISC microprocessor design was released in 1984, by [[MIPS Computer Systems]], the 32-bit [[R2000 (microprocessor)|R2000]] (the R1000 was not released). In 1986, HP released its first system with a [[PA-RISC]] CPU<!-- NOT microprocessor -->. In 1987, in the non-Unix [[Acorn computers]]' 32-bit, then cache-less, [[ARM2]]-based [[Acorn Archimedes]] became the first commercial success using the [[ARM architecture family|ARM architecture]], then known as Acorn RISC Machine (ARM); first silicon [[ARM1]] in 1985. The R3000 made the design truly practical, and the [[R4000]] introduced the world's first commercially available 64-bit RISC microprocessor. Competing projects would result in the IBM [[IBM POWER Instruction Set Architecture|POWER]] and [[Sun Microsystems|Sun]] [[SPARC]] architectures. Soon every major vendor was releasing a RISC design, including the [[AT&T CRISP]], [[AMD 29000]], [[Intel i860]] and [[Intel i960]], [[Motorola 88000]], [[DEC Alpha]].

In the late 1990s, only two 64-bit RISC architectures were still produced in volume for non-embedded applications: [[SPARC]] and [[Power ISA]], but as ARM has become increasingly powerful, in the early 2010s, it became the third RISC architecture in the general computing segment.

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SMP ''[[symmetric multiprocessing]]''<ref>{{Cite web|url = https://techdifferences.com/difference-between-symmetric-and-asymmetric-multiprocessing.html|title = Difference Between Symmetric and Asymmetric Multiprocessing (With Comparison Chart)|date = 22 September 2016|access-date = 18 July 2021|archive-date = 18 July 2021|archive-url = https://web.archive.org/web/20210718110824/https://techdifferences.com/difference-between-symmetric-and-asymmetric-multiprocessing.html|url-status = live}}</ref> is a configuration of two, four, or more CPU's (in pairs) that are typically used in servers, certain workstations and in desktop personal computers, since the 1990s. A [[multi-core processor]] is a single CPU that contains more than one microprocessor core.

This popular two-socket motherboard from [[ABIT BP6|Abit]] was released in 1999 as the first SMP enabled PC motherboard, the [[Pentium Pro|Intel Pentium Pro]] was the first commercial CPU offered to system builders and enthusiasts. The Abit BP9 supports two Intel Celeron CPU's and when used with a SMP enabled operating system (Windows NT/2000/Linux) many applications obtain much higher performance than a single CPU. The early [[Celeron]]s are easily overclockable and hobbyists used these relatively inexpensive CPU's clocked as high as 533Mhz - far beyond Intel's specification. After discovering the capacity of these motherboards Intel removed access to the multiplier in later CPU's.

In 2001&nbsp;IBM released the [[POWER4]] CPU, it was a processor that was developed over five years of research, began in 1996 using a team of 250 researchers. The effort to accomplish the impossible was buttressed by development of and through—remote-collaboration and assigning younger engineers to work with more experienced engineers. The teams work achieved success with the new microprocessor, Power4. It is a two-in-one CPU that more than doubled performance at half the price of the competition, and a major advance in computing. The business magazine ''eWeek'' wrote: ''"The newly designed 1GHz Power4 represents a tremendous leap over its predecessor"''. An industry analyst, Brad Day of Giga Information Group said: ''"IBM is getting very aggressive, and this server is a game changer".''

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The Power4 won "''Analysts’ Choice Award for Best Workstation/Server Processor of 2001", and'' it broke notable records, including winning a contest against the best players on the Jeopardy!<ref>{{Cite web|url = https://www.ibm.com/ibm/history/ibm100/us/en/icons/watson/|title = IBM100 - A Computer Called Watson|website = [[IBM]]|date = 7 March 2012|access-date = 19 July 2021|archive-date = 19 July 2021|archive-url = https://web.archive.org/web/20210719124129/https://www.ibm.com/ibm/history/ibm100/us/en/icons/watson/|url-status = live}}</ref> U.S. television show.

Intel's [[Yonah (microprocessor)|codename Yonah]] CPU's launched on Jan 6, 2006, and were manufactured with two dies packaged on a [[multi-chip module]]. In a hotly- contested marketplace [[List of AMD processors|AMD]] and others released new versions of multi-core CPU's, AMD's SMP enabled [[Athlon MP]] CPU's from the [[Athlon-XP|AthlonXP]] line in 2001, Sun released the [[UltraSPARC T1|Niagara]] and [[UltraSPARC T2|Niagara 2]] with eight-cores, AMD's [[Athlon 64 X2|Athlon X2]] was released in June 2007. The companies were engaged in a never-ending race for speed, indeed more demanding software mandated more processing power and faster CPU speeds.

By 2012 ''dual and quad-core'' processors became widely used in PCs and laptops, newer processors - similar to the higher cost professional level Intel Xeon's - with additional cores that execute instructions in parallel so software performance typically increases, provided the software is designed to utilize advanced hardware. Operating systems provided support for multiple-cores and SMD CPU's, many software applications including large workload and resource intensive applications - such as 3-D games - are programmed to take advantage of multiple core and multi-CPU systems.

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==Market statistics==

In 1997, about 55% of all [[central processing unit|CPU]]s sold in the world were 8-bit [[microcontroller]]s, of which over 2&nbsp;billion were sold.<ref>{{cite web | title=Microchip on the March | year=1998 | author=Cantrell, Tom | url=http://www.circuitcellar.com/library/designforum/silicon_update/3/ | archive-url=https://archive.today/20070220134759/http://www.circuitcellar.com/library/designforum/silicon_update/3/index.asp | archive-date=2007-02-20 }}</ref>

In 2002, less than 10% of all the CPUs sold in the world were 32-bit or more. Of all the 32-bit CPUs sold, about 2% are used in desktop or laptop personal computers. Most microprocessors are used in embedded control applications such as household appliances, automobiles, and computer peripherals. Taken as a whole, the average price for a microprocessor, microcontroller, or [[digital signal processor|DSP]] is just over {{US$|6|2002}}.<ref name="turley">{{cite web | title=The Two Percent Solution | last=Turley | first=Jim | date=18 December 2002 | website=Embedded Systems Design | publisher=TechInsights (United Business Media) | url=http://www.embedded.com/print/4024488 | access-date=2009-12-23 | url-status=live | archive-url=https://web.archive.org/web/20150403140448/http://www.embedded.com/print/4024488 | archive-date=3 April 2015 }}</ref>

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[[Category:Digital electronics]]

[[Category:Microcomputers]]

[[Category:Telecommunications engineering]]

[[Category:1971 introductions]]