Editing Intel 4004 (section)

{{short description|4-bit microprocessor}}
{{redirect|4004|4004 BC as the putative beginning of the world|Ussher chronology|4004 BC in other contexts|5th millennium BC}}
{{Use American English|date=February 2023}}
{{Use mdy dates|date=February 2023|cs1-dates=y}}
{{Infobox CPU
|name           = Intel 4004
|image          = Intel C4004.jpg
|caption        = Intel C4004 processor with grey traces
|produced-start = {{Start date and age|November 15, 1971}}
|produced-end   = 1981<ref>{{Cite web |title=The Life Cycle of a CPU |url=https://www.cpushack.com/life-cycle-of-cpu.html |website=www.cpushack.com}}</ref>
|slowest        = 740 | slow-unit = kHz
|fsb-slowest    = | fsb-slow-unit =
|fsb-fastest    = | fsb-fast-unit =
|manuf1         = Intel
|size-from      = [[10 μm process|10&nbsp;μm]]
|transistors    = 2,300
|arch           = 4-bit [[binary-coded decimal|BCD]]-oriented
|data-width     = 4 bits
|address-width  = 12 bits (multiplexed)
|pack1          = 16-pin [[dual in-line package]]
|successor      = [[Intel 4040]]<!-- The Intel 8008 is an 8-bit design, not a direct successor -->
|application    = Busicom calculator, arithmetic manipulation
|sock1          = [[dual in-line package|DIP16]]
|support status = Unsupported
|soldby         = [[Intel]]
|designfirm     = Intel
|fast-unit      = kHz
|fastest        = 750
}}

The '''Intel 4004''', was part of the 4 chip MCS-4 micro computer set,<ref>{{Cite web |title=CPU-Zone MCS-4 |url=http://www.cpu-zone.com/MCS-4_chipset.htm |access-date=2025-04-21 |website=www.cpu-zone.com}}</ref> released by the [[Intel|Intel Corporation]] in November 1971.<ref>{{Cite web |title=Intel - MCS-4 Micro Compute Set, November 1971 |url=https://ieeemilestones.ethw.org/w/images/2/2d/Ref2-Intel_MCS-4_DataSheet.pdf |url-status=live |website=IEEE Milestones}}</ref> The 4004 being part of the first commercially marketed [[microprocessor]] chipset, and the first in a long line of [[List of Intel processors|Intel central processing units]] (CPUs). Priced at {{US$|60|1971|link=yes|round=0}}, the chip marked both a technological and economic milestone in computing.

The [[4-bit computing|4-bit]] 4004 CPU was the first significant commercial example of [[large-scale integration]], showcasing the abilities of the [[Self-aligned gate|MOS silicon gate]] technology (SGT). Compared to the existing technology, SGT enabled twice the transistor density and five times the operating speed, making future single-chip CPUs feasible. The MCS-4 chip set design served as a model on how to use SGT for complex logic and memory circuits, accelerating the adoption of SGT by the world's semiconductor industry.

The project originated in 1969 when [[Busicom|Busicom Corp.]] commissioned Intel to design a family of seven chips for [[electronic calculator]]s, including a three-chip CPU.<ref name="IntelEra">{{cite web|url=https://www.intel.com/content/www/us/en/history/virtual-vault/articles/the-intel-4004.html|title=Announcing a New Era of Integrated Electronics: The Intel 4004|work=[[Intel]]|access-date=March 6, 2025}}</ref> Busicom initially envisioned using shift registers for data storage and [[Read-only memory|ROM]] for instructions. Intel engineer [[Marcian Hoff]] proposed a simpler architecture based on data stored on RAM, making a single-chip CPU possible. Design work, led by [[Federico Faggin]] with contributions from [[Masatoshi Shima]], began in April 1970. The first fully operational 4004 was delivered in March 1971 for Busicom’s 141-PF printing calculator prototype, now housed at the [[Computer History Museum]].<ref>{{cite web |url=http://www.intel4004.com/proto_calc.htm |title=The Intel 4004 Microprocessor and the Silicon Gate Technology: The Busicom Engineering Prototype |website=Intel4004.com}}</ref> General sales began in July 1971.

Faggin, who had developed SGT at [[Fairchild Semiconductor]] and used it to create the [[Fairchild 3708]], the first commercially produced SGT [[integrated circuit]] (IC), used SGT, a method of using poly-silicon instead of metal, at Intel to achieve the integration required for the 4004. Additionally, he developed the "[[bootstrap load]]," previously considered unfeasible with silicon gate technology, and the "buried contact," which enabled silicon gates to connect directly to the transistor's source and drain without the use of metal. Together, these innovations doubled the circuit density, and thus halved cost, allowing a single chip to contain 2,300 transistors and run five times faster than designs using the previous MOS technology with aluminum gates.

The 4004's architecture laid the foundation for subsequent Intel processors, including the improved [[Intel 4040]], released in 1974, and the 8-bit [[Intel 8008]] and [[Intel 8080|8080]].