Intel ships the 4004, the first commercial microprocessor
A calculator contract accidentally produces a CPU on a single chip
Quick facts
- Designers
- Ted Hoff, Federico Faggin, Stanley Mazor, and Masatoshi Shima
- Delivered
- March 1971 (Busicom prototype); general sale July 1971
- Transistors
- 2,300
- Original client
- Busicom (calculator chipset)
What happened
Japanese calculator maker Busicom hired Intel to build a set of chips for a new calculator line. Rather than design several fixed-purpose chips, Intel engineer Ted Hoff, with Stanley Mazor, proposed a single general-purpose processor chip that could be programmed for different tasks, working with Busicom engineer Masatoshi Shima to define what the chip needed to do. Federico Faggin, assisted by Shima, used his experience with silicon-gate MOS technology to fit the design's 2,300 transistors into a single 16-pin package. The first fully working Intel 4004 was delivered in March 1971 for Busicom's calculator prototype, and Intel began selling it to any customer that July.
Why it matters
The 4004 packed an entire central processing unit, the part of a computer that executes instructions, onto one chip for the first time, rather than spreading that logic across a circuit board of separate components. Every processor since, from early personal computers to the phone this article might be read on, is a descendant of putting a whole CPU on a single piece of silicon.
How we know
The Computer History Museum's Silicon Engine project documents Hoff's architectural proposal, Faggin's fabrication work, the 2,300 transistor count, and the Busicom origins from its own historical record of the chip's development.
Sources
- Computer History Museum (The Silicon Engine). 1971: Microprocessor Integrates CPU Function onto a Single Chip · Reputable sourcecomputerhistory.org · The domain "computerhistory.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- IEEE Spectrum. Chip Hall of Fame: Intel 4004 Microprocessor · Peer-reviewedspectrum.ieee.org · The domain "spectrum.ieee.org" is on our Peer-reviewed registry. · Link is live and its text matches the event's key terms (Jul 2026)
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Related timelines
- History of Video Games → · General-purpose microprocessors like the 4004 made it possible to build affordable dedicated game hardware later in the 1970s.