Intel 4004: the calculator deal that built the first microprocessor
The chip is smaller than a thumbnail: 12 square millimetres, 16 pins, 2,300 transistors packed onto a sliver of silicon. On November 15, 1971, Intel ran an ad in Electronic News under the headline “Announcing a new era of integrated electronics.” Most readers had no idea what they were looking at.
The Intel 4004 started life as a compromise. In April 1969, Busicom — a Japanese calculator manufacturer — hired Intel to design a set of twelve custom chips for its new 141-PF printing calculator. Ted Hoff, the engineer Intel assigned to the project, looked at Busicom’s proposal and found it unwieldy: twelve chips, each hardwired to a specific task, none reusable. He proposed instead a set of four chips built around a single programmable logic unit — a tiny, general-purpose processor that would run software rather than bake its function into hardware (Wikipedia). Busicom’s engineers, led by Masatoshi Shima, resisted. After months of technical argument, Busicom management sided with Hoff.
The architecture was agreed by late 1969. Intel then did almost nothing with it for five months.
When Shima flew from Tokyo to Santa Clara in April 1970 to check progress, Federico Faggin had just reported for his first week at Intel. Faggin recalled later that Shima “was furious when he found out that no work had been done in the five months and he became very angry at me” — a striking reception for someone who had been an Intel employee for roughly 72 hours (IEEE Spectrum). It took, Faggin noted, almost a week for Shima to calm down.
Then the two of them built it. Faggin adapted a silicon-gate manufacturing process he had developed at Fairchild Semiconductor to squeeze the CPU’s logic into the 16-pin package — a geometry tight enough to push the process to its certified limits. They finished the full four-chip set in early 1971. The prototype worked in March. By August, Intel was shipping in quantity.
Busicom originally held exclusive rights to the chip set. In May 1971 — before the public launch — Intel persuaded Busicom to waive exclusivity in exchange for lower unit pricing and a $60,000 rebate on development costs (Wikipedia). Busicom accepted, apparently without grasping what it was giving up. Intel now owned the right to sell a general-purpose programmable processor to any buyer in the world. The calculator company had accidentally funded the first microprocessor and then returned the rights for sixty thousand dollars.
The 4004 ran at 740 kilohertz and processed data four bits at a time — slower than room-filling machines from a decade earlier by every raw measure. But it was reprogrammable, mass-producible, and small enough to sit in a pocket calculator. The follow-on 8008 arrived in 1972; the 8080 in 1974; and from that lineage came the x86 architecture still running most of the world’s servers and laptops (Computer History Museum). Every one of those chips carries the idea Hoff sketched, the silicon Faggin shaped — and the initials “F.F.” that Faggin etched quietly into the layout of every 4004 ever made.
Busicom filed for bankruptcy in 1974.
Sources
- Intel 4004 — Wikipedia — designers, timeline, specifications (2,300 transistors, 740 kHz, 10 μm process, 12 mm² die), the Busicom exclusivity buyback for $60,000.
- 1971: Microprocessor Integrates CPU Function onto a Single Chip — Computer History Museum — development team, the MCS-4 chip set, path from 4004 to the 8080 and later processors.
- Chip Hall of Fame: Intel 4004 Microprocessor — IEEE Spectrum — Shima’s arrival in Santa Clara, Faggin’s impossible deadline, the “F.F.” initials etched into the chip.