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The Intel 4004: Recovered, Rebuilt, Remembered

An international project keeping Intel’s first microprocessor alive for future generations.

Our mission is to make computer science and digital electronics accessible to historians, students, hobbyists, and curious museum visitors around the world. Were you an engineer in the 1970s with stories to tell? Are you a maker with a vintage electronics project you are proud of? Contact us at tim at tuva dot us

The 35th anniversary talks (2006): two of the 4004’s inventors, Ted Hoff and Federico Faggin, and Tim McNerney at the Computer History Museum. Video, audio, transcript and slides →

Latest: November 15, 2025 — Happy 54th anniversary, 4004!

Swiss Enter Museum’s Intel 4004 interactive exhibit (opening 2026), a sneak preview.

November 2025 update: Klaus Scheffler and Lajos Kintli recently finished a complete MCS-4 (Intel 4004 family) 4-bit computer built from discrete transistors. Finally implementing all of the original Busicom 141-PF calculator logic in hardware (and 4004 assembly language) plus their additional fine-tuning was rewarded with additional performance that now exceeds the original 4004's clock speed of 740 kHz by a factor of 2x. This seven "chip" computer can now run at speeds up to 1.5 MHz (÷8 to get 187,500 instructions/s). This result was achieved by Scheffler's original choice of low-capacitance, 4-terminal FETs designed for RF applications... and many hours of hard work! (Most modern, discrete FETs are designed for power switching, and thus have a high gate capacitance.)

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Photo credit: Klaus Scheffler

Photo Legend: Center bottom: 4004 CPU. Center top: 4001 ROM. Upper left: Three 4003 shift registers. Right: Two 4002 RAMs. Lower left: Interactive Busicom 141-PF calculator user-interface replica.

All news, 1971–2025 →

Explore

The exhibit storyHow the 4004 schematics came out of Intel’s vault (2004–2006).Schematics, masks, simulatorThe whole MCS-4 chip family, reverse-engineered.Busicom 141-PFThe calculator that started it all: firmware, simulator, replicas.WritingsStories, essays, talks and documents, 1971–2025.The 2006 exhibitThe Intel Museum exhibit, its story and credits.DownloadsFirmware, simulators, schematics.

Recent news

  1. Complete discrete-transistor MCS-4 computer; Enter Museum exhibit preview
  2. Busicom 141-PF simulator in WebAssembly
  3. Discrete-transistor 4004 core computes digits of Pi
  4. First fully functional discrete-transistor 4004
  5. MCS-4 analyzer / simulator repackaged
  6. Federico Faggin publishes his memoir, Silicon
  7. Erturk Kocalar’s 4004 RetroShield