Intel 4004

The Intel 4004, released by the Intel Corporation on November 15, 1971, was the first in a long line of Intel central processing units (CPUs). Priced at US$60 (equivalent to $477 in 2025), the chip marked both a technological and economic milestone in computing. The 4-bit 4004 CPU was the first significant commercial example of large-scale integration, using the abilities of the MOS silicon gate technology (SGT) to integrate the CPU into a single chip. 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 chipset design, of which the 4004 was a part, 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 Corp. commissioned Intel to design a family of seven chips for electronic calculators, including a three-chip CPU. Busicom initially envisioned using shift registers for data storage and ROM for instructions. Intel engineer Marcian Hoff proposed a simpler architecture based on data stored on RAM, making a single-chip CPU possible. Hoff's approach was agreed by Busicom management over their own team's development work, led by Masatoshi Shima and Shima pivoted to the new architecture, working on the architectural design. With Hoff reassigned by Intel to another project, design work, led by new Intel hire Federico Faggin and supported by 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. Shima led the first commercial implementation of the 4004 chipset, developing the Busicom 141-PF calculator, and Busicom went on to make 4004-based calculators, billing machines, teller machines and cash registers, mostly on an OEM...