Intel 4004

Intel 4004

Intel C4004 processor with grey traces
General information
Launched	November 15, 1971; 53 years ago (November 15, 1971)
Discontinued	1981[1]
Marketed by	Intel
Designed by	Intel
Common manufacturer	Intel
Performance
Max. CPU clock rate	740 kHz to 750 kHz
Data width	4 bits
Address width	12 bits (multiplexed)
Architecture and classification
Application	Busicom calculator, arithmetic manipulation
Technology node	10 μm
Instruction set	4-bit BCD-oriented
Physical specifications
Transistors	2,300
Package	16-pin dual in-line package
Socket	DIP16
History
Successor	Intel 4040
Support status
Unsupported

The Intel 4004, was part of the 4 chip MCS-4 micro computer set,^[2] released by the Intel Corporation in November 1971.^[3] The 4004 being part of the first commercially marketed microprocessor chipset, and the first in a long line of Intel central processing units (CPUs). Priced at US$60 (equivalent to $466 in 2024), 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, showcasing the superiority of the MOS silicon gate technology (SGT). Compared to the incumbent technology, SGT enabled twice the transistor density and five times the operating speed, making future single-chip CPUs feasible. The innovative 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 Corp. commissioned Intel to design a family of seven chips for electronic calculators, including a three-chip CPU.^[4] 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. 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.^[5] 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), leveraged SGT at Intel to achieve the unprecedented integration required for the 4004. He also applied the self-aligned gate technique he had developed at Fairchild, which utilized poly-silicon instead of metal, allowing components to be placed closer together and operate at higher speeds. 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 8080.