Intel 4004
On November 15, 1971, a small advertisement appeared in Electronic News. Intel Corporation presented the 4004, which it described as a “microprogrammable computer on a chip.” Behind this wording lay an invention that would change the world: the first commercial microprocessor in history.
This innovation was born from an unlikely encounter between an American startup specializing in memory and a Japanese calculator company. In 1969, Busicom was looking for a partner to develop integrated circuits for its future calculators. Intel, founded the previous year by Bob Noyce and Gordon Moore, accepted this contract to balance its finances while waiting for its main business to take off.
Busicom’s initial specifications called for twelve different integrated circuits, each dedicated to a specific function. Three Japanese engineers, including Masatoshi Shima, arrived at Intel in June 1969 to supervise the project. Ted Hoff, the company’s twelfth employee and head of applications, had to liaise with this team from Asia. He examined the specifications and frowned. The proposed system required too many connections between chips, which would make the final product prohibitively expensive. He proposed abandoning the idea of specialized circuits to create a universal programmable processor, accompanied by a few memory chips. The architecture would be simpler, cheaper, and above all infinitely more flexible.
Stanley Mazor joined the venture in September 1969. His experience at Fairchild in computer design brought the necessary technical credibility to the project. Together, Hoff and Mazor refined their vision and managed to convince Busicom’s skeptics. They developed a 20-byte interpreter to execute macro-instructions, thus demonstrating the viability of their approach.
In October 1969, at an official meeting, Busicom gave Intel’s new architecture the green light. Shima extended his stay until December to write the calculator’s basic programs. The signed contract granted the Japanese company exclusivity over this system. All that remained was to transform this great idea into physical reality. However, neither Hoff nor Mazor mastered integrated circuit design. Intel recruited Federico Faggin in April 1970. This Italian had developed the silicon-gate MOS technology at Fairchild, essential for achieving the desired performance and integration density.
The team finalized the MCS-4 system architecture. Four circuits made up the whole: the 4004 processor, the 4001 ROM memory, the 4002 RAM, and the 4003 input-output register. The heart of the system, the 4004, contained approximately 2,300 transistors on a 3.0 × 4.0 mm chip. It executed 8,000 instructions per second and addressed up to 4 KB of ROM and 640 bytes of RAM.
Manufacturing of the first prototypes began in October 1970. The peripheral chips worked fairly quickly. The 4004 proved more resistant but required several revisions before reaching maturity in March 1971. A month later, Busicom validated the entire system in its calculator. Intel pulled off a masterstroke in negotiations. In May 1971, the company recovered the marketing rights for the MCS-4 for all applications other than desktop calculators, in exchange for a price reduction for Busicom. Ed Gelbach, the new vice president of marketing, orchestrated the official launch of the 4004 in November 1971.
The success exceeded expectations. Intel followed up with the 8008, the first 8-bit microprocessor, announced in April 1972. These two processors opened two distinct paths that still structure the semiconductor industry today: on one side, integrated microcontrollers for embedded systems, heirs to the 4004; on the other, processors for programmable computers, descendants of the 8008.
The 4004’s legacy can be measured in staggering figures. In 1995, twenty-four years after its birth, 4-bit microcontrollers represented half of the units produced worldwide. The 8008 architecture evolved into the 8080, then into the x86 processors that equip the majority of today’s personal computers.
In 2024, nearly 70% of semiconductors manufactured globally are microprocessors, microcontrollers, or associated components. This market is worth over 100 billion dollars. From automobiles to phones, household appliances to connected devices, these chips descended from the 4004’s DNA populate our daily lives.
This technology has changed our relationship with machines and transformed the way we live. It perfectly illustrates how an elegant technical solution to a specific industrial problem sometimes generates unpredictable societal upheavals. The 4004 was initially just a component for Japanese calculators. It became the foundation of our digital civilization.