Intel 4004 - History and Production

History and Production

The first public mention of 4004 was an advertisement in the November 15, 1971 edition of Electronic News, though unconfirmed reports put the date of first delivery as early as March 1971. Packaged in a 16-pin ceramic dual in-line package, the 4004 was the first commercially available computer processor designed and manufactured by chip maker Intel, which had previously made semiconductor memory chips. The chief designers of the chip were Federico Faggin and Ted Hoff of Intel, and Masatoshi Shima of Busicom (later of ZiLOG, founded by Faggin).

Federico Faggin, the sole chip designer among the engineers on the MCS-4 project, was the only one with experience in MOS random logic and circuit design. He also had the crucial knowledge of the new silicon gate process technology with self-aligned gates, which he had created at Fairchild in 1968. At Fairchild in 1968, Faggin also designed and manufactured the world's first commercial IC using SGT, the Fairchild 3708. As soon as he joined the Intel MOS Department he created a new random logic design methodology based on silicon gate, and contributed many technology and circuit design inventions that enabled a single chip microprocessor to become a reality for the first time. His methodology set the design style for all the early Intel microprocessors and later for the Zilog’s Z80. He also led the MCS-4 project and was responsible for its successful outcome (1970–1971). Ted Hoff, head of the Application Research Department, contributed only the architectural proposal for Busicom working with Stanley Mazor in 1969, then he moved on to other projects. When asked where he got the ideas for the architecture of the first microprocessor, Hoff related that Plessey, "a British tractor company", had donated a minicomputer to Stanford, and he had "played with it some" while he was there. Shima designed the Busicom calculator firmware and assisted Faggin during the first six months of the implementation. The manager of Intel's MOS Design Department was Leslie L. Vadász. At the time of the MCS-4 development, Vadasz's attention was completely focused on the mainstream business of semiconductor memories and he left the leadership and the management of the MCS-4 project to Faggin.

The Japanese company Busicom had designed their own special purpose LSI chipset for use in their Busicom 141-PF calculator with integrated printer and commissioned Intel to develop it for production. However, Intel determined it was too complex and would use non-standard packaging and so it was proposed that a new design produced with standard 16-pin DIP packaging and reduced instruction set be developed. This resulted in the 4004, which was part of a family of chips, including ROM, DRAM and serial to parallel shift register chips. The 4004 was built of approximately 2,300 transistors and was followed the next year by the first ever 8-bit microprocessor, the 3,500 transistor 8008 (and the 4040, a revised 4004). It was not until the development of the 40-pin 8080 in 1974 that the address and data buses would be separated, giving faster and simpler access to memory.

The 4004 employed a 10 µm process silicon-gate enhancement load pMOS technology and could execute approximately 92,000 instructions per second; a single instruction cycle was 10.8 microseconds. The original clock speed design goal was 1 MHz, the same as the IBM 1620 Model I.

The Intel 4004 was designed by physically cutting sheets of Rubylith into thin strips to lay out the circuits to be printed, a process made obsolete by current computer graphic design capabilities.