Half a century of microprocessors – Intel 4004 celebrates 50th anniversary
It has been fifty years since the first commercially available microprocessor appeared on the market. That was the Intel 4004, a 4bit CPU with a clock speed of 740kHz. The chip consisted of 2300 transistors and was made at 10 µm.
In 1969, calculator manufacturer Busicom approached Intel to design chips for its Busicom 141-PF calculator. The Japanese company requested twelve different chips, each designed for a specific purpose. Intel co-founder Gordon Moore was shocked by that number, he says in a video call with Intel’s current CEO Pat Gelsinger. At the time, Intel did not have the capacity to design so many different chips, according to Moore.
However, Intel engineers Marcian ‘Ted’ Hoff and Stan Mazor come up with the idea of designing a general purpose chip that can be used for various tasks. This is how the idea for the central processing unit, or the CPU, arises. Neither are chip designers, and according to IEEE Spectrum, the project almost grinds to a halt in the early 1970s. The project will not really get off the ground until Intel hires chip designer Federico Faggin that year. The team is developing four chips, including the Intel 4004, which was officially announced on November 15, 1971.
The Intel 4004 has entered the books as the first semiconductor in which all parts of a CPU are packed in one chip. The processor clocked at 740kHz and was made on a 10-micrometer process. Today, chip production processes are quoted in nanometers, which is a factor of a thousand smaller. The 10µm process on which the Intel 4004 was made is equivalent to 10,000 nanometers.
Making the microprocessor was relatively easy for Intel at the time. It was a design with 2,300 transistors, and Intel was already making memory chips with more than 6,000 transistors, says Moore. The microprocessors could be produced in large volumes and used for many applications. Moore saw opportunities to further expand Intel. Although the Intel 4004 was succeeded by the 4040 in 1974, the first model remained in the range until 1981.
Micro Computer Set 4
The Intel 4004 was part of Intel’s MCS-4, or Micro-Computer Set-4. That was the 4bit chipset that Intel made for Busicom. In addition to the 4004 microprocessor, that system consists of the 4001 ROM, 4002 RAM and 4003 Shift Register. These components could be used to make compact computers. The combination of the 4004 CPU and 4001 ROM is enough for a working system. Expansions such as the 4008 address latch and 4009 I/O Interface also appeared, which ensured compatibility with the memory chips that Intel was already producing.