Intel built the first commercially available microprocessor, the Intel 4004. Released in 1971, it was a 4-bit central processing unit implemented on a single silicon chip, a major step toward putting a computer’s processing logic into one compact component.
The 4004 grew out of Intel’s work for the Japanese calculator company Busicom. Intel engineers Federico Faggin, Ted Hoff, and Stanley Mazor helped create the architecture and chip, while Busicom engineer Masatoshi Shima contributed important calculator-system requirements. The original design was intended for a programmable calculator rather than a general-purpose personal computer.
The chip operated at about 740 kHz and contained roughly 2,300 transistors. Intel obtained permission to market the chipset to other customers, helping turn the 4004 from a calculator component into a commercial product. People sometimes confuse “first microprocessor” with “first computer on a chip” or with earlier room-sized computers; the key distinction here is the commercially available, single-chip processor.