The personal computer and its operating system

The January 1975 issue of Popular Electronics put a box with rows of switches and lights on its cover and called it the world's first minicomputer kit to rival commercial models. It was the Altair 8800, from MITS, a small firm in Albuquerque, New Mexico, built around Intel's 8080 microprocessor.

Hobbyists soldered it together themselves. Out of the box it did almost nothing: you entered programs by flipping switches. Two young programmers, Bill Gates and Paul Allen, wrote a BASIC interpreter for it, which MITS licensed. The personal computer had arrived, and so had the idea that its software could be a business of its own.