In 1972 the C programming language is developed at AT&T Bell Labs by Brian Kernighan and Dennis Ritche. The UNIX operating system, also written at Bell Labs, is rewritten using C. This later makes UNIX one of the most portable operating systems.
In 1975 the MITS Altair 8800 was released in kit form. This was the first easily available microcomputer. It had 256 bytes of memory and ran a version of BASIC written by Bill Gates.
Also in 1975 Bill Gates and Paul Allen form Microsoft.
In 1976 Steve Jobs and Steve Wozinak form Apple Computer and begin marketing the Apple I.
In 1978 VisiCalc is released. This is the first spreadsheet program and it made microcomputers useful to businesses. All modern spreadsheets, such as Lotus 1-2-3 and Excel, are descended from VisiCalc.
In 1979 the first microcomputer word processor, Wordstar, is released. This program later developed into WordPerfect.