UNITED STATES - DECEMBER 07: The IBM Personal Computer System was introduced to the market in early ... [+] 1981, at a time when IBM was the world's largest mainframe computer manufacturer.

Copies shipped per month rise from 500 to 12,000 between 1979 and 1981. By 1980 Apple has captured 50% of the personal computer market. In 1980 Microsoft is approached by IBM to develop BASIC for ...