disk operating system

That product, called Microsoft Disk Operating System, or MS-DOS, was a watershed for the company.

Eventually the product refined by Microsoft - and renamed DOS, for Disk Operating System - became the core of IBM PCs and their clones, catapulting Microsoft into its dominant position in the PC industry.

For those too young to remember, DOS was the Disk Operating System that ran most household PCs from 1981 until around the turn of the millennium. 

Disk operating system computers were popular in the 1980s and early 1990s.

Described by Tilly Blyth, a computing curator at the Science Museum in London, as “a very significant machine,” the 5150 and its software, the Microsoft Disk Operating System or MS-DOS, established industry standards, which have dominated personal computer design ever since.