A line of personal computers produced by IBM, first introduced in August 1981. These machines initially shipped with an operating system called PC-DOS 1.0, which was developed by Microsoft for IBM. PC-DOS 1.0 was based on Microsoft’s own operating system called MS-DOS, which was later used by many other computer manufacturers who produced IBM PC compatible machines. PC-DOS and MS-DOS were essentially the same operating system, and the terms were used interchangeably. PC-DOS and MS-DOS were command-line operating systems that required users to type commands to perform tasks, and they were not as user-friendly as later graphical user interface-based operating systems.
