MS-DOS 2.0: The Rewrite That Almost Didn't Happen
The Road to MS-DOS 2.0
MS-DOS 2.0 was a major rewrite, but it nearly stayed a minor update. IBM wanted only hard disk support, but Paul Allen pushed for a UNIX-inspired hierarchical file system, installable drivers, and print spooling. Despite Bill Gates' fears of alienating IBM, Allen's team of six delivered a much larger OS, shipping with the IBM PC XT in 1983.
But it soon became clear that IBM was committed to keeping DOS 2.0 as close as possible to the eight thousand bytes used by DOS 1.1, so as not to disrupt their existing user base.