When IBM set out to build a personal computer on a one-year deadline, it needed an operating system fast. CP/M, from Gary Kildall’s Digital Research, was the established 8-bit standard and an obvious candidate. IBM ended up shipping Microsoft’s DOS instead. IBM’s own history of the machine records the team’s broader strategy plainly: to hit the deadline and the USD 1,500 price target, they decided to “use off-the-shelf parts,” chose Intel’s 8088 chip, and “Microsoft provided the OS, which would later become known as MS-DOS.”
What is documented and undisputed: the outcome was not obvious at the time. The Computer History Museum, presenting Kildall’s memoir, notes that “it was unclear at the time which company — Kildall’s Digital Research or Microsoft — would win the contest for the dominant PC operating system,” and that CP/M was “a strong influence on the eventual development of DOS from Microsoft.” Microsoft did not write the system it sold IBM; it acquired 86-DOS (QDOS) from Seattle Computer Products, a system whose author had built it around the CP/M application interface.
What is disputed is the popular story of why Digital Research lost. The legend says Kildall blew the deal by flying his airplane instead of meeting IBM’s representatives. The Computer History Museum and Kildall’s children directly reject this framing. In presenting his memoir, they cite “the myth that he ‘missed’ the opportunity to become Bill Gates by going flying instead of meeting with IBM,” and call it a “tall tale” that unfairly reduces a serious inventor to a “could-have-been.”
The honest version separates the two. It is firmly documented that IBM shipped Microsoft’s DOS, that the DOS lineage traces back through QDOS to the CP/M interface, and that the winner was not predetermined. The neat morality tale of a single missed meeting is exactly the part that the people closest to Kildall say is embellished, and primary sources do not support the simple “went flying” caricature.