After purchasing the rights to 86 DOS, Microsoft rebranded the software and MS DOS was born in July 1981. That became the basis of PC DOS 1.0, which Microsoft adapted for the IBM Personal Computer 5150 that debuted in August 1981. Microsoft would then go on to license MS DOS to other IBM compatible PC makers like Compaq and Zenith. These versions of DOS disk operating system are what came before Windows, and until Windows XP, served as the brains behind the operation. Windows would effectively...
