Forming Alliances: The Key to Success In the early years, Microsoft needed IBM more than IBM needed Microsoft. As IBM sought ways to exclude “clones” from the PC market, Gates protected his partnership with IBM by co-developing OS/2 and offering IBM the successor to MSDOS, an operating system called Windows. “We’d lost the chance to make Windows and OS/2 compatible, and because we’d lost the struggle to make OS/2 run on modest machines, it only made sense to continue to develop Windows.”