The PC Primer: Operating Systems: Other OS's

Other OS's

OS/2

In 1987 IBM introduces would-be DOS replacement OS/2 and the PS/2, a PC based on a new architecture called MicroChannel. Neither product makes much of a long-term impact.

OS/2 is an operating system created by as a joint venture between Microsoft and IBM, however in 1990 Microsoft pulled out and the system went on to be developed by IBM exclusively. OS/2 stands for "Operating System/2".
At the time of writing (2005) There are still a number of OS/2 users and developers, along with loyal company customers that are hoping that IBM will release OS/2 or a significant part of it as an open source, like Linux. However It is unlikely due to the large amount of third-party code inbuilt, much of it from Microsoft.