OS/2

OS/2 is an operating system, first developed jointly by Microsoft and IBM and later by IBM exclusively. OS/2 stands for Operating System/2, in the same fashion as PS/2 means Personal System/2. It was first released in December 1987 and its last release was in December 2001. IBM ended support for OS/2 in 2006, and the project has since been maintained by SerenitySystems under the name eComStation.

The goal of OS/2 was to create a 32-bit successor to MS-DOS, in fact, many parts of OS/2 resemble and are compatible with MS-DOS. During development of OS/2 2.0, Microsoft and IBM ended their cooperation on the project, with Microsoft pursuing development of DOS-based Windows and Windows NT (heavily influenced by their work on OS/2) instead, and IBM continuing OS/2 development on their own. Windows has since become a commercial success, while OS/2 failed to catch on and was mostly used as a niche OS.

OS/2 1.x

 * IBM OS/2 1.0
 * IBM OS/2 1.1
 * IBM OS/2 1.2
 * IBM OS/2 1.3

OS/2 2.x

 * IBM OS/2 2.0
 * IBM OS/2 2.1
 * IBM OS/2 2.11

OS/2 Warp 3

 * IBM OS/2 Warp 3

OS/2 Warp 4

 * IBM OS/2 Warp 4
 * IBM OS/2 Warp Server for e-Business
 * IBM OS/2 Warp 4.51
 * IBM OS/2 Warp 4.52