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.

Known versions

OS/2 1.x

IBM OS/2 1.0
IBM OS/2 1.1
IBM OS/2 1.1 Extended Edition
IBM OS/2 1.2
IBM OS/2 1.2 Extended Edition
IBM OS/2 1.3
IBM OS/2 1.3 Extended Edition

OS/2 2.x

IBM OS/2 2.0
- Beta build 6.66
- Beta build 6.67
- Beta build 6.83
- Beta build 6.86
- Beta build 6.106
- Beta build 6.109
- Beta build 6.112
- Beta build 6.117
- Beta build 6.138
- Beta build 6.149
- Beta build 6.167 - leaked
- Beta build 6.177
IBM OS/2 2.1
- Beta build 6.479 - leaked
- Beta build 6.498 - leaked
- Beta build 6.514 - leaked
IBM OS/2 2.11

OS/2 Warp 3

Beta build 8.142 - leaked
Beta build 8.152 - leaked
Beta build 8.162 - leaked
Beta build 8.234 - leaked

OS/2 Warp 4

Beta build 8.239 - leaked
Beta build 9.002 - mentioned in Fate 98 warez CD
Beta build 9.014 - mentioned in several BBS lists, probably a scene leak
Beta build 9.017
Beta build 9.018 - leaked
Beta build 9.019
Beta build 9.020
Beta build 9.021
Beta build 9.022
Beta build 9.023b
Beta build 9.023d - mentioned in Fate 113 warez CD
Beta build 9.023g
Beta build 9.023q - leaked, also mentioned in BBS lists
IBM OS/2 Warp 4.5
IBM OS/2 Warp 4.51
IBM OS/2 Warp 4.52

Needs to be completed.