DeveloperIBM, Microsoft (1.x)
Source modelClosed source
Initial releaseOS/2 1.0
(December 1987)
Latest releaseOS/2 Warp 4.52
(December 2001)
Supported platformsx86, PowerPC
Kernel typeHybrid
User interfaceWorkplace Shell

OS/2(Operating System/2) was an operating system originally developed jointly by Microsoft and IBM, in development was codenamed "CP/DOS". Between the release of Windows 3.0 and OS/2 1.3, Microsoft stopped all cooperation with IBM, due to a feud between the companies' significantly different cultures and visions. IBM later on handle the development of the operating system by itself.

OS/2 have features like a virtual DOS machine, the WinOS/2 subsystem (Windows 3.0/3.1x inside OS/2), Presentation Manager, and more.

Microsoft later used OS/2 code to develop Windows NT 3.1. OS/2 code was later used by Serenity Systems to develop eComStation in 2001, which in turn was used by Arca Noae LLC to develop ArcaOS in 2017.

Timeline[edit | edit source]

OS/2 Classic versions

Name Version Codename Notes
OS/2 1.0 1.0 CP/DOS Released in 1987-12 without GUI.
OS/2 1.1 1.1 Trimaran Released in 1988-10, first version with the Presentation Manager.
OS/2 1.2 1.2 Sloop Released in 1989, updated UI to look like Windows 3.0.
OS/2 1.3 1.3 Cutter Released in 1990
OS/2 2.0 2.0 Cruiser Released in 1992-04, First version of OS/2 that developed by IBM without Microsoft's help.
OS/2 2.00.1 2.00.1 Riker Released in 1992-10
OS/2 2.1 2.1

Borg, Yawl

Released in 1993-05, Updated version of the WinOS/2.
OS/2 2.11 2.11 None

Released in 1994-02

OS/2 Warp versions

Name Version Codename Notes
OS/2 Warp 3 3.0 Warp Released in 1994-10, First version to introduce the Warp branding.
OS/2 Warp 4 4.0 Merlin Released in 1996-09
OS/2 Warp Server for e-Business 4.5 Aurora Released in 1999-04
OS/2 Warp 4.51 4.51 MCP/ACP Released in 2000-11
OS/2 Warp 4.52 4.52 MCP2/ACP2 Released in 2001-12

Planned versions that were never finished[edit | edit source]

Warp era[edit | edit source]

Version 5.0
Codename Gandalf or Merlin 2
Developed 2003, probably scheduled for release in 2005.
Development started but project was later scrapped.