Following are the versions of OS/2, initially developed by both IBM and Microsoft. See
OS/2.
OS/2 16-bit Version 1.x - Microsoft and IBM
Released in 1987, Version 1.0 was written for the 16-bit 286. DOS compatibility was limited to about 500K. Version 1.3 (OS/2 Lite) used only 2MB RAM instead of 4MB and included Adobe Type Manager. The Extended Edition included Communications Manager and Database Manager.
OS/2 32-bit Version 2.x - IBM Only
Introduced in 1992, this 32-bit version for 386s multitasked DOS, Windows and OS/2 applications. Data could be shared between apps using the clipboard and between Windows and PM apps using the DDE protocol. Version 2.x provided each application with a 512MB virtual address space that allowed large tasks to be easily managed.
Version 2.1 supported Windows' Enhanced Mode and applications could take full advantage of Windows 3.1. It also provided support for more video standards and CD-ROM drives.
Communications and database management for OS/2 were provided by Communications Manager/2 (CM/2) and Database Manager/2 (DB2/2). CM/2 replaced Communications Manager, which was part of OS/2 2.0's Extended Services option.
OS/2 32-bit Version 3 - IBM
In late 1994, IBM introduced Version 3 of OS/2, renaming it OS/2 Warp. The first version ran in only 4MB of memory and included a variety of applications, including Internet access.
Windows NT - Microsoft
Originally to be named OS/2 Version 3.0, this 32-bit version from Microsoft was renamed "Windows NT" and introduced in 1993. See
Windows NT.