Operating System/2 (OS/2) is an operating system for PCs developed originally by Microsoft and IBM, but sold, supported and managed solely by IBM. It's intention was to replace the antiquated Disk Operating System (DOS) as the operating system of choice. OS/2 is compatible with DOS and Windows. In other words OS/2 can run all DOS and Windows programs. However, programs written specifically to run under OS/2 will not run under DOS or Windows.

OS/2 is a 32 bit, pre-emptive multi-tasking, operating system for the personal computer. The graphic system of OS/2 has a layer named Presentation Manager that manages windows, fonts and icons. On top of this lies the Workplace Shell (WPS), introduced in OS/2 2.0, which is an object-oriented shell allowing the user to access files and printers, and launch programs. WPS follows IBM's Common User Access user interface standards.

OS/2 represents objects such as disks, folders, files, program objects, and printers using the System Object Model (SOM), which allows code to be shared among applications, possibly written in different programming languages. A distributed version called DSOM allowed objects on different computers to communicate. DSOM is based on CORBA. SOM is similar to, and a direct competitor to, Microsoft's Component Object Model. SOM and DSOM are no longer being developed.

OS/2 also includes a compound document technology called OpenDoc, which was a developed with Apple. OpenDoc is also no longer being developed.

Due to limited market success, IBM stopped marketing OS/2 (Warp V4 and Warp Server) for e-business programs on the 12th of March 2003.

Related Terms: DOS, Windows