IEEE Bushy Tree

The first version of OS/2 was released by IBM in December of 1987. Supposedly it was nearly complete in 1986 but a decision was made to delay the release, so that IBM could release the PS/2. Strong comparisons were made with DOS, but there were major differences, as well. For example, the command line and familiar commands were common to both. But, the internal workings of OS/2 had brought in features that were never before offered on a PC. The lead architects of OS/2 were Gordon Letwin, from Microsoft, and Ed Iacobucci (who would later be the co-founder of Citrix) from IBM. Because of time restraints, not all features were released on 1.0, most notably being the Presentation Manager, the installable file systems and the named pipes.

OS/2 1.0 was said to have lead the way for other operating systems and included important features such as:

  • Preemptive multitasking
  • Multithreading
  • Interprocess communication features (for example, shared memory, pipes, queues and so on)
  • virtual memory support (otherwise known as swapping)
  • fully protected operation
  • dynaming linking (DLLs)
  • support for up to 10 megabytes of physical memory

In light of this, OS/2 did have it's drawbacks:

  • lack of memory support for the 286 PCs.
  • many applications had to directly access hardware, instead of using DOS API
  • memory constraints in real-time mode

The interface of OS/2 1.0 was text-only, as the Presentation Manager was not finished.[1]

OS/2 Warp 4.0 Branch
Preceded by
IBM OS/2 1.0 Followed by
IBM OS/2 1.x
TopView Branch
Influenced by
IBM OS/2 1.0 Influenced