NEXTSTEP

At the time of Doom's production, id Software was using a for its graphic engine development, so the  version of Doom actually existed before the MS-DOS version. The application is sluggish on anything other than an -based NeXTstation or NeXTcube (the more memory, the better), and has no sound support (DMX was not supported on NeXTSTEP). With OPENSTEP on the most recent hardware, it runs smoothly under all conditions up to screen sizes of 400%. The released version is labeled v1.2, with programming credited to John Carmack, John Romero, and Dave Taylor.

Trivia

 * NeXTSTEP was extremely graphically advanced for its time, allowing programmers to create user interfaces with ease. The first web browser,, was introduced on it for this very reason.
 * Quake and Wolfenstein 3D were also first developed on NeXT hardware.
 * Despite modern versions of the being based on NeXTSTEP,  is incapable of running the NeXT version of Doom. This is due to  and  differences between NeXT and modern Macs that have slowly grown over time.