GEM
<operating system> One of the first commercially available
GUIs.
Borrowing heavily from the
Macintosh WIMP-style interface it was available for both the
IBM compatible market (being packaged with Amstrad's original
PC series) and more successfully for the
Atari ST range.
The PC version was produced by
Digital Research (more famous for DR-DOS, their
MS-DOS clone), and was not developed very far.
The Atari version, however, continued to be developed until the early 1990s and the later versions supported 24-bit colour modes, full colour icons and a nice looking sculpted 3D interface.