Versions of GEM
The major versions of PC GEM have been:
nb: This version tree is missing GEM/5. For a better one, see Ben Jemmett's tree
GEM/1 looked too much like the Mac for Apple's liking. It had disc drives and a trashcan on the desktop, shading in the titlebars, and scrollbar thumbs as wide as the scrollbars themselves.
This version looks the most like the original Atari GEM (though the desktop is blue rather than green).
Apple's lawsuit caused a number of visual changes to be made - new window controls, narrow scrollbar thumbs, no icons on the desktop and no resizing of desktop windows. The API is almost identical to GEM/1.
This version was supplied with the Amstrad PC1512.
GEM/XM is a multitasking version of GEM/2 (it reports itself as version 3.0B3, but its features are those of GEM/2). Partial source for this version is available.
GEM/3 looks almost exactly the same as GEM/2; the improvements made were mainly to do with support for new font formats. It is also possible to set whether a click is needed to activate menus, or whether they just drop down when the mouse moves over their titles. Source for v3.0 is available.
GEM 3.1 added support for Bezier curves.
GEM/4 was bundled with some graphical applications (such as Artline). The look and feel is, again, identical to GEM/2 and GEM/3. It is possible for windows to have their own menu bars, as well as the menu bar at the top of the screen.
GEM/5 (not on the diagram)
GEM/5 was bundled with some GST programs. It had scalable font support (using XMS memory) and a rather Motif-ish 3D look and feel (much more thoroughly 3D than ViewMAX - 3D menus, 3D window borders, everything). The font support is not backward compatible.
X/GEM (not on the diagram)
A protected-mode version for genuine multitasking OSes; versions apparently existed for FlexOS and OS/2 Presentation Manager.
ViewMAX is a cut down version of GEM/3 used as the DRDOS graphical shell. This version was supplied with DRDOS 5, and incorporates menu shortcut keys (ALT+F for file, etc.). Support for features not needed by the desktop (fonts, the scrap directory, the Item selector) was removed or left in a state that would crash calling programs.
The window gadgets in ViewMAX are based on the DOS font, not the GEM one.
ViewMAX/2 looks much prettier than previous versions of GEM. It adds the ability to define colours for window gadgets (titlebars, buttons etc.) and 3D drawing code for buttons, scrollbars and dialog boxes.
This would have been the DRDOS 7 graphical shell, but was never released. Beta code is downloadable; from a brief examination, it appears that it would have been an Explorer - like shell, with coloured icons, movable windows, icons on the desktop, user-settable backgrounds, windowed DOS sessions and a built-in screensaver. How much of it was implemented I don't know, not having got the beta running yet.
Since GEM was released under the GPL, various programmers are attempting to get working builds from the source code that remains. The components that have been reconstructed so far (AES and Desktop) can be copied into a GEM/3 system to give movable file windows and ViewMAX/2 look and feel.
John Elliott 10-6-1999