Editing GEM (desktop environment) (section)

===={{anchor|ST GEM|GEMDOS}}Atari versions====
[[File:Tos492.png|thumbnail|TOS 4.92 ([[Atari Falcon]]) running HomePage Penguin and Desktop]]
{{Main article|Atari TOS}}

Development of the production 68000 version of GEM began in September 1984, when Atari sent a team called "The Monterey Group" to [[Digital Research]] to begin work on porting GEM. Originally, the plan was to run GEM on top of [[CP/M-68K#16-bit versions|CP/M-68K]], both ostensibly ported to [[Motorola 68000]] by DRI prior to the ST design being created. In fact, these ports were unusable and would require considerable development. Digital Research also offered GEMDOS (originally written as GEM&nbsp;DOS, it was also called "Project Jason"), a DOS-like operating system aimed to port GEM to different hardware platforms. It was available for [[Intel 8086|8086]] and [[Motorola 68000|68000]] processors and had been adapted to the [[Apple Inc.|Apple]] [[Lisa 2/5]] and the [[Motorola]] [[VME board|VME]]/10<ref name="Motorola_VME10"/> development system.<ref name="Harris_GEMDOS"/> Atari decided in January 1985<ref name="Landon 2008"/> to give up on the existing CP/M-68K code and instead port DRI GEMDOS to the Atari ST platform, referring to it as [[Atari TOS|TOS]].<ref name="Daniels_1988"/>

As Atari had provided most of the development of the 68000 version, they were given full rights to continued developments without needing to reverse-license it back to DRI. As a result, the Apple-DRI lawsuit did not apply to the Atari versions of GEM, and they were allowed to keep a more Mac-like UI.

Over the next seven years, from 1985 to 1992, new versions of TOS were released with each new generation of the ST line. Updates included support for more colors and higher resolutions in the raster-side of the system, but remained generally similar to the original in terms of GKS support. In 1992, Atari released TOS 4, or [[MultiTOS]], along with their final computer system, the [[Falcon030]]. In combination with [[MiNT]], TOS 4 allowed full multitasking support in GEM.