is the operating system released in 1995 by Atari for its 16/32 bits computer series.
At first, Atari had licenced both CP/M 68k
(lower layer operating system) and GEM
(upper layer graphical extension) from Digital Research Inc. As CP/M 68k
proved to be too slow when accessing floppy disks, Atari decided to write its own lower layer from scratch, GEMDOS
based on the next and faster operating system standard, i.e. MS-DOS
. This is why GEMDOS
can read and write on MS-DOS FAT?
filesystems (FAT12 floppy disks, FAT16 hard drives). However a driver is still needed to safely read and write FAT32 partitions, and handle long file names (LFN)
This mixture of GEM
by Digital Research and GEMDOS
by Atari was named TOS
, for Tramiel Operating System, and later became The Operating System
, Atari also wrote BIOS
responsible for dealing with Atari hardware. Within the higher layer of TOS
, Digital Research had already divided GEM
into a lower layer called VDI
and a higher one, built on the latter and called AES
. See the TOS Design
section for an in-depth discussion of TOS
Between 1985 and 1995, many TOS versions
were released, shipping different versions of the embedded system layers (GEMDOS
). These TOS versions
are discussed and listed in a separate article.