From AtariForumWiki
Jump to navigation Jump to search

TOS stand for The Operating System, and was the operating system distributed with all members of the TOS Family of computers manufactured by Atari. TOS was distributed on ROMs mounted on the motherboard. It was loaded from these ROM's at boot time.

TOS was a single-tasking operating system at the kernel level, but this kernel did develop into the multi-tasking MultiTOS in 1993. Today the MiNT kernel continues to be developed as a descendant of MultiTOS. It is complemented by modern interface implementations in the form of MyAES and XaAES

See also The Operating System of the Atari ST, which may need to be merged into this article.


TOS is a collective of numerous operating system components. From XBIOS at the hardware-interface level, through to GEM at the GUI level. GEM is in turn made up of VDI and AES


TOS had releases and continued to be developed from 1985 to 1992. It started as a very minimal, single-tasking interface in version 1.0, through to multitasking, colourful and sophisticated environment in MultiTOS.

See also History of Atari TOS (which may need to be merged with this article)


1.0 Released with the original ST. The first ST's were shipped with a minimal boot-ROM and TOS on a floppy, but the boot-ROM was soon replaced with TOS 1.0 in ROM

1.02 STF and STFM

1.04 Nick-named "Rainbow TOS" for the cycling rainbow graphic shown when viewing TOS information under the File menu. Used in the Mega ST and later STFM's. Support for blitter to accelerate graphic operations

1.06 First STE's

Hard drive bug

Had behaviour of not only corrupting certain hard drives when connected through the ACSI port, but could damage the hardware permanently. Correction: This was not a TOS-bug. It was caused by a faulty DMA chip and the problem can not be fixed by upgrading TOS. Atari replaced the DMA-chip for free in the affected machines.

1.62 Second revision for STE's, bug fixes including hard drive bug fix.


Mega STE - Originally released for the Mega STE - It can be used on a STE, but not on previous ST or Mega without modification.



2.06 Final Atari version of TOS 2 - In-depth guide on this wiki


Used in TT, written for 68030. Also licensed to GE-Soft for use in their Eagle TT-clone, and Medusa Computer Systems for use in their Medusa and Hades clones.





Developed for the Falcon





4.92 Unofficial release, leaked after Atari had stopped producing computers. Some advanced features but unstable.


Originally promised to be replacing TOS in ROM, MultiTOS was shipped with the Falcon on two floppy disks. MultiTOS consists of two main parts - MiNT (the kernel, originally developed by Eric Smith and bought by Atari) and a new version of the AES that supported multitasking. Unfortunelately the AES was very slow and buggy, which caused almost irreparable damage to MiNT's reputation. After Atari ceased to produce TOS computers, a beta version of an improved version of the AES was leaked. This was much faster, but unfortunately still buggy.

When Atari ceased to produce TOS computers, MiNT was released under the GPL licence as FreeMiNT.


There have been numerous TOS replacements and additions released throughout the lifecycle of TOS itself, and into the 2000's. TOS is actually a collection of components, and alternatives vary in the scope of what they replace. There are replacements of the VDI components which speed up the graphical operations of any TOS instance they are applied to (eg NVDI). There are also replacements of the desktop and interface look and feel (eg NeoDesk), replacements of the kernel only (eg MiNT), or indeed replacements that do replace the entire set of TOS components (eg EmuTOS).

  • FreeMiNT replaces the operating system kernel and focusses on robust and proper implementation of multitasking. Development is continued into today (2009)
  • MyAES replaces AES component of TOS, providing new interface API features, window rendering, textures, effects etc
  • XaAES as wiith MyAES, replaces AES and has similar features to MyAES. XaAES performs very well, being implemented as a service of the MiNT kernel.
  • N.AES, the first available alternative to MultiTOS. Fast and stable, and is still used by many. Published by Woller Systeme.
  • KaosTOS
  • MagiC. A commercial multitasking TOS-replacement. Was very popular in the nineties, but commercial support ended by the turn of the century.
  • Geneva. Popular in the nineties. Favoured by many for it's compact size and stability, but also a bit "odd".
  • EmuTOS

External Links

Wikipedia link

  • Thought to unofficially stand for Tramiel Operating System, however this has never been proven. Several Atari officials (including Sam Tramiel) has denied this. TOS still stands for The Operating System.