Atari TOS

TOS (The Operating System also Tramiel Operating System from Jack Tramiel, owner of Atari Corp. at the time) is the operating system of the Atari ST range of computers. This range includes the 520ST and 1040ST, their STF/M/FM and STE variants and the Mega ST/STE. Later, 32-bit machines (TT, Falcon030) were developed using a new version of TOS, called MultiTOS, which allowed multitasking. More recently, users have further developed TOS into FreeMiNT.

The Atari TOS (The Operating System) debuted with the Atari 520ST in 1985. TOS combines Digital Research's GEM GUI running on top of the DOS-like GEMDOS. Features include a flat memory model, MS-DOS-compatible disk format, support for MIDI, and a variant of SCSI called ACSI in later versions. Atari's TOS is usually run from ROM chips contained in the computer: Thus, before local hard drives were available in home computers, it was an almost instant-running OS. TOS booted off floppy disks in the very first STs, but only about half a year after the ST was introduced, all ST models started shipping with the latest version of TOS in ROM.

TOS consisted of the following:

The following were extensions to TOS (loaded separately):

True multitasking was not directly supported, but TOS allowed up to six desk accessories to be loaded into the system, which are similar to TSRs (Terminate and Stay Resident) on PCs. MultiTOS was developed to allow TOS to preemptively multitask.

The TOS desktop uses icons to represent files and devices, windows and dialog boxes to display info. The desktop file "DESKTOP.INF" was read to determine window settings, icon placements and drive icons, otherwise the standard default desktop of two floppy icons and the trash icon was used.

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