Atari Forum ST FAQ

The Atari ST Operating System is called The Operating System or TOS.

The first version of Atari ST requires TOS to be loaded from Floppy disk. Internally on the motherboard is just a Boot Loader.

Later version of Atari ST came with TOS already burned on to the Read Only Memory (ROM) on the motherboard and is able to boot with any Floppy loaded TOS.

There are various version of TOS and is available for specific machines type.

• TOS 1.x
• TOS 2.x
• TOS 3.x
• TOS 4.x
• TOS 5.x