Atari DOS

Atari DOS is the disk operating system used with the Atari 8-bit computers. Operating system extensions loaded into memory were required in order for an Atari computer to manage files stored on a disk drive. These extensions to the operating system added the disk handler and other file management features.

The most important extension is the disk handler. In Atari DOS 2.0, this was the File Management System (FMS), an implementation of a file system loaded from a floppy disk. This meant at least an additional 32 KBRAM was needed to run with DOS loaded.

It is accessed by typing "DOS" at the BASIC or Assembler/Editor prompt to exit the cartridge, If DOS isn't loaded, on the 400 and 800, this exits to the memo pad, which is a text editor built into the firmware of those computers, or on XL and XE machines, the self test.