Explore Disk Operating System (DOS) Versions (30-60 mins)

Task: Explore Disk Operating System (DOS) Versions

Needed: DOS ATR files

Time: 30-60 minutes


I remember vividly the excitement of getting my first Atari 810 disk drive and the magic of the disk operating system (DOS). Since we got our 800 and 810 around 1983 the version of DOS I first used was 2.0S for single-density drives. I was of course amazed at the speed of the disk drive compared to the 410 I used with my 400 for the preceding two years. I had fun learning how to load and save files from BASIC, how to run executables using binary load, how to format disks, how to copy disks, etc. I also had fun relearning DOS years later after getting back into the Atari computing hobby. 

The first version of Atari DOS (1.0) was released in 1979 to coincide with the release of the Atari 400 and 800 and the 810 disk drive. Atari continued to release DOS versions through the XL and XE series of computers. In addition to Atari DOS, we used several third-party operating systems including Smart DOS, Sparta DOS, Top DOS, and My DOS. Each had their own twist on the basic concept that was represented in Atari DOS. These are fun to explore. I have provided a list of some of these below along with links to the ATR files to each so you can download them and try them in an emulator or burn them to a floppy for use on original hardware.

Atari DOS 2.0S
Atari DOS 2.0S


The following is not meant to be a comprehensive list but rather a sampling of the flavors of DOS for the Atari 8-bit computers. Check out the Wikipedia page for more in-depth information about each. Also, these and other DOS ATR files can found here (Holmes Collection), here (Atari Mania), and here (Internet Archive).

Atari DOS 1.0 – The first from 1979. ATR file. Manual.

Atari DOS 2.0 – The second version came in single-density (2.0S) and double-density (2.0D) flavors. The 2.0D was briefly released for the 815 dual disk drive that never really made it out into the market and is thus quite rare. Above is a photo of the box DOS 2.0 came in along with the included manual, DOS disk, and blank formatted disk. Here is the 2.0S ATR and the 2.0D ATR. Manual.

Atari DOS 3.0 – The third version was designed for the 1050 disk drive. Unfortunately, it was not backward compatible with 2.0. This came out in 1983. ATR file. Manual.

Atari DOS 2.5 – The fourth version released in 1984 that made 3.0 backward compatible. ATR file. Manual.

Atari DOS XE – Released in 1988 for the XF551 drive used with the XE line of computers. Was not compatible with DOS 2.0 and 2.5 or the 400/800 line of computers. ATR file. Manual.

Eclipse Software TopDOS – This started out as a mod to Atari DOS 2.0 and grew into a commercial product with lots of interesting features. ATR file. Manual.

ICD SpartaDOS – I recall this DOS being very popular in the mid and late 1980s. It was one of the few that had a command line interface. ATR file. Manual.

Optimized Systems Software OS/A+ – Compatible with Atari DOS 2.0. Also had double-density support. Unique in that it used a command line interface instead of a menu. OSA stood for operating system advanced. ATR file. Manual.

Rana SmartDOS – Compatible with Atari DOS 2.0. Also had double-density support. ATR file. Manual.

Atari DOS 2.0S Menu
Atari DOS 2.0S Menu


I often wonder why Atari didn’t build DOS into a ROM and make it available on boot up like they did Memo Pad or BASIC on the XL series. I assume it was because of memory issues and cost. I guess it also makes sense due to the rapidly changing landscape of disk media and disk drives.

If you are interested in the technical details of Atari DOS, I recommend reading Inside Atari DOS by Bill Wilkinson. 

What was your favorite DOS?