MYDOS is an alternative DOS for the Atari. Produced by SWP, Inc. (makers of the ATR8000), MYDOS is intended primarily for their machine, but will also work with Percom and other higher-density drives (double density and double sided).
The strenght of this DOS lies in its power and ease of use. The program is not necessarily user friendly - you must know what you're doing, or you could trash an entire disk - but it is easy to use. Like TOP-DOS, it lets you enter multi-line, multi-keystroke commands on one line, with fewer keystrokes and far more clearly.
MYDOS takes both upper- and lowercase filenames, too. It's another "useful but not necessarily friendly" feature. Although you can predefine the density of the drive (and disk) you're using, MYDOS is smart enough to read a disk in a format other then that specified. When copying an entire disk with the "J" command, MYDOS is nice enough to automatically format the disk, unless you say other wise.