This was my introduction to DOS, Atari style, when I received my first disk drive, the Atari 1050. Since I hadn't used any incarnation of Atari DOS before, this was my foray into an operating system that I found out all too soon that it was buggy, bloated, and incompatible with prior versions of Atari DOS. It did have an option that would convert Atari 2.x files to 3.0, but it was irreversible if you didn't keep the original copy of the file. And this OS was also poorly written that the way files were stored; it wasted far more space than was necessary. I don't remember the technical specs about it other than it really did no favors to the enhanced density feature of the 1050. I think Antic did publish a program to reconvert the 3.0 format back to 2.x. In any event, Atari saw the errs of its way and offered a free trade-in for the 3.0 its 2.5 DOS. (Yes, I was one of those who dumped 3.0 quickly after reading so many complaints.) This program classically in that "if ain't broke...." category!