This is a good article about Atari released DOSs. It was taken from the Unix newsnet system. Transferred by Mike Blenkiron. Tidied by Dean Garraghty.¢-----------------------------------¢¢DOS 1.0 -- A very early DOS distributed by ATARI.¢¢DOS 2.0 -- This is the UNIVERSAL, generic ATARI DOS. If you are distributing programs through uploading or downloading, make sure they use the DOS 2.0 or DOS 2.5 binary load address. --EVERYONE-- owns a copy of DOS 2.0 no matter what drive or equipment they have.¢¢DOS 3.0 -- A troubled, nasty ATARI DOS, quickly abandoned by all of the userbase.¢¢DOS 2.5 -- The new GENERIC, UNIVERSAL ATARI DOS. DOS 2.5 is essentially DOS 2.0 with a fix to run ATARI --ENHANCED DENSITY-- for the 1050. ATARI DOS 2.5 was the first DOS released by ATARI to come with utilities programs to UNDELETE deleted files, check floppy disk directory integrity, and configure drives. Basically DOS 2.5 was still a single sided, single density DOS, with the addition of ATARI special --ENHANCED-- density to stretch out the single sector file density to expand your floppies from 707 sectors to around 1200 sectors on a floppy. (Sometimes ATARI ENHANCED DENSITY was affectionately referred to as "single density and a half". There had been patches for "enhanced" density floating around before ATARI officially incorporated it into their DOS.) DOS 2.5 works very well. Any files that are past the 707 sector limit show up in angle brackets. "<tictacto.bin>". These files are unreadable on the "very old" ATARI drives, which is why programmers use DOS 2.0 to create working software under, and is why DOS 2.0 has the widest circulation, i.e. they know beforehand that it will work on --EVERYTHING--.¢¢DOS XE -- DOS XE is the latest, and probably the last, officially released ATARI DOS. It is a double sided, double density DOS, that was finally pushed late out the door, for use with the new ATARI XF551 disk drive. Unfortunately, as the name implies, for DOS XE to work correctly, it really needs to be run on an ATARI 130XE machine (grey case with slanty function keys across the top.) It only works correctly on the ATARI XF551 disk drive if you have an ATARI 130XE connected to it. DOS XE is the first DOS released by ATARI to support the concept of subdirectories and date stamping. Unfortunately, when using DOS XE with any other combination besides an ATARI 130XE and an ATARI XF551 disk drive, you seem to end up with a single sided, single density DOS with all of the overhead of subdirectories and date stamping thrown in. If I remember correctly, DOS XE was also divided into a three level tree of DOS menus: a directory menu, a utilities menu, and a file menu. DOS XE has the reputation of being an overly complicated dog of a DOS. I would tell you more about what DOS XE can do except I think I through the manual away (which came in the form of a paperback book). On the otherhand, I keep the ATARI DOS 2.5 and the MYDOS manuals close at hand. ATARI DOS XE was written as a collaboration between ATARI INC., and Bill Wilkinson founder of O.S.S., programmer of ATARI BASIC and the ACTION! computer language. I have always wondered to this day what the heck was going on at ATARI that created DOS XE. Suffice it to say, not many people find DOS XE useful. I think I have met maybe one programmer in fifty who uses it.¢ Well, that's about it for all of the officially released ATARI DOSes. Suprisingly enough, although the naming convetion for the XF551, like the designation for the 520STFM, implies that the disk drive unit is an XE Floppy Disk Drive 551 Unit, you do not need an ATARI 130XE to use a XF551 floppy disk drive in double sided (i.e. front and back), double density (double 128 or 256 bytes per disk sector) mode. Several non-ATARI DOSes will do this. For example, I am using an XF551 floppy disk drive in double sided, double density mode from a stock, unexpanded ATARI 800XL under MYDOS 4.5... but more on that at another time.¢¢ P.S. There is a RAM-disk driver built into ATARI DOS 2.5. If you own an unexpanded ATARI 800XL and have the DOS 2.5 RAM-disk program for the 800XL, you can create a single density RAM-disk of 105 SECTORS for use with text editors and terminal programs. (Even without this program it is possible to use the 800XL DOS 2.5 RAM-disk, but it is much harder to do so.)¢
