Section includes contributions by Andreas Koch (most DOS 2 clone
descriptions); Jeff Williams (12/6/04, Mike Gustafson wrote SpartaDOS)

Atari DOS versions are very popular, but many 3rd-party DOS versions have also
been developed over the years.  Of these, MyDOS and SpartaDOS seem to be the
most-used today.


MyDOS 4.53
==========
MyDOS is modelled after Atari DOS 2.0S/2.5, but provides subdirectory and
hard-drive support, along with many other "high-end" features.

MyDOS 4.53/3 was released as freeware by David R. Eichel on 1/1/90. 
Defaults to a 3 character file length/free sector count instead of MyDOS's
normal 4. Supports multiple AUTORUNs at boot up (*.AR0 through *.AR9).
Supports Axlon RAMdisks.

MyDOS 4.53/4 is the same as 4.53/3, but uses a minimum of four characters in
the sector count just like most versions of MyDOS.

MYDOS 4.51 was developed by Wordmark Systems (Charles Marslett).  Source code
is available as "abandonware" at: http://www.wordmark.org/

MYDOS 4.50 was released on 11/28/88, developed by C. Marslett & R. Puff
http://www.nleaudio.com/css/files/MYDOS45M.ARC

Mathy van Nisselroy's MyDOS page, including recent patches by Lee Barnes:
http://www.mathyvannisselroy.nl/mydos.htm


SpartaDOS 3.2, 3.3, 4.41
========================
SpartaDOS is a completely different command-line DOS modelled after MS-DOS,
though it is perfectly capable of reading all Atari DOS and MyDOS disks.

There are many versions available.  Hopefully this list will help keep them
all straight.

SpartaDOS X 4.41 (8 Feb. 2008)
----------------
Greatly enhanced/expanded compared to disk-based SpartaDOS; completely
different source code.

    SDX upgrade project

     The purpose of this project is to add new functions to the best disk
     operating system for the Atari 8-bit computer ever created, and to clean
     up few bugs at the occasion. The last SpartaDOS X version (4.22) was
     released 10 years ago. Most users got used to its bugs and shortages. New
     software and hardware developments, however, made us think about a new,
     cleaned up and modernized version of the DOS, which would be compatible
     with the 4.22 (from FTe), and enhanced both in software and hardware.

     http://trub.atari8.info/index.php?ref=sdx_upgrade_en
    
     CREDITS
      - based on works done by: Prof!, MMMG, DLT Ltd.
      - new code and design: DLT Ltd.
      - hardware: Pasiu/SSG, Jad, Zenon/Dial, DLT Ltd.
      - hosting: krap.pl
      - devtools: DLT Ltd., Tebe/Madteam, others
      - other support: ABBUC, Epi/TRS, Krap, Mikey, Pin/TRS

    4.41    2-08-08  released by DLT
    4.39RC 10-01-06  released by DLT
    4.22   11-05-95  released by Fine Tooned Engineering (FTe, Mike Hohman)
    4.21    7-10-89  released by ICD
    4.20    2-06-89  released by ICD
    4.19    1-16-89  released by ICD
    4.18   10-29-88  released by ICD 
    4.17   ??-??-88  released by ICD
SpartaDOS X versions 4.17-4.21 were written by Mike Gustafson at ICD.

SpartaDOS Pro 3.3a, 3.3b, and 3.3c - 1994-1997
----------------------------------
The SpartaDOS Pro 3.3 versions were developed for FTe by programmers Stephen
J. Carden and Ken Ames, based upon a disassembled copy of the older (more
stable?) 3.2c release from ICD.
-- SpartaDOS Pro Ver 3.3a  3-Nov-94 -- Added MUX support and MS-DOS Commands.
   Highspeed SIO routines NOT included.  Recommended for use in emulators 
   (especially Xformer) only.
-- SpartaDOS Pro Ver 3.3b 25-Dec-95 -- Has two different SIOV handlers, one
   for the MUX and one for the MIO.
-- SpartaDOS Pro Ver 3.3c  1995 -- Looks at your system and by checking it
   determines what CIO handler to load, and has MS-DOS command set.  Black
   Box, MUX, and MIO are fully supported, though none of these are required.
-- SpartaDOS Pro Ver 3.3c 19-Dec-97 -- The same 3.3c produced on a 16K ROM
   cartridge and available for purchase from Video 61.
-- SpartaDOS Pro Ver 3.3d -- Contains additional fixes for MIO users.
   unreleased?

According to Lance Ringquist of Video 61:
K-Products contracted with FTe to develop SpartaDOS Pro 3.3 for exclusive use
and distribution with K-Products' BBS Express! Pro, to provide this BBS system
with the most stable platform possible.  As Video 61 purchased the rights to
the entire K-Products product line, SpartaDOS Pro 3.3 became a product of
Video 61.

SpartaDOS 3.2g and 3.2gx - Dated 6/4/94.
------------------------
Last official disk-based versions, released as shareware by Fine Tooned
Engineering (FTe), who had purchased the rights from ICD.  3.2g is the primary
version; 3.2gx differs only in that it locates the disk buffers under the OS
to save RAM.  3.2gx is intended for use in systems that include a PBI device
(MIO, Black Box); it is not compatible with BASIC XE nor any other programs
using RAM under the OS.

First shareware release from FTe: 3.2f.

Earlier major releases from the original developer, ICD: 3.2d, 3.2c, 2.3, 1.1
SpartaDOS 1.1-3.2d were written by Mike Gustafson at ICD.

Only the SDX cartridges and the original version 1.1 are compatible with the
400/800 computer models; SpartaDOS 2.x and 3.x require an XL/XE.

Many disk-based SpartaDOS versions are available for download from
Thunderdome, kept by SysOp Fox-1:  http://thunderdome.atari.org/ or
http://www.mixinc.net/atari/download_a8/sdsys.htm


BW-DOS 1.30 - FreeWare, published 95-12-17 by ABBUC
===========
Another popular, powerful DOS is BW-DOS (it is pronounced "Bay Vay Dos"),
freeware by Jiri Bernasek - BEWESOFT.  SpartaDOS compatible.  Does not use any
speeder internally, but comes with external XF551 speeder.  Supports 4 drives
and RAMdisk, comes with RAMdisk driver for XE compatible RAMdisks up to
1Megabyte; supports 4 densities: a) Single (90k), b) Enhanced/Medium (130k),
c) Double (180k) and d) DSDD (360k); does not use any RAM under OS ROM (so it
works on an Atari 800 and with Turbo BASIC); unlike SpartaDOS most commands
are external, thus the DOS is only 5kbytes short; supports a PAL clock (made
by ABBUC regional group "ARGS"); comes with many great utilities (which can
also be used with SpartaDOS).

BW-DOS 1.30 disk images and User Manual are available at:
http://atariwiki.strotmann.de/xwiki/bin/view/APG/BeweDOS

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

The other DOS varieties mentioned below are all, like MyDOS, Atari DOS-2
clones and thus DOS-2 compatible; available as PD or Freeware...


TOP-DOS 1.5+
============
Carolyn Hoglin writes:
This superior DOS was written by R. K. Bennett of Eclipse Software in
Sunnyvale, CA.  It was based on Atari DOS, but with many, many more features.
It fully supports my double-density, double-sided Astra drives, automatically
sensing the proper density and sidedness of both drives 1 and 2.  (MYDOS only
seemed to do that on drive 1.)  Also supported are large RAMdisks for Axlon,
Mosaic, etc.  The latest version was TOP-DOS 1.5+, which came with an
excellent manual explaining how to use its powerful capabilities.


SuperDOS 5.1
============
supports 4 formats SD/ED/DD/DSDD; supports 256k Xtra RAM/RD; supports 4
speeders: Happy+Speedy+XF551+US Doubler and its compatibles; has an AUX.SYS
file with option to use / not use RAM under OS ROM; has unfortunately a very
slow RAMdisk;


BiboDOS 5.4 and 6.4 
===================
3 versions available, one without speeder - 5.4NT, one with Happy/Speedy
support 5.4HS and one with XF support 6.4XF; supports 4 formats / up to 360k;
supports 256k Xtra RAM / RD; the DUP.SYS uses RAM under OS ROM, thus Turbo-
BASIC must load without DUP;


Turbo-DOS 2.1 
=============
Master-Disk produces 4 different versions: 2.1NT without speeders, 2.1HS for
Happy/Speedy, 2.1XF for XF551 and 2.1EX for 3 speeders: Happy+Speedy+XF551;
supports 256k Xtra RAM / RD and supports use of batchfiles; has converter for
DOS 3 and DOS 4; supports 4 formats, up to 360k; does not use RAM under OS
ROM; DUP uses a Command Processor; all commands are available via HELP key;
works with XL/XE computers only, does not load/boot on Atari 400/800 no clue
why;


RealDOS Ver 1.0a Build 0024 2-Oct-06
====================================
Integrated Logic Systems (ILS - Stephen J. Carden)
A potential modern replacement for SpartaDOS.
http://www.tcpipexpress.com/realdos.html