Classic Computer Magazine Archive ANTIC VOL. 4, NO. 3 / JULY 1985


Including the brand-new DOS 2.5


Why in the world are there so many versions of DOS (Disk Operating Systems)? Flip through your favorite Atari magazine (Antic, of course) and you see ads and reviews for products with names that end in DOS. Who uses them, and why? The following will answer key questions and point out some of the good and not-so-good points of the major Disk Operating Systems available for the Atari computer.
   For those of you who are new to the Atari, DOS 2.0S has been the most widely used DOS since its introduction in 1980. It is a good, reliable product. But the reason it is widely used is not so much because it is superior but because it is the "official" Atari DOS and was the first major DOS released for the Atari line of computers. Most major Atari software vendors conformed to it, so it became the "standard" by default, independent of merit.
   If you wish an introduction to Atari DOS 2.0 and some of its functions, please refer to "Why You Want DOS 2" (Antic, April 1985). For those experienced in DOS 2.0, and yearning to explore greener pastures, read on.

This long awaited product, successor to Atari 2.0, will become the new 'official' Atari DOS. It was written by the same group of people (headed by Bill Wilkinson of Optimized Systems Software) who are responsible for Atari BASIC, DOS 2.0, BASIC A+, BASIC XL, DOS XL, ACTION! and other top-ranked Atari products.
   DOS 2.5 supports both single density and the enhanced (dual) density mode on the Atari 1050 disk drive. If you format a disk in your 1050 drive with this DOS, you'll find that you now have 1010 sectors (129K) of available disk storage. This represents a 43% increase in capacity over DOS 2.0. DOS 2.5 maintains the use of 128 byte sectors but increases the number of sectors per track from 18 to 26. Most importantly, DOS 2.5 maintains file compatibility with DOS 2.0. Thus if you have a 1050 drive, you can boot up DOS 2.5, format a disk, directly copy your DOS 2.0 files onto the disk and have considerably more room left over. All this with no hardware modifications to the disk drive.
   Otherwise, this new DOS looks and acts exactly like DOS 2.0. The menu will be reassuringly familiar as there has been only one addition: Option [P] on the DOS 2.5 menu will allow 1050 disk drive users to force a single density disk format instead of the default enhanced density.
   Those of you with 810 drives need not despair, this DOS is for you too. Although you will not be able to use the enhanced density feature, you can boot DOS 2.5 disks that were formatted and written in single density on 1050 drives. The way that DOS 2.5 handles this is to "hide" files from the 810 drive that cross over sector 720, which is normally the last DOS 2.0 sector. If you completely fill a DOS 2.5 disk (1010 sectors) on a 1050 and then check the disk directory at some point you will see files listed like this:
 FILE1.BAS  025
<FILE2.BAS> 025

   This tells you FILE1.BAS is entirely contained within the first 720 disk sectors and can therefore be accessed by an 810 drive. The file(s) with the "< >" characters around them are NOT accessible with an 810 drive because they are physically located where the 810 drive can't read them. So if you have an 810 and ask your friend with a 1050 to copy some of his files, make sure the files you want don't have <> around them!
   Other features of DOS 2.5 are:

   1. Though the directory of an empty formatted disk will read "999 + FREE SECTORS". You really have 1010 sectors.

   2. Option J (Duplicate Disk) now formats the destination disk before copying.

   3. DOS 2.5 will allow 64K of memory in the new 128K Atari 130XE computer to be used as a ramdisk.

   4. A file conversion utility to convert Atari DOS 3.0 files to the DOS 2.5 format.

   5. A utility to create autoboot basic programs.

   6. An un-erase capability to retrieve accidently erased files.

   7. You can easily turn write verify on or off and change the number of disk buffers, without resorting to POKEs.

   8. The ability to test for bad sectors-whole disk only.

   Options 3 through 8 are not directly accessed through the menu but are included on the DOS 2.5 disk as binary load files.
   One thing that concerns me, as a user, is the lack of a disk utility program for enhanced density disks. In some preliminary checks, I've found that DiskWiz 2 will read all enhanced density sectors out to sector 1023 (the difference between 1023 and 1010 is taken up by the boot and directory sectors where program data is not . stored). It won't trace or map sectors that run past sector 720, however.
   I hope some company or individual will soon produce a full-featured disk utility compatible with this highly impressive new DOS 2.5.

DOS 3.0 is the DOS Atari has been shipping with the 1050 disk drive. It supports enhanced density but, unfortunately, will not read DOS 2.0 files directly and vice versa. DOS 3.0 permits conversion from DOS 2.0 files to DOS 3.0 format, but disastrously no provision was made to go the other direction.
   Once you converted your DOS 2.0 files to DOS 3.0, you'd never be able to share your programs with an 810 drive owner. Antic published a method to convert back to DOS 2 (January 1985) and there are some public domain utilities around. Check your local users group, Compuserve SIG*Atari, or wait for DOS 2.5.
   The DOS 3.0 file management is a more serious flaw. It stores files in "blocks" of 1024 bytes as opposed to the DOS 2 (and compatibles') 128 byte "sectors." This can be wastefully inefficient. If you save a file of 1025 bytes (one block plus one byte), DOS 3 will save it as 2 blocks, wasting 1023 bytes of disk space!
   This product should be avoided. It's a shame so many newer Atari users have been saddled with it.

DOS XL 2.3
DOS XL is a superb product, written and marketed by Optimized Systems Software (OSS). Though no one DOS is ideal for the needs of all users, this product comes close.
   DOS XL is shipped with both single and double density versions on the disk. It directly supports both single and TRUE double density.

DOS XL includes some
features which make it
truly unique

   True double density utilizes 256 byte sectors as opposed to the 128 byte sectors of single density, with the number of sectors and tracks remaining the same. Therefore, the storage capacity of a double density disk is 256*18*40 bytes or 184,320 bytes, which exceeds the capacity of the enhanced density mode of the 1050 drive by more than 50,000 bytes-a substantial difference by anyone's standards.
   Of course, you must have a disk drive capable of double density to take advantage of this increase, and to date no Atari-manufactured drive has had true double density capability. Owners of other drives such as Rana, Indus, Trak, Percom and Astra already enjoy the benefits of this extra storage.
   Atari 1050 owners will find available at least two hardware upgrades to true double density. They are manufactured by Happy Computers, Inc. of Morgan Hill, Ca. and by lCD, Inc. of Rockford, Ill. These modifications take advantage of special DOS's which we'll look at in a bit.
   DOS XL includes some features which make it truly unique. Three versions of DOS XL are included on the master disk. Each supports different memory configurations possible on Atari computers in order to maximize free memory for programming purposes.
   As shipped, DOS XL is configured for use on any Atari with Atari or OSS -BASIC. Another version of DOS XL on the disk is intended for use in conjunction with the bank selected OSS SuperCartridges (BASIC XL, ACTION! and Mac/65). This allows the DOS to occupy the RAM "under" the Super-Cartridge, effectively increasing the amount of free RAM by 4608 bytes in a 48K Atari 800. Owners of 800XLs can utilize yet another version of DOS XL which takes advantage of the extra RAM available on the XL machines under the OS.
   DOS XL can be either menu driven, like Atari DOS 2, or command driven like Apple DOS, CP/M and UNIX. People with a wide variety of computing backgrounds can therefore feel comfortable almost immediately with this product.
   A menu driven system provides prompts and doesn't require that the user memorize numerous DOS commands. A command driven system is far faster once the user has mastered the commands. Also, the command mode occupies about 2K less memory since a menu doesn't have to be loaded into memory.
   DOS XL supports numerous "intrinsic" and "extrinsic" commands. Intrinsic commands are those which can be issued in the command mode and do not require disk access (they reside in memory). Examples include: disk directory, change default drive number, protect and unprotect files, process batch file, run cartridge, erase file, etc.
   Extrinsic commands are commands whose code resides on the disk, not in RAM. Examples include: copy, initialize disk, menu, etc. Actually, any binary load file, with the .COM (command) extender, can be a DOS XL extrinsic command.
   Many long-time users of Atari DOS find the use of extrinsic commands irritating because they are not used to the requirement of having the various extrinsic command files present on the disk along with the DOS itself. A simple solution is to make a copy of DOS XL including only the files for extrinsic commands used most often.
   Another complaint expressed is that all these extra files eat up too much disk space. There are three ways around this problem: Include only the files you need on your working DOS disk, use 2 disk drives (This allows you to get by with no DOS files on your disk, assuming you have a master disk in one of the drives), or get a true double density drive and increase your available space.
   DOS XL also supports "batch processing". This allows you to put together a special text file made up of valid DOS commands and file names, then have those commands run in sequence by giving only one command.

Documentation for
DOS XL is extensive

   Batch files differ from extrinsic commands in that they contain only text and have their own special extender, .EXC (execute). Extrinsic commands and other files called by the batch file must be present on the disk for proper execution. In a special case, much like the familiar AUTORUN.SYS file, a batch file with the name "STARTUP.EXC" will execute when the disk is booted. This allows the user to autorun BASIC programs, something not easily done with Atari DOS 2.0.
   OSS also has available special versions of DOS XL which directly support the Axlon Ramdisk, the Mosaic 64 board, and the Bit-3 80 column board. This makes it possible to program BASIC XL, ACTION!, andMAC/65 in an 80 column format.
   The Axlon Ramdisk version of DOS XL automatically recognizes the Ram-disk, formats it (with 883 free sectors) and defines it as drive 4. This is the easiest, most efficient utilization of the Ramdisk I have seen. Most DOS's require special additional hardware to utilize a Ramdisk, such as the Omnimon or the Integrator Board. I'm surprised Axlon and Mosaic haven't licensed DOS XL from OSS and distributed it with their hardware.
   Documentation for DOS XL is extensive and well written, and customer support is excellent. Additionally, OSS has begun including BUG/65, an assembly language debugger, with DOS XL.
   DOS XL is a well thought out, highly professional product worthy of your attention.

SmartDos by Astra Systems is the DOS that Astra has been packaging for some time with its own drives. Even though it is packaged with Astra drives, it is compatible with all Atari drives and all Atari DOS 2 compatible DOS's.
   This is menu driven DOS with some notable differences from Atari DOS 2. It supports single and double density and displays a "status" line above the menu indicating which drives are active, their density and the size of free memory.
   SmartDos has some useful menu additions that allow sector copying, drive speed checking, bad sector testing, write verify on/off, and drive reconfiguration (single to double density and vice versa). You're given the option of having DUP.SYS (the Disk Utility Package) resident in memory, though this uses considerable memory.
   If you've ever needed a double density sector copier, now you've got one. SmartDos will copy 121 double density sectors per pass on a 48K machine, so several swaps are necessary to copy an entire disk (with one drive).
   Like Atari DOS 2, there are no extrinsic commands to keep in mind. SmartDos does not require any special hardware and does not directly support any. It seems to have difficulty workin with an Axlon Ramdisk, even with Omnimon  installed. But this will be a minor concern to most users.
   In general, this is an easy to use product, with more than just the basics.

SpartaDos is more of a specialty product than those previously mentioned. It is specifically designed to be used in conjunction with a hardware modification for the 1050 drive called the LCD Doubler. This modification is one of two which will convert the 1050 to true double density.
   In addition to supporting double density, SpartaDos, with the LCD Doubler, supports ultra-fast disk I/O. Incidentally Happy 1050's also support SpartaDos's ultra fast disk I/O. Not surprisingly, SpartaDos and the lCD Doubler are marketed by the same company, ICD, Inc. of Rockford Ill.
   The other "specialty" use for this product lies in its ability to operate with various drive formats simultaneously. This should be of interest to ATR8000 owners who are running 5 1/4" and 8" drives, single or double sided, single or double density.
   SpartaDos is a command driven DOS featuring intrinsic and extrinsic commands and batch processing. It also features time and date stamping of disk files and multiple subdirectories with 128 file names per directory (double the usual number). There is an 'unerase' command, which allows you to recover a previously deleted file-if you haven't writen to the disk since deleting that file.
   All of these features sound great, and they are-if you have the hardware. If you don't have a modified 1050 drive or an ATR8000, you may find few actual advantages to this product.
   SpartaDos is not directly compatible with disk files created with any other DOS for the Atari. However, a file copy utility is included which will convert from DOS 2 type files to SpartaDos and back again. This utility will also copy between densities with ease. The only DOS with which this utility currently will not work is Atari DOS 3. SpartaDos is an intelligent copy utility which does not have to told in advance what file type or density it is copying to or from.
   There are four versions of SpartaDos included on the master disk, two standard DOS's, one for normal drives and one for hardware modified drives, and two "read only" versions for normal or modified drives.
   The idea of a read only DOS is a bit unusual, as most of us sooner or later actually need to save something onto disk and "read only" means just that, it will read files but not write them. The option is provided because it takes up less memory, loads faster, and is ideal for loading games where writing to disk is not important. The standard version supports all of the SpartaDos features.
   The high speed versions of SpartaDos, when used with the appropriate hardware, provide extremely fast disk I/O. An improvement in reading and writing speed of 2 to 4 times over Atari DOS 2. SpartaDos is comparable to Happy Enhancement WarpDos in speed. This increase in disk I/O is made possible by the additional disk hardware which, among other things, increases the data transfer rate on the serial bus between the drive and the computer from 19.2k bps to over 40k bps.

All of these features
sound great, and they
are-if you have the

   Tremendous flexibility is provided for ATR8000 owners who may be using different types of generic disk drives. Special drive formatting is provided under SpartaDos with choices of 35, 40, 77 and 80 tracks, single or double sided, and single or double density Additionally, a special RS232 handler is provided for use specifically with the ATR8000.
   Multiple subdirectory capability is another unusual feature of this product. If, for example, you have a large number of game files which need some organization, you would do the following: When SpartaDos asks you for the "volume" enter GAMES. Create two subdirectories, call one BASIC GAMES and the other BINARY GAMES. Under each of these two subdirectories, create two more subdirectories called ARCADE and EDUCATIONAL.
   You now have a single disk on which you can store, under the appropriate catagories, basic arcade games, basic educational games, binary load arcade games and binary load educational games. All the directories are linked and each directory can contain up to 128 subdirectories or file names, and so on.
   This is only useful to people who have large capacity drives since all the programs that fit under the subdirectories that you create eat up disk space rapidly Ideally a large capacity hard disk would be what you want to take advantage of this capability-if one were available.
   SpartaDos is not without its problems. Error handling could be improved. If you call a non-existent cartridge you get a system crash. If you attempt to format a write protected disk, the drive keeps spinning until you turn it off. And you won't get an error message if you tell SpartaDos to format your 1050 like an 8" drive.
   Many of my binary files would not run under any of the four versions of SpartaDos. This did not seem to be due to errors in the file conversion utility as I was able to reconvert the files to DOS 2 and run them. I did not have any trouble running basic programs under SpartaDos. There must be some memory conflicts with this DOS and some machine language programs.
   Another small complaint: The disk directory lists the individual file lengths in bytes, and free disk space in sectors. So keep your calculator handy.
   SpartaDos cannot be used with the Axlon Ramdisk. This DOS attempts to find something in the drive hardware which is not present in the Ramdisk and gives an error message.
   You realy have to commit yourself to this DOS because you must go through lengthy conversions to use it. If you're at all like me, with hundreds of disks in DOS 2 compatible format lying around, you will probably find the time required to convert over to this DOS prohibitive.
   SpartaDos is a very fine product, but its appeal is limited to a relatively small number of Atari owners with very specialized requirements. Consider this product carefully before you buy.

MYDOS, by Wordmark Systems, is the DOS shipped with the ATR8000. It is a menu driven DOS which supports all documented Atari DOS 2 functions and is compatible with all Atari drives and DOS 2 type files. The menu is nearly identical to DOS 2 with a couple of additions: There is a status line above the menu informing the user of online drives and their densities and default drive number, and two different options, O and P.
   MYDOS option O is used to specify drive type, number of buffers, and write verify on/off. If you have a configurable drive, you can specify formatting for 5 1/4" and 8" drives with options similar to SpartaDos. MYDOS allows 35,40,77 and 80 track formats for single or double sided drives in single or double density.
   MYDOS option P allows the user to change drive density and specify the default drive (it need not be drive 1).
   MYDOS preserves the best features of both Atari DOS 2 and SpartaDos. No special hardware is required but special drive types are supported. MYDOS files are directly compatible with single density DOS 2 files. MYDOS does not seem to have the same memory conflicts with machine language programs that SpartaDos has.
   This is definitely one of the easiest to learn and one of the most potentially useful DOS's available for the Atari.

TOPDOS is one of the most friendly full-featured and useful DOS's for the Atari. In fact, it's hard to imagine that any one person could think of all the commands and utilities provided by this product. In spite of its apparent complexity TOPDOS remains easy to use. The newcomer can take to it like DOS 2, while the more experienced can really customize TOPDOS to fit just about any conceivable system configuration and purpose.
   TOPDOS is menu driven with command options identical to Atari DOS 2, except they provide considerably more flexibility The disk directory command A, for example, includes such options as: number of columns to display directory (up to 2 on screen and 6 on a printer), alphabetize disk directory, compress file directory (to overwrite deleted files and minimize search time), list deleted files (which haven't been overwritten) and list current and deleted files (which can also be un-deleted).

Many people will convert
to this product as they
are exposed to its
many features.

   Some of the other standard commands which are considerably enhanced over DOS 2 are:

   1. Copy with the following options: append, query/no query, merge and update.

   2. Delete, with query/no query.

   3. Initialize disk in TOPDOS format, Atari format, and nonstandard drive format. TOPDOS format differs from Atari format in that the files do not include file numbers within the individual file sectors. This special format is required to take advantage of a few special features of TOPDOS such as alphabetization and compression of the disk directory, and to handle double sided double density drives. Atari DOS cannot read the TOPDOS format but TOPDOS can read and write Atari DOS formatted disks.
   The nonstandard format option allows those users with compatible drives to specify the number of sectors desired, up to 944 per side in single density and up to 1968 in double density (8" drive).
   It is also possible to reformat only the VTOC, on a previously formatted disk. This takes approximately 3 seconds instead of the usual 40 seconds.

   4. Duplicate Disk, will sense if your destination disk is of the same format as your source disk and will reformat your destination disk, if required.

   5. Binary Load, includes the option to load but not run a binary file. It will also report the load addresses present in a binary file.

   6. An online help facility for each command.

   Besides the commands shared by DOS 2 and TOPDOS, there are some significant additions. Directly from the main menu you can build "command files" similar to the batch processing files of DOS XL. These command files can call other command files, something DOS XL won't allow. There is a mini-monitor which allows the user to examine and modify specific bytes of memory, and a trouble option to translate cryptic error numbers into brief English explanations.
   The "Set/Status" command reveals a TOPDOS customizing menu. Just a few of the options include definition of drive density and system drive number, residence on/off (resident TOPDOS uses 9-10K.), bypass cartridge allowing the user to bypass the cartridge on boot-up and directly access the TOPDOS menu, and such bells and whistles as change left margin and redefine command prompt.
   The Axlon Ramdisk and the Mosaic 64 board are fully supported with some versatile options. One can use the Ramdisk in single or double density change the drive number of the Ramdisk, define it as the system drive, and define which 16K banks are active.
   A summary of system status can be called by typing [/] [RETURN]. The status summary includes: the number and density of online drives, current system drive number, the current MEMLO and MEMTOP, number of disk buffers, TOPDOS or Atari disk format, MEM.SAV on or off, DOS resident on or off, cartridge bypass on or off and write verify on or off.
   Describing all the subtleties would take about 82 pages (the length of the TOPDOS documentation). I have a feeling that many people will convert to this product as they are exposed to its many fine features.

Before you buy any DOS, keep in mind that some kind of DOS is going to come with (or came with) your disk drive, making it essentially free. If you're going to buy an additional DOS, examine your needs and look for a product that fits your purposes. Certain things, like special hardware requirements, narrow the field. And ease of use is important.
   One personal opinion (shared by the Antic editors) Don't waste your time with Atari DOS 3!
   Atari DOS 2.5 will surely be a hit with many users because its performance (very good) to price ($0.00) ratio is tough to beat. Just keep in mind that DOS 2.5 won't do everything! There may be a DOS out there more suited to your needs that's deserving of your hard-earned money

Eric Clausen has owned his Atari since January, 1982. He is a member of ABACUS, the San Francisco users group, and he recently received his dentistry degree from the University of the Pacific. Eric plans to continue his medical training toward a PhD in medicine.


Atari Corp.
1196 Borregas Avenue
Sunnyvale, CA 94088-3427
(408) 745-2000
Send in your DOS 3.0 Master Disk for exchange.

Astra Systems
2500 South Fairview, Unit I
Santa Ana, CA 92704
(714) 549-2141
Packaged with Astra drives.

lCD, Inc.
1220 Rock Street, Suite 310
Rockford, IL 61101 -1 437
(815) 229-2999
$39.95 DOS alone, $69.95 with doubler(add $4 shipping to either)

Eclipse Software
1058-G Marigold Court
Sunnyvale, CA 94086
(408) 246-8325

Newell Industries
3340 Nottingham Lane
Piano, TX 75074
(214) 423-1781
S.W.P. Microcomputer Products
1000 W. Fuller
Ft. Worth, TX 76115
(817) 924-7759