Christoph Fuchs <mailto:email@example.com>
v.1.13, Jan. 1, 2004 (note: the newest version of this file will always be available at http://www.drdos.net/faq/)
Please read the copyright notice at the end of the text. If you miss any questions, feel free to send me an e-mail.
DOS is a Disk Operating System, that means it's an OS that uses a disk. Operating systems for IBM PCs since the early 1980s were called DOS.
DOS consists of the command prompt, mostly command.com and two kernelfiles. That's a basic DOS system. DOS was a mainstream OS until Windows 95 (which also uses DOS, btw) threw it off the market.
First, you need a computer which is IBM compatible. The computer should have 640 KB of RAM or even more :)) (in some cases it will work with fewer RAM, too, but I would use more). Then, you need a floppy drive, a harddisk or something simular. It would be great to have a keyboard or a mouse and if you want to see something you might need a monitor... but that's all.
For those who always were happy with Windows it might be annoying to type a lot at the command prompt. But for those who want the computer do what it should do it's the first choice. DOS is small in size, very fast and everybody can effort a DOS system. For less than 100$ you can set up a system that is much faster than many Windows machines and is very stabile. You can do quite a lot with DOS and nearly all your system resources are free, DOS only takes a few kilobytes of your RAM. You can find a lot of programs and hardware for that OS.
But if you always want to play the newest games and don't want "to give up" your buggy Windows 9x, you might be on the wrong place here.
Well, that's a quite silly question. Everybody likes the DOS best she/he uses. My personal opinion is that DR-DOS is the best and highest developed DOS. The second choice should be ROM DOS.
Another really great DOS is FreeDOS <http://www.freedos.org>. It's available under the terms of GPL and I really love it.
Search for DOS newsgroups like comp.os.msdos.misc or
de.comp.os.msdos, look at the manufacturer's website(s)
you find above, look at the DR DOS forum at http://senac.com/forums/4356/
or at the OpenDOS documentation library at http://www.thur.de/~igs/USEFULL/OPENDOS/.
In many cases it's also a big succes to go to your local library to
search for old DOS books. They often have some, normally it's not
difficult to find them.
If you don't have a clue about DOS, I advise you to read some
sites with the DOS basics, e.g. http://www.computerhope.com/msdos.htm.
That's fairly easy: You simply need to add a line to your
CONFIG.SYS file, for example:
Please change C:\CDROM\IDE_CD.SYS to your cd driver for DOS. You
can get the driver with the drive on a diskette or try to use a
different one from
After that, you need to add this line to your
(The example shown above is for MS DOS, for FreeDOS it would be
FDEX /D:CD0001 and for DR DOS it would be NWCDEX /D:CD001).
Look also at What is conventional
memory? (2.8) or How can I get as much free conventional memory as
You can access your FAT32 partition with this driver:
To configure your systemfiles, add to your CONFIG.SYS:
(assuming that X:\DRFAT33.SYS is the path to the drfat33.sys
The following line should be added to your AUTOEXEC.BAT:
X:\DRFAT32.EXE /m:120 >NUL
(assuming that X:\DRFAT32.EXE is the path to the DRFAT32.EXE
If you want to read the files on your NTFS partiton (used by
Windows NT or Windows 2000), I suggest to use this driver:
http://www.drdos.net/files/ntfsdos.exe. A few people told me
that they had problems using this driver with DR DOS (look at Lineo DR-DOS (4.4) for more detailed
You can get a LFN driver at http://www.sylpher.com/dosuser/. I haven't tested it
yet, it would be nice if someone could tell me her/his opinion
You just need to copy a himem.sys from a Windows 9x/ME system
to your DOS system and load it before your emm386 (e.g.: add
to your CONFIG.SYS).
Might be that emm386 will print some errors, but you can
On modern system with harddisks >8GB you often have got the
problem that you must use the new 0Fh extended partition (LBA)
instead of the old sort 05h extended partition (CHS). DR-DOS 7.03
won't accept this new type 0Fh and won't have access to the data.
A solution would be to use the old 05h partition type but then
you would have access to 8 GB under DR DOS but you would be
limited to these 8 GB under Windows 9x/NT, too.
The only "real" solution would be to create two extended
partitions, first one with DR DOS FDISK (all the space above the
primary partition but below the 8 GB) with the C5h type ("DR DOS
secured"). MS DOS won't be able to recognize this partition.
Afterwards, you must create another extended partition with
the rest of the space for MS DOS which won't be recognized by DR
DOS using FDISK of MS DOS 7.10 or higher with the 0Fh type (not
readable for DR DOS).
First of all, you need a DOS compatible modem or ISDN card. I
advise to use the Arachne browser, a
great DOS webbrowser with PacketDriver and dialer. It's not
difficult to set it up.
These sites might also be interesting for you:
The first 640 KB of your RAM are called "conventional memory"
under DOS. DOS can only address this first 640 KB of RAM
directly, the other part won't be recognized if you don't load a
memory manager like himem.sys. Most programs need a special
amount of conventional memory to run, so it would be good to have
as much free memory as possible within this 640 KB. How can you
do this? Well, that's not quite difficult, but it is not fairly
Many drivers etc. are loaded into conventional memory by
default setting. You only have to tell them to load themselves
high, that means in the higher memory area. How to do this?
Simply tell them in the autoexec.bat or config.sys
somthing like LH (=load high, only use in autoexec.bat) or
devicehigh / installhigh (in config.sys). As an example:
If you want to load a CD-ROM driver in higher
memory, simply add to your config.sys the line
and to your autoexec.bat
LH MSCDEX.EXE /D:CD0001
(assuming that C:\CDROM\IDE_CD.SYS is the location of your cd-rom
driver and that you loaded a memory manager before in
Before you can do this, you need a memory manager (I suggest
QEMM386.SYS instead of himem.sys and
emm386.exe, it uses not as much memory as the others). Add the
to your config.sys before you load any other drivers in
the higher memory area.
Note: QEMM386.SYS is not compatible with
Florian Xaver postet a list of intersting DOS network links to the FreeDOS mailing list: http://www.freedos.org/freedos/news/technote/157.html. Thanks a lot!
Many people think that DOS is a very very old OS and has got a
lot of problems with Y2K. Folks, I can tell you that DR DOS 7.03
even corrects the BIOS date if your BIOS has got problems with
the year 2000. So DOS isn't as bad as you might think of this
I don't really had problems with PC DOS (IBM DOS 7) and FreeDOS,
neither with PTS DOS and ROM DOS. If somebody of you made other
experiences, please send me an e-mail (mailto:firstname.lastname@example.org).
Sure, you can. Create a primary partiton BEFORE your Windows
partition (e.g. with PartitionMagic) and get a boot manager (I
use the german tool 'Bootmanager', you can get a free trial version at
Another very good bootmanager is the eXtended Operating Systems Loader.
This solution should also work with linux.
These sites have got a lot of fine DOS programs:
A list of good DOS websites can be found at the DOSNET netring:
There exist several GUIs for DOS. The most frequently used one is Windows
3.x, but it's not developed any more and it's not for free.
If you like DOS and want to discuss your problems or the
experiences you made, then sign up to the OpenDOS mailing list at
mailto:email@example.com (to subscribe, send an e-mail to
with the text add opendos or add opendos-digest in
the body. If you subscribe to opendos-digest, you'll get
all e-mails every sunday in a digest form).
If you can program, make a few free programs for the FreeDOS project or help people with
Please buy your DOS versions legally (only commercial ones,
sure:)) ), because then you support the manufaturers and
-hopefully- the producers will get so much money that they will
continue to develop DOS.
There are several really great FAQs and tutorials around here,
Prof. Timo Salmi wrote an outstanding one, for example.
Sure, it is. You need a program like taskmgr.exe in
DR-DOS 7.03, but a tool like that clutters your memory like
nothing else... Another very good and well-known tool is
DesqView, look at
http://www.chsoft.com/dv.html and you will know much more
Try it with this fine program: http://www.dosemu.org.
You can do that using an ansi-driver like ansi.sys (load it in
config.sys: DEVICEHIGH=C:\DOS\ANSI.SYS). Let's assume that
you want to start Windows by pressing the F1-key. To start
Windows with the F1 key, you have to modify/create the
prompt-section in your autoexec.bat:
The last $P$G tells command.com to show your active working
directory (e.g. C:\DOS>) on the prompt. With the number 59 you
can use the key F1, with 60 F2, 61 F3 and so on. With the code
133 you reach the key F11 and with 134 the key F12.
If you want to format a diskette in drive A: by pressing F2,
you should add that at the end of the prompt command but
before something like $P$G in your autoexec.bat:
The complete command would look like that:
PROMPT $e[0;59;"C:\WINDOWS\WIN.COM";13p$e[0;60;"FORMAT A:";13p$P$G
code 59: key F1 code 60: key F2
If you use the dir command always with a lot of options
like /O /W or whatever you want, it's nasty to type them all the
time. You can solve this problem by setting the varibale
DIRCMD in autoexec.bat:
The example above will set the parameter /W as default, you
only type dir and you'll get the same result as dir
Note: This doesn't work for DR-DOS! In DR-DOS, you may
set the default paramenter with dir /C [parameters],
"dir" gives now the same result as dir /W.
You have to change the country-settings in config.sys (add 21000 to the country code):
This will switch the currency from "DM" to "EUR" and the format of the date from "dd.mm.yyyy" to the new format defined in DIN EN 28601 (ISO 8601) "yyyy-mm-dd".
This will also work for the other countries in the European Union which take part in the
currency union and which are supported by DR-DOS: Simply add 21000 to the country code in config.sys (you find the "normal" country codes in the DOSBOOK).
I added a german posting from Matthias Paul in de.comp.os.msdos to the Quicknote section.
4DOS is a command shell replacement for DOS. It allows more powerful batch scripts and is much more customizeable than the normal command.com.
4DOS is developed by JPSOFT, you can download a free evaluation version there. Klaus Meinhard is an expert for 4DOS, you can find his
regularly updated website at http://www.4xbtm.de.
This part of the FAQ is based on my personal opinion. Some
of you might have another one, please let me know about it and send your comment to
firstname.lastname@example.org. Thank you.
MS-DOS is the most-used DOS and most compatible :) It's very
stable, but it doesn't has as many features as some of the other
DOSes. It's not developed any more and it's difficult to buy it
(the only chance would be something like ebay...). MS-DOS 7.x is part of Windows
9x and Windows ME contains MS-DOS 8.0. The versions > 7.10
support FAT32 and partitions > 8 GB.
Since version 5.02, PC-DOS is independent in its software package and is not longer the same as MS-DOS. Since version 7.0 or 2000 (it's nearly the same, but it's different though ;-)) ) PC-DOS doesn't have more in common than PTS/DOS or DR-DOS. PC-DOS has got a few new really great commands like dynaload. With version 6.3, IBM cleaned the source code. This speeded PC-DOS up a bit, but a few programs needed the old code and that may cause errors, but only two programs like that are known.The editor is a
bit strange, I personally don't like it but some people like the
/C and /A switch to edit the configuration files
autoexec.bat and config.sys... You can purchase IBM
PC DOS at
Thanks a lot to Thomas König for detailed information about PC-DOS.
FreeDOS is still developed, it's OpenSource and it aims to be
100% MS-DOS 3.3 compatible. It comes with a big software package with lots
of great tools. Visit the
FreeDOS Website for more information. There you can also find some documentation stufff and lots of FAQs for FreeDOS.
Unfortunately, FreeDOS isn't 100% MS-DOS compatible., e.g.
Windows 3.x won't work with FreeDOS, but I'm sure that will change! A list of known bugs can be found at http://www.freedos.org/bugs/. If you want to take part in the FreeDOS community feel free to suscribe to the FreeDOS mailinglist at http://www.freedos.org/freedos/join/.
Since kernel 2024h, FreeDOS also supports FAT32 partitons (kernel 2024h is an alpha-version, you can download the kernel at http://prdownloads.sourceforge.net/fdlfn/kernel_2024h_fat32.zip).
There exist two different FreeDOS distrubtions: at http://www.fdos.org you can download the ripcord version which is updated more regularly - you'll find always the latest versions of the software in that package, but it might not be as stable as the "normal" distributions at http://www.freedos.org.
Jeremy Davis created a bootable ISO-CD-ROM image with the ripcord distribution. It's available for download at http://www.darklogic.org/fdos/ripcord/. Please tell him what you think about it and if you have got some suggestions for further versions.
In my opinion, DR-DOS is the highest developed DOS. It has the
best memory management, can run in DOS Protected Mode, is an
32BIT OS and comes with a taskmanager/-switcher for multitasking.
If you run on a fast machine, >300Mhz, various utilities will
break down because of a bug in the Borland C libraries. In DR-DOS
7.03 these have been recompiled with a fixed version of the
library and they will not crash on fast machines anymore. The
tool NTFSDOS (allows to read NTFS
partitions) doesn't work with DR-DOS correctly, this fact shows
that disk (files?) access by DR-DOS differs much from MS/PC-DOS.
DR-DOS is free for personal use, but it's not developed any more.
If you download the right package, it comes with Personal Netware
DPM stands for DOS Protected Mode. That means that you are
able to use the memory above 1 MB for TSR programs or simular.
Using DPMI, you will have more free convential memory.
- "VERIFY ON", "BREAK OFF", "FILES=40", "BUFFERS=10"
- CACHE: write-thru, 700 to 1024k, A=OFF, B=OFF, XMS
- ANSI.COM not ANSI.SYS, use 28-line screen, shadow BIOS and
- HD data at 0:300, get the fastest possible Video Card don't
use that extra video memory for RAM
- Do NOT use EMS unless forced, "FRAME=OFF/NO", "EMS=NO"
- Use LH(LOADHI/HIGHLOAD), DOS=HIGH,UMB, devicehigh is
- Don't use FASTLOAD, do use CACHE: PC-TOOLS, NORTON,
- Avoid TSRs (or load them high)
- Parity memory is preferred, tune the BIOS for speed.
- Use QCRT 3.1 or Zeno 2.74 for much faster screen writes.
- Don't use deep directory structures, that will increase the
These files are OEM versions of Ontrack. They have got a big
bug: an error occures when you want to rename a file. The
IBM*.COM files nativly support the new partition type 0Fh
It's not recommended to use these files if you don't know what
you do. The COMMAND.COM file seems to be okay, but I didn't
notice any changes.
If you want to try these files, please go to
http://www.drdos.net/err705.htm. - good luck.
Download it from
You can get the OpenDOS documentation at
An alternative to the official documentation is the
outstanding file nwdostip.txt in the MPDOSTIP.ZIP archive
from Matthias Paul. This package isn't an official document, but
it contains much information about DR-DOS and other DOS related
topics like NC and a file with many undocumented features of
DR-DOS. Unfortunately, these files only exist in german
Yes, there is. Lineo sells licenses in big packages, but if you
only want to buy a single license you can get it at
Caldera (only version 7.02) or - if you live in or near
Germany you can purchase it at
If you need >5 licenses, feel free to get them from Lineo
Q: I have a NetWare 5.1 server and I need to create a multiple config boot. With MS-DOS, it was as simple as using the following structure in CONFIG.SYS.
Menuitem=BootServ, Boot Server
Menuitem=BootWork, Boot Workstation
Then AUTOEXEC.BAT looked like this.
Could someone please tell me how to do this in DR-DOS? Thanks.
A: Here is a sample CONFIG.SYS that will do the job. You can keep your autoexec.bat like in MS-DOS (you get an environment parameter CONFIG that you can use in auotexec.bat to specify the operations you want to do).
switch server, drdos
I found an outdated (March 14, 1997) OpenDOS FAQ at http://www.delorie.com/opendos/faq/. If you know any other DR-DOS/OpenDOS FAQ, please contact me <email@example.com>.
PTS DOS is a russian DOS, written in assembler. It's really
fast. It comes on two floppy disks, one with the system and the
utilities, the other one with Arachne as webbrowser. It
claims to be MS-DOS compatible, but it's a bit strange in
configuration and memory management but it is still developed. At
http://phystechsoft.com/en you will find more detailed
information about PTS DOS.
On their website, they provide a PTS DOS FAQ and
help, which is very useful in my opinion.
There are two versions of PTS-DOS: One at PhysTechSoft (PTS DOS) and another
Paragon called Paragon DOS. They seem to be the same,
somebody told me that Paragon consists of former PhysTechSoft
Paragon DOS has also the following features:
- supports harddrives bigger than 8 GB
- FAT32 support
- Partiton Manager
- package also contains source code!
Wolfgang Elsässer published a website with a very big FAQ about PTS-DOS (http://www.almnet.de/ptsdos/). An english version is available.
In version 2000 from PhysTechSoft exists a built-in cd-rom
driver. In former versions you can use MSCDEX.EXE or
NWCDEX.EXE from MS-DOS/PC-DOS or DR-DOS if the drive doesn't
work correctly with the PhysTechSoft files.
(First answer:) Start PTS-DOS with a CONFIG.PTS and an
AUTOPTS.BAT containing only the most neccesary lines and the
keyboard driver for installing Windows (minmal configuration).
After the Windows installation, choose the "Windows compatible"
option at startup.
(second answer:) Some newer versions of PTSDOS offer a
"Installation Mode" in the Boot-Menu. This should also work!
Use himem.sys from Windows instead himemx86.sys
from PTS DOS.
- FF: searches for matching files and changes current
directory (more information with FF /?)
- TRUE[NAME]: displays canonized names of files despite
subst or join (more information with true
- LS: like in Unix, only in Paragon DOS > version
- Some commands can be used abbreviated: ATTR[IB], BR[EAK],
CO[PY], ERROR[LEVEL], EX[IT], TY[PE] and VERI[FY]
- The command TYPE has got an undocumentated switch
/QUIET. Using this switch, the type-command won't show the
message ---content of ...---
This commands aren't described in the online help or in the
||Beside CPU86, CPU286 and CPU386 the following CPU types are also possible:
CPU88, CPU486, PC, AT, PS1 and PS2.
||same syntax like ECHO (PAUSE = "<text>", but waits for
||With the parameter "TTY" the screen output of the DOS is set
to "Teletype-Mode" (terminal mode)
||Sets the default extension for system temp files, e.g. TMPEXT
= TMP. Normal default is no extension.
||Decides, whether the built-in UMB routines (UMBSRV =
INTERNAL) or extern ones (UMBSRV = EXTERNAL) are used. If you're
using UMBSVR = INTERNAL, the name of the chipset must be given,
the following ones are supported: 85C471, SIS471, UM82C491,
UMC491, W83C491 and WINBOND491.
Example: UMMBSRV = INTERNAL SIS471
||Here you can define the address sector (in HEX), which should
be used for the UMBs, e.g. USERAM = E000-EFFF.
The UBM-functions haven't been tested yet, please tell me about your
||Beside ON and OFF there is also the parameter HDONLY for
using the virtual DMA only for harddisk access.
PTSCACHE.SYS is able to manage a RAM-disk and the
disk-cache at the same time.
||Parameters for RAM disk are following:
||creates a RAM disk with <size> KB
||Sets the number of the RAM disks's root-directory to
<root>. Default is 64 (63 files + 1 volume label)
||Sets the sector size of the RAM disk to <size> bytes.
Default is 512. Using a sector size of 256 bytes in a RAM disk
smaller than 1 MB will save a bit of memory.
DEVICE = C:\PTSDOS\PTSCACHE.SYS 512 /V:512
creates a disk-cache and a RAM disk with 512 kilobytes each.
The drive letters are assigned automaticly and can be influenced
by the succession of the drivers loaded.
Programs which had been compressed with an old PKLITE version
(1.03) will crash with PTSCACHE installed.
The possible commands of the bootmanager in the directive
[BOOTMGR] in the file config.sys aren't fully described in
the manual. Therefore you find here a list of the bootmanager's
functions since PTS-DOS 6.42:
|AutoCheck = ON
||Checks whether a file (mostly AUTOBOOT.SYS) or an
entry in the CMOS-RAM is available with a choice from the last
bootmenu. If this is the case, the bootmenu won't be displayed to
choose, but the system will be booted with the saved selection.
That only happens if the selection had been made with one of the
funtion-keys. If a selection is chosen with the number-keys, it
won't be saved. During the boot, the bootmenu can be shown by
pressing [ESC], although AutoCheck may be set ON.
Default value: AutoCheck = OFF
|Color = ...
||Sets the color of the bootmenu. Possible colors can be found
in the online help.
Default: Color = LIGHTGRAY ON BLACK
Example: Color = GREEN ON BLACK
|Default = ...
||Defines the paragraph in the config.pts which should
be started after the "time out". This paragraph is marked with a
"v" in the bootmenu.
Example: Default = Standard
|Filename = ...
||Sets the filename, in which the last selection of the bootmenu
is saved. Only makes sense in combination with the "STORAGE =
Default: Filename = AUTOBOOT.SYS
Example: Filename = BOOTSEL.SYS
|Force = ...
||Defines a paragraph or a number of paragraphs, which will be
exectued every time, independent from the selection made in the
bootmenu (simular to [PTSDOS] and [COMMON] in
Example: Force = $System
|Ignore = ...
||The opposite of FORCE, defines paragraphs, which won't be
executed by the bootmanager. But that doesn't make sense in the
[BootMgr] paragraph ;-)
|Storage = ...
||Establish the place where the election of the bootmenu should
be saved. Two options are possible:
|Storage = CMOS
||Saves the choice in CMOS-RAM.
|Storage = FILE
||Saves the choice in a file. Defalut filename is
AUTOBOOT.SYS (look FILENAME above).
|TimeOut = x
||Sets the time out value, after x seconds, a default paragraph
will be started. Makes only sense in combination with the command
"Default = ...".
Default value: TimeOut = 5
If the space key is pressed in the bootmenu, only the
directive [COMMON] or [PTSDOS] will be exectued. If there doesn't
exist a shell command, COMMAND.COM will be searched
in the root directory or you must enter the path and the name of
the command interpreter if it can't be found.
This patch written by Jens Guenther fixes some bugs in the command.com of the german versions 6.51CD and 6.62. I don't know wheather it works with other versions, too, sorry. If you've tried it with a different version please tell me your experiences. Thank you.
<http://www.drdos.net/files/cmdptc19.zip> (51 KB)
ROM DOS is an MS-DOS compatible OS (I run MS-Windows 3.1x with
it) and comes with a large software package. It's still developed
by Datalight, you can get more information on their website at
http://www.datalight.com/rom-dos.htm. They offer for example
a webserver to control your DOS computer with a webbrowser
interface or to use your DOS computer as a FTP server. You can
control your DOS box with specific e-mails you send to it. It
supports FAT32 and long filenames (Long File Names can be read,
written, and deleted with ROM-DOS 7.1). On their website they
talk about something like 'Dynamic Device Driver Loading', they
explain that ROM DOS 7.1 has the ability '...to detect hardware
and load device drivers dynamically and to configure itself'.
Unfortunately, Datalight offers ROM DOS only to OEMs. There
exist a development package for around 1200 US $, but I think
that's a bit too expensive. But feel free to try the trial
version on a bootdisk which can be downloaded on the Datalight website.
RxDOS is a small DOS kernel with FAT32 and long filename
support, but it's quite buggy. You can download the newest files
MOE-DOS is an experimental freeware-DOS by Martin Coleman
which can be downloaded at
http://moedos.net. Unfortunately, it's still in beta-version
and not really MS-DOS compatible, but I think that will change
This document may be reproduced and distributed in whole or in
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redistribution is allowed and encouraged; however, the author
would like to be notified of any such distributions.
All translations, derivative works, or aggregate works
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Exceptions to these rules may be granted under certain
conditions; please contact the author of this document at the
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In short, I wish to promote dissemination of this information
through as many channels as possible. However, I do wish to
retain copyright on the document, and would like to be notified
of any plans to redistribute the FAQ.
If you have any questions, please feel free to contact the
The author is not accountable for any damage or data loss on your
computer or on others which may be produced by the use of the
advice given in this document. I don't guarantee that all the
things I write are right and will work with your machine.
Changes made on this document:
- July 23, 2001: started to write FAQ
- August 1-31, 2001: added a lot of stuff, links and
- September 6+7, 2001: updated information about PC-DOS [thanks to Thomas König], corrected some mistakes
- November/December, 2001: corrected the language mistakes in the FAQ [thanks a lot to A. Schultze]
- December 18, 2001: added the PTS DOS command.com patch and some internet/network stuff [thanks to Jens Guenther, Florian Xaver and Michael Bernardi]
- December 31, 2001: "How to use the EURO-symbol in DR-DOS?" [thanks to Matthias Paul]
- February 12, 2002: fixed a link to the DOS System Basics
- February 26, 2002: added 4DOS information
- May 26, 2002: changed design, re-wrote HTML code, added some stuff
- August 30, 2002: fixed broken link to Timo Salmi's BATFAQ (thanks a lot to Ben Weaver)
- August 31, 2003: updated a few links, some are still broken; added link to PTS-DOS FAQ
- January 1, 2004: changed link to OpenDOS documentation library