The DR-DOS/OpenDOS Enhancement Project

Other projects
(21.7.2011): At last a new WIP version! Everyone who has a feeling of deja vu now is absolutely right. ;-)
Quite some time has passed since the last official release - almost two years, to be more precise - and some people were afraid that I had abandoned the project. Well, I have not abandoned it, I just had two very stressful years, and the project suffered from this. At least I have now managed to compile a new WIP version. Alas, it does not feature the improved USB support I had promised, that will have to wait a bit longer.

(23.7.2009): New WIP version with improved USB support!
The latest WIP version of Enhanced DR-DOS 7.01.08 features improved support for removable USB block devices; in particular, experimental support for USB memory sticks has been added. It has not seen much testing so far, mostly due to the fact that I lack the devices to test it with. Any feedback is welcome; I would especially like to know whether it works with large (>8 GB) memory sticks and those that have been formatted on another machine or OS.
Other changes include fixes to the FAT+ API and some changes to the network redirector with respect to whether paths are considered local or remote. Again, I would appreciate it if people who use networking regularly could test it and report any problems.

(28.3.2009): New WIP version with new FAT+ functions!
This new version includes several additions to the FAT+ API which previously were only available by loading DOSLFN. Also, it contains code to improve the compatibility with non-standard boot managers and MBR codes. Last but not least, it resolves a long-standing conflict between the DR-DOS file password protection system and DOSLFN. There are also several other fixes and enhancements.

(2.1.2009): New WIP version with several bug fixes!
The new WIP version of Enhanced DR-DOS v7.01.08 includes mostly bug fixes, though there are also some other changes. If you have been using FAT+ or COLOUR before, this is a recommended update. It may also fix some other miscellaneous problems you might have encountered.

(28.12.2008): New contributions page!
I have finally found the time to add the new contributions page to the site where I will put contributions to the project by others. Currently, there is only one item on it, but I will add more over time.

(26.7.2008): It's a colourful world - new WIP version with improved COLOUR support!
The new WIP version features a new COLOUR command for COMMAND.COM which works similar to the one for CONFIG.SYS but with enhanced syntax. It allows you to change the DOS screen colours anytime. Also, two feature requests have been addressed in this version: The RENAME command can now rename not only files but also directories, and the TIME and DATE commands support the option /T to display the current time or date without prompting for a new one. Last but not least, the heap/stack space of COMMAND.COM has been adjusted again to fix two more of those dreaded "Batch files nested too deeply" errors.

(12.4.2008): New WIP version!
This is actually the work of four weeks ago which I did not have the time to release until now. It features several fixes to the TRUENAME command, LFN support for COPY and finally support in DIR for displaying the sizes of FAT+ files, though this currently only works with DOSLFN 0.40d or later. Since the LFN support in COMMAND.COM needs more stack space than before, I also increased the combined heap/stack size quite a bit and activated checks to guard against overflows. Since the development cycle for v7.01.08 is nearing completion, please report any problems, in particular any spurious "Batch files nested too deeply" messages, to help making the release version as stable as possible.

(29.2.2008): First release of the new DR XCOPY command!
Today I have released the first version of the new XCOPY tool, which will serve as a replacement for the XCOPY command included in the DR-DOS 7.0x distributions. Unlike the old version, it can copy files >2 GB, so it is suitable for copying FAT+ files. It also features a new option to clone the timestamps of the source directories it copies when creating the destination ones.

(8.2.2008): New WIP version with LFN support for most internal commands!
It is quite some time since I released the last WIP version, but I hope you will find the new one worth waiting for. It features full LFN support for most internal commands in COMMAND.COM, except for COPY, which is a large beast and will have to wait for the next version, CALL, which I will rewrite together with the rest of the batch file subsystem, and SUBST and ASSIGN which might need special support in the kernel. It also fixes some problems with input redirection and free disk space computation on nearly full FAT32 drives.

(4.7.2007): Fifth anniversary of the project!
Today it is five years ago that this project was born. I certainly would not have expected it to last that long at that time, nor that I would still not consider my work finished after so many improvements to the OpenDOS source code. Thank you all for your continued support and interest in this project!
Originally, I had planned some releases for this day, but as usual, they got delayed, so you will have to wait for them a bit longer. ;-)
One of the things I have been working on recently which has been requested many times was making the forum more Spam-proof. I have achieved this goal by blocking the so-called anonymous proxy servers, which were responsible for the vast majority of Spam posts in the forum. It works like a firewall that only accepts connections from properly configured proxies, which most ISPs' proxy servers seem to be. Eventually, the Spammers will probably find a way to circumvent this protection, but for now it has proved quite effective. There have been no reports of problems so far, and I do not really expect any, either, but if you have difficulties posting in the forum, check the proxy settings of your web browser and change them accordingly.

(17.6.2007): New WIP version release!
The new WIP version of Enhanced DR-DOS 7.01.08 brings with it the usual assortment of fixes and enhancements, of which you might find the support for DOSLFN on CD-ROM drives and the increase of the maximum length of the command line and PATH variable to 255 characters the most useful. It also improves the compatibility with several other utilities.

(21.4.2007): New Enhanced DR-DOS WIP version with several fixes and enhancements!
I have compiled a new WIP version of Enhanced DR-DOS 7.01.08 which features LFN support for the DIR command, fixes for the Int 19 fast boot function and last but not least a fix for a potentially critical bug that was introduced with the 64-bit file support. If you are using any of the WIP versions with FAT+ support, it is recommended that you upgrade to this version.

(17.12.2006): New Enhanced DR-DOS WIP version - codename "Speed Demon"! :-)
If you have been following the discussions in the forum lately, you may have read something about a so-called "Speed Demon" patch that is supposed to make file read/write operations in Enhanced DR-DOS faster. Well, here it is. This new patch contains fixes and optimisations that improve the speed of file writes, especially when the destination file is created or replaced rather than overwritten. Read performance is also improved to a lesser degree. The performance improvements range from 10% to well over 1000%, depending on the machine and the type of operation. There is still room for improvement, so perhaps I may release another "Speed Demon" patch soon.

(7.11.2006): First public release of DPMI Arachne!
In case you have wondered when the next WIP version of Enhanced DR-DOS will be released - sorry, today is not the day. ;-)
That is mostly because I have been working on a DPMI (DOS Protected Mode Interface) version of the web browser Arachne instead, which I hereby make publicly available. Actually, I already had a working version four weeks ago, but as usual, I did not find the time to release it. Anyway, here it is!
This is the second alpha version of DPMI Arachne, though you will not find this info displayed anywhere in the program. You can download it from the newly created page "Other projects", where I will release all things not directly related to Enhanced DR-DOS. As an alpha version, it is known not to work on some machines, and there may be other issues as well. I have also compiled a DPMI version of the tool PING, which you can use to test whether there are problems with running the DPMI version of WATTCP on your machine. Feedback is welcome! :-)

(20.8.2006): At last a new WIP version! Haven't I said that before? ;-)
Well, here it is - the new WIP version that you had to wait for so long. It features several bug fixes; in particular, the problems with LFN-aware programs and with sporadically vanishing drive letters have been fixed. Also, there are fixes to the FAT+ API and two new 64-bit functions, also somewhat related to FAT+. If you have been experiencing any of the problems mentioned above, updating to this version is recommended.

(11.2.2006): Enhanced DR-32(tm) v0.03 is now available!
The new version of Enhanced DR-32 features a new error handler that displays address, register contents and the code sequence that caused an exception 13 (General Protection Fault) instead of hanging the machine, thereby offering a chance to identify the code that caused the crash. Also, compatibility has vastly improved since the last version; it now works on all machines I have tested it on, including those that previously caused problems.

(15.1.2006): New WIP version which supports file sizes of up to 256 GigaByte!
The most spectacular feature of this new WIP version of Enhanced DR-DOS 7.01.08 is, of course, support for the new FAT+ filesystem extension which breaks the 4 GB limit of the traditional FAT filesystem. In fact, files can now become as large as 256 GB (minus one byte). Less spectacular but nonetheless critical is a bugfix for a problem with deleting files in very long directories which had been introduced by the LFN support, so if you have followed the v7.01.08 WIP (4.7.2005) upgrade path, this is a recommended update.

(23.12.2005): The first version of Enhanced DR-32(tm) that can run DOS software!
I have finished v0.02 of the Protected Mode extension for Enhanced DR-DOS. The new version features a hardware interrupt handler and some improvements to the Virtual Monitor, so for the first time, you can actually run some simple DOS programs under it! Also, it might now work with some device drivers like mouse drivers, etc. However, it is far from being complete and still does not work on some machines. If you encounter problems with it that do not seem to be due to the restrictions mentioned in the readme.txt file, please report them in the forum. By the way, this is most likely the last update in this year, so I wish you all Merry Christmas and a Happy New Year! :-)

(6.12.2005): At last a new WIP version!
Finally, five months after the last one, I have managed to compile a new WIP version! This one contains mostly work I had done before I got ill, which I had planned to release two months ago. Except for the new SWITCHES /F command, it features mostly fixes for more or less critical bugs. In particular, if you are using the last WIP version, you should upgrade to this one because of the LFN bugfix.

(28.9.2005): Bugfix for UPX-compression script
I have uploaded a fix for a bug in the pack script that caused the packed DRBIO.SYS file to fail to load DRDOS.SYS when started from hard disk. You can download the Pack v1.01 archive from the download page. To conserve bandwidth, I have not included the UPX 1.25 tool in this package; if you need it, you can find it in the file in the Download Archive.

(11.9.2005): Support for compression of DRBIO/DRDOS.SYS using UPX!
I have devised a way to use UPX-compression on DRBIO.SYS and DRDOS.SYS, which is useful for environments where space is scarce, like boot disks. The new packer consists of a set of batch files and DEBUG scripts which compress the two kernel files using UPX and modify the decompression routine to make it compatible with Enhanced DR-DOS. Current versions of Enhanced DR-DOS up to 7.01.08 WIP (4.7.2005) only support DRBIO.SYS compression because compression of DRDOS.SYS needs special treatment by DRBIO.SYS; the next WIP version will also support DRDOS.SYS compression.

(7.9.2005): First release of the new Enhanced DR-32(tm) Protected Mode Extension!
I have uploaded the first version of the new Protected Mode extension for Enhanced DR-DOS. When it is finished, it shall incorporate all the Protected Mode functionality that is currently present in HIMEM and EMM386, and probably some more.
This first version only features a simple mode switching test. If you want to test it, please run it after a clean boot and report if it works on your PC.

(4.7.2005): Third anniversary and a new WIP version!
For the third anniversary of the project, I had planned to release something special which I had begun to work on three months ago, but as usual, it got delayed due to Real Life issues, so a normal WIP version will have to do. Oh, well.
Anyway, the new WIP version adds some interesting features, like a much improved COLOUR command, a run-through option for the autoexec.bat file which works similarly to the one for config.sys, and last but not least, the first basic foundation for native LFN support. Long filenames are now handled properly in all delete, rename, move and remove directory operations. The new routines will even fix some LFN errors on the fly, thereby hopefully putting an end to the questions why Enhanced DR-DOS cannot remove some directories even though they appear to be empty. :-)

(30.6.2005): New Enhanced DR-DOS Forum!
Since the old forum at went down without forewarning after being online for just half a year, I have created a new forum on the same server that The DR-DOS/OpenDOS Enhancement Project is on. While this has the obvious disadvantage of not being able to post if the server is unavailable, it is hopefully more reliable than

(30.5.2005): First version of Enhanced DR-DOS 7.01.08 and the new DR-DOS FORMAT command!
This is a double release, because I am releasing both the first WIP version of Enhanced DR-DOS 7.01.08 and the new DR-DOS FORMAT command v1.0 at the same time.
With the new WIP version, you get a new command to change the default colours of Enhanced DR-DOS from black and white to anything you like, more comfort in single-stepping config.sys, probably more free memory and some improvements of the handling of FAT32 drives, amongst other things.
With the new FORMAT command, you get a disk formatting tool that supports both the FAT32 filesystem and the 64K/128K cluster size feature of Enhanced DR-DOS, and is a suitable replacement for the FORMAT command in the DR-DOS 7.0x distributions.

(7.3.2005): Enhanced DR-DOS 7.01.07 stable release version available for download!
After 14 months of work, version 7.01.07 of Enhanced DR-DOS is finally finished! Actually, I had planned to release it two months ago, but real-life trouble slowed down the development. This version comprises all of the features that I have developed in the course of the last year, namely support for the FAT32 API, so that ScanDisk and other disk tools will now work properly on FAT32 drives, the ability to boot from FAT32 and all primary partitions, and last but not least, the new powerful memory management which features many new commands to increase the free base memory available to applications. Also, the compatibility with MS-DOS and DR-DOS 7.03 has been improved. I hope you will enjoy the new version. Now, onwards to v7.01.08! :-)

(23.2.2005): A long-standing bug in TaskMgr has been fixed!
After a long fight with it, I finally managed to find and fix the bug that kept the DR-DOS TaskManager from working under Enhanced DR-DOS in TaskSwitcher mode! This probably could have caused problems in Multitasker mode as well. I have uploaded patched binaries of the TaskMgr.exe files from the DR-DOS 7.01, 7.02 and 7.03 distributions. If you have problems with TaskMgr, please try and see if this fixes them.

(25.1.2005): Enhanced DR-DOS 7.01.07 has reached Release Candidate status!
I have uploaded RC1 of Enhanced DR-DOS 7.01.07. BTW, that has been its unofficial name for quite some time, but now it's officicial. :-)
The new version adds two new variants of the INSTALL command to work around problems with INSTALLing older drivers, allows setting the True DOS Version in config.sys, and fixes a few bugs. Also, it adds support for many DR-DOS 7.03 system variables, both in batch files and on the command line.
Since v7.01.07 is now nearing completion, the emphasis is more on bug fixes than on new features. If you find any bugs, please report them in the forum so they will hopefully not make it into the stable release.

(17.1.2005): New version of the DR-DOS SYStem installer available!
I have uploaded the new version 3.5 of the DR-DOS SYS command packages. This version should not only fix the problem with some versions of MS-DOS or MS Windows destroying DR-DOS partitions prepared with older SYS versions, it might also be necessary to install future kernel versions. This tool is still experimental, so use it with care.

(2.1.2005): New Enhanced DR-DOS Forum and Links page!
I have set up a new Enhanced DR-DOS Forum for discussions about DR-DOS. From now on, I will post any announcements of new Enhanced DR-DOS versions there, and I would like to ask you to use the new forum for any questions regarding these versions. I hope that it will also become the preferred forum of the DR-DOS community for general discussion and support and thus serve to replace the old spam-ridden forum.
Also, I have put together a collection of links to other interesting sites on the new Links page.

(26.12.2004): Archived DR-DOS versions now available for download!
I have added a new Download Archive page to the site where you can find older versions of DR-DOS kernels and tools which are no longer listed on the downloads page. These had been downloadable all the time, but until now there was no page linking to them. You can access the archive page from the main download area.

(24.11.2004): A new Enhanced DR-DOS WIP version - Booting from drive D:, more free memory and many bug fixes!
I have uploaded the latest work-in-progress version of DR-DOS 7.01.07. It allows booting from any partition that the master boot record (MBR) can select, including a second or third primary partition on a hard disk. So basically, you do no longer need a boot manager to hide non-active primaries; you just have to make one active and DR-DOS will boot from it. Also, with the history and deblock buffers, another two structures can now be loaded high, saving more conventional mem for applications. FILES and FCBS go now in upper mem by default, too, since Windows no longer complains about this. Last but not least, several bugs have been fixed, most related to DOSDATA and INSTALL/HIINSTALL, but also two of that were already present in the original OpenDOS 7.01.

(29.9.2004): Another WIP version with many bug fixes and enhancements!
The new 7.01.07 WIP version makes many programs that had stopped working in the last one work again, including XMSDSK, and it also contains some other useful enhancements. The HIFILES command is now compatible with Windows 3.x, and the new XBDA command can now move the Extended BIOS Data Area to upper memory if the memory manager has not already done it, thereby increasing the precious conventional mem by another kilobyte. This is probably especially good news for those who are using HIMEM and UMBPCI.

(30.8.2004): New DR-DOS 7.01.07 WIP version with more conventional memory and 128 KB cluster support!
The new development snapshot makes it possible to load programs like XMSDSK in config.sys with the INSTALL/HIINSTALL command, and allows deeply nested IF statements in batch files. It also features experimental support for drives with 128 KB cluster size. Last but not least it provides more conventional memory with the new config.sys commands DDSCS=HIGH,UMB and DOSDATA=UMB which move the drive descriptor tables and DOS data segment to upper or high memory if possible.

(24.7.2004): New DR-DOS 7.01.07 WIP version released!
I have uploaded a new work-in-progress version of DR-DOS 7.01.07. It fixes several bugs, including a hideous one that prevented access to very large files on some partitions, and adds support for new DOSLFN versions and use of internal variables on the command line. I have also added a new experimental VERSION=x.x command that sets the global DOS version in config.sys and (hopefully) fixed the broken disk image in the binaries package. :-)

(4.7.2004): The DR-DOS/OpenDOS Enhancement Project turns two!
Exactly two years ago, on the 4th of July in 2002, the first Enhanced DR-DOS version was finished and this project was born! To celebrate the anniversary, I have changed the layout of the web site. I hope you like the new design. :-)
For nostalgic reasons, I have also included a link to the (now defunct) original web site of the project.
© Copyright 2002-2011 by Udo Kuhnt - Last updated 21.7.2011