OpenDOS FAQ list (as of 14th March 1997)


Welcome to the OpenDOS FAQ. This was researched and produced in a bit of a hurry in order to get something out of the door, so bug reports would be most welcome!

Warning! This document makes an extensive use of the HTML bookmarks or named anchors. A bug in Netscape 3.xx makes them appear as though they all were at the end of the page!

Legal Stuff

This FAQ list is copyright © Alaric B. Williams, 1997. You may distribute it freely in any form as long as the meaning is unchanged. If any information contained herein is wrong, I will be delighted to fix it, but I can't be responsible if you damage anything because of this. Sorry!

Also see, and the Archives of the mailing list and DJ's earlier FAQ are The two main Caldera pages are and

About OpenDOS

Q: What is OpenDOS?

A: OpenDOS is a clone of the popular MS-DOS operating system. Like MS-DOS, it is a 16 bit OS, and includes the full range of standard utilities (sort, chkdsk, etc), most of which are improvements over their counterparts supplied with MS-DOS. The supplied game, NetWars, is far better than MS-DOS"worms"!

Q: Where can I get it?

A: The OpenDOS full-featured evaluation release can be obtained from The sources are not yet available, but they will be. The full evaluation version, including a copy of Personal Netware, weighs in at 7Mb; the reduced non-networking version is around 2Mb. They are available as floppy disk images to install from floppy or as sets of files to install from the hard disk.

Q: Who owns OpenDOS?

A: OpenDOS is the sole property of Caldera, but they are releasing a free "evaluation" copy which can be used for non-commercial use and evaluation. They plan to release the sources to the public within the next month or so, too.

Q: What's the catch?

A: So far, no "catch" has been found. OpenDOS is stable - some of us have been running it for more than a month. There are known to be some bugs (see, but nothing really serious has turned up.

Q: I've heard something about Gene Buckle. What/Who's that?

A: Gene's a real live human being. He is more or less running the effort to get the sources into a releasable format, and is the main liason between Caldera and the DJGPP crew.

Q: What's the EDC?

A: European Development Center. That's where all the OpenDOS work is being done. It's in England.

Q: And GEM is...?

A: GEM is a graphical user interface. It stands for Graphical Environment Manager. It isn't quite as flashy as the Windows 95 shell, but it certainly gets the job done.

Q: What's DJGPP?

A: DJGPP is a freely available 32-bit development system based on the GNU tools. See

Q: What's WINE?

A: A Windows Emulator for X running on Intel platforms. Written by the Internet Community.

Q: Isn't that what WABI is?

A: Almost. WABI is a Windows Emulator for X that runs on any platform, written by Sun Microsystems.

Q: What's an IFS?

A: In this context, it's an Installable Files System - a file system module that can be installed after the system boots. For example, NWCDEX is an IFS, as would be any NFS software. In other contexts, it's an Iterated Function System.

Q: What's "loading high"?

A: A trick used to free up more DOS memory by moving drivers and parts of the system into other memory areas.

Q: What's FAT32?

A: FAT12, FAT16, an FAT32 are all cluster-based disk layouts. FAT12 is usually used on floppies and FAT16 on hard drives (more clusters). FAT32 is new, and supports more (and thus smaller) clusters, making disk storage more efficient.

Q: What's XFree86?

A: An X11 server that's available in source format. Runs on many platforms.

Q: Is there an IRC channel for discussing OpenDOS?

A: I hoped you'd ask that. *opendos on EFNet.

Q: I'm having trouble finding it

A: You probably have an old page. You need to go to

Q: I've found it but it never downloads completely

A: This is due to the way that Caldera's web server is set up - it times out. If you have access to a high-speed network at your ISP or work, download it there and then transfer it over your modem. Until Caldera modifies their license, no mirrors can be set up. Send email to if you really need it to find out what the current best way to get it.

Q: I found the right page and downloaded it... but IBMBIO.COM and IBMDOS.COM are missing!!!

A: Please re-download the binaries. They aren't really missing. Honest.

Q: Is there any documentation available?

A: Run the program dosbook that comes with OpenDOS.

Q: What's FaX?

A: FaX - yes, the name's a ripoff of TeX - is the FAQ formatter created especially for this FAQ, but is showing signs of usefulness for FAQs in general, so I'll be making a nice public release sometime. Anyone who's interested should mail

Q: I can't find what I need in dosbook or this FAQ. Help!!!!

A: is still around; it may also have information still useful to OpenDOS. Then again, you could just ask away on the mailing list or IRC channel.

Q: Did you say "mailing list"?

A: Yes, handles all subscriptions for the three OpenDOS mailing lists - and - all at Some discussion happens on the DJGPP mailing lists as well. The mailing list is archived at DJ's page. See the introduction. Also, take a look at the OpenDOS Mailing Lists page at

Q: Is there a newsgroup?

A: Not yet. A few people have shown interest, but there probably will be eventually.

Compatability - does OpenDOS support:

Q: 4DOS?

A: Yes.

Q: Boot managers?

A: Yes. The OS files are IBMBIO.COM and IBMDOS.COM if you need to know. Current advice (as always) is to back up your existing stuff before trying anything; this also applies to OpenDOS. One that has been mentioned is GRUB at Also note that OpenDOS currently needs to be installed in the primary partition of the first hard disk to work. See using GRUB for more information.

Q: Booting from the second hard drive?

A: Nope. However, once the sources are released, check out the IBMBIO.COM sources. A simple fix should be possible.


A: Yes, but you can't use EMM386's DPMI - it's buggy. Disable it and use cwsdpmi instead.


A: Yes, but it's buggy. Use cwsdpmi instead for DJGPP programming.

Q: DPMI 1.0?

A: Nope. Very few things do. Yet...


A: Yes. (it's Dos Protected Mode Services, used by TSRs to reduce their conventional memory usage)

Q: FAT32 partitions?

A: Nope. File system support is currently a hot topic on the mailing list, though, so we will see...

Q: Loading high?

A: Yes. More than MS-DOS, too; there are reports of a 629K TPA. How? It uses the HMA as well as UMBs for loadhi. For more information about loading high, follow this link.


A: Yes, but it comes with NWCDEX which can load 100% into high memory. See NWCDEX for more information on NWCDEX.

Q: Multi-config? (in config.sys)

A: In banging around the IBMBIO code, Gene discovered that it supports SWITCH, GOTO, GOSUB, and labels. Check DOSBOOK.EXE to find more info on it. IBMBIO will also process DCONFIG.SYS _before_ config.sys if it is present. OpenDOS sets the OS environment variable to OPENDOS and VER to 7 while processing autoexec.bat; you can use that to help keep the two straight.

Q: Multi-processor machines?

A: Nope. OpenDOS can do multitasking and multithreading, but there is no multi-processor support. Yet.


A: Yes.

Q: Netware with 802.3 packets?

A: Apparently not, as checksums are not supported. However, see

Q: Norton Utilities 8?

A: Yes, but not under the multitasker. You might need patches from semantec's web site.


A: Yes, but the driver isn't ready.

Q: Windows 3.1?

A: Yes. You need to install himem.sys before you can install windows, but you can remove himem.sys afterwards.

Q: Windows 95?

A: Yes, but the long file names confuse chkdsk, so don't try it. You must install OpenDOS before Win95 in order to boot to "a previous version of dos"

Q: Windows NT?

A: Yes. It is possible to make NT load OpenDOS from the boot manager. Using a disk editor, save a copy of your NT boot sector. Install OD as usual on the drive, then using the disk editor, write the boot sector to a file in the root directory called "bootsect.dos". Write the NT boot sector back into place, edit "boot.ini" to change the title from "MS-DOS" to "Caldera OpenDOS", and away you go. Not for the faint hearted.

Using OpenDOS

Q: When I set the cache size for nwcache, it stops at 7Mb!

A: Edit autoexec.bat manually; the 7Mb limit is in the setup tool, not nwcache.

Q: My games crash when EMM386 is installed!

A: EMM386 is known to be buggy. Hopefully, the source release will let us fix it! The HIMEM/EMM386 from MS-DOS will work. If DOOM2 locks up at IStartupTimer(), it's EMM386. Also, try "EMM386 PIC=Y" (or PIC=ON) at the dos prompt (it doesn't work in config.sys), although that didn't fix everyone's problems. Use "EMM386 /?" to see a list of options.

Q: How do I get GRUB working?

A: See or from DJ's mail archives.

Q: I can't uninstall!

A: Make sure that delete protection is disabled before running uninstall, or you'll have lost clusters (run chkdsk to fix it). Also, you must DELPURGE before running chkdsk or scandisk.

Q: With MSCDEX, I was using a switch /D:MSCDxxxx. Do I need to change that to NWCDxxxx?

A: No. The /D: switch is used to link MSCDEX or NWCDEX to the CD-ROM driver, so you can have more than 1 CD-ROM drive. As long as the name is the same as that given to the CD-ROM driver in CONFIG.SYS, everything will be fine.

Legal Issues

Q: How free is it?

A: Caldera has promised to make the sources for OpenDOS available to anyone, and OpenDOS may be used (modified or otherwise) without a license for any non-commercial use (i.e. your home computer). It is NOT freeware, public domain, shareware, or GPL. It is copyrighted by Caldera.

Q: What about the License?

A: Caldera is still working on the final license; anything you read may not apply when the final release is made. They claim that for non-commercial use, you can do whatever you please with it, including modify it. For commercial use, they require a license for legal and libel reasons.

Q: What about the lawsuit with Microsoft?

A: Caldera is suing Microsoft for antitrust, unfair practices, and monopolizing. See

Technical and Source-Code Related Issues

Q: What parts will be available in source format? When?

A: The first parts to be released will be the basic OS, which is the boot loader, IBMBIO.COM, IBMDOS.COM, and COMMAND.COM. Caldera claims that all of the DOS utilities will be made available "as soon as we can get them out of source control" :-) Apparently, the sources are intact, but in a source control system that is difficult to deal with. Estimates on source size are around 2900 files (53 Mb), plus another 2700 (78 Mb) for tools (until they can reduce the number of tools needed).

Q: What about Caldera's other pre-dos products?

A: They are not included in this process; it is unknown if their sources can be found, much less freed. If they can be found, there's a good chance they'll be freed also, but no promises.

Q: What's the relationship between DJGPP and OpenDOS?

A: The DJGPP and OpenDOS groups expect to work closely together to "clean up" the OpenDOS sources and integrate the GEM, TCP/IP, and EMM386 APIs into DJGPP's development kits. While no official arrangements have been made, suffice to say that there will be many DJGPP developers with OpenDOS sources! As for porting OpenDOS to DJGPP, remember that DJGPP doesn't support 16-bit machines, which will be a popular platform for OpenDOS.

Q: What's the holdup on getting sources?

A: Caldera inherited a weird source control system that all the sources are stored in, and they use an even more weird build system. Getting them "releasable" is a two step process. First is to get all new makefiles written. At last estimate, there are about 120+ of them. After the makefile for each package is complete, it will be sent back to Caldera for approval. Gene assumes that they will release each package as the extraction/new makefile is done for each, but he's not sure. He really can't predict a timeline right now.

Q: Will the CP/M sources be available?

A: Gene claims that Caldera will release the CP/M sources when they're found. The problem is that those (and other) sources were sent to an archiving company in Monterey. They're still sorting through the DRI assets, etc. trying to catalog and locate things.

Q: What will I need to build OpenDOS?

A: Each part is built with a different development package. To build everything (once the sources are found and cleaned up), you'll need nine different development packages to build it all. The hope is that this list can be reduced to two or three. The current list is approximately "Turbo Cv2,v3, BCC v2,v3.1, Watcom C v7, 3 versions of MASM, 2 version of TASM... and a partridge in a pear tree.....", according to Gene! EMM386 is all in assembler.

Q: What are the future development kits?

A: One, of course, will be DJGPP. The other will probably be some free 16-bit DOS compiler, or maybe someone will make gcc produce 16-bit code finally.

Q: Will OpenDOS be ported to DJGPP?

A: Well, the core OS can't be (IBMBIO.COM, IBMDOS.COM, and COMMAND.COM) but there's no reason why the utilities couldn't all be 32-bit DJGPP programs. However, that means that a 386 is required, which otherwise wouldn't be true.

Q: Where do I get specs for EMM386's extra stuff?

A: contains contains all the API calls for the task interface to EMM386. Gene hopes that better docs will show up eventually. Caldera has found the MRS for the EMM386 API docs. See for more details.

Q: DJGPP doesn't work!

A: Make sure you aren't using EMM386's DPMI. Use cwsdpmi instead.

Other Questions

Q: Is there an OpenDOS logo?

A: Not officially, but the unofficial page has, of course, an unofficial logo.

Some suggested OpenDOS slogans from the mailing list

286s! They are $9.99/lb.
Close Windows, OpenDOS
Close those Windows, OpenDOS!
Close your Windows - OpenDOS!
OpenDOS - Where do you want to go NOW?
OpenDOS - Where else would you want to go?
OpenDOS - Why go through windows when you could have a !&$^&* DOOR?
OpenDOS, Windows DOSnt

OpenDOS: Now you will get actually there.
Why open a Window when you can OpenDOS?
Windows can break, invest in a solid 'OpenDOS'


Most of the questions here are based on answers in DJ Delorie's earlier version. Thankyou, DJ! Also, thanks to Mark Habersack for getting me started, and slaving over producing the HTML macros I ditched in favour of my own system (I still feel guilty!), and to Rob Hommel, who made nearly all the pictures on the HTML version of this page, among other things!