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DOS/4G and DOS/4GW FAQ:
Compatibility


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  1. Is DOS/4G(W) compatible with Windows 95?
  2. Is DOS/4G(W) compatible with Windows 98?
  3. Is DOS/4G(W) compatible with Windows ME?
  4. Is DOS/4G(W) compatible with Windows NT?
  5. Is DOS/4G(W) compatible with Windows 2000?
  6. Is DOS/4G(W) compatible with Windows XP?
  7. Can DOS/4GW be used with Borland Turbo C/C++?
  8. I'm experiencing problems trying to run my DOS/4G application with Novell. Any idea what might be happening?
  9. Is DOS/4G compatible with Windows NT, Windows for Workgroups and Windows 95?
  10. Is 32-bit development with Microsoft supported by DOS/4G?
  11. Is DOS/4G compatible with Linux DOS emulation?
  12. Why does my DOS/4G program run perfectly on some machines and hang on others?
  13. Are you aware of any compatibility problems between a DOS/4G program and a Novell/Eagle NE3210 EISA NIC which uses a shared RAM area at address D000h-D7FFFh? Is there some way I can exclude this area from DOS/4G?
  14. My game's video hangs at the same spot after several hours playing. The game manufacturer says that the DOS extender (version 1.97) might be incompatible with my IBM 6x86 166+ CPU. Could this be possible?
  15. Is DOS/4G compatible with the Metaware Compiler?
  16. When we try to run our protected mode application under Windows 95 in the same DOS session as Btrieve, Windows tells us that protected mode cannot be entered. Any idea what might be the problem?
  17. I'm getting the following error: 'DPMI host error: cannot lock stack'. What does this error mean?
  18. Are there problems when repeatedly spawning DOS/4G applications under OS/2 2.1?
  19. Is there a problem with resizing a DOS box window under OS/2 Warp while a DOS/4G application is running?
  20. Why am I having trouble running my DOS/4G application from inside Lotus 1-2-3?

1. Is DOS/4G(W) compatible with Windows 95?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.


2. Is DOS/4G(W) compatible with Windows 98?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.


3. Is DOS/4G(W) compatible with Windows ME?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.


4. Is DOS/4G(W) compatible with Windows NT?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.

Also, if you are trying to run a DOS game built with DOS/4G(W), you may well run into problems.
See Games Under Win/NT/2K/XP> for more details.


5. Is DOS/4G(W) compatible with Windows 2000?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.

Also, if you are trying to run a DOS game built with DOS/4G(W), you may well run into problems.
See Games Under Win/NT/2K/XP> for more details.


6. Is DOS/4G(W) compatible with Windows XP?

Yes.

However, you may run into the PATH too large bug if your PATH environment variable grows too long.

Also, if you are trying to run a DOS game built with DOS/4G(W), you may well run into problems.
See Games Under Win/NT/2K/XP> for more details.


7. Can DOS/4GW be used with Borland Turbo C/C++?

No, for two reasons:

  1. DOS/4GW is limited to the Watcom compiler by license (if not by code).

  2. The Turbo C/C++ compilers are 16-bits, and DOS/4GW is a 32-bit DOS extender.

There are, however several 16-bit DOS extenders that you could use -- Phar Lap, Borland's PowerPack, and, of course our DOS/16M.


8. I'm experiencing problems trying to run my DOS/4G application with Novell. Any idea what might be happening?

Some versions of a program from Novell called TCPIP.EXE, a real mode program, will cause the high words of EAX and EDX to be altered during a hardware interrupt. This bug breaks protected mode software (and other real mode software that uses the 80386 registers). Novell has released a newer version of TCPIP that fixes the problem.


9. Is DOS/4G compatible with Windows NT, Windows for Workgroups and Windows 95?

Yes. However, Windows NT, Windows for Workgroups, and Windows 95 all include a DPMI host, DOSX.EXE, with several serious bugs, some of which are difficult to work around. As a result we could not warranty operation of DOS/4G under any early versions of these operating systems.

We have worked around some of these problems in version 2.0 of DOS/4G and would be interested in hearing whether or not you experience problems running your DOS/4G programs under these environments.

You may wish to contact Microsoft Corporation to inquire about the availability of a new version of DOSX.EXE.


10. Is 32-bit development with Microsoft supported by DOS/4G?

Yes. You need Microsoft's Visual C/C++ version 4.x, together with our DOS/4G version 2.5 or later.


11. Is DOS/4G compatible with Linux DOS emulation?

Although we do not currently QA any of our products against the Linux DOSEMU package, and cannot promise that it will work, we have been following the DOSEMU development. It appears that most programs built with the DOS/4G family extenders do, in fact run under Linux, particularly with versions of DOSEMU of .60 or later.

A number of different games, including DOOM, which are built with DOS/4G, are on the 'success' list of DOSEMU.

It appears that DOSEMU provides a good DPMI host, and that's all DOS/4G needs to work successfully.

There may be other DOS and/or BIOS and/or hardware features that are not supported under DOSEMU, so your application may not work, but the DOS/4G family of products seem to work very well.


12. Why does my DOS/4G program run perfectly on some machines and hang on others?

It can be difficult to determine the cause of a system hang, because the system freezes before you can get any real information about the problem. A system hang often indicates a problem in real mode code, or that DOS has been corrupted somehow.

If the program runs on other machines, compare the configuration of the two machines to find the source of the problem. Pay particular attention to make sure that any drivers required by the program are properly loaded. For example: if DOS/4G attempts to handle mouse interrupts without a mouse driver having been loaded, the results may vary from a General Protection Fault to a system hang depending on the condition of the system at the time the interrupts were generated.


13. Are you aware of any compatibility problems between a DOS/4G program and a Novell/Eagle NE3210 EISA NIC which uses a shared RAM area at address D000h-D7FFFh? Is there some way I can exclude this area from DOS/4G?

We are not aware of any compatibility problems with DOS/4G and any NICs from any manufacturer. This may be a problem with the program and not DOS/4G

If you are using any memory manager (Windows, QEMM, EMM386, etc.) they will control what memory a DOS/4G program uses. All except Windows provide a way to exclude a region of memory.

If you are not using any memory manager, you can use DOS16M=4M@2M, as an example, to say use 4MB only starting at address 2MB.


14. My game's video hangs at the same spot after several hours playing. The game manufacturer says that the DOS extender (version 1.97) might be incompatible with my IBM 6x86 166+ CPU. Could this be possible?

It's possible, of course. However, at present, we are not aware of any problems with any of the IBM, AMD or CYRIX chips. We have several AMD machines that we use for development and testing and we see no problems.

At the same time, 1.97 is several years old, so there may have been some bug that has been fixed in later versions of DOS/4G. You might consider upgrading to a newer version. See our Upgrade page for details.

Also, there have been a number of revs of the CYRIX/IBM chips -- maybe you have one with a problem.

For your information, we get a lot of reports from people suspicious that their AMD/CYRIX/IBM chip is incompatible and is causing the problems they are experiencing. So far, they have all proven to be some other problem and not caused by the chip. It may be that people are more sensitive due to all the Intel advertising, or maybe there really is a problem or two. In any case, we are not aware of DOS/4G or DOS/4GW compatibility problems with AMD, CYRIX or IBM chips.


15. Is DOS/4G compatible with the Metaware Compiler?

DOS/4G is compatible with the last version we know of. We have not had any contact with Metaware for several years, so there may be a version later than the one we know about.


16. When we try to run our protected mode application under Windows 95 in the same DOS session as Btrieve, Windows tells us that protected mode cannot be entered. Any idea what might be the problem?

Yes. You are running into a limitation of Windows. Windows can only handle one dos-extended program at a time. Unfortunately, this limitation has been formalized in the DPMI spec.

You will have the same problem in any DPMI implementation, such as Win 3.1, Win NT, or OS/2.

The only solutions are to not use a dos extender for one of the applications; to not run in a DPMI environment (i.e. just boot Win95 to DOS mode); or to use the same dos extender for both applications (not very practical).


17. I'm getting the following error: 'DPMI host error: cannot lock stack'. What does this error mean?

This error almost always indicates insufficient memory, rather than a real incompatibility. If you see it under an OS/2 DOS box, you probably need to edit your DOS Session setting and make DPMI_MEMORY_LIMIT larger.


18. Are there problems when repeatedly spawning DOS/4G applications under OS/2 2.1?

We know of a bug in OS/2 2.1 that prevents one DOS/4G application from spawning another over and over again. The actual number of repeated spawns that are possible under OS/2 varies from machine to machine, but is generally about 30.

This bug also affects programs running under other DOS extenders, and we have not yet found a workaround, other than linking your two programs together as a single program.


19. Is there a problem with resizing a DOS box window under OS/2 Warp while a DOS/4G application is running?

We know of a bug under Warp which occurs when a Warp DOS box running a DOS/4G application is switched from either full-screen to a window or vice-versa and then switched back to the original mode.

We know of no workaround at present.


20. Why am I having trouble running my DOS/4G application from inside Lotus 1-2-3?

In order to run DOS/4G applications while 'shelled out' from Lotus 1-2-3, you must use the PRIVATXM program included with your WATCOM compiler. Otherwise, 1-2-3 will take all of the memory on your machine and prevent DOS/4G from using it.

Before starting 1-2-3, you must set the DOS16M environment variable to limit Lotus' memory (see your WATCOM manual). After shelling out, you must run PRIVATXM, then clear the DOS16M environment variable before running your application.


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Last modified 2003.04.08. Your questions, comments, and feedback are welcome.