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DOS/4G and DOS/4GW FAQ:
Known Bugs and Problems


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  1. What is the 'PATH too large' bug?
  2. Is there any work-around for the 'PATH too large' bug?
  3. Is there a way to run games that use DOS/4G(W) under Windows/NT/2K/XP?

1. What is the 'PATH too large' bug?

Under Win32 operating systems (Win/95, Win/98, Win/ME, Win/NT, Win/2000 and Win/XP) the PATH environment variable can become longer than DOS/4G(W) can handle.

Symptoms include various kinds of crashing, hangs, reboots and a wide variety of other (sometimes spectacular) symptoms. The key to identifying this problem is that it always occurs when the DOS/4G(W) application is starting.

Currently, DOS/4G(W) can only deal with PATH's which are 250 characters or shorter.

PATH lengths can become this long as more and more complex software is installed on a computer. This bug particularly shows up on Win/2000 or Win/XP, but it can happen on any Win32 system, even Win/95.


2. Is there any work-around for the 'PATH too large' bug?

Yes. The simplest is to create a batch file to save the old value of PATH, set a minimal PATH, and then restore PATH after your program is finished. For example:

  @ECHO OFF
  rem so that none of this extra stuff is displayed when run
  rem
  rem save the existing PATH
  SET SAVE_PATH=%PATH%
  rem
  rem set the PATH to whatever is needed by your program
  PATH whatever_is_needed_for_your_program
  rem
  rem run program, passing on any arguments to this batch file
  your_application %1 %2 %3 %4 %5 %6 %7 %8 %9
  rem
  rem restore PATH
  SET PATH=%SAVE_PATH%
  rem
  rem delete temp variable used to save PATH
  SET SAVE_PATH=


3. Is there a way to run games that use DOS/4G(W) under Windows/NT/2K/XP?

That will depend entirely on the game.

There is nothing in DOS/4G(W)'s interaction with Win/NT/2K/XP that would prevent DOS/4G(W) based games from running.

However, unlike Win/3.1/95/98/ME, Win/NT/2K/XP does not allow direct access to the video hardware -- not even in full screen mode.

Simlarly, Win/NT/2K/XP does not allow direct access to sound cards or other hardware.

As a result, we suspect most DOS games built with DOS/4G(W) won't run under Win/NT/2K/XP.


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Last modified 2003.03.17. Your questions, comments, and feedback are welcome.