DOS/4G from Tenberry Software is the most widely used 32-bit DOS extender, designed to allow 32-bit DOS programs to eliminate the inherent DOS 640KB memory limit by addressing all the memory on Intel 386 and above machines in MS-DOS, PC-DOS, DR-DOS, the DOS boxes of OS/2, Windows, Windows NT and Windows 95 and DOS clones
Under most Windows systems this doesn't cause any problems, but some systems are unable to free up enough memory for the game to run. 



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Using Virtual Memory in DOS4GW 
 
 To temporarily increase the amount of memory in GS32/GM32 or any other
program that uses the DOS4GW DOS extender, type the following
environment variable at the c:\ prompt:
                                        SET DOS4GVM=virtualsize#64000 

This will increase the amount of memory available to the program to a
maximum of 64 MB. The virtual memory component will be 64MB less the
amount of available RAM in the PC. 

If you want to increase the amount of total memory available to DOS4GW
more permanently then you must place the above environment variable in
the AUTOEXEC.BAT file. 

For example if you have a PC with 16MB ram and want an extra 16MB for
virtual memory for DOS4GW then the set command should read:
                                         SET DOS4GVM=virtualsize#32000. 

Caution should be exercised when using this procedure as it can cause
GS32 to slow down dramatically. It is recommended that virtual memory
be used only as a stopgap measure and if more memory is frequently
needed then additional RAM should be installed. 


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FAQ
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1. Is the version 2.01a update a direct replacement for my version 1.97? 

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Yes. You should be able to just replace your DOS4GW.EXE file with the one in the update, and things will work at least as well as before. 

 For DOS games, application's, etc that have DOS4GW built in
with the .EXE. Examples being DOOM.EXE and DOOM2.EXE and Duke3d.exe.

