From: Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Memory limit in 64 Mb under DOS?
Date: Thu, 23 May 2002 11:03:38 CDT
Organization: Rice University, Houston TX
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> We use DJGPP-compiled program under "pure" DOS on compure equipped more than
> 64 Mb of memory, as usual 128 and ever more till 512 Mb. The program works
> under stress memory-usage conditions, so it needs many memory and all memory
> blocks locked at physical memory. But the program cannot allocate physical
> memory more then 64 Mb. Why? 

It's something in your config.sys or BIOS.

1) Make sure you are using CWSDPMI r5
2) Remove any EMM386 (or similar) products from config.sys, or add 
   NOVCPI NOEMS to them.  EMM386 is frequently limited to less than 64Mb.
3) If you have HIMEM.SYS in the config.sys, make sure it's from Windows 95
   or later.  If you can't get a newer version, remove it completely.
   HIMEM.SYS versions before Windows 95 will limit memory to 64MB.
4) If you have a completely empty config.sys, and only see 64Mb, then 
   you need a newer BIOS.