Xref: news2.mv.net comp.os.msdos.djgpp:4697
From: Francisco Gochez <arcanix AT pop DOT erols DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Simplest way to access VGA memory
Date: 6 Jun 1996 19:14:24 GMT
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Here is the safest, easiest way that I have found to access the video 
memory:

#include <dpmi.h>
#include <malloc.h>

unsigned char *screenptr;

int main(void) 
 {
   screenptr = malloc(65536);
   __djgpp_map_physical_memory(screenptr, 65536, 0xA0000);    
.............

This sets up a pointer to the video memory area. (ex. screenptr[1] = 2 ; 
)
Of course, this will only work under DPMI 1.0 ( or CWSDPMI ). I am using 
it for a game I am working on, and it has always worked so far.