Xref:	news2.mv.net comp.os.msdos.djgpp:7716
From:	root AT ursa DOT smsu DOT edu (Tony O'Bryan)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: How to plot points (in 320x200x256)
Date:	21 Aug 1996 03:31:58 GMT
Organization:	Axiom Enterprises
Lines:	40
Message-ID:	<4vdvve$mbe@ursa.smsu.edu>
References:	<4v9dtt$397g AT news-s01 DOT ny DOT us DOT ibm DOT net>
NNTP-Posting-Host:	huwawa.smsu.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Dean (deanph AT ibm DOT net) wrote:
> I've finally got DJGPP up and running.  I can get in mode 13h
> and all that, I can write text, but what I can't do is write
> directly to memory to plot points, what with all the protected
> mode and all.  Is there some other way to plot points on the
> screen, is there something I could read (not FAQ200b.zip, it was
> no help:)

I just got DJGPP installed and discovered, through this newsgroup, *one* 
way to access video memory directly:

#include <sys\nearptr.h>
#include <dos.h>
#include <string.h>

main()
  {
  unsigned char *Screen;
  union REGS Regs;
  unsigned long Count;

  if (__djgpp_nearptr_enable() == 0)
    {
    puts("Can't disable protection");
    exit(1);
    }
  Regs.x.ax = 0x0013;
  int86(0x10,&Regs,&Regs);
  Screen = (unsigned char *)(__djgpp_conventional_base + 0xa0000);
  for (Count = 0;Count < 5000;Count++)
    memset(Screen,Count & 255,64000);
  Regs.x.ax = 0x0003;
  int86(0x10,&Regs,&Regs);
  }



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