From:	"Bob Koon" <loganproductions AT SPAMFREE DOT internetmci DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Problem with Direct Video Memory Access
Lines:	28
Message-ID:	<vF6Q1.278$Fh.320270@news.cwix.com>
Date:	Tue, 29 Sep 1998 10:05:34 -0500
NNTP-Posting-Host:	166.55.208.244
NNTP-Posting-Date:	Tue, 29 Sep 1998 15:03:55 GMT
Organization:	CWIX
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hi folks...

I have a problem with trying to draw (or even transfer) stuff directly to
video memory.  I'm using the far pointer method to access the screen and it
works when I call it _before_  any memory allocations, but as soon as I put
the code where I want it, I get nothing. (I get exactly the same results
with all three methods of direct video access.) What am I (not) doing to
cause this?

Below is the code fragment I'm using:

  /* draw some dots to the screen */
  _farsetsel(_dos_ds);

  _farnspokeb(0xa0000, 1);
  _farnspokeb(0xa0002, 2);
  _farnspokeb(0xa0004, 3);
  _farnspokeb(0xa0006, 4);
  _farnspokeb(0xa0008, 5);


Thanks in advance for the help.

-- Bob

- Raw text -