Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!uwvax!dogie!dorl@vms.macc.wisc.edu
From: dorl@vms.macc.wisc.edu (Michael Dorl - MACC)
Newsgroups: comp.sys.ibm.pc
Subject: Microsoft Quickc - Pointers to arbitrary memory location
Message-ID: <666@dogie.edu>
Date: 1 Sep 88 01:57:32 GMT
Sender: news@dogie.edu
Organization: University of Wisconsin Academic Computing Center
Lines: 31

I've been trying to reference screen memory directly from Quickc.
The stuff I've tried looks something like this

  char far *p;
  long i;

  p = (char far *)0xb8000;
  for (i=0; i<0x8000; i++) {
   *p = '\000';
   p++;
  }

What i'm trying to do is blank out the screen on a Hercules card after
setting graph mode.  The manual for my machine says the graph memory is
at 0xb8000 and I've done similar things from GWBasic so I know they work.

When I run the above program, the PC hangs up.  I'm not even able to reboot
using ctrl-alt-del.

Questions:

  Is this kind of thing legal?

  If not, is there some other way to go about it?

  What should I set the pointer to so that *p referneces
  the right place?

Michael Dorl (608) 262-0466
dorl@vms.macc.wisc.edu
dorl@wiscmacc.bitnet