From:	brett AT allegro DOT cs DOT tufts DOT edu (Brett J. Wiesner)
Newsgroups:	comp.os.msdos.djgpp
Subject:	i can't memcpy to screen memory
Date:	1 May 1997 00:14:31 GMT
Organization:	Tufts University
Message-ID:	<5k8n97$hu0$1@d2.tufts.edu>
NNTP-Posting-Host:	allegro.eecs.tufts.edu
Lines:	15
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

i'm trying to write a vga lib, but i've reached a big blockade.
i can't seem to address the screen memory.
i use a pointer to the memory address of the screen like so:
unsigned char *SCREEN = (unsigned char*) 0xa0000;
is this correct? i belive it is.
then i set up a "page" to write pixels to like this:
paper = (unsigned char*) malloc(320 * 200);
and then i try to memcpy paper to the screen like this:
memcpy(SCREEN, paper, 320 * 200);
the memcpy line crashes and throws me back into windows with an illegal 
operation at 00A7:1CB8
it might be that screen memory isn't located at 0xa0000. i read somewhere
that it was though.
please help, if you can.

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