From: rri!potter AT vtserf DOT cc DOT vt DOT edu (Mark Allen Potter)
Subject: Extended Memory Display
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Date: Thu, 22 Jul 1993 12:03:01 -0400 (EDT)

I have a problem, that I was wondering if anyone else may have encounted or may
have possible solutions.  I have been looking into DJGPP as a possible means to
port some unix code (typically using GCC) to MS-DOS.  My main hurtle is the
graphics display.  The code is written for a Cornerstone Technology's display
(the 150I to be persice).  Most of the Cornerstone displays map there display
memory up into extended memory at the 12 Megabyte mark (C00000).  The simple
question is how do I get to this while in DJGPP.  Under unix I had a device
driver that one could make a call to that would map the cornerstone memory in
and return a pointer that the program could use as the base address of the
screen memory.  If an equivalent call exists, or could be written, this would
be the ideal solution.  I've played around a bit with trying to make DPMI calls
but not luck so far.  The other solution is ofcorse writing a video device
driver for the cornerstone.  Has anyone already attempted this?  I would doubt
it.  But has anyone written a video device driver for a similar display system?
As an asside has anyone written anything to access a Weitek coprocessor?  I
understand that it typically is mapped up at the 3 Gigabyte mark.  Any help
would be appreciated.  Thanks in advance.
						Potter
						rri!potter AT vtserf DOT cc DOT vt DOT edu