From: bert.tyler@satalink.com (Bert Tyler)
Newsgroups: comp.os.os2.misc
Subject: Re: XGA-2 Information...
Date: 11 Oct 92 10:34:00 GMT
Reply-To: bert.tyler@satalink.com (Bert Tyler)
Organization: Datamax/Satalink Connection * Ivyland, PA (215) 443-9434

MW>The XGA-2 has something they call "Display Mode Query Set" (DMQS), which
MW>is supposed to automaticly adjust the resolution/update frequency to the
MW>screen connected.  Does this implicate that I have to use one of IBM's
MW>XGA-2 displays for the XGA-2 adapter?

I have just received some documentation on DMQS, and the folks who sent
it to me told me that I am free to talk about it, so here goes...

(The quick answer: no, it doesn't.  You can use other monitors and still
gain the advantages of the XGA-2.)

DMQS is basically a collection of files located in a specific directory.
A program (or, in the case of OS/2, a video driver) that uses DMQS first
determines which XGA adapter is the one to be activated (remember, there
can be up to eight of them on a single system) and reads the monitor ID
off of that adapter.  Then, it builds a filename using that monitor ID
and reads that file to collect the information as to which resolutions
and refresh rates that monitor supports (which resolution to actually
*use* is something for the program/driver to decide).  I believe that IBM is
publishing the format of those "Display Information Files", so third-party
monitor vendors will be able to distribute their own.

There is also an override/customization capability (XGASETUP.PRO) that
lets the user select which XGA adapter is to be used as the main display
and lets him/her give the driver an alternate monitor ID to use instead
of the one that is actually on the adapter.  This means that if your Gateway
CrystalScan monitor has the same capabilities as one of IBMs, you can
just tell the video driver to assume it has that IBM monitor.

(BTW, DMQS is XGA-specific in that part of the Display Information file
consists of programming tables - put this value in that XGA register.)

Finally, an extra feature of the XGA-2 (which has nothing to do with
DMQS) is an extra INT 10H call that returns the ramp-up information
on your XGA adapter that used to require MCA-specific code that wandered
through all of the MCA adapters looking for POS-IDs.  This means that
software can now detect the presence of XGA-2 adapters in a straightforward
fashion regardless of which bus the hardware is using, making ISA
implementations of XGA-2 adapters easy to access.  In fact, there is
now nothing preventing anyone from coming out with a local-bus version
of the XGA-2 <wow!>.

MG>I can't believe *DRIVER'S* are going to be available *before* the card!!!

Well, remember that in this case IBM is acting as a hardware vendor, and
IBM is doing their level best to give the user community a reason to
purchase their hardware - which means both giving the user community drivers
and the development community programming information.

I *like* what IBM is doing with the XGA-2.

                   Bert Tyler   (bert.tyler@satalink.com)
---
 . DeLuxe./386 1.25 #343sa . Did you expect mere proof to sway my opinion?
                              
Newsgroups: comp.os.os2.misc