From: mascot@bnr.ca (Scott Mason)
Subject: Help Need w/ ATI VGA Graphics Card
Summary: How do I get this card to work w/ a digital monitor?
Keywords: CGA, EGA, VGA, ATI, graphics, digital, video, monitor
Organization: Bell-Northern Research, Ottawa, Ontario, Canada
Distribution: na
Date: Tue, 6 Oct 1992 19:43:57 GMT

I could really use some help with this one.

I have a (new to me) AT 286-16 and an ATI VGA Basic 256 graphics card. I
do not have, and cannot afford at this time, a VGA monitor. I selected
this graphics card because it provides both analog and digital outputs
at a variety of frequencies. I do have an A1080 monitor which has both
analog and digital inputs but with sync specs that include only 15.8kHz
(horizontal?) and 60Hz (vertical?). It is rated up to 640x400
(interlaced) and 640x200 (noninterlaced) at 60 Hz.

I tested the system using a CGA card and the A1080 monitor operating in
digital RGB mode and everything worked fine.

I installed the ATI card and connected the monitor to the 9 pin digital
connector. On power-up, the screen remained blank. It was my
understanding from the manual that the card would automatically detect
that a digital monitor was being used. The monitor compatibility chart
includes EGA and RGB (presumably CGA) for the digital connector. There
are no jumpers on the card.

I borrowed my neighbours ATI VGA Wonder 512, but it behaved the same. So
we lugged the monitor and cards over to his 386 + Nec 3D to do some more
testing. In all cased the A1080 was in digital RGB mode and connected to
the 9 pin digital output. The VGA Wonder was used. The  ATI
configuration software was used to configure the card in VGA, EGA and
CGA modes upon boot, but the results were the same:

1. A1080 only connected: blank screen

2. Nec3D only connected: Normal display. Passes all ATI tests

3. Both connected:
                          
Nec3D - Normal display. Passes all ATI tests
       
A1080 - Required adjustment of V-Hold but then provided an
        interlaced display with a normal vertical display but
        with partial duplication of the screen horizontally.

        Passes all tests up to 640x480, except for horizontal
        duplication as noted above. Unable to sync to higher
        resolutions. 256 colour modes are displayed with
        reduced colours. All resolutions are interlaced.

        Ideas: I suspect that the sync rates were adjusted by
        the card for the VGA display and the same rates were
        used on both connectors. The card had "auto detected"
        the presence of a VGA display. For instance, CGA
        shouldn't have been interlaced on the A1080 and must
        have been scan doubled by ATI card. This might also
        explain why about 75% of the screen was duplicated
        horizontally.

Important Question:

How do I get the ATI VGA Basic 256 to display on a digital RGB monitor?
That is, without also connecting up a VGA monitor :-). Without this, I
can't use the card at all :-(.

Bonus Questions:

Is there any way I can use the analog output? The manual shows 32kHz
modes only for the analog output. Maybe it will use slower sync rates if
I prevent it from detecting a VGA monitor (can it tell from the plug
somehow?). Maybe I can force it from software?

There is an extra bank of sockets for DRAM. The manual indicates *not*
to add memory to these except on a VGA 1024, and the board has a waranty
sticker over them. Will the board use the extra DRAM if I add it?

Except for the extra DRAM and the ROMs, my board looks like my
neighbours VGA Wonder, to me at least. Can I just change the ROMs and
have a VGA Wonder? What would I gain?

Thanx for reading this far. Thanks in advance for *any* suggestions. If
you e-mail, I will summarize to the net.

------------------------------------------------------------------------
#include <disclaimer.h>                          Bell-Northern Research
Scott Mason                                      P.O. Box 3511 Station C
Internet: mascot@bnr.ca                          Ottawa, Canada, K1Y 4H7