Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: USING TWO GRAPHICS CARDS IN A COMPAQ 386/25
Keywords: VGA CGA COMPAQ 386 GRAPHICS
Message-ID: <1845@bucket.UUCP>
Date: 24 Dec 89 07:52:01 GMT
References: <5209@arctic.nprdc.arpa>
Organization: Rick's Home-Grown UNIX; Portland, OR.
Lines: 38

trejo@nprdc.arpa (Leonard J. Trejo) writes:


>We're trying to use two graphics cards in a Compaq 386/25 computer
>running MS-DOS 3.1.  One card is the Compaq Video Graphics Controller
>(VGA-compatible) and the other is the Compaq Video Display Controller
>(CGA-compatible).  We'd like to use, simultaneously, the VGA for 
>graphics-only display purposes only and the CGA as a text-only 
>console which echoes keyboard input.  Problem is that despite our 
>best efforts, graphics always go to the CGA card.  I'm told that 
>this is because VGA and CGA screen memory overlap, plus that 
>whenever another graphics card is installed with the Compaq VGA, 
>graphics are forced to go to the other card and the VGA runs in 
>monochrome mode.


Sorry, but you *can't* do it with the setup you have. Everything from the
BIOS level up is against you. The PC was designed to allow two displays, 
one color, one monochrome. Even the video modes in the BIOS are set up
like this. Mode 7 is the *only* mode that you can't put the VGA in.

So what you need to do is take out the Compaq CGA-clone and dig up an old 
IBM Monochrome Display Adapter. Then it'll work. You *may* be able to get
by with a Hercules clone card, but they do use some memory that overlaps 
the CGA area.

I'm typing this from an XT clone with both a Hercules card and a VGA card.
It works fine. I can't put the VGA into any of the monochrome modes, but
I don't need to.

An IBM MDA ought to be locatable for $25 or so, and the monitor (assuming
that you don't already have one will run about $75)

-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short