trejo@nprdc.arpa (Leonard J. Trejo) (12/23/89)
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. Compaq service reps. have not been helpful at all. Anyone out there have some words of wisdom for us? We'd appreciate them greatly. Sincerely, L. J. T. ============================================================================ ARPANET : trejo@nprdc.navy.mil UUCP: ucsd!nprdc!trejo U.S. Mail: Leonard J. Trejo, Ph. D. Phone: (619) 553-7711 Neuroscience Laboratory (AV) 553-7711 NPRDC, Code 141 San Diego, CA 92152-6800
brown@vidiot.UUCP (Vidiot) (12/24/89)
In article <5209@arctic.nprdc.arpa> 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.
You have been told correctly. You can only run a monochrome and a color card
in the same system. Both the VGA and CGA use the same memory mapped space and
control registers (CGA is a sub-set of VGA cards).
You are SOL.
--
harvard\ att!nicmad\
Vidiot ucbvax!uwvax..........!astroatc!vidiot!brown
rutgers/ decvax!nicmad/
ARPA/INTERNET: <@spool.cs.wisc.edu,@astroatc:brown@vidiot>leonard@bucket.UUCP (Leonard Erickson) (12/24/89)
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
bcw@rti.UUCP (Bruce Wright) (12/28/89)
In article <5209@arctic.nprdc.arpa>, 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. You can install an MDA or a Hercules card, as some have noted, at least with a few VGA boards (this is more commonly done with EGA, I'm not sure it's "officially" supported for VGA). There are also a few companies that sell video cards that can be configured to allow multiple EGA or multiple VGA cards in the same machine at the same time (I've seen it done, but don't remember the company names offhand). The cards work by a variation on a bank- switching scheme: an extra, nonstandard register exists which tells the graphics cards which one is to be the currently active card. This allows the vast majority of standard PC software to be run on the cards without modifications. You probably can't do anything like that with the Compaq cards unless you can figure out a way to retrofit such a scheme onto the cards, and this is unlikely and would require significant hardware expertise. Be warned that the cards I've heard about that allow this sort of thing are *expensive* - I seem to remember that they retailed for around $1000. Lots cheaper than a second PC though, if you are running them in a fast 386 with lots of disk space. The computer I saw them on was a Compaq 386, BTW ... Bruce C. Wright
akcs.amparsonjr@vpnet.UUCP (Anthony M. Parson, Jr.) (01/06/90)
Speaking of running mono with color, I also have a question: In running mono + ega/vga, will hercules-type board work? I had assumed (haven't tried this yet, but I want to use 2 monitors with Codeview) that only a MDA (Ibm mono without ability to display graphics) was the required mono card. Can the graphics part of Hercules-graphics cards be turned off???
leonard@bucket.UUCP (Leonard Erickson) (01/20/90)
akcs.amparsonjr@vpnet.UUCP (Anthony M. Parson, Jr.) writes: >Speaking of running mono with color, I also have a question: >In running mono + ega/vga, will hercules-type board work? I had assumed >(haven't tried this yet, but I want to use 2 monitors with Codeview) >that only a MDA (Ibm mono without ability to display graphics) was the >required mono card. Can the graphics part of Hercules-graphics cards be >turned off??? I am happily running a Hercules card with a VGA card. There are 3 possible configurations for real Hercules cards an most clones. 1. DIAG (looks like an MDA to the system) 2. HALF (only use memory from B000-B7FF) 3. FULL (use all memory on card, B000-BFFF) Hercules cards come with a utility (HGC.COM) for setting these modes. Most clone cards do too. Half mode is compatible with EGA/VGA as when they detect a mono board, they don't use the B000-B7FF area anyway. So this means you can use the first of the two graphics screens available on the Hercules card. If you have a VGA that will let you disable it through software, you can use both screens. My VGA board does (probably because it was made by Hercules :-). So I have a pair of batch files: MONO.BAT mode mono vgaset off hgc full CO80.BAT hgc half vgaset on mode co80 -- 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