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Dual Monitor Support?

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  • Dual Monitor Support?


    In reading the docs for pb, I ran across dual monitor support
    ability. I installed a (hard to find) MDA / HGP compatible card
    in combination with a VGA card and lost the ability to boot up.

    Hardware is a 386DX-40 no other conflicts before installation.
    Box is loaded with 4 com ports, bus mouse board, etc.
    All interrupts are spoken for.

    My questions:

    1. Am I missing the obvious?
    (ie: is there an interrupt this board uses as default?)

    2. Is there an available mono display board that co-exists
    peacefully with other video boards?

    3. As a survey, if you are currently running dual monitors,
    what video cards are you currently using?

    Thanks in advance for your help.


  • #2
    Since moving from Windows 95 to Windows 2000, I can no longer use a VGA+MONO dual setup (Win2K does not support direct access to hardware and does not support mono cards anyway), but I used to use a dual setup when using Win95, etc.

    Back then (about a year ago now) I used a stock-standard 8-bit Herc/Mono ISA card, and a PCI VGA card (Trio 64/V+). However, over the duration of several years, I used many different mono & VGA cards without any problems at all. Ever.

    (These days I use a dual-head Matrox G450 card but PB/DOS does not support that specific arrangement - can't win them all).

    However, if you cannot boot up then you must have an IRQ or hardware problem (such as a bad socket connection or a bent pin or a faulty card/slot) - most likely guess would be the MONO card is faulty.

    Try removing the VGA card (and ALL other cards you have installed) and boot from a DOS floopy boot disk.

    If that works, start adding cards until you find the clash. If it is a clash, you may have to manually assign IRQ's in the BIOS, and set the BIOS to "Non-PNP O/S" mode (if the 386 supports that one).

    Out of curiousity, what sort of MB and VGA card are you using? (All are ISA I guess?).

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    • #3

      Thanks for the rapid reply. I neglected to mention, the system is
      a dos only development box, no pnp. The motherboard is an isa only
      model from Peak technologies. circa 1990. BIOS is by AMI, VGA by Trident.

      I'm wondering, is there a standard interrupt that the mono display
      cards used? My doc on the board gives no info on this.




      • #4

        I am making the assumption, that the computer is indicating power?
        However, am I to assume that there is no video appearing on either
        display with both the monochrome and color cards in the computer?

        When I had a 386 computer, there was a dip switch that I had to set
        for the default video diplay that would be used for the computers
        boot up. Normally, a monochrome video card will have presidence
        over a color card. If this is the case, this is where you conflict

        You will probably need to change that dip switch. On the 386 that
        I had it was in the back of the computer. However, on some machines
        it was located on the motherboard.

        Also, you will probably have to make a change in the bios settings.




        • #5
          Most monochrome cards include a parallel port that uses an IRQ, but the
          video side of the card does not use an interrupt. I would suggest
          checking your CMOS setup screen, setting the video option to "MONO"
          then shut down, remove the VGA card, and see if you can boot to the
          monochrome screen. If you can boot with either card, but not when
          they are together, it's a conflict. If the board won't boot with just the
          mono card, then it's the card or the slot you have it plugged into
          (if you get the start up BEEP, but no video on your monochrome monitor,
          then it could be your monitor).

          I've been using a combo VGA/MONO setup like this for about 10 years now,
          including Trident VGA cards and AMI bios. Only recently have I had
          problems; the AMI BIOS in my new PC doesn't support monochrome video!
          But a motherboard as old as yours should have no problems with it.



          • #6

            Thanks for your input. I will try your suggestions and give feedback.