Dual VGA PC-601170-R2

Dual VGA PC-601170-R2

Dual VGA PC-601170-R2

This card is made by Colorgraphic Communications in 1988, and has two VGA ports, and works well with a 80486 computer.

I tried to used that with IBM 5150 and other XT clones, but I failed. According to my guess, the reason for the failure is the wrong jumper setting of the card. So I've tried a few cases, but I've failed again. There is no information about this card on the Internet.

What is known about this card?

  • 2
    Guess: At least some of the switches determine the base addresses (both I/O and video RAM) for each of the two VGAs. There are various ways to do that, but looking at the traces may help. For example, if half the switches go to one chip and the other half to the corresponding other chip on the same pins, then you can select addresses for each VGA instance independently.
    – dirkt
    Commented Nov 23, 2022 at 10:51

1 Answer 1


See a blurb about it in InfoWorld 5 Mar 1990 on page 88. The mention of PC/AT and compatibles likely means it won't work in PC/XT and compatibles.

From a Google Books search result for VGA2 board: https://books.google.ca/books?id=KzsEAAAAMBAJ&pg=PA88&dq=VGA2+board&hl=en

enter image description here

The company website colorgrahic.net is no longer around but there are some captures in the Wayback machine. No luck finding manuals for this specific product there. http://web.archive.org/web/20001018131648/http://www.colorgraphic.net/first/navig.html

  • 2
    Very interesting blurb.. I tried the number of all possible cases with SW2. When it is set to 0111, I can see the VGA bios screen before POST starts. However, the screen will be blacked out again after that. Looking at this, I'm sure the correct jumper setting will allow me to use this card on the 5150.
    – Sung
    Commented Nov 22, 2022 at 12:41
  • 3
    One of those jumper blocks is possibly controlling the base address of the card. Given upto 4 cards are supported, I'd maybe expect two jumpers at least are used to give you the 2^2=4 possible base addresses.
    – bodgit
    Commented Nov 22, 2022 at 13:30
  • 7
    I don't think the ad's mention of PC/AT means it won't work in an XT. It's just answering the common question of the time, whether this standard-slot card will work in an AT's extended-slot. (and the answer is "Yes, it will")
    – Sotto Voce
    Commented Nov 22, 2022 at 14:39
  • 3
    ATs had been out for 6 years by then - if someone wanted two VGA displays they had one of them, not an XT much less a PC.
    – Jon Custer
    Commented Nov 23, 2022 at 0:51
  • 1
    @JonCuster While you're not wrong that it would be unlikely to add an expensive card like this to an XT class machine it's not inconceivable. Clone manufacturers were still very much selling brand new turbo-XT class machines to the lower end of the market well into the early 90s and consumers don't always make perfectly rational decisions.
    – mnem
    Commented Nov 23, 2022 at 12:56

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