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Multiple video cards on 486 motherboard ?

flavio75

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Dec 26, 2007
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I have one of those later 486 motherboards with all three types of slots on it (ISA, VLB, PCI). I was wondering... is it possible to put two VGA cards at the same time in this motherboard, one in a PCI slot and one in a VLB slot ? As far as I know, it's possible to have one VGA card and one or more 3D accelerators (like the Voodoo card from 3Dfx), but two VGAs ? And would DOS recognize both of them or just one at a time ? Thanks :)
 

Anonymous Coward

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I have one of those later 486 motherboards with all three types of slots on it (ISA, VLB, PCI). I was wondering... is it possible to put two VGA cards at the same time in this motherboard, one in a PCI slot and one in a VLB slot ? As far as I know, it's possible to have one VGA card and one or more 3D accelerators (like the Voodoo card from 3Dfx), but two VGAs ? And would DOS recognize both of them or just one at a time ? Thanks :)

No, it is not possible to have two VGAs on the same system. However, it is possible to have a VGA card and a separate coprocessor installed in the same system. One popular coprocessor from the early 90s was the TIGA (Texas Instruments). Those can coexist just fine. The 8514/a was another fairly popular one. ATi made a card called the "Ultra" that did 8514/a. They also made another board called the "Graphics Ultra" which combined a VGA wonder with the 8514/a. Infact, I believe that most of the coprocessors that come with some VGA boards are based on the 8514/a.

Some of the VGA cards with coprocessors allow you to switch off the VGA section of the card and just use the card as a coprocessor. For example, I have an S3 928 based ElSA card that can turn off the VGA. I ran it together with a VLB Tseng ET4000W32P based card. Normally the system uses the Tseng card, but when I load the S3 928 driver, the output will switch over to the EISA board. Unloading the driver goes back to the VLB. While the setup certainly works, the drivers for Windows 3.11 were buggy, and I get a little screen artifacting.

But, before you get too excited I should tell you it is VERY difficult to find combinations of graphics cards that can work together like this.

PCI cards may be a different story though. I am pretty sure there are certain cards that are designed to be installed in pairs that support dual monitors. However, this support has to be implemented in both hardware AND software to work. You can forget about doing this in DOS or Windows 3.11. Windows 95 can do it though.
 
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flavio75

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Cool info!! Thanks :)

Too bad it's not possible, LOL... I also have a VLB-only motherboard. I guess I'll have to choose if I want to have a VLB or PCI based 486 for DOS gaming...
 

kb2syd

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I had CGA and Mono on the same machine. Autocad loved it, although the resolution was not that great. I THINK it worked with EGA and Mono too. I don't know if VGA and mono would work. Never tried it.
 

Anonymous Coward

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It depends on what kind of DOS gaming you want to do. For CGA and Booter games, a 4.77MHz 8-bit ISA system would be ideal. For EGA/VGA you'd definetly be okay with a pure 16-bit ISA system. For early DOS extender games, a VLB setup would be ideal. But, if you want to play the later games that use DOS extenders a PCI system or very high end VLB would be the way to go.
 

Unknown_K

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I prefer a Tandy 1000 for the early disk based CGA games, either a 286/16 ISA or 486/66 VLB for mid era DOS games and a Pentium 233MMX for the last gasp of DOS games.

The 286 was best for early VGA games, 486 for later games, and Pentium for DOOM/Quake type games (also great for the vest 1st 3dfx titles).
 

JDT

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As it has PCI- maybe a 3dfx Voodoo card might work as second (gaming) card?

I recently found a box of voodoo and voodoo 2 cards in my parts cache.

My 486 box uses just a 2MB Mach32 VLB card.
My Duel 200MHz P Pro system uses an ATI mach64PCI and a 4mb Voodoo card
My 233MMX box uses 2x 12mb voodoo 2 3dfx voodoo cards and an ATI AIWP AGP card as primary.

Love the voodo based accelorators, amazing performance for the era.
 
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Anonymous Freak

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Two cards that use different memory addresses work just fine in ISA/VLB computers. Realistically, this means one CGA, EGA, or VGA card and one Monochrome or Hercules card.

A 3d accelerator in PCI works just fine with a primary video card in PCI or VLB. That's because the 3d accelerator doesn't actually identify itself as a 'video' card the way a VGA card does.

In PCI systems, with an OS that supports it (Windows 98 or later,) you can use multiple video cards, even ones with different chipsets. I used a Matrox Millenium II, a Matrox G200, and some random Tseng-based PCI video card in one machine back in the day. (Flight Simulator 98 was fun with three monitors.)

In AGP systems, again, with an OS that supports it (Windows 98 or later,) you can use one AGP card plus multiple PCI cards. (When I upgraded to AGP, I moved both Matroxes over {Or would that be "Matroces"?})
 

evildragon

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What I don't understand, is how can an AGP card "help" a PCI card?

Here's the deal. Got an old PCI video card, no 3D features at all. I install it in my Pentium 4 computer, along with the GeForce 4 AGP card thats installed.

Magically, that PCI card has 3D functions that look as good as the GeForce card (but not so good performance). When I take out the GeForce card, the PCI card all of a sudden, has no 3D again.

This ONLY works when I set the AGP card as Primary. If the PCI card is primary, then it didn't have 3D.

3D functions as in Direct3D and OpenGL.

This was a Windows XP running Pentium 4 system...
 
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carlsson

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Perhaps the AGP card can grok 3D calls, pre-calculate data and transmit it over to whichever video display card is set as output. Or if it is an XP thing, that the driver is specially written to do so. On the other hand, other than for experimental reasons, why would you run a computer with that setup?
 

evildragon

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Because the primary AGP card is for my overal needs, while the cheaper PCI card is good for things like iTunes, and DVD. (it oddly has Overlay hardware, and once again, GeForce card does MPEG decoding for it, it seems)
 

IBMMuseum

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No, it is not possible to have two VGAs on the same system. However, it is possible to have a VGA card and a separate coprocessor installed in the same system. One popular coprocessor from the early 90s was the TIGA (Texas Instruments). Those can coexist just fine. The 8514/a was another fairly popular one. ATi made a card called the "Ultra" that did 8514/a. They also made another board called the "Graphics Ultra" which combined a VGA wonder with the 8514/a. Infact, I believe that most of the coprocessors that come with some VGA boards are based on the 8514/a...

There is also XGA (which didn't really take off for anything other than microchannel) that allows for 8 "instances" (unique, identical cards on the system). Microchannel itself is limited to eight slots maximum (at least in the "PC" systems commercially released) anyway, so I don't really know whether that limit has been reached. And it is an unusual system that would have all of those eight MCA slots available without needing them for other functions (the two 9585 models are the only ones I can think of).
 
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