ISA and AGP video card in one system? \ VOGONS

ISA and AGP video card in one system?

Topic actions

First post, by ychh0

Posted on 2024-12-11, 07:16

ychh0 Offline

Rank Newbie

Rank: Newbie
Posts: 98
Joined: 2012-02-19, 01:31
Location: South Korea

Hello

I wonder is it possible to use ISA and AGP video cards in one system simulteneously.
There is bios option for Pentium II or III system to choose primary video as AGP or PCI but there seems no option for ISA.
My purpose is to use ISA video card for old DOS softwares and AGP Video card for Win9x or higher in Pentium III system.
If it’s possible ISA card could be MDA/CGA or MDA/CGA/EGA, even multi video card like ARI VGA Wonder which can output MDA to VGA.

Reply 1 of 3, by RetroPCCupboard

Posted on 2024-12-11, 08:49

RetroPCCupboard Offline

Rank Oldbie

Rank: Oldbie
Posts: 696
Joined: 2024-03-06, 23:03

There are some motherboards like the ASUS P2B-VM that have onboard graphics (3D Rage Pro in the case of this board) and you can disable it via jumper. I would guess that you can then use an ISA graphics card. Note that Pentium 2 and 3 are not that flexible with regards to slowing them down. A slow ISA graphics card will of course help with that.

Reply 2 of 3, by douglar

Posted on 2024-12-11, 20:10

douglar Offline

Rank l33t

Rank: l33t
Posts: 2423
Joined: 2019-11-04, 15:37
Location: Ohio, USA

I think the main conflict would be the VGA BIOS, no? If you use two VGA cards, they are both going to want to put their ROM BIOS at C0000, which could make things difficult for the ISA card and it isn't clear if you can get your windows driver to load without a functioning BIOS. There are also possible IRQ issues.

You could solve that issue by using a non-VGA ISA card, like MDA, Targa, or 8514a card.

This thread has more, since PCI & AGP are so similar:
Using multiple video cards (ISA + PCI) in a single DOS build -- possible or not?

Reply 3 of 3, by ychh0

Posted on 2024-12-12, 00:39

ychh0 Offline

Rank Newbie

Rank: Newbie
Posts: 98
Joined: 2012-02-19, 01:31
Location: South Korea

If ISA VGA can get priority (I saw somewhere that ISA video card always has priority) I guess it would be possible to use ISA video card as primary for DOS and Windows 9x and AGP card primarily for Windows 2000 and above (ISA video card can be disabled).

But if it’s not, there may be conflicts as you pointed and cannot be used. I wonder it is possible to use EGA or CGA ISA video card with AGP video card simultaneously in this case.

douglar wrote on 2024-12-11, 20:10:
I think the main conflict would be the VGA BIOS, no? If you use two VGA cards, they are both going to want to put their ROM BIO […]
Show full quote

I think the main conflict would be the VGA BIOS, no? If you use two VGA cards, they are both going to want to put their ROM BIOS at C0000, which could make things difficult for the ISA card and it isn't clear if you can get your windows driver to load without a functioning BIOS. There are also possible IRQ issues.

You could solve that issue by using a non-VGA ISA card, like MDA, Targa, or 8514a card.

This thread has more, since PCI & AGP are so similar:
Using multiple video cards (ISA + PCI) in a single DOS build -- possible or not?

Go to top of page Go to top of page

Back to General Old Hardware