Looks to me like your computer already has a VGA chip integrated on the motherboard. Thus you need to disable it if you want to use another VGA card in ISA slot. Often there is a jumper for it on the motherboard.

Only one VGA card can be active.

No need to install any drivers.

Excellent, thank you so much!
I've even been staring at my motherboard manual for weeks trying to work something out.
Seriously, I appreciate this so much!

You need disable onboard VGA (S3 I think?), it is jumper J23 - pins 2-3 enabled, 1-2 disabled. You can download manual here: https://www.manualslib.com/products/Digital-E … dx-9032719.html

One more Newbie question please... it says I can also disable on-board VGA (IRQ9) do I need to do this as well?

If you disable on-board VGA chip then you shouldn't need to disable the IRQ as the disabled chip won't be generating any interrupts.

On the other hand VGA IRQ is rarely used feature so it is almost always good idea to disable it even on the active card.

So the onboard video, I suspected is VLB. I looked at the manual just shared, and it says it has the S3 86C805, which is VLB compatible. So without looking at the machine with it in front of me to see how it was integrated on the board, it may actually be better to stick with the onboard in this case.

A good local bus S3 '805 system should beat the Trident 8900CL in nearly all disciplines. It might not actually be VESA local bus if it is onboard, but the chances are very high that the onboard video is located on the 486 local bus in some way. The VESA part of VESA local bus is about how the chipset and the graphics card agree on who handles the cycle, and when exactly the cycle is over. Onboard graphics solutions might use different ways to dispatch the cycle.

Thanks again everyone, I ended up just playing around with both jumper settings until it worked, as the onboard vga was already set to disable. I got it installed properly in my Windows 3.1 (800x640 256 colour) which looks really nice, however, in ms dos 6.22 the screen gets glitchy in game. I have both versions (win 3.1 and dos) of the utility and drivers, but even going through the dos drivers, I can't find the same settings as win 3.1, but I will keep trying and keep you all updated.
Being an ISA, and living in Australia, I find it hard to get compatible graphics cards. Going off my system, what would be a better upgrade please?

Going off your system, what we are saying is if the S3 805 is integrated properly, there is no ISA card I'd expect that could exceed that. So that's would be the best you can do.

If you had other requirements than simply DOS games, then maybe the late model ISA windows accelerators, or boards with more RAM for higher resolutions in Windows might perform nicely, and come close if the S3 805 is a poor performer. But no ISA card can out-perform the speed of a VGA on a 486 local bus. Considering this is a DEC machine, and how it's advertised in the manual, I really think video performance was a selling feature. So I think the onboard chip is the best option.

I think DOS compatibility is probably the most desired here, and so I'd try the onboard S3 to see if it runs better, or if you have another ISA card handy, you can see on that too. I wouldn't try to hunt down a more sought after late model ISA card just yet. The Trident isn't bad, I had one back in the day. They were very cheap, and maybe just a little more finicky. I think the Cirrus Logic cards are pretty good and fairly common. But I don't think it's going to improve much ultimately. Perhaps if you have any trouble, please explain what game is having trouble, and someone might be able to help with that.

DarkProdigy wrote on 2021-05-07, 00:02:

in ms dos 6.22 the screen gets glitchy in game.

Can you please elaborate what problem you are experiencing? What game is affected, and if the game allows you to select a resolution, what resolution is problematic? Is the picture unstable? Do you get random garbage only when scrolling in a game? Do you get single bad pixels during fade-in and fade-out? Depending on the problem, the cause might be different. If it just affects one certain game, it might be an incompatiblity between that game and the Trident graphics chip, but if you experience general problems, you might have issues with the ISA bus or the timings of it.

Sorry for the late reply, as I've been doing some serious testing. So after installing the correct drivers and setting in both windows 3.1 and dos 6.22, setting my monitor to colour instead of monochrome most games are running perfectly. Everything from crystal caves, duke nukem 1, Jill of the jungle, space simulator, Microsoft golf 2.0, sim city, commander keen 1 - 4, doom etc etc don't skip a frame. But 2 games I'm having glitch issues with are wolfenstein 3d and Blake Stone. I thought maybe it was because of the HUD overlay, but like I said, doom runs great. It honestly has me scratching my head 🤣.