Runar77 wrote on 2024-01-06, 21:44:

I am currently building a 486 PC, with a DX2-66 CPU. It will mainly be used for DOS-gaming, I am not planning on installing Windows on it.
Among the games I want to play on it, are Doom, Comanche and Under a Killing Moon.

Will there be a big difference in performance using the more expensive VLB graphics-cards, or can I just go for a random Cirrus Logic VLB-card?

With a DX2-66 a Cirrus 542x VLB card is fine. The better cards (Trio64, S3 868 or Ark Logic 1000 for example) gain more on a Am5x86 @133 and a bit more @160, but at 66MHz the additional speed is not worth it.

I am not sure if a DX2-66 is a good setup for Doom honestly spoken. It is borderline.

There will be a minor performance difference (maybe a couple extra FPS) depending on the game .

https://dependency-injection.com/vlb-vga-group-test/
A good comparison.

CoffeeOne wrote on 2024-01-06, 22:11:

Runar77 wrote on 2024-01-06, 21:44:

I am currently building a 486 PC, with a DX2-66 CPU. It will mainly be used for DOS-gaming, I am not planning on installing Windows on it.
Among the games I want to play on it, are Doom, Comanche and Under a Killing Moon.

Will there be a big difference in performance using the more expensive VLB graphics-cards, or can I just go for a random Cirrus Logic VLB-card?

With a DX2-66 a Cirrus 542x VLB card is fine. The better cards (Trio64, S3 868 or Ark Logic 1000 for example) gain more on a Am5x86 @133 and a bit more @160, but at 66MHz the additional speed is not worth it.

I am not sure if a DX2-66 is a good setup for Doom honestly spoken. It is borderline.

Doom on a 486 DX2 IMHO, was the definitive contemporary experience. Sure, you weren't locked at 35 FPS the whole time. But it was plenty playable, by the standards of it's time.

That said, standards have changed, and if you didn't grow up on "playable" framerates being anything above 10-15 fps, the meager 20-30'ish you get with Doom on a DX2, with occasional dips into the mid teens, might seem unplayable. But I promise you, in 1993, when Doom came out, a DX2 was probably the best computer anybody had, and it was amazing.

The thing to understand is that there is no such thing as a video driver in DOS and that therefore acceleration functions of chips aren't used. In DOS the cards basically function as unaccelerated frame bugger, so the main performance indicator is how fast a card can get data from the system bus into the framebuffer video RAM. That is usually limited by the bus itself, so in general, performance in DOS of VLB cards is very similar (and much better than ISA card limited by that bus).

The exceptions are cards doing weird stuff (usually associated with better accelerated performance). That means things like dual-chip cards with Weitek accelerators, or cards with dual ported VRAM instead of DRAM. They perform worse under DOS.

So performance ranking under DOS is very, very different to performance under an OS with drivers using acceleration hardware. In DOS you get best performance with stripped-down simple chips/cards, so ARK1000VL is one of the fastest, followed closely by WD 90C33. UMC 82C419 or S3 864-based cards. Slowest are 'high end' VRAM cards like ATi Mach64, S3 9xx series and dual-chip cards with Weitek accelerators. Only the very oldest VLB chips (S3 805..) join those high-end solutions at the lower end.

In Windows on the contrary, acceleration is everything and cards with dual-ported VRAM and fastest accelerators (Mach64, 964 and Weitek, for example) are vastly faster than slow Ark, WD or UMC frame buffers.

Thanks for the thorough answers.
That's what I expected. Good thing I don't have to spend a lot of money on the graphics card then.

Contemporary collection of benchmarks, plenty of dx2-66 results listed in different hardware configurations: http://www.complang.tuwien.ac.at/misc/doombench.html
There is also hyper optimized FastDoom https://github.com/viti95/FastDoom port

Try to get the latest model VLB card that's also good value. If you can visibly see the date code on the back (four numbers yyww - year / week), of any manufacturer later cards are faster.

Runar77 wrote on 2024-01-07, 11:28:

Thanks for the thorough answers.
That's what I expected. Good thing I don't have to spend a lot of money on the graphics card then.

So long as you're only interested in DOS, nope. A CL-GD5428 will perform within a few percentage points of the most expensive unobtainium card.

One weak point of those cards which won't be an issue in DOS only, where even SVGA games tend to cap out at 800x600xnot too many colours, is that their support for higher modes and resolutions is very limited due to the integrated RAMDAC. They support 2MB of video memory, but all you get over the default 1MB config is two eye-killing interlaced modes. Same applies to a few other VLB chips, like the WD90C33. If you want to run any kind of desktop at 1024x768@high colour (normally what 2MB would give you), you need a card with a decent RAMDAC that can really use the 2MB. Think CL-GD543x, S3 86x/96x (or Trio), ATi Mach32/64 etc. Probably the cheapest option that can do decent modes (due to prejudices agains the brand) is the Trident TGUI9440, which is also a pretty decent performer.

But again, this is desktop stuff. I'm not aware of any DOS SVGA games that do anything that won't work on a bog-standard 1MB card like the ubiquitous GD542x, with the added bonus that those Cirrus Logic chips of this generation have the best SVGA VESA compatibility of any VLB chipsets (see: https://gona.mactar.hu/DOS_TESTS_VLB/)