Honestly, what no one will admit to you is that there is absolutely no performance benefit going from ISA to VLB unless you are running Windows 3.1 or above.

Ther is no benefit in DOS with a VLB videocard, period.

Upgrade to a VLB video card whenever possible. One huge example that benefit from VLB is Doom, ISA cards are much slower. The bandwidth difference is abysmal.

mockingbird wrote on 2021-07-30, 14:29:

Honestly, what no one will admit to you is that there is absolutely no performance benefit going from ISA to VLB unless you are running Windows 3.1 or above.

Ther is no benefit in DOS with a VLB videocard, period.

citation needed

Take a look at this chart.
It breaks down classes of isa vlb and pci video cards tested on the same system.
Can point you to the thread if you want more details, but the numbers are self explanatory.

mockingbird wrote on 2021-07-30, 14:29:

Honestly, what no one will admit to you is that there is absolutely no performance benefit going from ISA to VLB unless you are running Windows 3.1 or above.

Ther is no benefit in DOS with a VLB videocard, period.

I disagree https://www.complang.tuwien.ac.at/misc/doombench.html
There's VLB cards there showing near 3x the Doom performance there than ISA cards on the same CPU.

But also you can find very well implemented chipsets on ISA cards (The Orchid Kelvin 64 ISA is hot stuff) and badly implemented ones on VLB cards, the GD542X cards can have a range from 20% faster than ISA to mixing it with the best pre '96 PCIs. If they put 80ns RAM on it, they didn't care, 60ns RAM ones are usually good.

I've had about 4 or 5 ISA Trident 8900 series and a couple of 9000s and every one of mine has been a turkey, possibly a frozen and stuffed turkey for all the life they had in them. However, there's been some recent info around about enabling framebuffer or something that seem to uncork them a tad.

Pretty much any VLB video card will run circles around an ISA card and substantial performance gains can be had since ISA is several times slower than VLB. How much faster does depend on how much data a game will try to push around though.

britain4 wrote on 2021-07-30, 14:04:

I have a 486DX2-66 machine at the moment with a Trident 8900D ISA card in it and was wondering if the upgrade to a decent VLB card would be worth it.

I’ve heard everything about the 8900D from “its a bottleneck for a 386” to “it’s one of the fastest ISA cards” and I wonder if anyone could advise on whether an upgrade to something like a VLB Cirrus Logic CL-GD5428 might be worth it? I can’t really find any benchmarks or objective experiences to be sure about it. I’ll bench it myself later on but don’t have anything else to compare it to.

You can be absolutely certain that ISA VGA card is a major bottleneck in your system. Go ahead and replace it with any decent VLB card like not to expensive Cirrus Logic 5428/3X or S3 805 or more expensive Tseng W32i/p, S3 864...

BitWrangler wrote on 2021-07-30, 14:51:

Ok, I stand corrected.

I was always under that impression from this that VLB only really matteres for Windows GUI acceleration.

mockingbird wrote on 2021-07-30, 16:06:

BitWrangler wrote on 2021-07-30, 14:51:

Ok, I stand corrected.

I was always under that impression from this that VLB only really matteres for Windows GUI acceleration.

Well, you may not have been completely off the mark as the bandwidth required for something running at 320x200, in 8-bit color and redrawing at a max of half the nominal 70Hz (Doom springs to mind) requires about 2187 KB per second , which if I am not mistaken, is within reach of some the faster ISA cards . So, within constraints such as those a VLB card might not necessarily outperform an ISA card under DOS . That being said, for any software displaying (or at least that is capable) of more than 35 fps at 320x200 8-bit or thereabouts, the ISA bus is a hard bottleneck .

See 386 VLB vs. ISA graphics for a comparison on a 386 (whose slowness additionally levels the playing field)

See also Fastest ISA video card for Doom and http://vgamuseum.info/images/vlask/bench/quake320.png where the faster ISA cards are shown to be able to push 36fps at 320x240 (presumably at 8-bit) in Quake which comes out to about 2700KB per second . EDIT: presumably on systems insanely faster than a 486. I doubt any 486 with an ISA video card would actually be able to push data that fast through an ISA bus shared with other devices (and it would not be able to do it running Quake).

Another opinion telling you: go VLB.

On both my Asus and MSI VLB boards I've put a decent ET4000AX ISA cards and afterwards a trident 9420 VLB. Three trident is known to be a below mediocre card, but still runs 50% faster than the ET4000. (Take any cirrus 542x and you're about 25% faster again. Preferably the 5426 or higher number so it supports 2MB for Windows.)

Thanks for the opinions folks - that’s my mind made up there, amazing how many conflicting opinions there are on it. The machine is running DOS 6.22 and Windows 3.1 but it’s mainly going to be a DOS machine tbh, the Windows install wasn’t really necessary.

I’ve got my eye on a nice CL 5428 card for it so hopefully that should be a nice upgrade along with going from 4MB to 32/64MB RAM.

To be clear, IMHO VLB OR PCI , whichever a board supports, is practically always worth it, especially at higher resolutions than 320x200 and/or for framerates higher than 35ish FPS .

No matter how good an ISA card is, it will always be constrained by the ISA bus, so getting a nice Cirrus Logic VLB card will be a nice addition .

britain4 wrote on 2021-07-30, 18:14:

Thanks for the opinions folks - that’s my mind made up there, amazing how many conflicting opinions there are on it. The machine is running DOS 6.22 and Windows 3.1 but it’s mainly going to be a DOS machine tbh, the Windows install wasn’t really necessary.

I’ve got my eye on a nice CL 5428 card for it so hopefully that should be a nice upgrade along with going from 4MB to 32/64MB RAM.

An excellent pairing with a 486DX2-66. One random thing I've noticed is that the Cirrus cards have superfast video BIOSes that don't make your POST take longer. Some of the S3s I have add a few seconds of delay.

As pshipkov's list showed, the only VLB card to look out for is the Weitek P9000 aka Diamond Viper VLB, and the reason is that those cards are really a VLB graphics accelerator + an ISA VGA card on a single card, so in DOS you're stuck with the ISA part.

Also for the sake of VLB's stability, please let's also make sure the DC power in the PC is clean.
ISA is much more forgiving here, I suppose, due to its simplicity and lower clock rate.

Btw, here's something to keep in mind - some systems ran ISA beyond 8.33 MHz.
The previous AT bus had no upper limit set in stone.

Some 80s cards thus ran at 10MHz and beyond - 12,5 MHz was not an uncommon clock rate, for example.
Some cards had selectable waistates, even. Like EMS boards. But if the RAM was quick enough, they could ran at 0 WS, also.

That being said, it's scarry how noisy DC in a PC usually is.
A (long) while ago, I attached an oscilloscope probe to points on an old motherboard.

These signals can't be called square wave anymore, judging by how noisy they are.
Except if we can agree on that they casually wear fur of some sort.

It's a miracle that TTL compatible chips still can make things out in that mess.

Considering this is going to be a 99% DOS machine that’s good to note about the P9000, I can’t imagine it’s going to see any Windows use at all other than for file management and stuff.

I may try and investigate the DC in there as well, the whole machine has barely been used judging on the condition but recapping the PSU would never be a bad idea. The board is all tantalums which are fine and no electrolytics so that’s a bonus (not sure if that’s standard for this age of board).

I recently put together a build similar to my original PC, which is Cirrus Logic 5428 VLB and a motherboard to suit, has 3 VLB slots. Also intel 486 dx2-66 and 32mb ram.
To my amazement I got 28.1 fps in doom using the philscomputerlab bench suite.
I don't think I have seen any more than a bit over 29fps with my PCI based 486 boards.
I have pretty much maxed out all the settings in bios.

Some of my testing figures.
Aquarius MB4DUV, 32MB 60ns FP ram, DX2-66.

[ Diamond Viper VLB ] - [ Cirrus 5424 ISA ] - [ cirrus 5428 2MB VLB ]

DOS bench 1.1:
34,8 - 32,7 - 46,7 fps

PC player vesa 320x240:
8,8 - 8,6 - 9,5 fps

Please note the Diamond Viper users the Oak OTI087 for VGA modes, the P9000 for accelerated modes and uses a tsr for vesa modes. That means you'll lose some conventional memory.

britain4 wrote on 2021-07-31, 10:19:

Considering this is going to be a 99% DOS machine that’s good to note about the P9000, I can’t imagine it’s going to see any Windows use at all other than for file management and stuff.

I may try and investigate the DC in there as well, the whole machine has barely been used judging on the condition but recapping the PSU would never be a bad idea. The board is all tantalums which are fine and no electrolytics so that’s a bonus (not sure if that’s standard for this age of board).

Seen quite a few tantalums go pop in YouTube videos - but it seems they are either good or bad, nothing inbetween

If I see performance in line with your figures that’ll be a huge win for me - thanks to you both for posting some data up.

The tantalums are all fine on there so from what I’ve read that means they will probably stay fine as long as the board is used semi-regularly?