Hmm... does it do that with the added ram removed ? Am wondering if a video ram may have an issue (a row/column address thingy)

Horun wrote on 2023-11-19, 20:49:

Hmm... does it do that with the added ram removed ? Am wondering if a video ram may have an issue (a row/column address thingy)

I tried with the soldered 1MB only - no difference. One of these chips could be flaky of course.

It´s funny that the bar is transparent, but I´m unable to draw any conclusions from that.

Video-RAM is not the problem here, as it seems. I replaced all 4 chips (both soldered and socketed ones), but the bar is still there.

A PCI-card with the same S3 "Trio64" chip works perfectly.

I wonder if some flaw in the video BIOS might be causing this bar at certain resolutions. The BIOS is integrated in the mainboard BIOS so replacing it would be difficult.

If it wasn't a RAM issue it suggests there is a fault internal to the chip, display line FIFO or something similar is faulty. To get such a bar only in one part of the image and stay in same place in different resolutions you need some active involvement and BIOS will not be able to actieve that, not when most apps write stuff to video memory directly and even if they didn't, it would take extra effort to single out some pixels per line to get the observed effect.

The bar does not appear at lower reolutions.

What other resolutions it does appear in besides 640x480 ? It looks like 70Hz text mode (720x400) is unaffected and I suppose 320x200 too ? One can try VBETEST from UNIVBE to try various resolutions via VESA and see what shows up.
I'm pretty sure it is a chip fault when there's no mechanical issues elsewhere (loose or shorted pins), you already swapped memories and nothing changed from that. This chip has internal RAMDAC so there isn't really more to blame either. It might be worth doing a finger test while machine runs, loose or otherwise problematic pins often react to presence or contact with finger, although care should be taken not to touch the two pins that connect to the nearby 14MHz crystal, that will disrupt clock generation and image is likely to disappear and other weird things happen. But ones connecting to memory are primary interest.

I have a couple of "donor-cards", but they all have some variant of this chip like Trio64 / + / V2 / DX. Would these be fully compatible? Or should I source some card with the original variant?
I will have to live with the stock BIOS, since there are no updates to be found and I also found no other mainboard with this VIA chipset and Trio64 onboard graphics.

I don't know the compatibility between different variations of the chip. I assume some will need specific BIOS too.
It shouldn't be too difficult to update/change the video BIOS, in many cases it is just before the main BIOS in the ROM chip, i.e in 128KB chip the first 32KB is video BIOS and rest is main BIOS, in which case you can just replace the first part with something new but only a dump will tell if that is actually the case.

I tried the tool "VESATEST" and it detects the following modes:

The vertical bar in Speedsys appears at 640 x 480, so I tested all the colour settings (8, 15, 16, 32) for this resolution with VESATEST and all the pictures are perfect.

It might be related to 4bit modes only then, Speedsys uses 16 color 640x480, like Windows desktop with the default VGA driver.

Here´s the vesatest output of some other PCI Trio64 card that displays the speedsys gui without any issues:

You should try to use the attached program (VBETEST from the freeware Scitech Display Doctor package) with any supported 4bit modes to see if they also produce the problem. It looks like the program you have been using doesn't support the 4 bit modes. It is worth to try Windows desktop in VGA mode (or just its setup as it also uses 640x480 in 4 bits).

Thanks for uploading VBETEST!

I tested all the available modes today. It does not offer 640x480 /4 bit, but 800, 1024 and 1280.
The odd vertical bar appeared in none of the tests.
The "Page Flipping" test, where it says "should be no flicker" does flicker in most 4bit and 8bit modes. With a regular Trio64 PCI-card there´s no flicker at all.
The "Wide DAC" test is always o.k.

Here´s the current (original) BIOS file:

Ok, interesting, so it is only the VGA mode that doesn't work right.
I see flicker on many cards I have tested, but I'm not sure what causes it. It isn't gonna be related to the problem you have though. It is certain that memory is fine, since everything else works properly and interface to the memory and the S3 itself from CPU side also works. That only leaves possible internal fault in the chip.

Looks like this BIOS actually needs Award BIOS editing tools to get video BIOS changed (or any other modifications done), it is all compressed modules type things. I don't have any experience with this sort of stuff unfortunately... There should be some people who have experience here on the forums, perhaps they can give the help on this matter.