Grzyb wrote on 2023-05-28, 20:29:

With 16 colors, 36 MHz pixel clock = 56 Hz refresh rate... With 256 colors, a pixel actually needs 2 clock cycles, so the same r […]
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With 16 colors, 36 MHz pixel clock = 56 Hz refresh rate...
With 256 colors, a pixel actually needs 2 clock cycles, so the same refresh rate requires 72 MHz pixel clock...

That would make perfect sense, but 8800 and 9000C are completely different chips, the latter is newer and shouldn't have that limitation.

Again, must be something wrong with configuration and/or software, something that makes it behave like the 8800.

Ok, the problem has been found. Is there any way to flash the BIOS through some utility? I downloaded the BIOS before and opened the files with UltraEdit. The 64kb .bin file showed the version of C4.3 10/15/93, which is earlier than mine. The 32kb .VBI file on the other hand showed the version of C4.4 12/13/93, which is newer than mine. I'm planning to try these rom files out, but haven't got the utility.

This is not the problem you are thinking about, the reason is, trident series is poorly understood.

8800 is earlier while 9000 series is cut down version and cheaper, poorer. The best tridents to have is 8900C and 8900D and has best hardware and software comparability, performance. Hence the cost is expensive due to ebay sellers knows this.

Get a 1MB 8900D, and eat the cost. The note about the 8800 had a wrong resolution issue while it stated 8900 is fixed so it is more compatible with typical monitors. Nowhere it mentions about the 9000.

Cheers,

@pentiumspeed
If I understand you correctly, this issue is unfixable right? Does it just affect 9000C or the whole 9000 Series?

9000C is 512K, and no support for 15 or 16 bit RAMDAC. Usually 66MHZ in the RAMDAC.

8900D, WDC WD90C30 1MB or 31 1MB or 1MB cirrus logic is what you want.

Cheers,

I'm inclined to trust the datasheet, and believe that 9000C can do 800x600x256 NI with 56..72 Hz refresh rate.

But I'm unable to provide any further assistance at this moment.
I feel like experimenting with such card myself, but currently don't have the necessary hardware.

So, if you really need 800x600x256, and don't want to do any hacking on your own, you probably need to replace the card...

Grzyb wrote on 2023-05-29, 22:29:

So, if you really need 800x600x256, and don't want to do any hacking on your own, you probably need to replace the card...

This card is not just another VGA card, it's my elder brother's first PC. He is not only my brother but also my good friend. He owned this first PC around 1996 and he was the first one owned a PC in my whole family. I used to go to his home and play games with him, but I don't quite have the knowledge of computers. I got my first PC about 5 years later, the system was Win98. To me, his DOS/Win95 486 PC was a mystery, just seeing him typing a lot of commands in a black screen then various programs appeared, it was just like magic. So when later he upgraded his PC and didn't need this one anymore, I collected it under his approve. That was about 2003 or so. The problem with that time is that the internet was not rich of information like it now, I had limited information to dig his machine. Last month I moved to a new house, when packing old stuffs I found this PC, it immediately reminded me the thought I had when I got this machine. Now I'm digging this old buddy just like him sitting in front of his new PC and enjoying it. I want to get the same experience he had back then.

This is the story/reason why I don't want to replace the card to any other one. Maybe he faced the same issue that time and didn't know why he didn't manage to set the desired resolution. If I can do it, I'll tell him. That will make me feel very content. 😀

I'm willing to experiment with the card, but I don't know what to do. I don't know if the jumper settings are correct, because there is no doc specifically about 9000C. Beside this, I found there are several versions of 9000C out there. Check this link. Mine is VC511TQ6. The jumper layout in these versions are different. I think maybe the datasheet was for a certain version not necessarily for mine. As for the CMOS settings, there seems no one related to the VGA stuff that makes me think it would be useful to solve the issue. Now I'm out of idea, despite the willingness to digging more about it.

Grzyb wrote on 2023-05-29, 22:29:

I'm inclined to trust the datasheet, and believe that 9000C can do 800x600x256 NI with 56..72 Hz refresh rate.

I have a TVGA9000C-based board (albeit with a different layout, like this one), and can confirm it does support 800x600 256 colors at 60 Hz and worked fine under Win9x in that mode, so I would assume that OP card's memory is too slow (the INB41256 chips are rated 100ns, which could be insufficient for reliable opeartion at higher refresh rates)

GunKneeNeon wrote on 2023-05-28, 18:45:

However, the images are not correct like this one.

Do those artifacts are static or flickering/shimmering over time? Try to set 800x600 256-color mode for 60hz refresh then run any VESA application that use this mode (i.e. VBETEST from SciTech Dispaly Doctor) and check if the image is correct and stable.

pentiumspeed wrote on 2023-05-29, 19:44:

8800 is earlier while 9000 series is cut down version and cheaper, poorer. The best tridents to have is 8900C and 8900D and has best hardware and software comparability, performance.

9000C is reportedly identical feature-wise to 8900CL/D (did you noticed the ID string in TELLSET?) and there is possibility to enable FIFO/0WS operation on 9000C with little modifications, more on this later (to not derail the thread :)

wbc wrote on 2023-06-01, 16:12:

I have a TVGA9000C-based board (albeit with a different layout, like this one), and can confirm it does support 800x600 256 colors at 60 Hz and worked fine under Win9x in that mode, so I would assume that OP card's memory is too slow (the INB41256 chips are rated 100ns, which could be insufficient for reliable opeartion at higher refresh rates)

Good point!
With 100 ns DRAM, certain modes are unavailable:

Note that the datasheet is most likely mistaken here - it doesn't make sense for 800x600x16 to require faster memory than 800x600x256.

Anyway, I'm calling this mystery solved.

wbc wrote on 2023-06-01, 16:12:

Do those artifacts are static or flickering/shimmering over time?

They are flickering.

wbc wrote on 2023-06-01, 16:12:

Try to set 800x600 256-color mode for 60hz refresh then run any VESA application that use this mode (i.e. VBETEST from SciTech Dispaly Doctor) and check if the image is correct and stable.

I can't do it except in safe mode. After restarting the screen becomes unreadable.
Which version of SciTech Dispaly Doctor do you prefer me to use? The Windows version or DOS?

GunKneeNeon wrote on 2023-06-01, 17:06:

Which version of SciTech Dispaly Doctor do you prefer me to use? The Windows version or DOS?

the DOS one, 5.3a should be enough

wbc wrote on 2023-06-01, 17:21:

the DOS one, 5.3a should be enough

I'm sorry, I forgot to set the color mode first. The result is a little better now!

Still unusable, but it's static and I can barely see the text now!

alright, so it seems that the memory could not cope with higher refresh rates. BTW, which monitor do you use?

wbc wrote on 2023-06-01, 19:17:

BTW, which monitor do you use?

AOC MW19N-AA 932Sw

GunKneeNeon wrote on 2023-06-01, 19:20:

wbc wrote on 2023-06-01, 19:17:

BTW, which monitor do you use?

AOC MW19N-AA 932Sw

couldn't find any detailed info (or even manual) for your monitor, but I may assume it silenty rejects any modes below 60hz refresh. Personally, I would suggest to find any CRT or 2000s-era 15-19" LCD display for testing, as those are reportedly support 800x600 at 56 Hz. on the other hand, this does not gurantee it would not have those artifacts on your video card, as 4Hz refresh difference is not a big headroom for memory performance, but why not?

It turns out I hadn't set the vga correctly before. I created my own monitor profile in tvgacrtc but not saving the settings. Now I use the Anymaker 60Hz profile and set the 800x600-256 mode as 108Mhz | Divide By 1.5 result in 56.07Hz and it works in TVGACRTC the first time. Though in VBETEST it still a lot of artifacts.

BTW, I find a setting in TVGACRTC by pressing F10, the Decode Mode. I can set it to Fast, but every time I enter the page it shows Slow. How can I set it to Fast permanently?

wbc wrote on 2023-06-01, 19:33:

couldn't find any detailed info (or even manual) for your monitor

Maybe you could search for AOC 931Sw instead, it's more popular and the model number are very close to mine.

GunKneeNeon wrote on 2023-06-01, 20:04:

wbc wrote on 2023-06-01, 19:33:

couldn't find any detailed info (or even manual) for your monitor

Maybe you could search for AOC 931Sw instead, it's more popular and the model number are very close to mine.

aaand this one becoming even more cryptic, as the service manual states that 800x600 56Hz is indeed supported:

Could you connect the monitor to more recent PC with VGA output and try 800x600 56Hz mode there?

wbc wrote on 2023-06-01, 20:10:

aaand this one becoming even more cryptic, as the service manual states that 800x600 56Hz is indeed supported:

See my previous post, it supports 56Hz.

Here is the interesting part, both 108.0MHz | divide by 1.5 and 72.0MHz | divide by 1 output the exactly 56.07Hz refresh rate and the monitor was proved to be able to work at 56Hz refresh rate (see my last post). Why one displays just fine while the other causes the Input Not Supported error?

Corruption is memory speed or memory had degraded. These chips you have is 4 of junk quality memory chips and other 4 chips made by IBM could be 100ns or 120ns that were made for IBM made 256K modules rated at 120ns or 100ns.

Unfortunately ram is soldered on this video card. My best advice is to bend period correctness a bit on your nostalgic computer is to replace the video card with another of bit better. I suggest get another trident video card 8900D with 1MB installed. It will say trident on start up still.

Cheers,