The BIOS is a 256 kBit mask ROM. You should be able to read it with any 27c256 setting - but you need to disable device ID verification.

The UM82c4010 on the picture in the VGA museum is obviously pin compatible to an ICS2494, which is a manufacturer programmable clock generator. But there are a lot of different editions of that chip with different programmed clocks. If you install an ICS2494 with a wrong set of clocks, some or all video modes will run at wrong refresh rates. The super VGA documentation collection "VGADOC" states about the ICS2494: "special versions such as the [...] UMC UM9502 exist", which might indicate that this chip uses a custom set of clocks that's not in any kind of standard ICS2494.

mkarcher wrote on 2022-11-29, 20:10:

The BIOS is a 256 kBit mask ROM. You should be able to read it with any 27c256 setting - but you need to disable device ID verification.

The UM82c4010 on the picture in the VGA museum is obviously pin compatible to an ICS2494, which is a manufacturer programmable clock generator. But there are a lot of different editions of that chip with different programmed clocks. If you install an ICS2494 with a wrong set of clocks, some or all video modes will run at wrong refresh rates. The super VGA documentation collection "VGADOC" states about the ICS2494: "special versions such as the [...] UMC UM9502 exist", which might indicate that this chip uses a custom set of clocks that's not in any kind of standard ICS2494.

I need an exact match to replace this 9502. That sucks.
Now I have to change the title with "Do you have a spare UM9502?"

Thanks for the explanation.

if that picture is of how it works at this point then your chip works, mounting backwards usually fries totally and there would be no output without proper clocks
if anything I would look for another ram

rasz_pl wrote on 2022-11-30, 03:47:

if that picture is of how it works at this point then your chip works, mounting backwards usually fries totally and there would be no output without proper clocks
if anything I would look for another ram

It is of how it worked before I made the mistake.

After it's no output at all.

Some ram chips had cracked solder joints, I guess it was probably that too.

After some research I found that this video card wasn't great, budget model.
I'm not crying about it.

Edit: I just put it back in to see if a miracle, but still dead. I see that the crystal has one lead with 3.04V, the other is 0.00V.
Maybe it says something to you.

You can still try a ICS2494 from a different card. Many of those chips have the two standard VGA clocks (25 MHz and 28 MHz) as clock 0 and 1, so standard modes would work at the correct refresh rates, even if the clock chip is not as expected by the BIOS.

mkarcher wrote on 2022-11-30, 14:14:

You can still try a ICS2494 from a different card. Many of those chips have the two standard VGA clocks (25 MHz and 28 MHz) as clock 0 and 1, so standard modes would work at the correct refresh rates, even if the clock chip is not as expected by the BIOS.

If you know where I can find one 😀
I'll keep it there trying to locate one, maybe in time...

It's easy to help if you have the knowledge, thanks to you too.