VOGONS


WDC VGA 16 (WD90C00-JK)

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Reply 20 of 29, by watson

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Indeed, it looks like it won't work. I too was misled by the part list under 3. Those are only examples of chips that will work as boot ROMs once flashed/programmed externally.
This is what is says EPROM wise:

2. Or you can program RPl ROM image into the EPROM using EPROM program machine.

I thought EPROM/EEPROM/flash was more or less the same thing, but that's not true.
From what I understand, EPROMs are "dumb" and have to be programmed byte by byte, and these devices don't support that.
Root42, what was the part number of the chip you programmed/flashed?

I guess I'll just set those EPROMs aside when they arrive in case I ever buy an actual programmer.
I don't think this particular card is worth the effort/investment right now.

One more thing I got wrong in my post, I didn't get the part number from OP's card (it's covered by stickers), but from VGA museum.

Reply 21 of 29, by TimWolf

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watson wrote:
I got this card as part of a bundle, but it's missing the VGA BIOS ROMs (I don't know why anyone would pull them out, they proba […]
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I got this card as part of a bundle, but it's missing the VGA BIOS ROMs (I don't know why anyone would pull them out, they probably didn't know what they were doing).
Naturally, this means the card doesn't work, i.e. there is a black screen on boot.

I ordered two 16Kx8 EPROMs (27C128, same as on OP's card) from China. The BIOS can be found on a Russian site.
I want to know if there are any DOS-based utilities for flashing ancient cards like this (with the help of a secondary PCI card) or am I basically SOL if I don't have a programmer.
The TL866 costs about $50, but I'm not willing to spend that much to fix this ultra-slow card. I have been planning to buy that thing for a while, but I haven't had a need for it yet.

If there aren't any such tools, this should supposedly be doable using a Realtek 8139 NIC (setting the window size to 16K with RSET8139.exe and flashing with RTFLASH.exe).
Flashrom might also be an option, but it doesn't seem to support ROMs smaller than 64K.

I've got an EEPROM writer but no clue how to use it. Want to work together and learn a thing or two? I've got the same card, so if you mail me the chips we can figure it out, burn yours and post some pics of the whole thing. I can even test them on my card to make sure they work. I'm in Tennessee.

Tim

Reply 22 of 29, by watson

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TimWolf wrote:

I've got an EEPROM writer but no clue how to use it. Want to work together and learn a thing or two? I've got the same card, so if you mail me the chips we can figure it out, burn yours and post some pics of the whole thing. I can even test them on my card to make sure they work. I'm in Tennessee.
Tim

Thank you very much for the offer, but unfortunately, I'm in Europe (and I don't have the ROMs yet, I'm waiting for them to come from China).
Postage from Croatia to US would be about $3 if I sent it as a letter (no tracking), but sending it back would probably be expensive.
For all I know, the card might be dead. Maybe that's why the ROMs were missing in the first place.

If you want to test your programmer and document the process, search for M27C128A on eBay, the cheapest one should be $1.15. You'll need two of them.
Dump the ROMs you currently have, program the new ones and see if the card works.
Of course, you should first verify that your programmer works with this particular EPROM.
Or, even cheaper, check if you have any motherboards with a socketed BIOS (preferably DIP). You can then flash it to your heart's content with different BIOS versions.

As for me, I had a crazy idea of making my own programmer with a 40-pin PIC microcontroller.
However, there's almost zero chance this would work the first time and I don't have a UV lamp to erase the EPROMs (and they are simply too sensitive in general).
It will probably be yet another failed project, but I would just be wasting $2.30.

Reply 23 of 29, by retro games 100

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I see that the WD90C31 graphics chipset is mentioned in this thread. I remember testing one of these WD cards, here. In that thread, Old Thrashbarg vogons user notes that "The 90C31 is interesting as it was the first accelerated Paradise card."

Reply 24 of 29, by RayeR

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I got one dead Paradise VGA card with WD90C00-JK - beep code as with no VGA inserted. I read BIOS chips with programmer and they are OK. I should have some spare PVGA1A-JK chip, it seems they should be nearly the same...

Last edited by RayeR on 2022-09-15, 11:59. Edited 1 time in total.

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Reply 25 of 29, by RayeR

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I sniffed by osciloscope around the VGA card. I saw signal activity on ISA bus side (addr + data) on BIOS chips but I didn't see any signals going to onboard VRAM and to RAMDAC. There are 4 oscillators - all are working, output voltage swing vary from ~2Vpp to 4,5Vpp, probably due to different output load. So I replaced the original WD90C00-JK with PVGA1A-JK but still receiving no VGA beeps 🙁
I sniffed again and now I can see bus activity also on VRAM but no data going to RAMDAC and no HSYNC, VSYNC only blank had some strange pulses ~700Hz. There are also 2 PAL circuits for address decoding. As they was in socket I pulled them out and dumped in programmer too - they ar OK and unlocked, so no problem here. I also replaced DRAM chips but no change. Do I need change video BIOS if there is some minor difference between WD90C00-JK and PVGA1A? Or maybe some of 74244 buffers is bad or PCB failure? How exactly system BIOS detect the VGA to decide if beep an error? Does it check some return value of VBIOS init routine called during ROMSCAN?

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Last edited by RayeR on 2022-09-15, 12:02. Edited 2 times in total.

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Reply 26 of 29, by RayeR

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I desoldered all the 74xx logic to test them outside the board...

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Reply 27 of 29, by RayeR

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Yeah, I made it, VGA booted with display.

I found one suspicious gate IC 74125, replace and solder all good ICs back to the PCB. There was significant change that I didn't get 8 noVGA error beeps but it was completly silent, no image. I pushed a POST card in and see it's spinning in a dead lock, few POST codes was looping forever. So I got suspicion about incompatible VBIOS. I have found a PVGA1A VBIOS image here: http://chukaev.ru54.com/video/par_u3.zip. So I take 2 spare 27128 EPROMs, erased them by UV lamp and programmed dowloaded VBIOS images and viola, it booted! I didn't perform full vmodes test yet. The original WD90c00 chip is probably dead. So even both chips WD90c00 and PVGA1 should be similar the VBIOS is not compatible!
Datasheets:
https://datasheetspdf.com/pdf/935719/WesternD … gital/WD90C00/1
https://www.datasheetarchive.com/pdf/download … e=O&term=PVGA1a

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Reply 28 of 29, by root42

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Congratulations! Good fix. Maybe the BIOS was corrupted or broken. Have you tried reading it out?

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Reply 29 of 29, by RayeR

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I have to correct my previous diagnostic, even the 74LS125 gate was good so there was not fault in this 74xx logic. I just soldered all them back. Maybe some solder junction was cracked but I didn't see anything suspicious visually. VGA tests passed.

The BIOS reading in programmer (multiple reading during various Vcc levels) was the first thing I did, as I wrote above, so it is OK...

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