Hi! I've found some information about the chipset a while ago.

See OAK OTI-037c - 800x600 mode ?

Maybe it is partially helpful.

Good luck! ^^

Yeah, I've seen the datasheet for OTI-37c.
Problem is - there are many cards built on this chip, and the PAL is typically used in glue logic around the chipset, implementing decoding of address and other control lines logic.
This varies wildly between cards, and the equations in this dead PAL are specific to the exact board and revision.

Meh, will return to this board later...

Seems I have a bit of luck with reverse engineering approach.
The dead PAL is only involved in generating IOR#, IOW#, ASEL and RESET signals for the OTI-37c, so basically only detects the addressing of VGA memory area and distinguishes I/O ports access from DMA transfers and refresh conditions. It's not involved in other onboard details, like the timings, data flow orchestration or BIOS chips mapping onto the bus. All the signals are coming directly from the ISA edge connector, and outputs are going into oti-037 directly or through 7404 inverter.

So I hope it would be just some looking into ISA specs and a bit of head scratching to map the i/o access logic.
I'm not sure yet if IOR#/IOW# are depending on the address lines or oti-037c filters addresses on its own. The datasheet did not include typical application schematics and the block diagram does not include needed details.

Googling around I see that ISA cards often/typically only decoded 1K of I/O address space, and not full 64K.
This matches well the A9-A4 lines I see on that PLA, so the answer should be "decode the addresses yourself on that PLA".

Here's the pinout of that PAL design.

Wrote the PLD design that decodes I/O ports access signals and VGA memory areas. It all looks ok in simulation, but still didn't bring up the card to life.
It's possible some other ICs are not ok, so I'd need a full-blown debugging on a breadboard (don't want to risk the motherboard's health).
Ordered some ISA edge connectors from Aliexpress...

PS: I know the card is garbage, it has only 8-bit data path to the video memory. I'm just kinda enjoying diving deeper in old hw, brings up memories 😀

vstrakh wrote on 2022-01-25, 09:18:

Googling around I see that ISA cards often/typically only decoded 1K of I/O address space, and not full 64K.

Seems to match my memories, too.
8-Bit ISA (PC Bus) mirrored so many addresses due to flawed / cheap decoding circuits.
Speaking of these, did you know that IBM CGA technically was able to do 640x200 in 4 colours, too? Not just black/white?
- If the address decoding wasn't so flawed.
CGA used merely 16 Kilobytes of its 32KB frame, also, if memory serves.
The other half was a copy/repeated memory pattern..
But I'm speaking under correction here. Please double-check my statements. 😀
Also, the dithering of CGA was/is cool. A simple mode-switch and.. Voila! Your 320x200 4c image becomes a nicely dithered 640x200 b/w image. 😀

That being said, the many mirror copies had its place. It just was a tiny bit frustrating to 286/PC-AT users. 😉
The PC AT platform had a huge 16MB address space (ISA..), but only a handful of i/o ports due to backwards compatibility.
And memory-mapped devices, like Weitek Abacus, were 386+ stuff.

vstrakh wrote on 2022-01-26, 09:22:

Here's the pinout of that PAL design. u12_pinout.PNG […]
Show full quote

Here's the pinout of that PAL design.
u12_pinout.PNG

Wrote the PLD design that decodes I/O ports access signals and VGA memory areas. It all looks ok in simulation, but still didn't bring up the card to life.
It's possible some other ICs are not ok, so I'd need a full-blown debugging on a breadboard (don't want to risk the motherboard's health).
Ordered some ISA edge connectors from Aliexpress...

PS: I know the card is garbage, it has only 8-bit data path to the video memory. I'm just kinda enjoying diving deeper in old hw, brings up memories 😀

No problem. The contrary is the case. You're doing it completely right, imho. Kudos. 😎👍

vstrakh wrote on 2022-01-26, 09:22:

PS: I know the card is garbage, it has only 8-bit data path to the video memory. I'm just kinda enjoying diving deeper in old hw, brings up memories 😀

Hi. I've found this beauty on Violity and bought it just because of this topic.

It's exactly your card model (there are few of them) but in worse shape - BIOS, DAC and both PALs are missing.

DACs are quite standard, I have one or two and even ordered CEG ones from EDSUN (AD?) to play with this interesting technology.

BIOS is also available, though if you provide yours it would be much simple to be in sync.

But mine missing both GALs and that makes everything even more interesting 😀 But why else we are here?

Could make a dump of a working one (vertical, horizontal?) and provide JED file for the one that is broken in your case. I can try and see what do we have.

I am not very experienced, especially in PAL programming, but at least I have XGecu, oscilloscope and some time to have fun 😀

I only hope it was salvaged while being working.

Also, is your working in EGA mode? I suppose one of the PAL is for VGA part.

Unfortunately I can't help you. The dead PAL replacement was my guesswork based on observed traces, and can't be taken as the true answer without validating it first.
And the other MMI-branded PAL16L8 seems not readable in my T48 XGecu. I can't tell if it's dead, or it can't be directly read as is and require other methods of dumping.

vstrakh wrote on 2024-03-20, 13:28:

Unfortunately I can't help you. The dead PAL replacement was my guesswork based on observed traces, and can't be taken as the true answer without validating it first.
And the other MMI-branded PAL16L8 seems not readable in my T48 XGecu. I can't tell if it's dead, or it can't be directly read as is and require other methods of dumping.

And what about BIOS?

rkurbatov wrote on 2024-03-20, 13:35:

And what about BIOS?

Here's the zip:

There's two ROM's - odd/even pair.

Thank you. Will try.

Dear friends, I think I have a similar card. How can i help you? How do I read the chip with an EPROM reader/programmer?

Toninetto wrote on 2024-04-27, 14:52:

Dear friends, I think I have a similar card. How can i help you?

I don't think it's possible with your card. The main chip is the same, but surroundings are different. Yours doesn't even have two PAL chips, there's just one.
The PAL chips are used as a programmable glue logic, it is very specific to the actual schematics of the video card model/revision/whatever. It just glues different things on different cards, so does it differently. Your card is definitely not identical, so the logic in PAL will be different.

vstrakh wrote on 2022-01-26, 09:22:

Here's the pinout of that PAL design. […]
Show full quote

Here's the pinout of that PAL design.

The attachment u12_pinout.PNG is no longer available

Wrote the PLD design that decodes I/O ports access signals and VGA memory areas. It all looks ok in simulation, but still didn't bring up the card to life.
It's possible some other ICs are not ok, so I'd need a full-blown debugging on a breadboard (don't want to risk the motherboard's health).
Ordered some ISA edge connectors from Aliexpress...

PS: I know the card is garbage, it has only 8-bit data path to the video memory. I'm just kinda enjoying diving deeper in old hw, brings up memories 😀

The pinout that you’re provided looks exactly as U8 in Hedaka version of OTI37C card, so i think you can try my dumps from here:

https://github.com/rpocc/PALDump/tree/8787c80 … _Hedaka_HED-622

rpocc wrote on 2024-12-24, 00:23:

The pinout that you’re provided looks exactly as U8 in Hedaka version of OTI37C card

U9 you mean 😀
Thx, it looks almost the same to what I wrote, but I surely could do some mistakes because of less than adequate experience with WinCUPL. Some syntax elements might have produce conditions that are not what I think it should. I will attempt that image too.

Hi, I saw your post and created account to reply here.
I have collected some old computers and parts and gearing up to one day restore some nostalgic pc-s from my childhood, so you could say I'm not at home with electronics yet but I have some experience, I'm able to solder-desolder and follow instructions, if necessary to complete some tasks concerning electronics and software engineering.
I was looking up information on the graphics card your post is about, because I have this same board.
FYI, I haven't been able to try out if the card actually works but it seems in good condition.
Can I help you solve your problem with the missing PAL16L8 information and if so then how?

vstrakh wrote on 2022-01-24, 13:29:

Got this board, it's not detected by bios. […]
Show full quote

Got this board, it's not detected by bios.

The attachment oak-vga-16.jpg is no longer available

Probing the power lines I see some suspiciously low resistance (88 Ohms, or 0.17v drop when measuring in diode testing mode).
It's not dead short, but still way too low. To avoid desoldering all tantalum capacitors I started with taking out all the socketed chips.

It turns out the dead IC is the PAL16L8 close to ISA connector, the one in row with 74LS244 buffers.
I think I would be able to replace it with modern GAL16V8 from Microchip, but I'd need the equations from the original chip. The original PAL is of L series, so just plain logic, no registers, and I think it would be relatively simple to probe the behavior of the original working chip. Or maybe I could reverse-engineer that piece if I had a schematics for that card.

Does anyone has this card and would it be possible to read/probe its content, or at least any hints on where to look for the board schematics?

onuheino wrote on 2025-01-08, 22:42:

Can I help you solve your problem with the missing PAL16L8 information and if so then how?

Your PAL ICs are soldered and I don't recommend to desolder them as they are pretty fragile (especially the old ones) and can easily be damaged. Also, you need to read the PAL values, not sure if this is possible via the standard programmers like TL866.

On the other hand, if you have one, you could dump the BIOS of your card - that's much simpler as it's socketed. It's interesting to compare both.

Anyway, thank you for you proposal.

vstrakh wrote on 2024-12-24, 08:35:

U9 you mean 😀
Thx, it looks almost the same to what I wrote, but I surely could do some mistakes because of less than adequate experience with WinCUPL. Some syntax elements might have produce conditions that are not what I think it should. I will attempt that image too.

@vstrakh, if you haven't seen yet - https://phantom.sannata.org/viewtopic.php?t=47690 there are some schematics and dumps on sannata forum. I think the last one (for now) with plenty of 245 and 255 ics is the same card as we have with more complex schematics but simpler PAL equations.

I'm going to try something at last once these holidays are finished. 😀

Hello!
I am attaching a photo and the bios of my oak card.
The card is functional - but I do not know how to read the PAL IC.

I just got this same card, FCC ID IEW-OAK-VGA-16.
I could not find working dip switch settings, however I noticed with Google image search most images had switch 1 and 2 ON and 3 and 4 OFF:
COLOR VGA:
1 - ON
2 - ON
3 - OFF
4 - OFF

When I tried that it fixed my Monchome VGA with all switchess off to proper Color VGA.
I've no idea for MDA, EGA or CGA or any other modes on this card though.
MONCHOME VGA:
1 - OFF
2 - OFF
3 - OFF
4 - OFF