Since the datasheet claims the EPDC is fully compatible with the IBM-PC EGA, maybe it should be possible to drop in the ROM from the IBM EGA?
https://www.os2museum.com/wp/reconstructing-the-ega-bios/

Sure it's still possible that the card's power-on values in registers might select the output signals in format suitable for flat panels (i.e. the vsync/hsync would carry the latch/scan_start logic), but nothing bad should happen with the card itself. And Sigrok-EGA or other EGA-to-something adapters should be used instead of real EGA to avoid risks of damaging the monitor.

Very good idea, thanks...I jut tried. However, there is no signal at all on the output. Tested with logic analyser.

Oh wow! I was just about to comment on your post showing this card 4 days ago in the "recently bought" thread, then I googled it one more time and found this post 🤣 .

The look of it piqued my interest and after finding SO little info about it online, I am even more curious.

I'm hoping you can get it working.

It's a long shot, but I would suggest checking the various archives and pages in this thread just in case there is a bios floating around some old FTP or driver site somewhere:
Link Repository for Vintage PC Driver\Documentation Archives, FTPs, Websites

EDIT: Also, try some of the other EGA BIOS files from here:
https://www.minuszerodegrees.net/rom/rom.htm
... just in case some of those chips more closely relate to the Yamaha one. For example, the CityGate chip on the card 2nd from the top of the chart says it was made in Japan.

... also just found this thread dedicated to EGA bios files! (which you made!) 😮
EGA Video cards - BIOS image collection

Another option to reasearch - find a laptop built with this chip, it's very likely such thing exists since Yamaha chip is built for flat panels support.
I found a topic on stackexchange, there's a laptop built with V6366 (CGA/MDA/Hercules).
It's not the needed V6377, but that topic gives an idea - apparently laptops could have manuals detailed enough to include video chip's pinouts and port maps: http://bitsavers.trailing-edge.com/pdf/zenith … erence_1988.pdf
It's clear the chip is "register-compatible" only after the bios does some tinkering with yamaha-specific registers, so generic EGA stuff is a no-go.
But there's still hope, as not only the docs could be found, the video bios still might be reachable, provided the laptop model using V6377 is identified.

vstrakh wrote on 2023-03-01, 07:35:

Another option to reasearch - find a laptop built with this chip, it's very likely such thing exists since Yamaha chip is built […]
Show full quote

Another option to reasearch - find a laptop built with this chip, it's very likely such thing exists since Yamaha chip is built for flat panels support.
I found a topic on stackexchange, there's a laptop built with V6366 (CGA/MDA/Hercules).
It's not the needed V6377, but that topic gives an idea - apparently laptops could have manuals detailed enough to include video chip's pinouts and port maps: http://bitsavers.trailing-edge.com/pdf/zenith … erence_1988.pdf
It's clear the chip is "register-compatible" only after the bios does some tinkering with yamaha-specific registers, so generic EGA stuff is a no-go.
But there's still hope, as not only the docs could be found, the video bios still might be reachable, provided the laptop model using V6377 is identified.

Here is an InfoWorld article from February 1989 saying that the EPDC is meant for laptop use:
https://books.google.com/books?id=IToEAAAAMBA … %20bios&f=false
Sadly, no mention of specific models. But I think EPDC will be the term to search for, rather than any other name it may have.

Apparently the list of EGA laptops is quite short, but I found a forum thread where people mentioned a few Toshiba laptops that were EGA:
T1600
T3200 (non SX)
T5100

The T3200 and T5100 seem to be a little too old, with most sites listing them as 1987 to 1988. The T1600 being from 1989 was really promising and I even found some pictures (and a really nice YT video) of one being dismantled (meaning, someone likely owns one). Sadly, after looking a bit more, it turns out the EGA solution in this particular laptop is called, unsurprisingly, Toshiba Enhanced Graphics Adapter (first page)... so unless there is some connection between Toshiba and Yamaha, then it's likely to be a totally different device.

So, if there are EGA based laptops out there that use this chip, they likely aren't Toshibas. I would think this is an extremely small list of devices to look for... with even fewer still existing today.

It may be worth asking in that forum thread above. Amazingly, the posts about EGA laptops are only about a month old.

IT WORKS...thank you very much!!! 😀

The CityGate BIOS from Minuszerodegrees poweres up the card! I attach it here for reference. The IC doesnt look that different.

I also found that InfoWorld article but almost nothing else about EPDC. So my idea would also have been to find a Laptop with this chip and use its BIOS.

Predator99 wrote on 2023-03-01, 18:57:

IT WORKS...thank you very much!!! :-) […]
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IT WORKS...thank you very much!!! 😀

The CityGate BIOS from Minuszerodegrees poweres up the card! I attach it here for reference. The IC doesnt look that different.

I also found that InfoWorld article but almost nothing else about EPDC. So my idea would also have been to find a Laptop with this chip and use its BIOS.

Unknown EGA card - Main chip is CITYGATE D10.jpg
Unknown EGA card - Main chip is CITYGATE D10.zip

You're welcome! That's amazing! 😁

It was just a random crazy hunch.

By the way, I have a motherboard box full of EGA and CGA cards (as well as several EGA + VGA cards), so at some point I would like to contribute to your EGA BIOS thread. At this point, nearly all of them are untested, so when I test them I'll also dump the BIOS.

I tend to just use NSSI (dos application) to dump a video BIOS to a .VBI file. Do you think that's sufficient? That program makes it incredibly easy.

I dont see any problem in using NSSI here when the card is working.

Looking forward to your contributions, thank you 😀

Hi @Predator99 - I have the same card, it has an Award Bios on it,