butjer1010 wrote on 2025-07-23, 19:32:

So i did my fist try, hope it is ok. pin 1/244 to pin 1/pal pin 5/244 to pin 11/pal pin 10/244 to pin 10/pal pin 18/244 t […]
Show full quote

So i did my fist try, hope it is ok.
pin 1/244 to pin 1/pal
pin 5/244 to pin 11/pal
pin 10/244 to pin 10/pal
pin 18/244 to pin 11/pal
pin 20/244 to pin 20/pal

Will not connect until You gave me Your "blessing" 😀
Hope You can see on picture every wire i have solder.

OK, this will not work as is, but it wont damage anything as well. First, you have a typo in your description. Pin 18 of the 244 is connected to pin 13 of the PAL, not pin 11.

The supply voltage connections are fine: Pin 10 and Pin 20 copied from the PAL to the 74LS244 is perfect. Also, applying the enable signal to pin 1 is fine. But this enables these four buffers: Pin 2 to 18, pin 4 to 16, pin 6 to 14 and pin 8 to 12. You connected pin 18 to PAL pin 13. This is fine: pin 18 is a buffer output pin of a buffer that is controlled by pin 1. But that buffer takes it input on pin 2, not on pin 5! Actually, pin 5 is an output pin of a different buffer. You thus need to move the wire that connects pin 11/pal to pin 5/244 to pin2/244. Everything else looks fine.

mkarcher wrote on 2025-07-23, 21:35:

butjer1010 wrote on 2025-07-23, 19:32:

So i did my fist try, hope it is ok. pin 1/244 to pin 1/pal pin 5/244 to pin 11/pal pin 10/244 to pin 10/pal pin 18/244 t […]
Show full quote

So i did my fist try, hope it is ok.
pin 1/244 to pin 1/pal
pin 5/244 to pin 11/pal
pin 10/244 to pin 10/pal
pin 18/244 to pin 11/pal
pin 20/244 to pin 20/pal

Will not connect until You gave me Your "blessing" 😀
Hope You can see on picture every wire i have solder.

OK, this will not work as is, but it wont damage anything as well. First, you have a typo in your description. Pin 18 of the 244 is connected to pin 13 of the PAL, not pin 11.

The supply voltage connections are fine: Pin 10 and Pin 20 copied from the PAL to the 74LS244 is perfect. Also, applying the enable signal to pin 1 is fine. But this enables these four buffers: Pin 2 to 18, pin 4 to 16, pin 6 to 14 and pin 8 to 12. You connected pin 18 to PAL pin 13. This is fine: pin 18 is a buffer output pin of a buffer that is controlled by pin 1. But that buffer takes it input on pin 2, not on pin 5! Actually, pin 5 is an output pin of a different buffer. You thus need to move the wire that connects pin 11/pal to pin 5/244 to pin2/244. Everything else looks fine.

Yes, i did a typo, it is connected to pin 13/pal, not 11. I did make a change from 5 to 2, and now is ready to try it 😀
Will let You know of the results

Yesss! it works perfectly!!!!
Now just to see if this GAL is ok, i will order it, and sometimes when i will have enough time, i will try to program it with this file deunan sent me, and see if that works either. If not, i can always revert to this state!
Need to find brightness potentiometer for this monitor, and IO bracket for this graphics card, and my 2nd EGA PC is done 😀
Thanks to all geniuses here, i don't know how much i can thank You enough!!!!

butjer1010 wrote on 2025-07-23, 17:39:

As You said, it is in list of my T48 (ATF16V8B) https://www.ebay.com/itm/226559768634?_skw=AT … ABk9SR-iO54WHZg https://www.ebay […]
Show full quote

Deunan wrote on 2025-07-23, 17:02:

Before you buy make sure it's a type supported by your programmer. That's why I suggested ATF16V8B - I know this one works because I've used them myself.

As for F and LS series, both will work but F is meant for much higher switching speeds. It will draw more power, run hotter - this might matter if you place this new chip close to existing ones. It can also inject more noise into power rails if you don't put a capacitor nearby. I would prefer LS, ALS, or maybe a more modern HCT or ACT would be good enough for this as well.

As You said, it is in list of my T48 (ATF16V8B)
https://www.ebay.com/itm/226559768634?_skw=AT … ABk9SR-iO54WHZg
https://www.ebay.com/itm/204789149078?_skw=AT … ABk9SR96wh4aHZg
Hope those ones are ok?
Ok, than F is out 😀
I have found GAL16V8D-25QP-LATTICE in one local shop, so it could arrive next day if this one is ok. I have it in T48 database, but is it ok for this job?
Thanks

I still didn't get answer if those 2 are ok. Should i order one of them to program it?

Yes, those will work, provided the chips are not fake or damaged somehow.

Deunan wrote on 2025-07-24, 19:28:

Yes, those will work, provided the chips are not fake or damaged somehow.

Thanks man, that's way i search in Europe, not China (hope for the best).
Will order one right....

Out of curiosity, why order from ebay and not a from electronic seller like tme.eu for example? In TME these chips (B, BQL and even the newer C variant) are less then 2EUR a piece. Shipping cost is probably the same. I go on ebay and such when I look for obsolete chips that nobody stocks anymore, but everything else I try to buy new.

Deunan wrote on 2025-07-25, 20:44:

Out of curiosity, why order from ebay and not a from electronic seller like tme.eu for example? In TME these chips (B, BQL and even the newer C variant) are less then 2EUR a piece. Shipping cost is probably the same. I go on ebay and such when I look for obsolete chips that nobody stocks anymore, but everything else I try to buy new.

Only because right now i don't need anything else. TME or Mouser had very high shipping costs to Croatia (around 20e). Only when i order more than 50e it is free.

Hello, my EGA-VGA card similarly causes my XT to give the same beeps:l 1 long beep, 8 short
i was quite impressed by this thread, the tips to use DEBUG.EXE and how you eventually zeroed in on the bad 74LS244.

I was hoping maybe I could get some suggestions from you guys on what I can check with my scope to
determine which part of the card is bad ? thanks

hires pics/data sheet can be found here OAK OTI-037C based mda/cga/ega/vga

randi wrote on 2025-08-02, 08:03:

Hello, my EGA-VGA card similarly causes my XT to give the same beeps:l 1 long beep, 8 short i was quite impressed by this th […]
Show full quote

Hello, my EGA-VGA card similarly causes my XT to give the same beeps:l 1 long beep, 8 short
i was quite impressed by this thread, the tips to use DEBUG.EXE and how you eventually zeroed in on the bad 74LS244.

I was hoping maybe I could get some suggestions from you guys on what I can check with my scope to
determine which part of the card is bad ? thanks

hires pics/data sheet can be found here OAK OTI-037C based mda/cga/ega/vga

Those guys are geniuses!!!
My lovely Ega is in my 386 now, and i'm playing space Quest 3 😀

randi wrote on 2025-08-02, 08:03:

I was hoping maybe I could get some suggestions from you guys on what I can check with my scope to
determine which part of the card is bad ?

Scope is a great tool but it needs to be targeted use, otherwise you'll end up probing a lot of places with questionable results. Preferably you should try the DEBUG route as well, but that requires a mono card (MDA or Hercules, or clone) and a suitable monitor for that.

What you can do right now:
- Note DIP switch position and try all combinations, there's only 16 in your case.
- Check if all the crystal generators do output correct frequency and level (this can be easily done by probing on the card back when in the slot)
- Try the card in 8-bit slot, some of them work and have auto-detection, that bypasses the upper 8 bits of the data bus
- Remove the EPROMs and dump them to check for valid image (one could've died or got corrupted for example), that will requrire EPROM reader/programmer

Which of these can you do, and what are the results?

Those are DIP Switch positions on my Oti 037 EGA/VGA card. Maybe these are the same like on Your card?

Deunan wrote on 2025-08-03, 09:16:

Scope is a great tool but it needs to be targeted use, otherwise you'll end up probing a lot of places with questionable results […]
Show full quote

Scope is a great tool but it needs to be targeted use, otherwise you'll end up probing a lot of places with questionable results. Preferably you should try the DEBUG route as well, but that requires a mono card (MDA or Hercules, or clone) and a suitable monitor for that.

What you can do right now:
- Note DIP switch position and try all combinations, there's only 16 in your case.
- Check if all the crystal generators do output correct frequency and level (this can be easily done by probing on the card back when in the slot)
- Try the card in 8-bit slot, some of them work and have auto-detection, that bypasses the upper 8 bits of the data bus
- Remove the EPROMs and dump them to check for valid image (one could've died or got corrupted for example), that will requrire EPROM reader/programmer

Which of these can you do, and what are the results?

Thank you for chiming in on this card as well. I suggest we continue the troubleshooting in the thread randi opened for that card, which is OAK OTI-037C based mda/cga/ega/vga to avoid duplication. I alreday wrote down an initial reverse engineering of that card and some DEBUG suggestions. BIOS is fine, and can be read in an XT with an MDA/Hercules card, as that thread says.

Hi again!!!
Just wanted to share great news with You all!!!
Even though card worked with 74LS244 buffer chip, today arrived ATF16V8b, and i programmed it with this jed file Deunan sent me!!! Everything works without buffer chip, so this thread now can officially be marked as SOLVED!!!!
Thanks again for all the help, especially to Deunan and mkarcher!!!!!