following this 😀

What is your ISA bus speed?

BitWrangler wrote on 2026-01-23, 16:03:

What is your ISA bus speed?

Sorry, i didn't mention that everything works with my other EGA card!

But still, anything over 10mhz and you're in the silicon lottery zone, some work some don't.

BitWrangler wrote on 2026-01-23, 17:32:

But still, anything over 10mhz and you're in the silicon lottery zone, some work some don't.

I don't know, i tried that card on some old pentium 75MHz. Do You think it would work ok on some 286, 386,...?
I bought that card like non working.... Sometimes it works, sometimes it doesn't

This is the screen when it won't work 😀

butjer1010 wrote on 2026-01-23, 17:36:

BitWrangler wrote on 2026-01-23, 17:32:

But still, anything over 10mhz and you're in the silicon lottery zone, some work some don't.

I don't know, i tried that card on some old pentium 75MHz. Do You think it would work ok on some 286, 386,...?
I bought that card like non working.... Sometimes it works, sometimes it doesn't

Usually pentium boards have ISA on a fixed frequency of half the reference crystal 14.313whatever/2 so 7 and a bit so that should be okay

BitWrangler wrote on 2026-01-23, 18:12:

butjer1010 wrote on 2026-01-23, 17:36:

BitWrangler wrote on 2026-01-23, 17:32:

But still, anything over 10mhz and you're in the silicon lottery zone, some work some don't.

I don't know, i tried that card on some old pentium 75MHz. Do You think it would work ok on some 286, 386,...?
I bought that card like non working.... Sometimes it works, sometimes it doesn't

Usually pentium boards have ISA on a fixed frequency of half the reference crystal 14.313whatever/2 so 7 and a bit so that should be okay

Somehow i think the best thing to start is to replace old one sided sockets? This look like RAM error to me, but i tested all the chips, and they are ok.

You’ve mentioned that it crashes after 5 to 10 minutes: is this measured started from a cold system? If you hard reset the system after a crash and start Prince of Persia again, is it still 5 to 10 minutes or does it crash sooner? Perhaps you can repeat this process a few times. If you end up with a crashing system in under 5 minutes there might be a correlation with the card/chips heating up. Doesn’t particularly point to the exact problem but might help in the problem solving strategy 😉 (for instance a bad solder joint)

Hi,
first time it crashed in about 2 minutes (before i could take sword on first level), and then it worked for 6-7, and every other time around 5-7 minutes (2nd level on prince). I tried the chips, they all were cool, neither one was hot.

That doesn't seem like a RAM problem.

If you can immediately reboot and be back to normal, I doubt it is a thermal issue then. Can you sit on the DOS prompt for 10 minutes and still function?

I agree with others. What kind of system is this being run in? Try the card in another computer.

Maybe a borderline capacitor ready to pretend it's the 4th of july? After a few minutes of operation, it falls too far out of spec, and causes logic errors?

Shame there's not a thermal camera that could be used.

the3dfxdude wrote on 2026-01-23, 20:36:

That doesn't seem like a RAM problem.

If you can immediately reboot and be back to normal, I doubt it is a thermal issue then. Can you sit on the DOS prompt for 10 minutes and still function?

I agree with others. What kind of system is this being run in? Try the card in another computer.

Yes, if I'm not playing games, it works. Card was tested in another computer with same error, an as i wrote before, another EGA (and every other) card works ok in this computer.

wierd_w wrote on 2026-01-23, 20:48:

Maybe a borderline capacitor ready to pretend it's the 4th of july? After a few minutes of operation, it falls too far out of spec, and causes logic errors?

Shame there's not a thermal camera that could be used.

I could replace this one, no problem. Don't have thermal camera, bat as i said, there is no hot chip while playing Prince...
It says 4.7 16
Is it 4.7 micro f or on tantalum is in nano?

butjer1010 wrote on 2026-01-23, 20:52:

I could replace this one, no problem. Don't have thermal camera, bat as i said, there is no hot chip while playing Prince... It […]
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wierd_w wrote on 2026-01-23, 20:48:

Maybe a borderline capacitor ready to pretend it's the 4th of july? After a few minutes of operation, it falls too far out of spec, and causes logic errors?

Shame there's not a thermal camera that could be used.

I could replace this one, no problem. Don't have thermal camera, bat as i said, there is no hot chip while playing Prince...
It says 4.7 16
Is it 4.7 micro f or on tantalum is in nano?

Besides the one tantulum in the lower right, there really isn't any cap that really should have that ability to cause enough ripple to cause a malfunction. And the tantulum in the corner, those types of caps are quite reliable, despite the youtube meme. Replacing those caps are likely a waste of time.

If you are worried about caps, I would look first at the power supply itself. Which again, you should just try the EGA card in another computer that has a different power supply. You'll know pretty quick where the problem is now isolated to.

Of course, it's not clear again, what kind of computer this is running in. Making sure this card is running on a normal ISA clock bus is nice to know for this question.

let me chime in because this used to be my card - the problem definitely comes from the card itself and not the PSU, bus speed or any other external factor - it exhibited the same behaviour when I had it and I used it in a 286 system.

MMaximus wrote on 2026-01-23, 21:08:

let me chime in because this used to be my card - the problem definitely comes from the card itself and not the PSU, bus speed or any other external factor - it exhibited the same behaviour when I had it and I used it in a 286 system.

Thanks.
As i mentioned earlier, i tried this card on other computer, You tried on Yours, and it had same behavior! And another cards are working on this computer! So the problem is in the card! PSU is ok, trust me, like motherboard, cpu and ram. It work fantastic with another card.

It's actually quite difficult for an ISA to freeze the whole system in a Pentium system. I'm afraid it's likely because one of the core chips is broken, that is the P82C435 or P82C436. There are two possible reasons why Prince of Persia might freeze: It might be due to the EGA card freezing the ISA bus, or it might be due to Prince of Persia waiting for the start or end of the vertical sync, and the card not reporting the sync state correctly. To distinguish between these two possibilities, you can take a look at the ISA signal IOCHRDY (location: A10). If the EGA card freezes the ISA bus, IOCHRDY will be permanently low. If Prince of Persia spins in a loop waiting for the vertical synchronization, it will repeatedly poll the input status #1 register, but there won't be other ISA activity. You can observe that by IOCHRDY being high, /MEMW, /MEMR and /IOW being high as well, but /IOR pulsing (reading a lower voltage on a DC meter than /MEMW, /MEMR and /IOW).

If you happen to have another EGA card using the C&T P82C435/P82A436 chipset, try swapping the chips.

mkarcher wrote on 2026-01-23, 23:45:

It's actually quite difficult for an ISA to freeze the whole system in a Pentium system. I'm afraid it's likely because one of the core chips is broken, that is the P82C435 or P82C436. There are two possible reasons why Prince of Persia might freeze: It might be due to the EGA card freezing the ISA bus, or it might be due to Prince of Persia waiting for the start or end of the vertical sync, and the card not reporting the sync state correctly. To distinguish between these two possibilities, you can take a look at the ISA signal IOCHRDY (location: A10). If the EGA card freezes the ISA bus, IOCHRDY will be permanently low. If Prince of Persia spins in a loop waiting for the vertical synchronization, it will repeatedly poll the input status #1 register, but there won't be other ISA activity. You can observe that by IOCHRDY being high, /MEMW, /MEMR and /IOW being high as well, but /IOR pulsing (reading a lower voltage on a DC meter than /MEMW, /MEMR and /IOW).

If you happen to have another EGA card using the C&T P82C435/P82A436 chipset, try swapping the chips.

Hi,
thanks for the explanation. So i guess the problem isn't simple as i thought it will be 🙁 (like memory or sockets)
I think i don't have another EGA card with those chips, i have one with paradise (You helped me fix it), and one OTI (VGA/EGA/CGA/MDA) 037.
Will try tomorrow morning to check voltages on A10 as suggest.