Hi, i've just registered to this nice forum to answer your question 😀 actually i have the exact same problem.

I also have the abit pb4, seems to have some issues with isa pnp audio cards in windows 95.
my pc: 5x86 133 , 32meg ram , 256k cache , s3 pci video

I've tried : awe 64 - not recognized
ct 2950pnp(sb16) - not recognized
ess 1868 f - not recognized
yamaha xg PCI -pnp sees it, but i have driver problems
sb 128 PCI -pnp sees it installation program aborts, saying that i need at least a P133 🙁
ALAS! Iv'e tried a
ess 1688 -recognized! And working in windows. <-- by the way this card is the only one to have irq and address jumpers on- board

1 out of 6
on the other hand , an ISA 3com parallel tasking 3 that has issues on my other 2 expertboard and hp 486 motherboards works flawlessy fine.

I've tried messing with the bios irq management, but it's quite cryptic, and changing to manual irqs was even worse

Hello, thanks for answer, great that this card works for you 😀 actually, I managed to find an ultimate fix for this problem - I just replaced the BIOS chip (the old-type EPROM ceramic chip) with an new 1MBit Flash memory, flashed with newest available BIOS. I did it by hot-flashing (that was risky, it would be best to ask someone to program a BIOS chip for you), PnP now works correctly, it is important to have FLASH memory and not EPROM, because PnP BIOS needs to write some values into flash in order to work. If you would like to improve your system further feel free to ask any questions.

Wow, that's very interesting, i might want to do that too!

i already have the right equipment to read eproms (also UV light to erase' em and so on) but i also have some programmers i use for microcontrollers.

May i ask where did you find this new BIOS and what kind of flash chip you need to replace the old eprom?

I used 29EE010 (that's EEPROM actually, but I think it works the same as flash), it's a 1mbit chip, pulled from a broken Pentium 1 board. I think that only the capacity and electrical compatibility matters. Just don't use another UV EPROM.

Here you can see the jumper settings correct for use with flash (I don't remember the details, but it probably changes the voltage).
(I have rev. 1.3 mainboard)

I attach the BIOS image I have used.
And the manual 😀

Here is probably the official FTP in case you need it,
http://abit.ws/file.abit.com.tw/pub/download/ … pb4/default.htm

but these files are compressed in some weird formats, especially the manual (it is an executable PDF-viewer, works only in win 9x, I managed to convert that into PDF file)

Thank you very much, this is really helpful.
I agree, eeproms usually work at 5 volts , eprom Vcc is 12 volts if i remember correctly, so i must be really careful to set the right jumpers too

Once i'll find the right eeprom i'll do some experiments too!

Eprom Vcc is 5v, they use +12v when they are being programmed.

Nearly all motherboards except some 486 and lower use eeproms, and there is a part of the chip that can be written to by the motherboard/OS/Hardware.
I used a UV eprom in my Pcchips Pentium motherboard and got an error at boot time as a result. Aside from that it seemed to work ok, but the time was out
after it was off.

Some even program at higher voltages, one such example is an unusually large Hitachi EPROM I saw on an unusual 386 board which had a programming voltage of 13.5 and I have heard of some using 16.5. This is highly unlikely on regular boards and all the ones I've tried will take EEPROMs to read just fine, just don't try flashing them in-board on the off-chance someone tried to be clever.

I have little to offer this thread but wanted to say thanks for posting the ABIT link as it seems to contain a BIOS for my PS5 which may be different to the one I have been using. Curiosity is getting the better of me and I might have to test that out.

Many of my dads EPROMs are from the 70s and require a voltage of 21v to 24v for programming.
A few of them are so old, that they need a long time exposure of UV light until they are erased.

I did it, Adalbert!

I have tried this intel 1 megabit eeprom. I've programmed it with my tl866 programmer, a cheap but nice chinese programmer you can find on Ebay. It's plcc32 so i had to use that DIP adapter you can see in the picture. It all went smooth, i did change the rightmost jumper near the old EPROM and installed the new EEPROM.

It's alive! I'm very happy now. I've immediately noticed the new detection list at startup

and the new PnP lines in BIOS

Thanks again, now all 'newer' 🤣 PCI and ISA cards are recognized in windows 95