Hi everyone,

so, I have made it work, heh. It seems that the only issue on the board was the damaged chipset, and bent legs, and a few of them were torn away from the board.
After seating the CPU there, AM486 DX40, it booted up. It seems that there is no documentation on the board - at least I didn't find any and thus I am not sure about a few jumpers to which I couldn't find any print on the mobo.

I had a hard time setting up the RAM. It has 4x 30pin and 2x 72pin slots. Without populating the 30pin slots, the motherboard will not start. After filling the 30pin slots, it will but again, after filling the additional 72pin slots, it will not start. A combination that worked for me was 1x 72pin and 4x 30pin slots with a total of 8MB. Nevertheless, I will try more combination when some RAM will arrive later on. It seems that there is nothing wrong with the motherboard and the new BIOS battery work as well.

thx, tomas

Well the BIOS ID says it is a Dataexpert. There is a manual for the 4407 but not 4407G Ver2 : https://theretroweb.com/motherboards/s/dataexpert-exp4407
Gemlight also used those chipsets but nothing much good found yet....

its ane early 486 chipset so remember it doesnt support EDO ram

thank you both for your answer

Horun wrote on 2022-09-24, 17:03:

Well the BIOS ID says it is a Dataexpert. There is a manual for the 4407 but not 4407G Ver2 : https://theretroweb.com/motherboards/s/dataexpert-exp4407
Gemlight also used those chipsets but nothing much good found yet....

Yes, the NSSI report is as well stating that the board is from DataExpert but I couldnt find any reference to the board online. Only some pictures of already assembled boards for sell. However, I have checked the jumper settings in the manual you have linked and as well, once more, the print on the board I have and it seems it is set right for this type of CPU. Well, it is working so I guess it is done right.

rasz_pl wrote on 2022-09-24, 19:31:

its ane early 486 chipset so remember it doesnt support EDO ram

Thank you, this makes sense and would explain why I had such a hard time to find suitable combination and RAM sticks for it. As for now, 8MB is running nicely, I hope the second 72pin slot is not damaged but I am awaiting another sticks to arrive soon so I will try more combinations.

thx again, tomas

Hi Tomas,

Thanks fort he BIOS dump from this interesting board!
As I was curious after this rare Award Unichip BIOS, I tried to open it with Modbin but was met by a checksum error. Opening the BIOS with a Hexeditor, I quicky found that your BIOS is a dump from shadow RAM. The presence of both User definable Harddisk tables is a clear giveaway. 😉

As I know how most of these uncompressed Award v4.50 and v4.50G BIOSes alter themselves in Shadow RAM, I was able to reverse this process and restore the BIOS to its original EPROM state.
A check with Modbin was fine and showed me an interesting 1993 early 486VLB BIOS. 😀

So if you want to send this nice EXP4407G Ver2 picture and BIOS to The Retro Web, please use the corrected BIOS below.

Greetings, Jan

or disable bios shadowing and do another bios dump

rasz_pl wrote on 2022-09-27, 19:42:

or disable bios shadowing and do another bios dump

Yes, that would have been simpler. 😉

This 4407G Ver2 BIOS indeed has a "System BIOS Shadow" option that can be Disabled. I wasn't expecting that...
I know this option is common in 286/386 BIOSes, but checking a few early (1993/1994) 486 ISA/VLB BIOSes, I see this option as well. 😀

Later 486 (PCI) BIOSes lack this option and are always shadowed to RAM.

Cheers, Jan