Hi tauro,

I don't know what the hardware differences are, between the v1.2 and v1. 3 boards.

But looking at an archived copy of Soyo's website, I see they specified the rev EH-1DA1 BIOS for all 5EH v1. 0, v1. 1, v1. 2, and v1. 3 boards. The EH-1DA2 BIOS however is only indicated for the v1. 3 board.

https://web.archive.org/web/20020613235131/ht … d586=5EH&bios=1

I think the EH-1DA2 BIOS will work on the other board versions as well, but was simply never validated by Soyo. If you have an EEPROM programmer, you can try to validate this yourself. 😉

Cheers, Jan

Hey Jan!

Thanks for that link, it's very enlightening.

So 1DA1 should be the latest BIOS for v1.2 according to SOYO themselves.

I tried it and after some basic testing I noticed some instabilities (Write fault error reading C) that I hadn't noticed with the original 1CA2 BIOS. Also, that BIOS includes in its name "5EH V1.2", instead of "5EH Family", as the 1DA1 does.

So I decided to go back to the original 1CA2 BIOS, but now I notice that my dump has a different checksum from the archived rom.
Here are both, my original dump and the archived rom. Maybe mine got corrupted?

Chkcpu wrote on 2025-05-27, 15:08:

I think the EH-1DA2 BIOS will work on the other board versions as well, but was simply never validated by Soyo. If you have an EEPROM programmer, you can try to validate this yourself. 😉

I briefly tried the 1DA2 (the one advertised as being only for the v1.3) on the v1.2 and it apparently worked fine.

It would be very interesting to try all three BIOSes and see if there are performance differences, benefits/problems. Can you think of any tests to find out which one is better or rather to find the possible incompatibilities/bugs?

I have the suspicion, call it a hunch, that the 1CA2 is the better choice for this motherboard.

Also, how can I set my L2 cache to WT? I can't find the option and I'm using 128 MB on a 512KB L2 motherboard.

tauro wrote on 2025-05-27, 17:10:

Hey Jan! […]
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Hey Jan!

Thanks for that link, it's very enlightening.

So 1DA1 should be the latest BIOS for v1.2 according to SOYO themselves.

I tried it and after some basic testing I noticed some instabilities (Write fault error reading C) that I hadn't noticed with the original 1CA2 BIOS. Also, that BIOS includes in its name "5EH V1.2", instead of "5EH Family", as the 1DA1 does.

So I decided to go back to the original 1CA2 BIOS, but now I notice that my dump has a different checksum from the archived rom.
Here are both, my original dump and the archived rom. Maybe mine got corrupted?

The attachment 5EHM.v1.2.BIOS.1CA2.original.dump.BIN.7z is no longer available

The attachment 5eh1ca2.bin.7z is no longer available

Chkcpu wrote on 2025-05-27, 15:08:

I think the EH-1DA2 BIOS will work on the other board versions as well, but was simply never validated by Soyo. If you have an EEPROM programmer, you can try to validate this yourself. 😉

I briefly tried the 1DA2 (the one advertised as being only for the v1.3) on the v1.2 and it apparently worked fine.

It would be very interesting to try all three BIOSes and see if there are performance differences, benefits/problems. Can you think of any tests to find out which one is better or rather to find the possible incompatibilities/bugs?

I have the suspicion, call it a hunch, that the 1CA2 is the better choice for this motherboard.

Also, how can I set my L2 cache to WT? I can't find the option and I'm using 128 MB on a 512KB L2 motherboard.

Hey tauro,

I’m away from home this week and only took my phone along. So I have no means to examine you BIOS dumps, but will do that next week when I’m back home.

However, a changed checksum on you own 1CA2 backup is not unusual because the BIOS uses a small section of the EEPROM to store it’s PnP data. This so called ESCD block is usually located at offset 1D000h on a 128KB BIOS.
When downloading an archived BIOS this 4KB ESCD block contains PnP data from another board, or is just empty and filled with FFh bytes.

So chances are good your own backup is fine.
Can you do a binary file compare between these two BIOSes and tell us the outcome?

Greetings, Jan

Chkcpu wrote on 2025-05-28, 19:59:

So chances are good your own backup is fine.
Can you do a binary file compare between these two BIOSes and tell us the outcome?

Greetings, Jan

Nowadays I use a hexeditor with file compare function for that, but the file compare tool from DOS works equally well. Use the DOS comnand:

FC /B BIOS1.BIN BIOS2.BIN > DIFF. TXT

This command will cause a byte for byte compare between the two files and sends it’s output to a textfile.
If you post this DIFF.TXT here, I can tell you if these BIOSes are okay.

Cheers, Jan

Hi tauro,

I just got home and took a quick peek into your SY-5EHM BIOSes.
The two 1CA2 versions you put in your last reply are different BIOSes and can’t be compared with a File Compare tool. So disregard my previous message.

Your own 5EHM V1.2 original dump is a 10/21/1999-VP3-586B-8669-2A5LES2AC-00 BIOS with an 5EH V1.2-1CA2 sign-on message.
When comparing this BIOS with the download from https://theretroweb.com/motherboards/s/soyo-s … 5-1-2-mvp3#bios I find that they are identical. So your own 5EH BIOS backup has no corruption and is valid, and can safely be flashed back on your board.

The other 5EH1CA2.BIN from the archive is a slightly older 08/03/1999-VP3-586B-8669-2A5LES2AC-00 BIOS with an EH-1CA2 sign-on.
This BIOS appears to be for another board revision and I found an identical copy at https://theretroweb.com/motherboards/s/soyo-sy-5eh5-1-1#bios
So this 1CA2 BIOS is for the Rev 1.1 board.

It's very confusing that Soyo used the same 1CA2 BIOS version number for non-identical BIOSes for different board revisions.
When I have more time, I will look into these 5EHM BIOSes more closely, and I will look for a possible L2 cache WT mode setting as well.

Greetings, Jan