I think it's possible. Although there are restrictions and rules.
For example, a bios image is protected by a checksum. The modules can be also protected with their own checksum. So editing using HEX editor only may cause a checksum error.
AMI branded utilities are AMIBCP and MMTool. I don't know which version will work for your bios image.
There're some utils here.
BTW it's better to have a hardware programmer and a flash memory placed in a socket if something goes a wrong way.

Ok thank's I found the programs, earlier DOS versions that working with 256k AMi bios, but the unbranded bios hasn't entry to put Tulip Computers logo, only the name on the string.

Anyway, the Tulip branded bios has the windows based AMI bios, strange I never saw it on non 486 class motherboards.

Hello, I would like to add microcodes to the AMI BIOS for a 440GX motherboard, but I can't find a suitable version of MMTool anywhere. Could you share a link, because this link no longer works.

chubabs wrote on 2026-05-09, 18:39:

Hello, I would like to add microcodes to the AMI BIOS for a 440GX motherboard, but I can't find a suitable version of MMTool anywhere. Could you share a link, because this link no longer works.

Which is the version of AMI BIOS ? What is a model of the mainboard?
Try to apply the latest version of the BIOS Patcher:
https://www.vogonsdrivers.com/getfile.php?fil … 241&menustate=0
It does lots useful things but I don't know exactly if it helps with the microcodes

Thank you, that was actually the first thing I did, but unfortunately the BIOS patcher doesn't work well with AMI BIOS. Although it successfully updated the BIOS, after checking the microcodes using IntelmicrocodeList, they weren't there. I unfortunately couldn’t find a working MMtool version lower than 3.x; there is MMtool beta 2.22 on Web Archive, but unfortunately it didn’t work properly. So I used amibcp to extract the microcode module, edited it in a HEX editor, and put it back.

chubabs wrote on 2026-05-10, 21:08:

Thank you, that was actually the first thing I did, but unfortunately the BIOS patcher doesn't work well with AMI BIOS. Although it successfully updated the BIOS, after checking the microcodes using IntelmicrocodeList, they weren't there. I unfortunately couldn’t find a working MMtool version lower than 3.x; there is MMtool beta 2.22 on Web Archive, but unfortunately it didn’t work properly. So I used amibcp to extract the microcode module, edited it in a HEX editor, and put it back.

I'm glad you found a solution.
I found some old mmtools. But I don't know if they would work for you or work at all. Though you can try them and give feedback here.

Roman555 wrote on 2026-05-11, 06:07:

chubabs wrote on 2026-05-10, 21:08:

Thank you, that was actually the first thing I did, but unfortunately the BIOS patcher doesn't work well with AMI BIOS. Although it successfully updated the BIOS, after checking the microcodes using IntelmicrocodeList, they weren't there. I unfortunately couldn’t find a working MMtool version lower than 3.x; there is MMtool beta 2.22 on Web Archive, but unfortunately it didn’t work properly. So I used amibcp to extract the microcode module, edited it in a HEX editor, and put it back.

I'm glad you found a solution.
I found some old mmtools. But I don't know if they would work for you or work at all. Though you can try them and give feedback here.

Thanks so much, I looked everywhere and couldn't find it =)