For the life of me I cannot find the bios files. I was able to find a startup disk online however, that wont help me since it wont even post.

I know its kinda rare for the bios chip to just up and fail, but the bios itself is just an eeprom with a label on it, so im wondering if those just dont last as long. Trying to check everything else as well, but alas, still that same beep code

Do you have access to an EPROM programmer? Dump the BIOS, the checksum can be tested in the binary image. This would at least tell you if the image is corrupted (and so the chip has failed) or is it a mobo problem.

Deunan wrote on 2021-05-10, 23:23:

Do you have access to an EPROM programmer? Dump the BIOS, the checksum can be tested in the binary image. This would at least tell you if the image is corrupted (and so the chip has failed) or is it a mobo problem.

I will on wednesday. I bought one. Ive been kinda wanting one for some other projects.

Without asking too much, do you know where i could get somw info on how to test the image? Thanks!

BIOS extensions (like video card BIOS, SCSI, etc) have rules - you can look that up, but the mobo BIOS itself can do it in any way, or even not check at all. Typically though the checksum is computed by adding all the bytes of the image and the result should be zero (that is, after masking it to just 8 bits obviously). All bytes are treated as unsigned values of 0-255. Again typically it's the last byte of the image that will be set by manufacturer to make up that final value to end up with zero.

TL;DR: Add all bytes. The least significant byte of the result should be zero. If it's not you can assume it's a problem with the BIOS image.

Deunan wrote on 2021-05-10, 23:56:

BIOS extensions (like video card BIOS, SCSI, etc) have rules - you can look that up, but the mobo BIOS itself can do it in any way, or even not check at all. Typically though the checksum is computed by adding all the bytes of the image and the result should be zero (that is, after masking it to just 8 bits obviously). All bytes are treated as unsigned values of 0-255. Again typically it's the last byte of the image that will be set by manufacturer to make up that final value to end up with zero.

TL;DR: Add all bytes. The least significant byte of the result should be zero. If it's not you can assume it's a problem with the BIOS image.

Thank you!! I appreciate it

My Rom Reader came in today. It appears to be able to read the Bios just fine. I created a dump of it. There is also the VGA bios, and that seemed to read ok and i created a dump of that too.

Not sure what I am really looking at in the software, the last bit on the bios seems to end in 00, and the vga bios ends in FE, is that where i am looking to verify if its ok?

This software shows for instance...

Checksum: 0x002c 7F5c Size 0x8000

Don't use the programmer software checksums, you don't know what and how they calculate. Maybe it's 16-bit or not even a checksum but CRC. Just write your own script to calculate that. Or post the mobo BIOS image here.
As for VGA BIOS, just like any other BIOS extension it has to follow specific rules, alhough there's also a requirement for it to be mapped at specific memory location:
https://en.wikipedia.org/wiki/BIOS#Exte ... tion_ROMs)
https://en.wikipedia.org/wiki/Option_ROM

Deunan wrote on 2021-05-14, 10:05:

Don't use the programmer software checksums, you don't know what and how they calculate. Maybe it's 16-bit or not even a checksu […]
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Don't use the programmer software checksums, you don't know what and how they calculate. Maybe it's 16-bit or not even a checksum but CRC. Just write your own script to calculate that. Or post the mobo BIOS image here.
As for VGA BIOS, just like any other BIOS extension it has to follow specific rules, alhough there's also a requirement for it to be mapped at specific memory location:
https://en.wikipedia.org/wiki/BIOS#Exte ... tion_ROMs)
https://en.wikipedia.org/wiki/Option_ROM

Heres an upload of the both Bios files I was able to dump. Not sure how to calculate

So the VGA BIOS looks OK - I mean it's a bit weird that it's header says it's only 24KiB long, but the checksum does match that entire area, so it's unlikely be a coincidence.
Now the mobo BIOS doesn't pass the checksum test, but possibly it's not calculated the usual way. I'd have to disassemble it to check further but I have no time for that at the moment... But if you want to try, get another EPROM, replace the last byte, which is 0x00 now, with 0x5D and program that, then try in the mobo. Even if the BIOS is glitched chances are it's not in a place you'll need to boot, so maybe it will work. Or at least give you different beeps or something, so that way you'll know it's bad.

Deunan wrote on 2021-05-17, 00:06:

So the VGA BIOS looks OK - I mean it's a bit weird that it's header says it's only 24KiB long, but the checksum does match that entire area, so it's unlikely be a coincidence.
Now the mobo BIOS doesn't pass the checksum test, but possibly it's not calculated the usual way. I'd have to disassemble it to check further but I have no time for that at the moment... But if you want to try, get another EPROM, replace the last byte, which is 0x00 now, with 0x5D and program that, then try in the mobo. Even if the BIOS is glitched chances are it's not in a place you'll need to boot, so maybe it will work. Or at least give you different beeps or something, so that way you'll know it's bad.

I appreciate you looking at it. What software would I use to make those changes. Im using XGpro to dump the bios, just not really sure how to change the last byte. Thanks again!

Most software for programmers have built-in hex viewer with a simple editing mode, that should be enough to change the last byte. If not, get yourself a copy of HxD hex editor, it's simple and small enough.

otherwise dump it here, I think more than one of us has a license for WinHex or similar.

I appreciate your help in all this. so please thank you again.
I got some eproms that should be arriving tomorrow, and I think i see what you mean.. heres a screenshot of what im looking at

Basically I highlighted in red the last 00 i see, so i wanna change that to 5d? (i notice on the "output " side that adds in a bracket like ])

90skidJohnny wrote on 2021-05-17, 23:08:

Basically I highlighted in red the last 00 i see, so i wanna change that to 5d? (i notice on the "output " side that adds in a bracket like ])

Er, how is it the last 00 if there are way more after it? Did you mean first? And anyway that's not the place. The last one, as in the very last byte of the file, which should be way lower still as you scroll down (at hex address 7FFF).

Ah ok! That was the last 00 i saw, so the last FF is where it will be. So basically change the last FF to 5D

Sorry, Been a Long Day 🤣 Like this? 😀

Yes, except now you have a wrong file (or no file) loaded since it's full of FF, the last byte should've been 00.

Deunan wrote on 2021-05-18, 00:20:

Yes, except now you have a wrong file (or no file) loaded since it's full of FF, the last byte should've been 00.

Thats how the file goes It ends in some 00's, but then starts FF's

OK, my bad. You have set the chip to 27C256, which is 32KiB device, but the dump you've made is 64KiB long from a 27C512 type chip. I should've paid more attention. In my defense I sometimes deal with older 286 mobos that have two smaller chips instead of one big so I didn't find it odd.

So, set the correct chip type and the software will allow full 64k image to be loaded from file (and edited). The actual last address is FFFF not 7FFF.