AMI Bios Mod - looking for help :)

Only for programmers and BIOS gurus with technical questions.
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Stoney
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Joined: Fri Jun 23, 2006 9:26 am

Wed Feb 20, 2008 9:48 am

Used utilities :
MMTool V3.12
Amimmwin/dos

Problem :
When I extract the System Bios File from the Bios image (ID 1B) and replace it inside the Bios image the file becomes unusable (same problem using amimmwin/dos or mmtool - no change at all)
- it can be flashed without a problem - but after this the system wont boot any more - just black screen - so I flash the unchanged original Bios again and everything is fine :roll:

I dont even change anything inside the file itself - just extract the file and replace and still the same problem so I suppose there is something else to do like recalculating the checksum or something like that in order to get a working bios file again?

With Award Bios this was simple by using modbin after doing changes with cbrom but what needs to be done with an AMI Bios in order to get it working ?

Thanks in advice
edwin
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Wed Feb 20, 2008 7:11 pm

what board, what bios version, where did you get your mod utilities from?
edwin/evasive

Do not assume anything

System error, strike any user to continue...
Stoney
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Posts: 4
Joined: Fri Jun 23, 2006 9:26 am

Thu Feb 21, 2008 9:57 am

1. Biostar TA780G Mainboard :
http://www.biostar.com.tw/app/en-us/t-s ... p?S_ID=344

2. The utilities come from the "Tool_8_RC1.Rar" Archive which can be found easily on various pages :)

3. Core Version : 08.00.14 / Rombuild Version : 4.18
RebelsHaven
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Thu Feb 21, 2008 6:33 pm

Could you post a zipped copy of the BIOS? I have a few tricks to try :D
Stoney
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Fri Feb 22, 2008 10:38 am

Here you find the Original Bios File without any change at all

Bios File

As soon as I just extract the 1B Systembios and replace it inside the file its not working any more.... eventhough the Ami Flash program says that all checksums are alright etc.

Tried it with mmtool and amimmwin - same problem with both programs

Sidedetail is that comparing the original bios file and the new one (after replacing the systembios) the hex editor finds various changes - so I suppose that one of these is the reason for the problem ?
indianoutlaw187
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Sun Jun 29, 2008 9:00 am

The very first instruction at the CPUs reset vector is a jump instruction that points to some real code. My suspicion is that when you are modifying the original file that jump instruction is not lining up or not being placed at the reset vector. I can't remember for sure, but the opcode on x86 for a "jmp" instruction is something like "E8 90" I think. You can verify this in the Intel developer's manual, volume 2. Just make sure the original file does not have some sort of a header before the actual BIOS code. You need to make sure the actual BIOS code is being loaded at the proper location.
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