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Dumping BIOS ROM

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  • Dumping BIOS ROM


    Can anyone give me any ideas on how to read the BIOS startup code? I think BIOS exec starts at FFFF:FFFF:FFFF:FFF0 in memory.

    My first idea was to create an asm prog that boots directly after BIOS, and reads these mem locs. But I think I read somewhere that the BIOS can fiddle with memory mapping, so that reading from FFFF:FFFF:FFFF:FFF0 may not be the BIOS. It might just be normal RAM, and the BIOS has "moved itself" somewhere else. But when I read Intel docs, I cannot find anything to suggest that it is possible

    Is this true? Or is my above tactic fine. Dont wanna waste my time doing it this way if it wont work. Any general hints on this kind of stuff would be great


  • #2
    I have to admit that I've never tried dumping a PC BIOS before; most of my experience in this area is with arcade games and cartridges. However, it seems as though it might be easier to simply obtain a BIOS update image from the motherboard's manufacturer and use that as your image - or use their software to dump your BIOS.

    Of course, if the goal is to write the program that dumps the BIOS, the above is something of a moot point. But if just getting the image is what counts, it may save you a lot of legwork.


    • #3
      Where's the fun in that?


      • #4
        there might be a tool on sourceforge to do that. to dump memory.

        i know a lot of the unix tools were ported. i got tcpdump for win32. do a search see if you find anything.
        $free = !$hope && !$fear;


        • #5
          As skroo said, your best bet is to find the BIOS flasher application for your particular motherboard. Most will also include functionality to dump an image of your current BIOS.

          As for writing such an application yourself? Good luck, you'll need to know quite a few specifics about your motherboard which you probably won't be able to obtain without an NDA. Disassembling the BIOS flasher application might give you some clues.
          45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B0
          45 5F E1 04 22 CA 29 C4 93 3F 95 05 2B 79 2A B1
          [ redacted ]


          • #6
            I agree with what skroo said as well, however I have heard of COMPAQ computers storing there BIOS on the hard drive, don't know if this is of any help to you, but thought I'd throw it out there =)
            When you draw first blood you can't stop this fight
            For my own piece of mind - I'm going to
            Tear your fucking eyes out
            Rip your fucking flesh off
            Beat you till you're just a fucking lifeless carcass
            Fuck you and your progress
            Watch me fucking regress
            You were meant to take the fall - now you're nothing
            Payback's a bitch motherfucker!

            Slayer - Payback