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Dumping a PC BIOS without a ROM reader #25850 01/12/07 03:51 PM
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Heihachi_73 Offline OP
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I just attempted to Google on how to image BIOSes from (multiple) Pentium 1 boards I have lying around but with a results number in the hundred thousands, and nothing useful (e.g. "How to dump your PS2 BIOS" and the same useless text threads ^10) I came back here with a software question.

All in all, I'm wondering if anyone could steer me to a (DOS/Win32) program that can run on the actual machines.

One such board doesn't seem to have the standard removable BIOS chip - matter of fact I can't even find something that resembles a BIOS. It's a Packard Bell machine (was originally a P166, then overclocked to 200MHz, it now has a P200 (non-MMX) CPU) which I've had since new.

The three or four other i586 BIOSes (which only work in the "proper" boards of course) I have are the standard Award types, whether they're any different to the current MESS version I don't know.

Re: Dumping a PC BIOS without a ROM reader [Re: Heihachi_73] #25852 01/12/07 09:22 PM
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AWJ Offline
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"awdflash.exe", the DOS-based program for updating Award BIOSes, also has the capability to save the current BIOS from ROM to disk. "amiflash.exe" is the corresponding program for AMI BIOSes.

I don't know if the modern versions of these utilities that you'll easily find by Googling will work with an old i586 motherboard, though--you might have to do some questing to find old versions.

Re: Dumping a PC BIOS without a ROM reader [Re: AWJ] #25854 01/12/07 11:29 PM
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MooglyGuy Offline
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Unless I'm utterly mistaken, shouldn't it be possible to write a short C or C++ program that casts 0x000f0000 into a pointer, reads out the 64k starting at that address and writes it to a file, and then compile it as a 16-bit DOS program?

Re: Dumping a PC BIOS without a ROM reader [Re: MooglyGuy] #25855 01/12/07 11:32 PM
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R. Belmont Offline
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Most 386+ BIOSes are > 64k and get banked somehow, so that wouldn't work. (If you could get 32-bit flat access the whole thing *might* exist extending down from ffffffff but I reserve the right to be horribly wrong).

Re: Dumping a PC BIOS without a ROM reader [Re: R. Belmont] #25864 01/13/07 02:29 AM
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AaronGiles Offline
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It's actually far worse than that. Most 386+ BIOSes copy themselves into the RAM from 0xe0000-0xfffff (yes, there is RAM there, just generally overlaid by the BIOS image by the memory controller), and then disable the BIOS mapping so that they can dynamically bank in bits and pieces. For example, the POST code is usually run with the default mapping, but then the ACPI tables and extracted and generated in RAM after switching off the ROM mapping.

However, the physical BIOS location should still be accessible. For a 256k BIOS, it will generally be right at the end of 32-bit memory at physical 0xfffc0000. You have to use big real mode or protected mode to get at it.

Re: Dumping a PC BIOS without a ROM reader [Re: AaronGiles] #25884 01/13/07 12:09 PM
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Justin Offline
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This won't help for your current problem, but for appropriately old PCs, you can use dumppc.c or dumpat.c from http://cvs.mess.org:6502/cgi-bin/viewcvs.cgi/mess/tools/messroms/

Re: Dumping a PC BIOS without a ROM reader [Re: Justin] #25886 01/13/07 02:03 PM
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Heihachi_73 Offline OP
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I also have an IBM 486 (based?) machine, but it might have the same problem with the i586 BIOSes. I haven't run it since finding it though - ripped parts out (sound, graphics card) to get the Packard Smell‚Ѣ going better, which has a sucky onboard S3 Virge (S3 Trio is better!).

Another question - With the Pentium range, are they identical processors or are they different in specs and not just clock speed? I have a 120, 150, two 166es and a 200. The 120, 150 and one 166 have the heat sink stuck on the chip itself, along with a stamped clock speed on the side.

Last edited by Heihachi_73; 01/13/07 04:18 PM.
Re: Dumping a PC BIOS without a ROM reader [Re: Heihachi_73] #25890 01/13/07 11:46 PM
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R. Belmont Offline
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There's 3 different Pentiums - the original 60/66 were on a larger process and ran very hot (for the time). The 90/100/120/133/150/166/200 were a die-shrink that ran cooler (and could be overclocked on a decent motherboard). Third was the Pentium MMX, which came in 166/200/233 speeds and added MMX but was otherwise similar to the previous one.

Last edited by R. Belmont; 01/13/07 11:47 PM.
Re: Dumping a PC BIOS without a ROM reader [Re: R. Belmont] #25892 01/14/07 01:35 AM
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Heihachi_73 Offline OP
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Unfortunately my old boards can't go faster than 200, and I have three non-working CPUs (I can't test them / they don't boot) - a Pentium 200 MMX, IBM PR200 and a Cyrix (233?). The non-Intel CPUs are possibly dead as they get extremely hot as soon as they power up (changing the voltage and/or clock speed doesn't do anything).

Re: Dumping a PC BIOS without a ROM reader [Re: Heihachi_73] #25900 01/14/07 09:21 AM
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AWJ Offline
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Quote:
Third was the Pentium MMX, which came in 166/200/233 speeds and added MMX but was otherwise similar to the previous one.


The Pentium MMX also ran at a different voltage than the non-MMX versions, so it didn't work in all motherboards (though that was hardly unusual in the Socket 7 era)

Last edited by AWJ; 01/14/07 09:26 AM.
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