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[hargle]

The BIOS is essentially x86 assembly language.
While parts of it may have been compiled in C, the level of hacking on it that we can do is going to be entirely in assembly because we don't have the full source code to it to make any changes.

The single best tool to use to disassemble such a thing is called IDA
http://www.datarescu...abase/index.htm

From there, it's a matter of finding what place you need to patch (not easy) then finding a way to make the patch work (not much easier)  

While not exactly BIOS related, here's some details on making changes at the x86 level to an .XBE file:
http://xbox.nugnugnu.../FlickerFucker/

The concepts should be similar.

[iamcheese]

from what i was told by an unnamed individual the major groups got ahold of the actual source from the bios

[red_butcher]

QUOTE(iamcheese @ Jun 21 2007, 12:55 AM)

from what i was told by an unnamed individual the major groups got ahold of the actual source from the bios

This is over my head as I dont know anything about programing but this might be helpful in answering some of your questions. from www.xbox-linux.org is a walkthrough about how they were able to find the algarythmes<--(whatever that is) to get the source code from the bios. If I am not mistaken.
Read it here: http://www.xbox-linu...ode_of_the_Xbox