How does somebody mod a BIOS?

[Espozo]

Yeah, this is something I started to wonder about. I have no clue how you'd be able to do anything, because I doubt the BIOS manufacturers would be giving away details, unless you actually have to disassemble the BIOS, which I have no idea how you'd do this in practice. I imagine "hacking" BIOSes is actually rewriting them, or do they actually have code for advanced options already made where all you need to do is change a couple of bytes at some location to access it? I don't even understand why most laptops don't give you advanced options; is it that computer companies don't want to deal with people breaking their computers from excessive overclocking?

Does this actually belong in this sub forum?