http://www.linuxclues.com/articles/11.htm

A reminder that physical access precludes absolute
security from a determined mal-doer: But it raises
a question:

Is there a way to burn a password into a ROM chip?
The BIOS will usually store a boot password that can be
required before grub loads, but for desktop computers
(notebooks are different) the whole BIOS can be reset
simply by removing the mainboard battery for a while
then replacing it. Many boxes have provision to be
locked, but locks can be broken.

Does anyone know about hard-wiring a password into
a separate ROM, then requiring Linux boot to check
that address? Might there be a few unused bytes in
a video or LAN card ROM? It's not important to me
in the moment, just asking for the sake of
development of more hack-proof systems.