There's some info here: http://www.rcollins.org/secrets/ http://www.rcollins.org/secrets/ http://www.rcollins.org/ddj/ddj.html http://www.rcollins.org/ddj/ddj.

There's some info here: http://www.rcollins.org/secrets/ http://www.rcollins.org/secrets/ http://www.rcollins.org/ddj/ddj.html http://www.rcollins.org/ddj/ddj.html Notably things like undocumented opcodes, processor modes, undocumented registers, undocumented bits within registers, etc. It's not uncommon to release a specific set of documentation to trusted partners only. Back in the day intel called these "gold books".