I found this http://www.akkadia.org/drepper/cpumemory.pdf http://www.akkadia.org/drepper/cpumemory.pdf to be a very good starting point for getting into serious

I found this http://www.akkadia.org/drepper/cpumemory.pdf http://www.akkadia.org/drepper/cpumemory.pdf to be a very good starting point for getting into serious low level development. It's a difficult read, so go through it slowly and with a pad of paper for notes, but very information dense and useful.