I'd suggest "Operating Systems: Three Easy Pieces". (http://pages.cs.wisc.edu/~remzi/OSTEP/ http://pages.cs.wisc.edu/~remzi/OSTEP/) I've found it very accessib

I'd suggest "Operating Systems: Three Easy Pieces". (http://pages.cs.wisc.edu/~remzi/OSTEP/ http://pages.cs.wisc.edu/~remzi/OSTEP/) I've found it very accessible. Largely, the way that they teach is to describe a system based on a set of assumptions, then slowly relax each of the assumptions one by one until you reach an example of a real system. That style of teaching really works for me.