Computer Systems: A Programmer's Perspective by Bryant and O'Hallaron might be a good resource. It also covers things like assembly code and caching that you mi

Computer Systems: A Programmer's Perspective by Bryant and O'Hallaron might be a good resource. It also covers things like assembly code and caching that you might not be interested in, but its a solid introduction to the low level details on how computers work. Its used in my university (and many others) in the Introduction to Computer Systems course.