Not strictly computer science - but the one textbook that I really liked from my computer engineering degree was "Computer Organization and Design: The Hardware

Not strictly computer science - but the one textbook that I really liked from my computer engineering degree was "Computer Organization and Design: The Hardware/Software Interface" (http://www.amazon.com/Computer-Organization-Design-Fourth-Edition/dp/0123747503 http://www.amazon.com/Computer-Organization-Design-Fourth-Ed...). It was surprisingly readable and easy to follow. It covers the design of a MIPS processor from the ground up (ALU, caches, memory, pipelining, etc) and also is self-aware enough to not pretend that x86/ARM don't exist.