And everything you could possibly want to know about Intel processors.
If you are programming in Assembly code then you need these tomes close to hand:
IntelĀ® 64 and IA-32 Architectures Software Developer's Manual
Volume 2A: Instruction Set Reference, A-M
IntelĀ® 64 and IA-32 Architectures Software Developer's Manual
Volume 2B: Instruction Set Reference, N-Zhttp://www.intel.com/products/processor/manuals/