Intel x86 Opcode Reference?

Question

What is a relatively quick and easy method of looking up what an arbitrary opcode means (say, 0xC8) in x86?

The Intel Software Developer\'s manual

Answer 1

While Intel Software Developer's Manual itself is definitely not very convenient to search through, the opcode tables in this manual could help. Take a look at the Appendix A "Opcode Map" in the volume 2B of the manual, it might be useful.