What are the MMX pairing rules? I read about them somewhere, can''t remember where though, and I can''t remember all the rules. I remember these: 1) Pack, unpack, and shift instructions do not pair with each other. 2) Multiplication instructions do not pair with each other. There were at least three others, does anyone know what they are? Also, is it necessary to pair instructions for Pentium Pros and above (which do out-of-order execution, register renaming, etc.)? ~CGameProgrammer( );