Looks like you answered your own question then :) When in doubt, push/pop all regs you don't want trashed. Or step through the code on an emulator and see what it does. > Does _divHLbyA scrap reg. B? The reason I ask is that I have a sniplet of > code that calls _divHLbyA and after wars, B is different (I think) than when > it went in....Does anyone know?