Probably not what you're looking for but Randall Hyde has put up a second edition of The Art of Assembly which is available for free download or at no starch. h

Probably not what you're looking for but Randall Hyde has put up a second edition of The Art of Assembly which is available for free download or at no starch. http://webster.cs.ucr.edu http://webster.cs.ucr.edu I don't know if he addresses x86_64 much, if at all though.