Most instructions on the 68k have a suffix that shows how much data should be used in the instructions. This can be a byte (.b), a word (.w) or a longword (.l). Another very important thing is that all instructions are backwards (compared to most CPUs). With that I mean that the source of the instruction is the first argument and the destination is the last argument. For example: MOVE.W D0,D1 moves (actually, copies) the first 16 bits (a word) from D0 to D1.