Use a processor-specific comment character anywhere on the line (the processor-specific chapter of this document explains whether such a character exists for your target processor). A 68K/Coldfire example is: move.l d0,d1 ;This is a comment
A PowerPC example is;
mr r1,r0 #This is a comment
Note: Gnu compatibility mode may involve a different comment character, and may involve a different meaning for the ; character.