why the instruction "MOV r9,#0" is understood by Keil as "MOV Rw,#data4",that is, its machine language is transfered as "E0 #n",which is only 2 bytes;yet I get the machine language "E6 RR ####" anciently,which is 4 bytes,that is,it was thought be "MOV reg,#data16" ,why? thank you! wangwei