-- Read Status Register (status into A)
<b>   MOV   DPTR,#02002H
   MOVX  A,@DPTR</b>

-- Write Command Register (command from A)
<b>   MOV   DPTR,#02000H
   MOVX  @DPTR,A</b>

-- Write Data Register (data from A)
<b>   MOV   DPTR,#02004H
   MOVX  @DPTR,A</b>