hi..... m doin a password based door lock system using microcontroller..... m using dtmf tones instead of a simple keypad and 2x16 lcd....... m using cm8870 to decode dtmf signals into binary code...... once i switch on the power it s taking d values itself(the previous value wch i entered).......m not getting how to make all bits of d port high(input port)..... i tried [mov p0,#0ffh]. but its not workin plz help me out.........