;interrupt service
IrqExt1:
   clr		EX1
   mov		P1,#INIT_FOR_P1
   mov		P2,#INIT_FOR_P2
   mov		P3,#INIT_FOR_P3
DO_DOWN:
   orl		PCON,#2 ;(I used also MOV PCON,#2 instead)
   jmp          DO_DOWN