This is my program:

ORG 0000H
LJMP START
START: ORG 0050H
MOV P0,#00H
MOV P1,#00H
MOV P2,#00H
MOV P3,#00H
SETB P0.0
SETB P0.2
SETB P0.4
SETB P0.6
SETB P2.0
SETB P2.2
SETB P2.4
SETB P2.6
END
I want to make the P0 and P2 on (in the order of the progam), but anyway it doesn't work. P0&P2 just flash randomly. Pin 31 is pulled up in case the 89C52 may search for the external ROM or RAM.
Any problems in the program?