hi all .... the P0 port in 89c52 doesnt work coz it doesnt have internal pullups , so u need to have external pullups or use this port as data lines to write ...use

#define ADDR (xdata unsigned char *) 0xxxx //some addr

and then pass to this value...as

*ADDR= data;//data to be passed

i hope this will solve ur problem ...

cheers,
--Asad