How about the programming code that I've used to program the AT89S51? I use the same program code for ATmega48 to open the port on the AT89S51, does it mean that it have different programming code between ATmega family? If yes, can you guy write me a very simple program code just to open the port P0.0 and P0.1?
This is the code I use on ATmega48 and it work, only can't program it into AT89S51.

#include <avr/io.h>

int main(void)
{
DDRB = 0xFF;

PORTB = 0xFF;

return 0;

}