#define DDRB (*(volatile unsigned char *)(0x37))
#define PORTB (*(volatile unsigned char *)(0x38))
#define PIND (*(volatile unsigned char *)(0x30))
#define DDRD (*(volatile unsigned char *)(0x31))
#define PORTD (*(volatile unsigned char *)(0x32))

int main(void) {
    int i;

    DDRB = 0xff;
    DDRD = 0x00;
    PORTB = 0x00;
    while(1) {
      PORTB = PIND;
      for(i = 0; i < 0xffff; i++);
    }

    return 0;
}