#define PORTA_DDR *(volatile uint8_t *)0x21
#define PORTA_DATA *(volatile uint8_t *)0x22

#define PORTB_DDR*(volatile uint8_t *)0X24
#define PORTB_DATA*(volatile uint8_t *)0X25
#define PORTB_PIN*(volatile uint8_t *)0X23

int main(){
  PORTA_DDR=0XFF;
  PORTB_DDR=0X00;
  PORTB_DATA=0XFF;
  volatile long i,j;
  while(1){
    if((PORTB_PIN & (1<<3))==0X00)
{
  PORTA_DATA=0X01;
  for(j=0;j<=7;j++){
    PORTA_DATA|=(1<<j);
  for(i=0;i<400000;i++){}
} 
 }
}
}