void setup() {
  volatile long i,j;
  volatile char *dirc,*dirf,*dirk,*dira,x;
  volatile char *outf,*outc, *ink, *outa;
  dirc =0x27;dirf = 0x30; dirk = 0x107; dira = 0x21;
  outc = 0x28;outf = 0x31; ink = 0x106; outa = 0x22;
  *dirf = 0x0F; *dirk = 0x00; *dira = 0x0F;
  
  while(1)
  {
    for(i=0; i<4; i++){
      *outf = 1<<i;
      
      *outa = *ink;
      if(*ink !=0){
        *outc = i<<i;
        for(j=0;j<100000;j++);
      }
    }
  }
}

void loop() {
  

}