while (STOP==FALSE) {
    printf(".\n");usleep(100000);
    /* after receiving SIGIO, wait_flag = FALSE, input is available
       and can be read */
    if (wait_flag==FALSE) { 
      res = read(fd,buf,255);
      buf[res]=0;
      printf(":%s:%d\n", buf, res);
      if (res==1) STOP=TRUE; /* stop loop if only a CR was input */
      wait_flag = TRUE;      /* wait for new input */
    }
  }