struct tchars
{
  char t_intrc;  /* Raises SIGINT */
  char t_quitc;  /* Raises SIGKILL */
  char t_startc; /* Starts terminal output */
  char t_stopc;  /* Stops terminal output */
  char t_eofc;   /* Marks end of file */
  char t_brkc;   /* Marks end of line */
};