void io_init(void)
{
  log("io_init() - before port initialize.\r\n");
  // Initialize port.
  regs.x.dx = PORT;
  regs.h.ah = 0x04;
  int86(SERIAL, &regs, &regs);
  log("io_init() - after port initialize, returned %d\r\n",regs.x.ax);

  log("io_init() - About to set line characteristics.\r\n");
  // Set line characteristics. 
  regs.h.al = 0x07; // 1200bps
  regs.h.al = (regs.h.al < 5) | 0x03;   /* 8/N/1 */
  regs.x.dx = PORT;
  regs.h.ah = 0x00;
  int86(SERIAL,&regs,&regs);
  log("io_init() - Set line characteristics.\r\n");

  log("io_init() - Set flow control\r\n");
  /* // Set RTS/CTS Flow control */
  regs.h.ah = 0x0f;
  regs.h.al = 0x02;
  regs.x.dx = PORT;
  int86(SERIAL,&regs,&regs);
  log("io_init() - Set flow control success\r\n");

  io_raise_dtr();
}