PCMCIA is the classic way of adding serial connectivity to laptops. Increasingly new laptops are coming without PCMCIA slots and using the new ExpressCard slots instead.
The PCMCIA range includes 1 or 2 ports in either RS232 or RS422/485 serial connectivity. As standard most PCMCIA cards have removable cables terminating in a 9 pin D connector. Ruggedised PCMCIA cards have permanently attached cables for increased security.