1 2references: 3http://www.beyondlogic.org/serial/serial.htm 4http://jamesthornton.com/freebsd/articles/serial-uart/ 5http://dugeem.net/david/work/freebsd-serial.html 6http://dugeem.net/david/work/etc/sio.c 7 8if you can understand it: 9http://lxr.linux.no/linux+v2.6.28.7/drivers/serial/ 10 11