Frederick Bruckman <fb@enteract.com> writes:

> Thanks for the explanation. It's looks as if CONSDEV_COM0 is suitable
> for what I want to do. One more question. What kind of response is it
> looking for? Would it do any good to put something in the "Answerback
> Message" field on the vt?

In principle there is supposed to be an electrical handshake option.
But this never worked for me.  So the boot prints out ":-(" then 
waits 7 seconds for you to type a character on the serial line.