> from reading tty(4) I understand that /dev/dty?? are the device files
> one should use to talk to an external device connected to one of the
> serial ports.  Is this correct?

As I understand it, "maybe".

My understanding is that /dev/dty* are the devices to use if the port
in question is used for both dial-in and dial-out (or some comparable
externally-vs-internally-initiated connection), and you're dialing out.
This makes a difference in respects such as the port not needing
carrier-detect in order to let the open succeed, and it locks out the
/dev/tty* version for the duration of the call.

If you're ignoring modem control, and/or don't have both incoming and
outgoing on the same line, then I think you can use /dev/tty* and
ignore /dev/dty*.

My understanding may be wrong.

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