Turning asynchronous lines synchronous - any standards?

[Geoff Kuenning]

With modern micromputers and their USART-based serial drivers, it becomes
sensible to support both asynchronous and synchronous protocols with the
same drivers and /dev/tty nodes, and to allow switching between synch
and asynch on the same port.  (My Hayes modem even supports this with
a mode where you autodial in asynch and then go synch).

The question then becomes, how does one tell the system which flavor to
use on a port, and when to switch between flavors if your feel like it?
And do you default to asynch, or have some way to specify how a port
defaults?  I'm sure somebody out there has addressed the problem (Sun?
Apollo? are you listening?) and I'd sure love to stay compatible.
--

        Geoff Kuenning
        {hplabs,ihnp4}!trwrb!desint!geoff