Do I really need to BREAK to change baud rates?

[Rahul Dhesi]

In <NELSON.90Dec24233400 at image.clarkson.edu>
nelson at sun.soe.clarkson.edu (Russ Nelson) writes:

>The problem is that I get random users calling into the BBS, and it's not
>practical to tell them that they have to press break...

My admittedly limited experience with setting of data rates suggests
that most hardware interfaces will detect a "framing error" when the
user types at the wrong data rate.  A framing error is all that the
software needs to switch to a different data rate.  In fact, from the
device driver's point of view, a "break" and a "framing error" should
be identical.  I believe this works for Microport System V/AT on
standard AT hardware, and for 4.3BSD on a VAX using dz-11 serial port
hardware.

If for some reason just typing carriage return doesn't cause the driver
to switch to a different data rate (before the user has logged in),
then your hardware, or the SCO Xenix device driver, is at fault.  I
would blame the specific hardware or software, not UNIX in general.
If the hardware or software does not correctly detect a framing error,
then it probably won't detect a break either.

All this assumes, of course, that the configuration files for the
dial-up ports have entries such that each entry has a pointer to the
next entry for a differnt data rate.  E.g., you might cycle through 300
-> 1200 -> 2400 -> 300.  This will make the initial getty process cycle
through these data rates, switching each time it sees a framing error.
--
Rahul Dhesi <dhesi%cirrusl at oliveb.ATC.olivetti.com>
UUCP:  oliveb!cirrusl!dhesi