19200 baud on the Unix PC serial port

[Bill Mayhew]

Hi,

Happy holidays.


Now that we have that out of the way, yes indeed, the serial port
on the Unix PC and/or 7300 is capable of running at 19200 bits per
second.  Be aware that 19200 is not supported by AT&T, so if it
doesn't work for you....

If you have the basic uucp and cu that comes with the machine, try
specifying "exta" for the baud rate fields in L.sys and L-devices;
that should work.  "19200" is recognized directly by the Honey
Dan Ber Basic Networking Utilities package, if you use that for
uucp.

There could be got-chas in using 19200.  The expansion slots have
differening interrupt priorities.  I don't have the manuals, so I
can't elaborate on the subject.  You may have to try the EIA Combo
board in different slots to see which (if any) work better.  I
noticed that my uucp xferstats via tty000 decreased when I had a
Voice Power board in the middle slot and ran the voice daemon.  I
didn't need the voice daemon for my voice application, so just
bagged the daemon.

The trailblazer will yield about 11000-12000 bits per second when
used with the Unix PC, so it is definitely worth the while to
experiment some to seem if running the port at 19200 will work with
your given machine and sofware configuration.  I've benn using a
Trailblazer since December 1987 without any porblems, though your
results may vary.

The absolute limit on thoughput with the tty000 port set to 19200
is about 14000.  14000 seems to be the limit that characters can be
stuffed into the port at a sustained rate.  This doesn't
necessarily mean thta you can pull characters into the port at
that rate too.  I experimented with uucp e protocol and found that
I started to lose characters on input with the port running as fast
as it would go on big files.  Best to stick with the default g
protocol.


--Bill