From: keith@ksmith.uucp (Keith Smith)
Subject: Re: Using 'cu' with speeds greater than 9600
Organization: Keith's Computer, Hope Mills, NC
Distribution: usa
Date: Wed, 23 Dec 92 04:01:06 GMT

In article <1g5p3uINN5up@matt.ksu.ksu.edu> brettw@matt.ksu.ksu.edu (Brett D. Watson) writes:
> Ok, I need some help from SOMEONE who has used 'cu' to connect to
>another computer over serial cable using a Digiboard, or similar
>serial expansion board.

I was going to reply directly, but here goes for the world to see.

>  I have a 483/33 with Digiboard PC/Xe 8 port board.  I connect one of
>the ports over serial cable to a 386/25.  On the 486, I have
>/dev/ttyi1b set for 38400 in /etc/ttys.  I use the letter 'o' which is
>defined in gettydefs.  On the 386, I have com 2, or /dev/tty2a set the
>same way in /etc/ttys, and also I specify this device in
>/usr/lib/uucp/Devices.  My Devices file has the following:
>
>Direct tty2a - 38400 direct
>

Which box is talking to which?  In other words 386->486 or vice versa? 
I'm going to assume that you are trying to cu from the 386 to the 486. 
What version of Xenix?

FIRST a nice try is a loopback wire on the com port of the cu end of the
connection.  Jumper pins 2 and 3 on the Dsub connector (9 or 25 pin)
(or the RD/SD lines of a digiboard RJ)  When you 'cu' you should be
talking to yourself, and your characters should echo straight back.

The "38400" notation is a problem in earlier versions of Xenix.  Try
exta, and extb also.  It's been a while, and I'm not sure if this even
worked on some of the older (pre 2.3) stuff.

The /etc/ttys file is *IRRELEVENT* on the 'cu' side of the connection. 
/etc/ttys is for the LOGIN side of the connection.  Here it is
important.  Note that the port should be enabled on the login side, and
(at least while testing) *DISABLED* on the 'cu' side.  In my assumption
that means disable the tty on the 386 and enable the one on the 486.

>  However, I cannot get the connection to run at 38400, or 19200 for
>that matter.  Is there something else, or someWHERE else I'm
>forgetting to set something?  I've had some people tell me you just

If you've got a loopback on the cu port:

# cu -ltty2a -s38400 dir

should turn the trick (try subbing extb or exta for 38400 in both
places, Devices & the command line)  also the port (/dev/tty2a) should
probably belong to uucp.  Double chek your permissions.  This should get
some output to the screen.  If not then you don't have the 'cu' side of
the connection up.  Once you have that move on to connecting the 2
together.  Then try banging something straight out over the tty.  it
should appear on the other end:

cat /etc/motd >/dev/ttyi1b

albeit perhaps sans carriage returns.

Now you've test the transmitter at the login end.  Some:

stty -a </dev/tty2a

from the 386 and

stty -a </dev/ttyi1b

from the 486 ends of the connection could be revealing too!

>can't run a terminal at speeds greater than 9600 but I don't buy that.
>Why the hell can't I get this to work?  I'm pulling my hair out.
>Help!

You can most certianly run a terminal at speeds greater than 9600.  You
will however most probably drop characters on the 386/cu side of the
connection (my assumption setup) during heavy output from the 486/login
side of the connection, as the SCO serial driver, uh, well, it sucks. 
For real performance you need 16550 chips and the FAS driver.  cu is a
"lousy" terminal.  A wy-150 using hardware or software flow control will
work nicely though.  The problem with the serial port is the RECIEVE
side of the interface has trouble on the computer.  As you simply cannot
TYPE on a KEYBOARD fast enough to swamp the serial driver the login cpu
should not have a problem.  The one that receives the screen output on
the other hand (the 'cu' system) is gonna get swamped.

If you need further assistance feel free to jot a note direct here, also
try keith@ksmith.uunet.uu.net

-- 
Keith Smith          uunet!ksmith!keith            5719 Archer Rd.
Digital Designs      BBS 1-919-423-4216            Hope Mills, NC 28348-2201
Somewhere in the Styx of North Carolina ...
Newsgroups: comp.unix.xenix.sco,biz.sco.magazine