Login through Computone Ports

[Steve Dyer]

This sounds like a generic problem, although it may require a
Computone-specific fix.  First, let's describe what's going on:

Ports are configured as either "wait for carrier" or "hard wired".
On the COM1 and COM2 ports, and the XENIX-supported multi-port "dumb"
boards, each serial line has two different special files, one for each
mode.  An open() system call on the hard-wired device succeeds immediately,
and the program doing the open (e.g., getty) will proceed to execute the rest of
its instructions (e.g., printing out the "Welcome to XENIX\nlogin:" banner.)
An open() on the wait-for-carrier device will not complete until carrier is
detected--i.e., the program attempting to do the open will be suspended until
someone dials in.  Only once carrier is asserted will the open() complete
and the banner be printed.

I believe that your Computone dialin lines are not waiting for carrier to be
asserted by the modem, and have already printed out the "Welcome to" banner
when your users log in.  This is why your users must type a return before
seeing a login prompt.

Now, Computone doesn't use two different special files (at least the unit I
used to use last year didn't).  Rather, the presence of carrier is set on a
port-by-port basis with jumpers on the board. I believe that what is happening
is that either your Computone board is set to assert carrier internally,
ignoring the state of your modem, or your cable to the modem might be jumpered
to be asserting carrier, or even that your modem might be set to assert carrier
regardless of whether someone is dialed in.

I have found the Computone support people very helpful.  If you can't clear
this up with this information I give here (and your Computone manual), I'm sure
you should get the help you need by calling them.
-- 
Steve Dyer
dyer at harvard.harvard.edu
dyer at spdcc.COM aka {ihnp4,harvard,husc6,linus,ima,bbn,m2c}!spdcc!dyer