Attaching a printer to a 68000 UNIX system

[WMartin%office-3 at sri-unix.UUCP]

From:  Will Martin <WMartin at office-3>

Hi!

This will probably be perceived by any UNIX wizards out there as
a very dumb group of questions.  I guess my main problem here is
not knowing where to look for printed or on-line documentation
that answers my inquiry, so pointers to such will be appreciated.
(My other problem is that the person I am most likely to ask
about this is on vacation...)

Anywho, the situation is as follows:

We have a CCI Power-5 68000-based machine here, with 16 ports
plus console port, which runs PERPOS, a UNIX look-alike devised
by CCI, and on which we run the Office Power office automation
software package.  Hooked to this machine are 16 CCI terminals
(made by Zentec) [including the console] and one system printer
(currently a NEC Spinwriter 5510).  The other day, merrily
thrashing about as "root" with insufficient knowledge of what I
was doing, I munged up the etc/ttys file.  I restored it to what
I thought was the correct form, re-wrote it out, and we tried
printing something on the system printer.  It worked fine.  Then
today, for another reason, we brought the system down and back up
again.  At that time, a "login:" prompt appeared on the printer,
and no print jobs would print out.

The printer is connected to port #7, which translates (according
to doing an ls -l dev/tty*) to tty09.  I had set the tty09 line
in etc/ttys to "19tty09", which means, according to our
documentation, "on-line, 1200 bps" for tty09.  I could do an
"echo test > dev/tty09" and see "test" print out on the printer.
I hadn't figured out what "tty01" was connected to, and I had set
it at "1itty01" (on-line, 19,200bps), which is the same as the
ordinary terminal settings.  I think this was my problem.

We finally looked at a different system and saw that the etc/ttys
file had 01 set to "07tty01".  Also, instead of being set to
"on-line", their printer port was set to "09tty09".  We changed
ours the same way, brought the system down and back up, and now
could print OK.

So we know how to get it to work; we don't know why what we did
fixed it.  I guess my questions are:

1) Since the printer worked OK AFTER I messed up etc/ttys and
before we took the system down, but not afterwards, does this
mean that etc/ttys is only looked at when the system comes up?
This doesn't seem to agree with the behavior of using etc/ttys to
bring a terminal online or take it off, which is done without
affecting the rest of the system.

2) Is tty01 the "real" printer line, to which the software writes
and then this is somehow translated to the line the printer
device is physically connected to (in this case tty09)?  If so,
what makes the tty01 > tty09 connection?  It looks like we could
have plugged the printer into any port; somehow we have to tell
the system which it is, but I haven't found out how that is done.

3) Does the physical printer tty line have to be shown in
etc/ttys as "offline", as in our "09tty09", and then some
background software overrides this to make it really online?

4) Where is this stuff described?  The UNIX manual talks about
lpr and various related commands, but nothing about the initial
setup of the hardware configuration, and the software commands to
implement it.  (There is no "man" database on this system, by the
way, so I couldn't get info there.)

5) What does the "7" in "07tty01" mean?  (We have limited
documentation that only mentions "9", "d", and "i" in that
field.)

Thanks for wading through all this...

Regards,

Will Martin

PS - Please send any replies to BOTH "WMARTIN at OFFICE-3" and
"WMARTIN at SIMTEL20".  Usenet people can send to brl-bmd!wmartin.