Re[2]: Debian + PC with multi RS... port -> n x (text dumb t
Printing to the aux port of a terminal has been done before. SCO Xenix used to
do it (about 10 years ago) with Wyse terminals. I have heard about printing
through vt type terminals off dec vax machines. I once wrote a program to do it
through hp terminals (with rte-a, not unix).
It probably doesn't work the way you want. Usually the terminal keyboard is
locked until the print is finished. Making the terminal useful for input at the
same time is generally not possible. It would require a very clever terminal
and an extremely clever driver.
jim
______________________________ Reply Separator _________________________________
Subject: Re: Debian + PC with multi RS... port -> n x (text dumb ter
Author: n.bern@mail.protos.it at ~AMSCCSSW
Date: 9/12/97 8:35 AM
On Fri, 12 Sep 1997, Joey Hess wrote:
> Nicola Bernardelli wrote:
> > 1) what about sending output TO A PRINTER which is NOT ON A PARALLEL
> > PORT (lpt1, lpt2, ...) but is instead on a serial line? (Maybe I just
> > need to write software which sends output to its stdout instead of
> > stdprn, and that output is merely redirected to a com port... maybe
> > such multiuser environments have typical and by now "traditional"
> > solutions to my question... that's why I said I lack the basics.)
>
> I think you need 2 lines. Assumming you want your software to be able to
> direct some output to the printer and some output to the serial port, as it
> wishes without human intervention to flip a switch, you need a separate line
> for each.
>
> Also, while it's possible to have a device that prints out what comes to it
> on a serial line, a PC's printer port works quite differenlty than it's
> serial port, (you can't just plug a printer up to it), and so it will be
> more economical to use a standard printer.
But I never heard of PC's with 8 or 16 LPTs, while I hear of multi serial
IO cards with that number of ports.
> > If yes, would the OS menage the distinction between the two devices
> > or should _my_application_ (or some wrapper) be aware of the hardware
> > each session runs on and eventually take care of sending special
> > characters to say "this goes to the display, this goes to the
> > printer"
>
> I've never heard of anything that did this. If you actually manage to find a
> serial terminal + printer combo that is switchable from terminal to printer
> mode via some escape sequence, then yes, linux could send the sigals. But I
> think that's unlikly.
>
> or should I just have two distinct cables run from the Linux
> > box to the place where the dumb terminal and the printer are?
>
> probably.
>
> > > 1) What serial devices allow longer cables than RS232 without use
> > > of modems (say 10-100-200 meters)?
> > > 2) Are there multi port cards of that kind which run well with
> > > Debian? Any brandname + model?
> > > 3) What if the text dumb terminals connected to a Linux Box also need
> > > a printer each (or almost any of them)? Is it possible that
> > > data is sent to the printer and terminal via the same line?
> > > Brandname + model?
>
> I'll bet you're setting up a point of sale system.
Bingo. I don't feel like doing it so much, but I should _hope_ to instead.
> If I were you, I would set up an ethernet network,
(I wouldn't like so much to have that possibly pretty high number of
ethernet points, I wouldn't like to be called once in a while and have to
go looking for bad connectors and so on... maybe some CPU-intensive task
deserves another complete powerful Debian box, maybe even more in future,
but using ethernet just to have terminal+printer...)
> with a linux server, and POS systems that were 286
> or 8088 machines with printers attached. Then you would set up software for
> the POS systems, to let them function as terminals, and/or output what data
> they receive to their printers. This fixes your cable length problem, you
> only run one cable, and the price is probably not much larger (unless you
> get them for free, dumb terminals cost more than you would expect).
What is a POS system? What software runs on it? What does such a PC need
to boot at startup? What ethernet cards are suitable for a 8088 or 80286?
(And - ignoring noise from the fan and need to boot some software - will
the people for which I will be building the application find good-looking
one-year-warranty such outdated machines? And, last, I will most probably
be stuck at 80x25... ok, I shall anyway _not_ be making assumptions on
that point...).
Nicola Bernardelli <nbern@mail.protos.it>
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