Re: Debian + PC with multi RS... port -> n x (text dumb terminal + printer)
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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