Michael,
I agree. Maybe I should have stated "The ISA bus doesn't care if you
share interrupts on a single card"? I.e. it's up to the card (and
software) to sort it all out.
My point was that the original poster should be aware that sharing IRQ's
between different cards is not a recommended idea. I'm sure you remember
that that was often done in the old DOS era, where people learnt that
you can share interrupts "as long as you don't use the cards at the same
time".
I guess this is (somewhat) OK in a system where you run one application
at a time by one single user.
Wouldn't want to try that under Linux (or any modern OS), though.
I am convinced that my old STB (16554 IIRC) handles this in a reasonably
good fashion. It was sold that way and it was 'state of the art' by
that time. I'm still using it with up to four simultaneous high speed
connections and I can see no performance degradation doing that. (On a
266-PII)
Maybe I'm lucky. (But then again, I *am* a lucky person from a general
point of view. :-)
Best regards
Gustav
"Michael H. Warfield" wrote:
>
> On Thu, Mar 09, 2000 at 12:34:23PM +0100, Gustav Schaffter wrote:
> > David,
>
> > I'm using an (old) fourport card from STB. Works fine for me.
>
> > The ISA bus permits sharing IRQ's as long as they are on the
> > *same*controller*card* but not on different cards. Of course, your
> > serial port software must handle shared interupts as well.
>
> Only if the controller card itself is designed to share those
> interrupts, and then it's not a function of the ISA bus anyways. You
> can't always tell which cards are designed the share the IRQ's and which
> ones are not. The old Diamond IO multifunction cards were not. I'm
> not sure about the newer KIA cards I use in some system, but wouldn't
> try it. If the IRQs are selected by physical jumpers or switches, I
> would be leary of trusting their ability to "wire or" that IRQ. If you
> trace the traces from the switches to the card edge connector, I can
> almost guarentee you that they don't.
>
> > You will of course need to use setserial at the boot to setup the card.
>
> > Regards
> > Gustav
>
> > David Kramer wrote:
>
> > > I need to get another serial port or two on my linux box. I have one for
> > > the mouse, another for my IR controller, and I would like at least one
> > > more for an X10 ActiveHome controller. Ideally I would have a fourth for
> > > a dial-in modem.
> > >
> > > If I get a normal add-on two-port serial card for ~$30-$40, could I use
> > > that in addition to the two ports I have now, or are they going to
> > > conflict with IRQ's?
> > >
> > > Real 4-port serial cards seem to be very expensive. Are there any that
> > > are not? I don't need fast. Does each com port need an IRQ? That would
> > > suck.
> > >
> > > Does anyone have experience with a particular make, model, or vendor?
> > >
> > > Thanks in advance.
--
pgp = Pretty Good Privacy.
To get my public pgp key, send an e-mail to: [EMAIL PROTECTED]
Visit my web site at http://www.schaffter.com
--
To unsubscribe: mail [EMAIL PROTECTED] with "unsubscribe"
as the Subject.
