Re: flexfax: How best use multiple modems?y

[Leslie Mikesell <les@Mcs.Net>]

> > I know this topic has been discussed earlier, however, I would be glad to
> > receive a specific advice. I want to connect 6 modems to a Linux machine. 
> > 
> > I wonder whether I should use internal modems (this reduces cabling) or
> > external modems, in which case I need a recommendation for a multi-port
> > serial board.
> > Which minimum RAM and Processor requirements would I need? SCSI?
> 
> More than 2 modems can cause grief real fast. PC clones normally have
> only two interrupt codes for serial ports. You can't just add new ones
> willy-nilly, they're very much built into the hardware and the
> drivers.
> 
> I suggest that for this many modems, you definitely need some sort of
> serial expander. Alternatively, there are several types of network
> ready multiple modem servers which might save you a lot of work and
> grief and be overall more reliable: you might then be able to use the
> Linux box to handle the fax service. I believe some people have done
> this on this group....
  
Serial ports are only a problem if you use ordinary PC UART chips
where the CPU does all the work.  An intelligent serial port
expansion card doesn't impose any more load than a network card
moving a similar amount of data.  I've used 6 modems on a 486
running sysvr4 with a digiboard C/X card without problems (I
think ghostscript was more of a bottleneck than the ports), but
you can't get drivers for that card for Linux.  I've used an 
8-port Cyclades card on a Linux box and it seemed fine, but I
never really loaded it.

  Les Mikesell
    les@mcs.com