[CQ-Contest] Expanding Comm Ports

[Kevin Schmidt]

Jeff Maass wrote:
>My Pentium II system is in that class: not even one spare interrupt.
>
>Has anyone seen a sloution (add on multi-RS232 interface) using the Universal
>Serial Bus (USB) port? 

I don't have any great solutions. The USB stuff may help eventually.
One way to save interrupts is to use SCSI and ethernet devices.  This
isn't cheap, but you can hang a printer off ethernet or the SCSI bus.
High speed scanners can use the SCSI bus.  On my Pentium Pro system at
home, an add on pci ethernet card, onbard ethernet, and SCSI controller
share an interrupt.  Presumbably a PCI soundcard would give me another
interrupt since I assume (perhaps wrongly) that that would also share
interrupt 11.  I have IDE drives on this, but if I replaced them with
SCSI disks, that would give me two more interrupts.

Here is /proc/interrupts to show what is assigned now:
newton%cat /proc/interrupts
 0:     302204   timer
 1:       7659   keyboard
 2:          0   cascade
 3:      31430 + serial
 4:          0 + serial
 5:          1   SoundPort
 8:          0 + rtc
11:         37   aic7xxx, 3c900 Boomerang 10Mbps/Combo, Intel EtherExpress Pro 10/100 Ethernet
12:      14194   PS/2 Mouse
13:          1   math error
14:      32065 + ide0
15:        124 + ide1

You may find it amusing that my first "personal computer" was an AT&T
3B2 (circa 1986) running unix. It had 10 serial ports, 2 parallel
ports, and an ethernet port. It ran about as fast as a 80286 and had
all of 4 MBytes of memory. If you like serial ports, buy from the
telephone company :-).

73 Kevin w9cf
=-------------------------------------------------------------
Kevin Schmidt w9cf at ptolemy.la.asu.edu
Department of Physics and Astronomy
Arizona State University, Tempe, AZ 85287-1504
(602) 965-8240
(602) 965-7954 (FAX)


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