
Simple.  First, Andrew is correct, although I can see where there might be
some confusion.  It is indeed possible to have two cards *configured* to use
the same interrupt.  They can not *share* the interrupt in the sense that it
is not possible to have both cards active at the same time.

Here is an example.  For some time, I was short of "free interrupts."  I had a
tape controller (not a "floppy tape") that needed one of IRQ0-IRQ7.  (It's an
*old* tape drive.)  My solution was to use IRQ3 (also used for COM2, where my
modem is).  I did this because I reasoned I would never be using the modem and
the tape simultaneously.  When kermit runs, it installs its own interrupt
handler for IRQ3 and uses the serial port.  If the tape drive were to generate
an interrupt, kermit would not have a clue what to do with/for the tape
controller.  (And since the tape controller would not be serviced, it would
most likely "hang.")  Likewise, when the tape backup software runs, it
installs an interrupt handler for IRQ3.  That handler won't do anything for
the serial port.

Under DOS, printing is NOT interrupt-driven.  Instead, the BIOS polls the
status of the parallel port to determine when another byte may be sent.
That's why you can have your sound card and LPT1 both configured to use IRQ7.
Try that on NT and see how far you'll get. :-)
-- 
Kenneth R. Ballou				VOICE:		 (617) 494-0990
Oberon Software, Inc.				FAX:		 (617) 494-0414
One Memorial Drive, Cambridge, MA  02142	Internet:     ballou@oberon.com