>As for serial ports this is not the case... you can purchase 4-8-16 or
    >even 32 port serial boards that only use 1 interrupt for all of the ports
    >on the board. "I dont have a free int. for that board you say? Disable an

    But do they work with existing software?

Probably.  Serial ports are less likely to be directly driven these days,
so there's less funny stuff to do with them.  There are cetainly 4 port
cards that are fully HW compatible with the original port designs, and can
share intrerrupts com1/com3 and com2/com4 (you can share interrupts within
a single ISA card - the problem is that the BUS doesn't allow interrupts to
be shared between cards.)

BillW