Avaya Partner 18 Connection Manual page 301

Appendix B: PC Serial Ports
Given the scenario described in item (1) above (that is, a mouse on COM1 a
fax/modem card on COM2, and PassageWay Solution on COM3), you might
buy a bus mouse and configure it to use, say, IRQ2 or IRQ5. This would then
permit you to move PassageWay Solution onto COM1 (IRQ4), where it could
then be used simultaneously with both the mouse and the fax/modem.
Likely candidates for conversion from a serial interface to some other interface
include mice (which can be converted to bus mice) and serial printers (which
can be converted to an additional parallel printer port).
Workaround 3: If your serial port hardware permits you to select IRQs
other than the default ones (IRQ3 and IRQ4), make use of one or more
unused IRQs in your system to assign each COM port a unique IRQ.
This solution is generally not possible for built-in serial ports since these are
usually "hard wired" and cannot be changed. Although most add-in cards
containing serial ports permit you to change the IRQs assigned to them, many
cards do not let you select IRQs other than IRQ3 and IRQ4. For example, an
internal modem card generally has jumpers or switches which permit you to
administer the serial interface on the card to be COM1, COM2, COM3, or
COM4, but the I/O port addresses and IRQs associated with each of these
configurations is usually fixed to the settings in the table.
Fortunately, some serial port add-in cards do permit you to select IRQs other
than 3 or 4 (the additional choices are often IRQ2 and IRQ5). If your serial
port hardware provides this flexibility – and at least one of the IRQ numbers
available as an option is currently unused in your PC setup – you can solve
the IRQ conflict directly.
For example, consider once again the scenario of a COM1 mouse, a COM2
fax/modem card, and a COM3 PassageWay Solution. If the COM3 serial port
is located on an add-in card which permits IRQs other than 3 or 4 to be
selected, you could configure the COM3 serial port to use a different
(available) IRQ in your system, say, IRQ5. After making the necessary
changes to the card (for example, adding or removing some jumpers or
adjusting the positions of some switches), the last step would be to configure
B-8