For example, consider once again the scenario of a COM1 mouse, a COM2 fax/modem card, and a COM3 PassageWay Service Provider. If the COM3 serial port is located on an add-on card that 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 Windows to monitor IRQ5 rather than IRQ4 for the COM3 serial port -- this is accomplished using the Windows Control Panel under the “Ports” option (see your Windows documentation for details).
If you attempt this solution, you must be certain that you do not choose an IRQ that is in use by some other device in your system -- if so, you will only trade one type of IRQ conflict for another. You should be aware that many common add-on cards use IRQs, including network cards and multimedia sound cards, both of which are commonly used under Windows. Your PC hardware vendor can assist you in configuring IRQs. You may also need to consult the documentation for your PC and any add-on cards that are installed to determine which IRQs, if any, are available on your system.
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