W H A T ' S   A N   I R Q ?
          
          IRQs (Interrupt ReQuests) refer to a mechanism within
          your computer that allows your computer's central
          processor to communicate with COM ports and other
          hardware devices. Each serial port is given a COM port
          address (expressed in hexadecimal numbers) and an IRQ
          value. However, only one device can use an IRQ value at
          a time. This is complicated by the fact that COM1 and
          COM3 use IRQ4 by default. Also, COM2 and COM4 use IRQ 3
          by default. Some hardware devices allow you to change an
          IRQ setting.   
          
          
          SOLVING IRQ CONFLICTS
          
          If you have the Microsoft MSD program, run it. The MSD
          program comes with DOS 6 and later versions and also
          Microsoft Windows 3.1. It will often show you which IRQs
          are used--and will help you avoid conflicts. If you are
          installing an external modem, you should not have any
          trouble. However, if you are trying to install an
          internal modem, you should read the modem manual
          carefully.
          
          You may have to set special dip switches or jumpers to
          configure an internal modem to avoid an IRQ conflict. The
          job of installing an internal modem is best left to a
          computer dealer or local GURU. It is not unusual for such
          individuals to charge $20.00 for installing a modem. Only
          a very bold beginner should attempt an internal modem
          installation. The main thing is to avoid an IRQ conflict.
          See the section on shareware for information about Modem
          Doctor and other useful shareware programs.  
          
          COM1 and COM3 use IRQ4. COM2 and COM4 use IRQ3. If you
          have a mouse using COM1, then IRQ 4 is already taken, so
          you will probably not want to set your modem for COM3.
          You will either have to disable the mouse driver (usually
          found in the AUTOEXEC.BAT or CONFIG.SYS file) or set your
          modem for COM2 or COM4 which use IRQ3. 
          
          Many people have success with setting an internal modem
          to use COM4 and don't plug anything into COM2. If you are
          using DOS 3.3 or later, your operating system will
          support four COM ports. 
          
          The most important thing to remember about IRQs is that
          only one device can use an IRQ address at a time. 

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