INTERNAL MODEM INSTALLATION HINTS

COMMUNICATION  PORTS (COM, SERIAL PORTS) 

A communication port (COM, SERIAL) is used for connecting  modems, printers, 
and other various input/output devices to your PC.  IBM PC/XT/AT and 
compatible systems support 4 COM ports.  COM ports also have specific I/O 
base addresses assigned to each COM port number.  COM port assignments 
are usually set by DIP switches or jumpers on the device that is provides 
the COM port.  COM ports require specific interrupt (IRQ) settings which 
must be set correctly.  A modem cannot share an IRQ with a device that is 
in use at all times (e.g. MOUSE), however it can share an interrupt with 
a device that is currently not using an IRQ when the modem is in use.  
After determining how many existing COM ports are in your system, set the 
modem for the next open COM port, regardless of whether a port is being 
used or not.  The IRQ will be set according to what COM port is available 
and what IRQ is currently being used by other devices.

The following table lists standard COM and IRQ settings.
 
COMMUNICATION PORT SETTINGS & IRQ'S     BASE I/O ADDRESS
COM 1 / IRQ 4                           03F8
COM 2 / IRQ 3                           02F8
COM 3 / IRQ 4,3 (5,7 alternate IRQ)     03E8
COM 4 / IRQ 3,4 (5,7 alternate IRQ)     02E8

STEP 1:

You must determine how many existing COM or SERIAL ports are currently 
installed in your system before setting the modem to the correct communication 
port.  This can be accomplished with a system information program such as 
those listed below.
 Norton Utilities  SI System Information Diagnostics
 Checkit Diagnostics
 Q & A Diagnostics
 Microsoft Diagnostic Utilities  MSD (included with Windows 3.1) Type MSD
 in the Windows directory.
If you do not have a system information program, CONTACT YOUR COMPUTER DEALER
and have them tell you how many existing COM or SERIAL ports are in your
system and what IRQ's  they are using.  Based on which ports are currently
in you system, use the table below to determine the correct COM and IRQ
setting.  The COM and IRQ jumper are designated by the jumpers (often blue)
on your modem board.
 
EXISTING INSTALLED COM PORTS    MODEM PORT & IRQ SETTING
 NO COM PORTS INSTALLED              COM 1/IRQ 4
 COM 1/IRQ 4                         COM 2/IRQ 3
 COM 1/IRQ 4, COM 2=IRQ 3            COM 3/IRQ 4, no mouse on COM 1.
                                     COM 3/IRQ 3, COM 2 not in use.
                                     COM 3/IRQ 5,7, COM 1 & 2 in use,
                                     software must support IRQ 5 & 7.

Trademarks:
All references to computer systems, software, and peripherals use trade marks
owned by their respective manufacturers.