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Internal Modem Installation with
Windows 3.x
56K Voice Faxmodem Internal - User’s Guide 21
Before you start your installation, make sure that you have the following
items:
Modem
U.S. Robotics Disk
RJ-11 Phone Lead
Tail Lead
Microphone
Analogue (Standard) Telephone Wall Socket
Phillips Head Screwdriver or ¼” Hex Screwdriver
Data/Fax/Voice Communications Software and Manual
A Word about COM Ports and IRQs
Most computer accessories — a mouse, sound card, enhanced graphics
card, scanner, etc. — require a special connection through which they
can communicate with the computer. For an internal modem, this
connection is called a communications (or COM) port. Most computers
have 1 or 2 COM ports, but they can have up to 4. Although internal
modems do not connect to COM ports directly, they do require a COM
port setting, which is determined by the setting on the modem’s COM
jumper pins.
Each COM port uses an interrupt request (IRQ). An accessory uses an
IRQ to get the attention of your computer’s central processing unit (CPU)
so that the accessory can perform a task.
The computer stops what it is doing, depending on the priority of the
request, to help the accessory perform its task. When two accessories
share an IRQ, it is like two people asking different questions in unison to
a third person. Just as the person being asked the two questions cannot
understand either request, a computer can lock up or otherwise fail to
communicate properly with your modem when there is an IRQ conflict.