FastTips: Using a Modem with Windows 3.0 Questions & Answers

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This article contains the complete text of the "Using a Modem with Windows 3.0" fax script.

This fax script is available to customers who call the Microsoft FastTips Service for Operating Systems at (800) 936-4200.

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                       Microsoft Windows, Version 3.0
               Automated Product Support Service Fax-Script
           Questions and Answers: Using a Modem with Windows 3.0
           -----------------------------------------------------

1. Q. I want to use my modem with Windows. Which COM port should I
      use?

   A. Since there is no single hardware standard for how COM ports 3
      and 4 are implemented in various computers, we recommend that
      you use COM port 1 or 2 for your modem, especially if you are
      running Windows in 386 enhanced mode.

2. Q. I want to use my modem on COM port 3 or COM port 4. What do I
      need to do?

   A. Since there are many different hardware configurations for COM
      ports 3 and 4 on different computers, we cannot guarantee
      Windows support of these ports. However, if your computer has a
      BIOS that supports COM 3 and COM 4, the following information
      should help you with this setup.

      A brief note on COM ports: Unless you are using an EISA or Micro
      Channel computer, you cannot use COM 1 and COM 3 at the same
      time. Nor can you use COM 2 and COM 4 at the same time. COM
      ports 1 and 3 share a single hardware interrupt, as do COM ports
      2 and 4. Therefore, if your mouse is installed on COM port 1,
      COM port 3 will never be available while using Windows.

      To configure Windows to support the use of COM ports 3 and 4,
      edit the SYSTEM.INI file. Start Windows Notepad and open the
      SYSTEM.INI file. Find the section title line that reads
      [386Enh]. Below it, enter the following four lines, with no
      spaces, and with uppercase and lowercase letters, as shown:

         COM1BASE=3F8h
         COM2BASE=2F8h
         COM3BASE=3E8h
         COM4BASE=2E8H

      If you have an EISA or Micro Channel computer, add one more line
      to allow you to use all four COM ports at the same time:

         COMIrqSharing=true

      Save your revised SYSTEM.INI file and restart Windows.