                        3Com (R) Corporation
                   EtherDisk (R) Diskette for the
      3C90X Fast EtherLink XL/EtherLink XL Bus Master NIC Family
                         Troubleshooting


If the NIC diagnostic tests fail, the NIC may not be defective.
Check the following:

1.  Make sure that the NIC is completely seated in its slot.  Review
    the installation instructions in the appropriate NIC guide.

2.  If you are running the Group 2 test, make sure that the NIC is
    securely connected to a loopback plug or to a properly cabled network.
    Running Group 2 tests while connected to an active network can cause
    intermittent failures.  These failures can be avoided by using a
    loopback plug or by connecting to an inactive network on which only 
    the computer being tested is operating.

3.  If you are running the Group 3 test, make sure that the NIC is
    securely connected to a properly cabled network and that an echo 
    server is set up and running on the network.

4.  If you are configuring the I/O base address, interrupt request level,
    or boot PROM base address, make sure that the settings you choose for
    these parameters do not conflict with any other peripheral or software
    program installed in the computer.  For a list of system resources
    commonly used by other peripherals, select Commonly Used Interrupt
    and I/O Base Addresses from the Configuration and Diagnostic submenu.

5.  Make sure that the configuration setting for the transceiver type is
    correct.

6.  If you installed a twisted-pair NIC in your PC, check the LED on
    the backplate of the NIC.  The LED should be checked only during or 
    after the diagnostic tests have been run.  The LED will be on when 
    there is a correct and active connection between the NIC and the hub.
    The LED will flash if the polarity of the connection is reversed.

7.  The slot in the computer may be defective.  Install the NIC in
    another slot and run the tests again.

8.  The computer in which the NIC is installed may be defective.
    Install the NIC in a known functioning computer and run the tests
    again.

9.  The components of the loopback plug you are using may be defective.
    Try a different loopback plug.

10. Replace the failed NIC with a known working NIC with the same
    configuration.  Run the test again.  If the second NIC fails,
    something is probably wrong with the test environment, not with
    the NIC.

                 (%VER  TROUBLE.TXT - Troubleshooting v1.0d)
