Dell Inspiron 3500 - Manual (Page 106)

4-24 Dell Inspiron 3500 Portable Computer Reference and Troubleshooting Guide
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If the computer displays an error message that is related to the external device
connected to a port, but corrections to the device do not resolve the error, run the
appropriate subtest in the Serial/Infrared Ports test group.
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The three subtests in the Serial/Infrared Ports test group confirm the following port
functions:
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Serial/Infrared Baud Rate Test
Checks the baud rate generator in each serial communications chip against the
computer’s clock.
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Serial/Infrared Interrupt Test
Checks the serial port’s ability to send IRQs to the microprocessor.
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Serial/Infrared Internal Transmission Test
Checks several internal functions of the serial port using the internal loopback
mode of the serial communications chip.
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The subtests in the Parallel Ports test group check the computer’s interface with
external devices, such as a printer, that are connected to the computer through the
parallel port. The subtests in this test group are not intended as a diagnostic test for
the actual peripheral attached to each port.
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If the diagnostics does not recognize the computer’s parallel port, check the Parallel
Port option in the System Devices menu of the Setup program to see if the port has
been disabled. (See Chapter 2, “Customizing System Features,” for information on
using the Setup program.) The subtests in the Parallel Ports test group cannot test a
port unless it is enabled.
When a port is faulty, it may not be immediately evident that the port, and not the
device connected to the port, is faulty. Instead, the peripheral (such as a printer) might
behave erratically or not operate at all. If the external device is not properly installed
through software, it also may not function properly. Try operating the peripheral from
different programs or through the operating system. If it still does not work, you can
eliminate the software setup as the cause of the problem.
Another possible cause for errors is a problem with the external device itself. Use the
documentation that came with the peripheral to troubleshoot it and confirm that it is
working properly. (Most printers have a self-test.)