Serial/Infrared Ports Test Group
The subtests in the Serial/Infrared Ports test group check the computer’s interface with external devices (such as a serial mouse or a printer). The subtests in this test group are not intended as a diagnostic test for the external device itself.
Why Run a Serial/Infrared Ports Test?
It may not be immediately evident whether the port or the external device is faulty. In both cases, the external device (such as a serial mouse or a printer) might behave erratically or not operate at all. Eliminate incorrect sys- tem configuration information settings, peripheral malfunctions, and software errors as potential causes of infrared (IR) port problems, before you run the subtests in the Serial/Infrared Port test group to check your hardware.
If the diagnostics do not recognize the computer’s serial or infrared port, check the Serial Port or Infrared Port option in the System Devices menu of the Setup program to see if the port has been disabled. (See Chapter 2, “Software Features,” for information on using the Setup program.) The subtests in the Serial/Infrared Ports test group cannot test a port unless it is enabled.
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.
If the external device is not properly installed through software, the device also may not function properly. Try operating the device from different programs or through the operating system. If it still does not work, you can eliminate the software configuration as the cause of the problem.
Although the following symptoms can be caused by faulty peripherals or software errors, these symptoms might also suggest a port problem:
•If a peripheral works intermittently, or produces intermittent errors, the port may be faulty.
•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.
Subtests
The four subtests in the Serial/Infrared Ports test group confirm the following port functions:
•Serial/Infrared Baud Rate Test
Checks the baud rate generator in each serial com- munications chip against the computer’s clock
•Serial/Infrared Interrupt Test
Checks the serial port’s ability to send IRQs to the microprocessor
•Serial/Infrared Internal Transmission Test
Checks several internal functions of the serial port using the internal loopback mode of the serial com- munications chip
•Serial External Transmission Test
If a loopback device is attached, checks the line con- trol bits of the serial port and sends a test pattern at several baud rates, checking the returned values
Parallel Ports Test Group
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.
Why Run a Parallel Ports Test?
If the diagnostics does not recognize the computer’s par- allel 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.
