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Before one can repair a broken system ¿ computer, industrial machinery, automobile electronics or avionics - two related, but not identical, activities are required. First, one has to determine that the system is in fact faulty. Often the determination is made by the user though sometimes incorrectly. For confirmation and for better assurance, a test is run. The test is usually built-in (BIT) or external test using manual or automatic test equipment (ATE). Once it is confirmed that the system is faulty, the related activity of identifying that fault, or diagnosis, is also needed. While diagnoses utilize results of tests, they are not the same thing as tests. Knowing that a computer will not boot up is far from being able to identify the cause and to begin repairs.