Automatic trouble diagnosis of complex logic circuits

This paper deals with the problem of maintaining the most complex portion of an experimental electronic telephone switching system, the central control. New and more effective automatic trouble detection and diagnostic techniques were used. In order to utilize these techniques effectively, a maintenance dictionary — that is, a table relating trouble indications with corresponding faulty plug-in package — had to be produced. The system itself was utilized to create this dictionary. More than 50,000 known faults were purposely introduced into the central control to be diagnosed by its diagnostic program. The corresponding test results were then recorded via a high-speed output. Finally, these test data were sorted and printed in dictionary form by a computer.