At the Bell Telephone Laboratories' experimental Electronic Central Office in Morris, Ill., the exchange is automatic, of course. But for all the functions the exchange performs without human attention, Bell is aware that all its components can hardly work right all the time. To avoid employing human troubleshooters, Engineer Sin Hsuin Tsiang has trained the machine to spot its own breakdowns and tell humans how to fix them.
When one of the 6,500 transistors or 45,500 diodes in the machine's control unit fails, a duplicate component takes over instantly. A few thousandths of a second later, the machine has diagnosed its...