Resourceful Machine

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 own ailment and an electric typewriter starts clacking out a coded description. A maintenance man-one humble surviving human in a world of strong-minded machines-looks up the code in a 1,290-page dictionary written by a computer. There the maintenance man finds instructions telling him which part needs to be replaced. He need not ask what the part does or how it went wrong. He merely pulls it out and puts in a replacement.

To ward off delay if a more vital component should fail-something that cannot be so easily replaced-Bell engineers have built into the system many alternative ways for the central to restart itself after a few millionths of a second of hesitation. While testing these precautions recently, they made a disquieting discovery: the loyal and resourceful machine was using an emergency procedure that had not been programmed into it by human brains. Poking into the mazes of wires with their clumsy human hands, the engineers found one wire that had been connected accidentally to a terminal that led nowhere. Says Director Ray Ketchledge of the Electronic Switching Laboratory: "This should have caused the system to stop, but it didn't. It combined several programs into one of its own and avoided using the open wire." Ketchledge thinks the central's "motivation" to keep running is an indirect result of human instructions. The other possibility: the machine has developed an independent personality of its own.

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