The arrival of the microprocessor in the 1970s brought about a revolution of control. For the first time, relatively complex systems could be constructed using a simple device, the microprocessor, as its primary control and feedback element. If you were to hunt out an old Teletype ASR33 computer terminal in a surplus store and compare its innards to a modern color inkjet printer, there s quite a difference.

Automobile emissions have decreased by 90 percent over the last 20 years, primarily due to the use of microprocessors in the engine-management system. The open-loop fuel control system, characterized by a carburetor, is now a fuel-injected, closed-loop system using multiple sensors to optimize performance and minimize emissions over a wide range of operating conditions. This type of performance improvement would have been impossible without the microprocessor as a control element.

Microprocessors have now taken over the automobile. A new luxury- class automobile might have more than 70 dedicated microprocessors, controlling tasks from the engine spark and transmission shift points to opening the window slightly when the door is being closed to avoid a pressure burst in the driver s ear.

The F-16 is an unstable aircraft that cannot be flown without on-board computers constantly making control surface adjustments to keep it in the air. The pilot, through the traditional controls, sends requests to the computer to change the plane s flight profile. The computer attempts to comply with those requests to the extent that it can and still keep the plane in the air.

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