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could operate only a few minutes without a tube failing. In addition, the puter weighed many tons and was very difficult to program. ENIAC was programmed through the use of thousands of switches. The $15 calculator available today is much more powerful than this early attempt. The real turning point in puter technology was the invention of the transistor in 1948. The transistor was the replacement for the vacuum tube. It was very small, cheap, dependable, used very little power, and generated very little heat: the perfect replacement for the vacuum tube. The transistor did not see much industrial use until the 1960s. INTEGRATED CIRCUITRY In 1959 a new technology emerged: integrated circuits (ICs). Integrated circuits were actually control circuits on a chip. When manufacturers discovered how to miniaturize circuits, it helped reduce the size and improve the dependability of electronic control even more than the transistor had. Largescale integrated circuits first were produced in 1965. In 1974 the microprocessor was invented. This made the microputer, and thus small application, possible. Great strides in the manufacture of memory for puters helped make puters more powerful and affordable. The original conception of numerically controlled machine tools occurred in the 1950s as a method of producing airfoils of great accuracy for the government. These plex parts were made by manual machining methods and inspected by paring them to templates. The templates also had to be manufactured by manual methods, which was very time consuming and inaccurate. However, in a shop in Traverse City, Michigan, a man named John Parsons was working on a method to improve the production of inspection templates for helicopter rotor blades. Parsons started as a