These machines have shown that enormous speeds can be realized: 5000 additions a second is Eniac’s record. High speed is needed for many problems in science, government, and business. In fact, there are economic and statistical problems, now settled by armchair methods, for which high-speed mechanical brains may make it possible to compute answers rather than guess them. Also, these machines have been shown to be reasonable in cost. The cost of each of the large calculators is in the neighborhood of $250,000 to $500,000. If we assume a ten-year life, which is conservative, the cost is about $3 to $6 an hour for 24-hour operation. Since each mechanical brain can, for problems for which it is suited, do the work of a hundred human computers, such a machine can save its cost half a dozen times. And these machines are only engineers’ models, built without the advantages of production-line assembly. The cost of giant mechanical brains under design in 1947 and 1948 is in the neighborhood of $100,000 to $200,000. The main reason for the reduction from the previous cost is the use of cheaper automatic memory. As designs improve and charges for research and development are paid off, the cost should continue to go down. NEW DEVICES FOR HANDLING INFORMATION In the laboratories working on new mechanical and electronic brains, scientists are doing a lot of thinking about new devices for handling information. Research into devices for storing information shows that _magnetic wire_ as used in sound recording is a rather good storage medium. Magnetic Wire For example, on a hundredth of an inch of fine steel wire we can “write” a _magnetized spot_ by means of a small “writing” _electromagnet_. The electromagnet is simply some copper wire coiled around some soft iron shaped in a U. When current flows through the coil, the iron becomes a magnet, and the tips of the U magnetize the little section of the wire between them. The magnetized spot can be of two kinds, say north-south or south-north, depending on which way the current flows. We can “read” this difference by means of another small “reading” electromagnet. We can erase the spot by means of a stronger “erasing” magnet that produces a uniform magnetic state throughout the wire. The difference between north-south and south-north corresponds to the difference between 1 and 0, or “yes” and “no,” etc., and is a _unit of information_ (see Chapter 2). Many other variations are possible. For example, the presence or absence of a magnetized spot may be the unit of information, or the “writing,” “reading,” and “erasing” electromagnets all may be the same.