วันพุธที่ 25 กรกฎาคม พ.ศ. 2550

how first computer use

Unlike modern digital computers, analog computers are not very flexible, and need to be reconfigured (i.e., reprogrammed) manually to switch them from working on one problem to another. Analog computers had an advantage over early digital computers in that they could be used to solve complex problems while the earliest attempts at digital computers were quite limited. But as digital computers have become faster and used larger memory (e.g., RAM or internal store), they have almost entirely displaced analog computers, and computer programming, or coding has arisen as another human profession.
Since computers were rare in this era, the solutions were often hard-coded into paper forms such as graphs and nomograms, which could then allow analog solutions to problems, such as the distribution of pressures and temperatures in a heating system.
Some of the most widely deployed analog computers included devices for aiming weapons, such as the Norden bombsight and Fire-control systems for naval vessels. Some of these stayed in use for decades after WWII. One example is the Mark I Fire Control Computer, deployed by the United States Navy on a variety of ships from destroyers to battleships.
The art of analog computing reached its zenith with the differential analyzer, invented by Vannevar Bush in 1930. Fewer than a dozen of these devices were ever built; the most powerful was constructed at the University of Pennsylvania's Moore School of Electrical Engineering, where the ENIAC was built. Digital electronic computers like the ENIAC spelled the end for most analog computing machines, but hybrid analog computers, controlled by digital electronics, remained in substantial use into the 1950s and 1960s, and later in some specialized applications

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