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The earliest work on core memory was carried out by the Shanghai-born American physicist, An Wang, who created the pulse transfer controlling device in 1949. The name referred to the way that the magnetic field of the cores could be used to control the switching of current in electro-mechanical systems. Wang was working at Harvard University's Computation Laboratory at the time, but unlike MIT, Harvard was not interested in promoting inventions created in their labs. Instead Wang was able to patent the system on his own.
Jay Forrester's group, working on the Whirlwind project at MIT, became aware of this work. This machine required a fast memory system for realtime flight simulator use. At first, Williams tubes —a storage system based on cathode-ray-tubes—were used, but these devices were always temperamental and unreliable.Two key inventions led to the development of magnetic core memory, which enabled the development of computers as we know them. The first, An Wang's, was the write-after-read cycle, which solved the puzzle of how to use a storage medium in which the act of reading was also an act of erasure. The second, Jay Forrester's, was the coincident-current system, which enabled a small number of wires to control a large number of cores (see Description section below for details).
Core arrays were manually assembled; the work was performed under microscopes and required fine motor control. Initially garment workers were used.
By the late 1950s industrial plants had been set up in the far east to build core. Inside, hundreds of low-paid workers strung cores for cents a day. This lowered the cost of core to the point where it had become largely universal as main memoryPrimary storage is a category of computer storage, often called main memory . Confusingly, the term primary storage has recently been used in a few contexts to refer to online storage ( hard disk), which is usually classified as secondary storage. Primary by the early-1960s, replacing both the low-cost/low-performance drum memoryDrum memory was an early form of computer memory that was widely used in the 1950s and into the 1960s. For many machines, a drum formed the main working memory of the machine, with data and programs being loaded on to or off of the drum using media such a as well as the high-cost/high-performance systems using vacuum tubeIn electronics, a vacuum tube (American English) or thermionic) valve (British English) is a device generally used to amplify a signal. Once used in most electronic devices, vacuum tubes are now used only in specialized applications. For most purposes, ths as memory.
Although the manufacture of core memory was never automated, costs almost followed the not-yet-formulated Moore's Law; over the lifetime of the technology costs began at roughly a dollar a bit and eventually approached roughly $0.01 per bit. Core was in turn replaced by silicon memory chips ( RAM) in the early 70s.
Dr. Wang's patent was not granted until 1955, and by this time core was already in use. This started a long series of lawsuits, which eventually ended when IBM paid Wang several million dollars to buy the patent outright. Wang used the funds to greatly increase the size of Wang LaboratoriesWang logo circa 1980. Wang logo circa 1970. Usage restricted. Trademarks on this page belong to their owner. See Image use policy. Wang Laboratories was a computer company founded in 1951 by Dr. The company was successively headquartered in Cambridge (195.
Core memory was part of a family of related technologies, now largely forgotten, which exploited magnetic properties of materials to perform switching and amplification. By the 1950's, vacuum-tube electronics was well-developed and very sophisticated, but tubes were fragile, and the use of heated filaments made them short-lived, high in power consumption, and unstable in their operating characteristics. Magnetic devices had many of the virtues of the transistorThe transistor is the key active component in practically all modern electronics. The transistor is a solid state semiconductor device used for amplification and switching. In essence, it has three terminals. A current or voltage applied through/across tw and solid-state devices that would replace them, and saw considerable use in military applications. A notable example was the portable (truck-based) MOBIDIC computer developed by Sylvania for the U. S. Army Signal Corps in the late fifties.
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