Information storage

INFORMATION STORAGE APPLICATIONS IN THE FIELDS OF MAGNETISM AND MICROELECTRONIC 

In general, it is most efficient for the microprocessor to access and store in the semiconductor main memory (DRAM) alone because the DRAM access time is 100 ns. However, DRAM is volatile and any information in the DRAM is lost once the computer is turned off. Thus, lower level of information storage devices is essential. The latter may include magnetic hard disc, magnetic floppy drives, etc. As a rule, the higher-level storage media are 

More recently, though, the chromium under layer, the magnetic recording layer, and the overcoat are produced mainly via vacuum-deposition methods. The reason for this is economical, that is, to ease the mass production at accurately fixed thicknesses. 

Combined read/write heads belong to the old technology. Newer technologies follow a trend toward using separate heads for reading and writing. 

Metal in gap (MIG) heads or ferrite ones are produced with a combination of machining, bonding, and thin film processes. Tliin-film inductive heads are manufactured by thin-film processes similar to the semiconductor IC technology (see Section III). Tliin-film head production process, however, is rather unique as it involves both, very thin and very thick films. We choose to present here a detailed summary of the fabrication process of thin-film inductive heads with a single-layer spiral coil. This should serve, once again, to illustrate the centrally important role of electrochemical deposition in coimection with modem IT. 

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An ion beam causes secondary electrons to be ejected from a metal surface. These secondaries can be measured as an electric current directly through a Faraday cup or indirectly after amplification, as with an electron multiplier or a scintillation device. These ion collectors are located at a fixed point in a mass spectrometer, and all ions are focused on that point — hence the name, point ion collector. In all cases, the resultant flow of an electric current is used to drive some form of recorder or is passed to an information storage device (data system). 

Tensile properties of importance include the modulus, yields, (strength at 5% elongation), and ultimate break strength. Since in many uses the essential function of the film may be destroyed if it stretches under use, the yield and values are more critical than the ultimate strength. This is tme, for example, where film is used as the base for magnetic tape or microfilm information storage. In some cases, the tensile properties at temperatures other than standard are critical. Thus if films are to be coated and dried in hot air ovens, the yield at 150°C or higher may be critical. 

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