Evolution of Magnetic storage

Evolution of Magnetic storage - L. D. Stevens The...

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L. D. Stevens The Evolution of Magnetic Storage Since delivery thefirst vacuum-column magnetic-tape transport in 1953 and movable-head disk drive in 1957, tape and devices in many configurations have been the principal means for storage large volumes data required by processing systems. drums other device geometries have also important system components, but to a lesser extent. Over the past twenty-five years signijicant developments made that increase capacity, reduce cost, and improve performance reliability these devices. With each improved range and nature applications undertaken expanded and, in turn, led to a need further improvement. This paper gives a general review and historical perspective magnetic development within IBM and is an introduction to the subsequent papers on disk, diskette, technology on manufacturing. Introduction Data processing applications of computers have grown overthepast twenty-five years fromincidental signifi- cance to a point where they now become a pervasive influence in our society. Early data processing systems used magnetic tape as the principal storage medium for large data files. Processing was batch sequential on a job- by-job basis application focus was accounting. These systems had only secondary impact on opera- tional aspects of business. Those early computers are in sharp contrast data processing systems of today, which allow many different jobs to run concurrently with very-large-capacity on-line magnetic storage (i.e. , di- rectly accessible without human intervention), data-base- oriented transaction processing, and an application focus on making more efficient use of operational resources. Improvements in the capacity, and performance of on-line magnetic storage have fueled these growing systemsandtheir applicationcapability. Three distinct periods can be identified in this evolution. During first-the early years from 1953 to 1962-limited on-line was provided by the tape drives (with mounted reels of tape) attached system. Disk storage was a scarce resource, found only in those systems where high cost, limited capacity, and difficulty of use could be justified by its capability for direct access of data. In next period-the transition years from 1963 to 1966- rapid development of disk technology and systems soft- ware removed many of these constraints. Disk storage and on-line processing began to be an part of most systems although tape batch were still dominant. During the third period-the growth from 1%7 to 1980-the cost per Mbyte of disk stor- age was reduced twentyfold and with further systems software, new terminals, communication facili- ties, on-line application development, substantial growth occurred in the on-line storage capacity of the av- erage system; see Fig. 1. Here, the main memory capac- ity of the average IBM data processing system is com- pared with its disk and storage capacity during this period. Disk capacity per system increased by a factor of forty from a base of 23 Mbytes, attached-tape capacity increased by a factor of seven from a base of 47 Mbytes,
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This note was uploaded on 05/01/2008 for the course EE 40 taught by Professor Chang-hasnain during the Spring '07 term at Berkeley.

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Evolution of Magnetic storage - L. D. Stevens The...

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