Dale - Computer Science Illuminated 155

Dale - Computer Science Illuminated 155 - middle of the...

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128 Chapter 5 Computing Components Figure 5.4 A magnetic tape Tape reel Take-up reel Tape Tape Tape Read/write head Tape motion A magnetic tape storage mechanism Magnetic Tape We mentioned card readers and card punches as very early input/output devices. Paper tape readers were the next input/output devices. Although paper tapes, like cards, are permanent, they do not contain much data. The first truly mass auxiliary storage device was the magnetic tape drive . A magnetic tape drive is like a tape recorder and is most often used to back up (make a copy of) the data on a disk in case the disk is ever damaged. Tapes come in several varieties, from small streaming-tape cartridges to large reel-to-reel models. Tape drives have one serious drawback: In order to access data in the
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Unformatted text preview: middle of the tape, all the data before the one you want must be accessed and discarded. Although the modern streaming-tape systems have the capability of skipping over segments of tape, the tape must physically move through the read/write heads. Any physical movement of this type is time-consuming. See Figure 5.4. Magnetic Disks A disk drive is a cross between a compact disk player and a tape recorder. A read/write head (similar to the record/playback head in a tape recorder) travels across a spinning magnetic disk, retrieving or recording data. Like a compact disk, the heads travel directly to the information desired, and like a tape, the information is stored magnetically....
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This note was uploaded on 01/13/2011 for the course CSE 1550 taught by Professor Marianakant during the Fall '10 term at York University.

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