2 tape cartridges recordread on the top half of the

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Unformatted text preview: ar in look and mechanical operation to the familiar home VCRs. A tape cartridge can be pushed inside or ejected from the tape drive just as a video tape cassette is pushed inside or ejected from a VCR unit. These tape cartridges provide a more convenient way to package tape, and greatly simplify the mounting of tape which is normally a problem with magnetic tape reels that have to be manually mounted on the tape drive. Moreover, tape cartridges also provide protection against dirt and contamination, since the tape is sealed inside the cartridge. Aside from the above mentioned differences in the mechanical shape and size of halfinch tape reels and half-inch tape cartridges, and the mechanical operation of their tape drives, there are two main differences in their data organization and data recording/reading: 1. The half-inch tape cartridge has 36 tracks, as opposed to 9 tracks for most half-inch tape reels. Like tape reels, tape cartridges also store data using parallel representation. Hence, 4 bytes of data are stacked across the width of the tape in case of tape cartridges, as opposed to a single byte of data in case of tape reels. This enables more bytes of data to be stored on the same length of tape. 2. Tape cartridges record/read on the top half of the tape in one direction and on the bottom half in the other direction. That is, out of 4 bytes (36 tracks) of data stacked across the width of the tape, 2 bytes (18 tracks) of data are read in each direction. Recall that in case of tape reels, data are recorded/read only in one direction. Other principles of data organization on half-inch tape cartridges are same as that for half-inch tape reels. That is, in case of half-inch tape cartridges also the concepts of blocking of records, IBG, file header label, file trailer label, tape header label, BOT marker, EOT marker, etc., are used for their respective purposes. Quarter-inch Streamer Tape In addition to the storage of data of those applications which process data sequentially, one of the primary uses of magnetic tapes is to serve as a ba...
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This document was uploaded on 04/07/2014.

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