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Historically, track following technology has been used to satisfy requirements of helical scan tape systems where a track must be read completely by a single scan of the head across the track. These systems employ a track following servo system and a track format that includes a servo pattern to allow for alignment of the READ head trajectory across the tape with the recorded track. Typically, mechanical component and mechanical alignment procedures must meet very precise tolerances in order for these systems to function reliably.
In 1985 Sony began work on design of a very small digital audio tape recorder; this product, the NT-1, was introduced in 1992. For various reasons the NT-1 could not use a track following servo, so Sony engineers began looking for another solution. The answer was non-tracking technology, or NT. NT is significantly different from track following technology in a few key respects:
* The track is read by making multiple scans of the head across the track;
* The track is divided into more than 100 blocks, each of which includes its own address and data integrity check;
* Data is retrieved by reading blocks in any order and storing them in a track buffer according to their self contained addresses, re-assembling the track in the process.
NT:MULTIPLE SCAN READ
NT records alternate azimuth tracks in a manner similar to 8 mm and DDS systems. These tracks are commonly designated A and B; and...