Quantum DLTtape DLT 2000, Руководство пользователя

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HISTORY OF DLTtape TECHNOLOGY 3.2
sette systems (DAT wasn’t out yet). Of course, the drive itself had
to be made somewhat larger than most to accommodate the inter-
nal take-up reel. Dubbed the TK50, the new tape drive was capable
of storing 94MB per cartridge.
Using a ferrite read/write head, the TK50 recorded data in linear
blocks along 22 tracks using two channels. The TK50’s read/write
head actually contained two sets of read/write elements. One set
was used when reading and writing forward and the other reading
and writing backward. The TK50 started recording at the begin-
ning of the tape, recording on one track. When it reached the end,
the system recorded back to the beginning along a new track. After
every two tracks were written, the system moved the head up the
width of one track and began the process again. The read-after-
write capability of the system ensured basic data accuracy.
The TK50 was introduced with the MicroVAX II in 1985. The drive
fit into a full height, 5.25" drive bay in the MicroVAX. Compared
to the DLTtape drive of today, the TK50 was like Neanderthal Man
– it walked upright and used tools, but it still had a long way to go.
The TK line of drives used only two guide rollers to hold the
streaming tape against the read/write head. This was okay for the
low data densities of these early systems, but would never work at
the extreme densities we’ve come to expect today.
In 1987, the year of the first IBM 80386-based PCs and Windows
2.0, Digital rolled out the TK70. This new tape drive offered 294MB
of storage on the same square tape cartridge, a 3x improvement
over the TK50. This was accomplished by upping the number of
tracks to 48 and increasing density on the same half-inch tape.
Millions of PCs were in use and had become a permanent part of
corporate America. Popular PC applications included desktop pub-
lishing, word processing, spreadsheet, and database management.