Tandberg Data
Introduction to the Drive
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2-4
Tandberg SLR Reference Manual
2.3. Tape Format and Drive Operation
Data is formatted into small blocks, each block containing 512/1024 bytes of data (1024 bytes
for the QIC-2GB and QIC-4GB formats).
Special address and checking bytes are added to each block. The basic layouts are shown in
Figure 2.2.
Preamble
Block
Marker
Control
Field
Data
(512 bytes)
CRC
Postamble
Standard Data Block – QIC-5010-DC / SLR6 (SLR24) / MLR3 (SLR50)
Preamble
Block
Marker
Data
(1024 bytes)
Control
Field
CRC
Postamble
Standard Data Block - QIC-2GB/4GB
Preamble
Block
Marker
Randomizer
Seed
Control
Field
Data
(512 bytes)
CRC
Pad Field
Randomized
VR
2
RLL Coded
Standard Data Block – ALRF-1 / ALRF-2 / ALRF-6
Figure 2.2 Track formats (ECC-blocks not shown)
Write Operation
The data bytes are transferred from the Host to the Drive and stored in the Drive’s data
buffer. The data is assembled into blocks of 512/1024 bytes. The Drive adds special address
and check characters to each block prior to writing the complete block on the tape. The Drive
performs read-while-write checking, and blocks with errors are automatically rewritten further
down the tape.
Read Operation
In read mode, data is read from the tape and the special address and check characters are
removed. The data bytes are then transferred to the Host via the built-in data buffer in the
Drive.
Any corrupted data will normally be corrected by the Drive.