Tandberg Data SLR7-140 PROGRAMMER Manual page 237

DDE
RED
Compression
Algorithm
Decompression
Algorithm
Tandberg Data
When using SLRtape140 to SLRtape7 or SLR32, media the
Data Decompression Enable (DDE) bit is ignored (data
decompression is always enabled regardless of the state
of the DDE bit).
When using other media the DDE is a status bit and not a
configuration bit.
command will ignore the DDE bit (data decompression is
always enabled). For the MODE SENSE command the DDE bit
is a status bit that indicates if the medium is being
written with compressed data (write mode) or if pre-
written compressed data is being read (read mode). The
DDE bit has a valid state after a READ, VERIFY
WRITE command.
See section 2.8 Data Compression for further details on
how to use the DDE bit.
The Report Exception
indicates how the Drive responds on certain boundaries
between compressed and uncompressed data read from the
tape. This field is ignored and can be set to any
value. The Drive will report CHECK CONDITION status when
compressed data is encountered which the Drive cannot
decompress (unsupported algorithm).
The default (factory programmed) value is 0.
The Compression
compression algorithm the Drive shall use to process the
data sent to it by the Initiator when the DCE bit is set
to one.
The following values are legal:
00 00 00 00h :
uncompressed data).
00 00 00 03h :
The default (factory programmed) value is 00 00 00
03h
The Decompression Algorithm field is ignored by Mode
Select because
recognition of the Compression Algorithm used to process
data encountered
Algorithm value returned in response to a Mode Sense
command will change dynamically to reflect the algorithm
used by the Drive to decompress the data most recently
transferred to the Initiator during a read operation. A
value of zero indicates that the data transferred to the
Initiator during
uncompressed.
1
VERIFY is not supported by SLR7 and SLR140
14-19 Tandberg SLR Product Line SCSI Functional Specifications
This means that
on Decompression
Algorithm field
No Algorithm
ALDC Data Compression Algorithm.
the Drive is
on the medium.
the most recent
Mode Select
the MODE SELECT
(RED)
indicates
Selected (identifies
capable of automatic
The Decompression
read operation
1
and
field
the
was