Command Descriptor Block - Tandberg Data SLR7-140 PROGRAMMER Manual

BYTE BIT 7
00 Operation Code 11h
01 Logical Unit Number (LUN)
02 Count
03
04
05 FAST
Table 27-1:
Code
Count
FAST
Tandberg Data

27.2. Command Descriptor Block

6 5
X RESERVED
SPACE Command Descriptor Block
The Space Code is defined as follows:
0 : Space over Blocks
1 : Space over Filemarks
2 : Space over Sequential Filemarks
3 : Space to End-Of-Data (EOD)
4 : Space over Setmarks
5 : Space over Sequential Setmarks
7 : Space over Bad Blocks
This field specifies
(Code=0), the number of filemarks to space (Code=1 or
Code=2) or the number of setmarks to space (Code=4 or
Code=5). The Count field is ignored when spacing to End-
Of-Data (Code=3)
(Code=7). A positive
positioning. A
notation) will cause reverse positioning. A zero value
in the Count field will cause no tape movement (except
for Code=3 and Code=7). This is not an error condition.
When the FAST bit is set to zero, the Drive will execute
the SPACE command in a standard sequential fashion. All
data between the
position are check-read by the Drive.
When the FAST bit is set to one the Drive will use a
special fast space algorithm. When using this algorithm,
the Drive is not able to test for possible bad/corrupted
data blocks on
details.
When spacing in the reverse direction, the Drive will,
if possible, use the fast space algorithm, even if the
FAST bit is set to zero.
Note that the FAST bit may be overridden by the FAST bit
in the Miscellaneous Page of the MODE SELECT parameter
data.
27-2 Tandberg SLR Product Line SCSI Functional Specifications
4 3
RESERVED Code
the number
and when spacing
Count field
negative Count
current position
the tape. See
2 1
Flag
if blocks to
over bad
will cause forward
field (2's complement
and the terminal
the next section
Space
0
Link
space
blocks
for