Command Descriptor Block - Tandberg Data SLR7-140 PROGRAMMER Manual

BYTE BIT 7
00 Operation Code 13h
01 Logical Unit Number (LUN)
02 Verification Length
03
04
05 Control Byte
IMM
CMP
FIX
Verification Length
Tandberg Data

29.2. Command Descriptor Block

6 5
Table 29-1:
The immediate (IMM) bit is ignored by the Drive.
When byte-by-byte data compare is performed (CMP bit is
set to one), the Drive sends status immediately after
data transfer.
SCSI-bus side of the data buffer, the VERIFY command is
terminated when status is sent.
When only CRC/ECC check is performed (CMP bit set to
zero) the VERIFY command does not return with status
until all the requested data has been verified.
A Byte Compare (CMP) bit of zero indicates that the
verification will be simply a CRC/ECC verification. No
data will be transferred between the Initiator and the
Drive. The VERIFY
equivalent to a SPACE block forward command (without the
FAST option).
A CMP bit of one indicates that a byte-by-byte compare
of the data on tape and the data transferred from the
Initiator will be performed by the Drive. Data will be
transferred from the Initiator to the Drive as in a
WRITE command.
A Fixed (FIX) bit of zero indicates that a single block
will be verified with the Verification Length specifying
the expected length of the block in number of bytes to
be verified.
A FIX bit of one indicates that the Verification Length
specifies the number of blocks to be verified beginning
with the next logical block. Note that a FIX bit of one
is not allowed when the Drive is in Variable Block mode
(see the Block Size field in the Block Descriptor List
of the MODE SELECT command for further details).
This field specifies
requested for verification.
0..16777215 is legal. Note, however, that the maximum
block size that can be written is 262144 bytes.
29-2 Tandberg SLR Product Line SCSI Functional Specifications
4 3
RESERVED
VERIFY Command Descriptor Block
Since the Drive compares data at the
command will
the number
Any
2 1
IMM CMP FIX
then be functionally
of bytes or blocks
value in the
Verify
0
range