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Command Specifications
The functions of this command are the same as those of the Group 0 READ
command (Section 4.2.1) with the exception that it is possible to specify 4-byte
logical block addresses and 2-byte transfer block counts. However, when zero is
specified for the "Transfer block count," the command is terminated normally
without seek and pre-fetch being performed.
•
FUA (force unit access)
When this bit is "0", it indicates that the IDD satisfy the command by
accessing the cache memory. Any logical blocks that are contained in the
cache memory may be transferred to the INIT directly from the cache
memory.
When this bit is "1", it indicated that the IDD shall access the media in
performing the command prior to returning GOOD status. READ commands
shall access the specified logical blocks from the media (i.e., the data is not
directly retrieved from the cache).
4.2.3 WRITE (0A)
Bit
Byte
0
1
2
3
4
5
This command transfers the number of blocks of data specified in the "Transfer
block count" field from the INIT and writes them in continuous logical data
blocks with the logical data block on the disk media specified in the "Logical
block address" field in the CDB as the top.
The transfer block count can be specified up to a maximum of 256 logical data
blocks. When zero is specified in the "Transfer block count" field in byte 4 of the
CDB, it specifies transfer of 256 logical data blocks and when a value other than
zero is specified, it specifies the number of logical data blocks that should be
transferred.
When transfer of multiple data blocks is instructed by this command, when the
data blocks which are to be processed come to a track boundary, cylinder
boundary or zone boundary, a head switch or cylinder switch is executed
automatically and writing of the specified number of blocks is performed.
4-138
7
6
5
0
0
0
Logical Block Address
Logical Block Address (LSB)
Transfer Block Count
0
0
0
4
3
2
X'0A'
Logical Block Address (MSB)
0
0
0
1
0
0
0
C141-C009
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