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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.
When the specifications in the "Logical block address" field and "Transfer block count" field
in the CDB exceed the maximum logical block address in the IDD, that command is
terminated with a CHECK CONDITION status (ILLEGAL REQUEST [=5] / Logical block
address out of range [=21-00]) and writing of data to the disk media is not executed.
The IDD performs the XFER-RDY frame transfer after receiving the CDB, but after
performing Loop OPEN processing once, it executes pre-fetching of data. The IDD either
completes transfer of all the data specified in the command or, at the point when the empty
space in the data buffer runs out, Loop CLOSE processing is executed. Positioning of the
specified data blocks is performed in parallel with this data transfer, and writing of data from
the data buffer to the disk media is executed immediately after positioning is completed. See
Section 2.1 "Data Buffer" for details of data buffer operation and control of the timing for
starting reconnection processing by the MODE SELECT parameter (buffer empty ratio).
7
6
5
0
0
0
Logical Block Address
Logical Block Address (LSB)
Transfer Block Count
0
0
0
C141-E054-02EN
4
3
2
X'0A'
Logical Block Address (MSB)
0
0
0
1
0
0
0
4 - 83
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