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Command Specifications
3 -
66
C141-E167
3.2.2 READ EXTENDED (28)
Bit
Byte
76543210
0 X‘28’
1LUN
×
FUA 0 0 0
2 Logical Block Address (MSB)
3 Logical Block Address
4 Logical Block Address
5 Logical Block Address (LSB)
6 00000000
7 Transfer Block Count (MSB)
8 Transfer Block Count (LSB)
9 0000000Link
This command reads the number of blocks of data in continuous logical data blocks specified in the
"Transfer block count" field with the logical data block on the disk media specified in the "Logical
block address" field in the CDB as the top.
The functions of this command are the same as those of the Group 0 READ command (Section
3.2.1) 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).