OEM MANUAL:K6602771
6 COMMAND DESCRIPTIONS
Revision: 2 / Date: 2002.12.19
Page: 292 / 313
6.41 XDWRITE:(50
H
)
Bit
Byte
7
6
5
4
3
2
1
0
0
Operation Code(50
H
)
0
1
0
1
0
0
0
0
1
Logical Unit Number
DPO
FUA
DAW
Reserved
0
0
0
0
0
2
Logical Block Address (MSB)
3
Logical Block Address
4
Logical Block Address
5
Logical Block Address (LSB)
6
Reserved
0
0
0
0
0
0
0
0
7
Transfer Length (MSB)
8
Transfer Length (LSB)
9
Vendor Unique
Reserved
Flag
Link
0
0
0
0
0
0
The XDWRITE command requests that the target XOR the data transferred with the
data on the medium. The resulting XOR data is stored by the target until it is
retrieved by an XDREAD command.
The DPO (Disable Page Out) bit is used to determine the priority of the logical block
data read by this command in the cache. This controller ignores this bit.
If the FUA (Force Unit Access) bit is set to 1, the Drive access directly the medium.
The data is not read from the cache. If the cache data is more recent than the disk
data, the disk is written prior to reading.
If the FUA bit is set to 0, the Drive may satisfy the command by accessing the cache.
This controller ignores this bit.
The DAW (Disable Write) bit of 0 indicates that the data transferred from the
initiator is written to the medium after the XOR operation is complete.
The DAW bit of 1 indicates that the data is not written to the medium.
The Logical Block Address specifies the starting logical block to write by this
command.
XDWRITE:(50h)