Write Same Command (41H) - Seagate SCSI Interface Product Manual

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5.54

Write Same command (41h)

The Write Same command (Table 177) requests that the target write the single block of data transferred by the
initiator to the medium multiple times.
Table 177: Write Same command (41h)
Bit 7
Byte
0 Operation Code (41h)
1 Logical Unit Number [1]
2 (MSB)
:
5
6 Reserved
7 (MSB)
8
9 Control [7]
Notes.
[1] The Logical Unit Number must be zero.
[2] A Physical Block Data (PBdata) bit of one requests that the target replace the first eight bytes of the data
to be written to the current physical sector with the physical address of the sector currently being written
using the physical sector format.
[3] A Logical Block Data (LBdata) bit of one requests that the target replace the first four bytes of the data to
be written to the current logical block with the logical block address of the block currently being written.
[4] A Relative Address (RelAdr) bit of one indicates that the logical block address field is a two's complement
displacement. This negative or positive displacement is to be added to the logical block address last
accessed on the logical unit to form the logical block address for this command. This feature is only avail-
able when linking commands. The feature requires that a previous command in the linked group have
accessed a block of data on the logical unit.
A RelAdr bit of zero indicates that the logical block address field specifies the first RelAdr logical block of
the range of logical blocks to be operated on by this command.
[5] The Logical Block Address specifies the logical block at which the read operation shall occur. The most
recent data written in the addressed logical block shall be returned.
[6] The Number of Blocks field specifies the number of contiguous logical blocks to be written. A number of
blocks field of zero requests that all the remaining logical blocks on the medium be written.
[7] See "Control Byte," paragraph 4.2.6.
6 5
Logical Block Address [5]
Number of Blocks [6]
SCSI Interface Product Manual, Rev. J
4 3
Reserved PBdata [2]
2 1
LBdata [3] RelAdr [4]
(LSB)
(LSB)
0