Write Long Command (3Fh) - Seagate SCSI Interface Product Manual

SCSI Interface Product Manual, Rev. J
5.53

Write Long command (3Fh)

The Write Long command (Table 176) requests that the target write to the medium the data transferred by the
initiator. The data passed during the Write Long command shall include the data bytes and all ECC bytes to be
written to the single logical block addressed in the command. The Read Long command is usually issued
before issuing a Write Long command. The Write Long data passed must be in the same order and must be
the same number of bytes as the Read Long command.
Table 176: Write Long command (3Fh)
Bit 7
Byte
0 0
1 0
Logical Unit Number [1]
2 Logical Block Address (MSB) [2]
3 Logical Block Address [2]
4 Logical Block Address [2]
5 Logical Block Address (LSB) [2]
6 0
7 Byte Transfer Length (MSB) [3]
8 Byte Transfer Length (LSB) [3]
9 0
Notes.
[1] The Logical Unit Number must be zero.
[2] 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 logical block at which the
write operation shall occur.
[3] The Byte Transfer Length specifies the number of bytes of data that shall be transferred. A transfer length
of zero indicates that no bytes shall be transferred. This condition shall not be considered as an error. The
byte transfer length requested must be equal to the current block size plus all ECC bytes for a data trans-
fer to occur. If an incorrect number of bytes is stated in the command block, this command terminates with
a Check Condition status. The correct number of bytes can be determined from the information returned
in the extended sense data bytes after issuing the Request Sense command. The Request Sense com-
mand shall result in the Illegal Field In CDB condition with the Illegal Request Sense Key. The extended
sense ILI bit shall be set. The extended sense information bytes contain the difference (residue) of the
requested length minus the actual length in bytes. (Negative values are indicated by two's complement
notation.)
[4] See "Control byte," paragraph 4.2.6.
6 5
0 1
0 0
0 0
0 0
4 3
1 1
0 0
0 0
0 0
2 1
1 1
0 0
RelAdr [2]
0 0
0 Flag [4] Link [4]
221
0
1
0