Seagate ST3285N, Руководство по эксплуатации продукта

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3.5.8 Write Buffer command (3B
H
)
In conjunction with the Read Buffer command, the Write Buffer command
can be used in the following ways:
•
To diagnose problems in the drive’s data buffer.
•
To test the integrity of the SCSI bus.
The Write Buffer command can also be used to download microcode to
the buffer and save it on the disc.
Note. This command treats the buffer as a single segment, regardless
of the number of segments specified in Mode Page 08
H
. (Mode
Page 08
H
is described in Section C.5.)
Bit
Byte
7 6 5 4 3 2 1 0
0 0 0 1 1 1 0 1 1
1 LUN 0 0 Mode
2 Buffer ID (00
H
)
3–5 Buffer offset
6–8 Parameter list length
9 0 0 0 0 0 0 Flag Link
Byte 1 If the mode bits contain 000, the initiator transfers data to the
drive buffer with a 4-byte header that contains all zeros. This
mode is called
write combined header and data.
If the mode bits contain 010, the initiator transfers data to the
drive buffer without the header. This mode is called write data.
If the mode bits contain 101, the initiator downloads microcode
to the drive buffer, and the drive saves the microcode in reserved
cylinders. The drive uses the new microcode for all future
operations. This mode is called
download microcode and save.
Note. If the mode bits contain 101, the flag and link bits must
be 0.
After the microcode has been successfully downloaded, the
drive generates a unit attention condition of
microcode has been
downloaded for all initiators except the one that issued the
current Write Buffer command.
All other settings for the mode bits are reserved.
Byte 2 The
buffer ID is not supported and must always be zero.
70 ST3655 Family SCSI Drives Product Manual, Rev. A