Mode Select Command (15 H ) - Seagate MEDALIST 1080SL Product Manual

42 Medalist 1080sl SCSI Product Manual, August 1995
The initiator should allocate 36
returned to the initiator is summarized in Appendix D.
Bytes
7 6
0 0 0
1 LUN
2
0 0
3 0 0
4
5 0 0
Byte 1 If the enable vital product data (EVPD ) bit is zero, the drive
returns the standard inquiry data. If the EVPD bit is one, the drive
returns the optional vital product data specified in byte 2.
Byte 2 The page code field specifies which page of the vital product
information the drive returns. If EVPD is zero, this field must be
zero.
Byte 4 The allocation length specifies the number of bytes the initiator
has allocated for returned inquiry data. The drive returns the
number of bytes specified by the allocation length up to a
maximum of 148 bytes. If the allocation length is zero, no data
is returned. This is not an error. The allocation length should be
at least 36 to allow the initiator to receive all of the standard
H
inquiry data.
3.4.10 Mode Select command (15
The Mode Select command allows the initiator to change parameters
stored in the mode pages. The mode pages are described in Appendix C.
The drive stores four copies of each mode page:
Current values copy. This copy contains the parameter values the
drive uses to control its operation. After a power-on reset, hard reset
or bus device reset, the current values are equal to the saved values
if the saved values can be retrieved, or the default values if the saved
values cannot be retrieved.
Changeable values copy. This copy does not actually contain any
parameters. Instead, it contains a map of each mode page indicating
which parameters are changeable by the initiator. If a bit contains a 1,
the corresponding value in the mode page is changeable. If a bit
contains a 0, the corresponding value in the mode page is not
bytes for inquiry data. The inquiry data
H
Bits
5 4 3 2
0 1 0 0
Reserved
Page code
0 0 0 0
0 0 0 0
Allocation length, in bytes
0 0 0 0
)
H
1 0
1 0
EVPD
0 0
0 0
0 0