Mode Select (6) Command (15H); Initiator-Changeable Mode - Maxtor ATLAS 10K IV User Manual

5.14

MODE SELECT (6) Command (15h)

SCSI refers to the drive's operational parameters as its mode parameters. SCSI
groups the mode parameters by function into a set of data structures referred to as
mode pages. The MODE SELECT (6) command allows the initiator to modify some
of these mode pages and thereby control some of the drive's operational
characteristics. The Save Page (SP) option in the Command Descriptor Block makes
the changes permanent. The new mode parameters are then stored in the drive's non-
volatile memory. The MODE SELECT CDB is described in Table 5-49 and a
description of the fields in Table 5-50.
Table 5-49
Bit
7
Byte
0
1
2 – 3
4
5
Table 5-50
Data Field
PF
SP
Parameter List Length
5.14.1 Initiator-Changeable Mode Pages
Table 5-51 lists the mode pages that are supported by the drive. An initiator can
change these pages by supplying them, with the desired changes included, in the
MODE SELECT command's data-out buffer transfer.
The initiator should first use a MODE SENSE command to read the appropriate
pages and leave non-changeable values as read when the initiator subsequently writes
the changeable pages with the MODE SELECT command. If a non-changeable field
contains an invalid value, the drive returns a CHECK CONDITION status.
MODE SELECT (6) Command Descriptor Block-Data Format
6 5
Reserved
MODE SELECT (6) Command Field Descriptions
Page Format. The drive ignores the content of this field and produces a mode
parameter list that contains a mode header optionally followed by a sector de-
scriptor and one or more pages that conform to the format shown here.
Save Pages. When SP = 0, the drive performs the specified MODE SELECT
operation and does not save any pages. When SP = 1, the drive performs the
specified operation and stores all savable pages, (PS =1 on MODE SENSE re-
turn) including any sent during the data-out buffer transfer. The changes made
when SP = 1 become permanent changes to the drive's SCSI setup.
This field tells the drive how many bytes of Mode Parameters to fetch in the
data-out buffer transfer. A CHECK CONDITION status is returned if this val-
ue truncates a page.
4 3 2
Operation Code (15h)
PF Reserved
Reserved
Parameter Length List
Control
Description
Maxtor Atlas 10K IV
SCSI Description
1 0
SP
5-37