5.12MODE 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
Table
Bit | 7 | 6 | 5 | 4 |
| 3 | 2 | 1 | 0 |
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0 |
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| Operation | Code (15h) |
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1 |
| Reserved |
| PF |
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| Reserved |
| SP |
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2 – 3 |
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4 |
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| Parameter Length List |
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5 |
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| Control |
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Table
Data Field | Description | |
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PF | 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 | |
SP | 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 | |
| when SP = 1 become permanent changes to the drive’s SCSI setup. | |
Parameter List Length | This field tells the drive how many bytes of Mode Parameters to fetch in the | |
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| ue truncates a page. | |
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5.12.1Initiator-Changeable Mode Pages
Table
The initiator should first use a MODE SENSE command to read the appropriate pages and leave