Mode Sense (1A) - IBM DCAS-32160 - Ultrastar 2.1 GB Hard Drive Specifications

7.9 MODE SENSE (1A)

Byte
7 6
0
1 LUN
2 PCF
3
4
5 VU = 0
Figure 66. M O D E SENSE (1A)
The M O D E SENSE (1A) command provides a means for the file to report various device parameters to the
initiator. It is the complement to the M O D E SELECT command.
Allocation Length indicates the maximum number of bytes the initiator has set aside for the DATA IN
phase. A value of zero is not considered an error. If the allocation length is smaller than the amount avail-
able, then that portion of the data up to the allocation length will be sent. It is noted that this may result in
only a portion of a multi-byte field being sent.
7.9.1.1.1 Page Control Field: P C F (Page Control Field) defines the type of Page Parameter values to be
returned.
PCF Meaning
0 0 Report current values. The file returns the current values under which the logical unit is presently
configured for the page code specified. The current values returned are:
1. The parameters set in the last successful M O D E SELECT command.
2. The saved values if a M O D E SELECT command has not been executed since the last
power-on, hard RESET condition, or BUS DEVICE RESET message .
Note: The file will not process the Mode Select command until the completion of spin-up.
Therefore, the initiator cannot modify the current values prior to the saved values being read in.
0 1 Report changeable value. The file returns the changeable values for the page code specified. The
page requested shall be returned containing information that indicate which fields are changeable.
All bits of parameters that are changeable shall be set to one. Parameters that are defined by the
file shall be set to zero. If any part of a field is changeable all bits in that field shall be set to one.
Note: For a value field such as the buffer ratios of page 2, the bit field will not indicate the range
of supported values but rather that the field is supported.
1 0 Report default value. The file returns the default values for the page code specified. The parameters
not supported by the file are set to zero.
90
O E M Spec. of DCAS-34330/32160
Bit
5 4 3
Command Code = 1Ah
Reserved = 0
Page Code
Reserved = 0
Allocation Length
Reserved = 0
2 1 0
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