144 Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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Table 5.2.1-19. Page Control Field Bits Affect On Mode Parameters Returned
PCF Bit
7
6
0
0
Return Current values. The Current values are the values currently being used by the disc drive
to control its operation. After a Power On Reset, a hard Reset, or a Bus Device Reset message
the Current values are equal to the Saved values (if Saved values can be retrieved) or the
Default values (if Saved values cannot be retrieved). The Current value of a parameter is up-
dated by a Mode Select command if the Mode Select Command ends with Good status re-
turned.
0
1
Return Changeable values. The changeable values of any page is a mask that indicates the
parameters that shall be changed via a Mode Select command and the parameters that shall
not. Each returned parameter byte shall contain ones where a field or bit may be changed and
zeros where a field or bit may not be changed.
1
0
Return Default values. The Default values are the values to which the disc drive sets the Current
values after a reset condition unless valid Saved values are available.
1
1
Return Saved values. The saved values are the values the disc drive stores in nonvolatile memory.
The Saved values of any changeable parameter can be set to new values via a Mode Select
command with the SMP bit set to one. For nonchangeable parameters, the Default value is
used.
The Block descriptor contains its normal values regardless of the value of the PCF. Unsupported fields or bits
within a page are returned as zeros for all PCF values.
[4] The Page Code allows the initiator to select one or all of the pages of Mode parameters supported by the
target. Page Codes that may be supported by the disc drive are summarized here (see individual drive
Product Manual):
Page Code
Description
0h
Unit Attention Page parameters (returned last of the pages).
01h
Error Recovery parameters.
02h
Disconnect/Reconnect Control parameters.
03h
Format parameters.
04h
Rigid Disc Drive Geometry parameters.
07h
Verify Error Recovery Page parameters.
08h
Caching Page
0Ah
Control Mode Page
0Ch
Notch and Partition Page
3Fh
Return all supported pages.
[5] The Allocation Length specifies the number of bytes that the initiator has allocated for returned Mode
Sense data. An Allocation Length of zero indicates that no Mode Sense data shall be transferred. This
condition shall not be considered as an error. Any other value indicates the
maximum number of bytes
that shall be transferred. The disc drive shall terminate the Data In phase when allocation length bytes
have been transferred or when all available Mode Sense data has been transferred to the initiator, which-
ever is less.
[6] See “Control Byte” paragraph 4.2.6.
