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C141-E124-01EN 3 - 37
(2) Block descriptor
The 8-byte "Block descriptor" indicates the logical attributes of the data format on the disk media.
a. Data block count
This field indicates the total number of logical data blocks (the block length is shown in the
"Data block length" field) existing in the "User Space" on the disk media. This value does not
include the number of spare sectors reserved for alternate block processing.
Furthermore, when this command specifies to transfer the "Default" value and "Variable"
value, the value shown in this field is X '00000000' (which means the maximum number of
logical data blocks that it is possible to rank in the "User Space").
b. Data block length
This field indicates the length (byte length) of 1 logical data block on the disk media.
(3) Page descriptor
The "Page descriptor" is configured from a parameter field which follows a 2-byte page header,
and is divided into units called "Page" for each parameter's functional attributes. See the
description of the MODE SELECT command (Section 3.1.5) concerning the configuration of each
page descriptor and their contents.
a. PS bit
When this bit is "1," the parameter value defined in that "Page descriptor" can be saved on the
disk media, and when it is "0", it indicates that this is a parameter which cannot be saved to the
disk. It is possible to save all the "Page descriptors" supported by the IDD. However, "1" is
always indicated in this bit for all "Page descriptors" transferred by this command.
b. Page length
This field indicates the length of the parameter field (number of bytes) from byte 2, excluding
the page header of that "Page descriptor." The IDD always shows a value in this field which is
the same as the length defined in that "Page descriptor" regardless of the type of parameter
requested in the "PC (page control)" field of the CDB, and reports all the parameter fields that
"Page descriptor" in byte 2 and subsequent bytes.
c. Parameter field
The parameter field in byte 2 and subsequent bytes, indicates parameter values of the type
(current values, variable values, default values or save values) requested in the "PC (page
control)" field of the CDB. See the description of the MODE SELECT command (Section
3.1.5) concerning the definition of each parameter, "Default" values and "Variable" values.