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C141-E124-01EN4 - 16
a. Parameters for specifying alternate processing areas for defective blocks (bytes 2 to 9)
The following 4 parameters specify the position and number of spare sectors for performing
defective block alternate allocation processing on the disk media. See Chapter 3, "Data
Format" of Product Manual for details of the IDD's alternate block processing.
x Track count/zone
This parameter specifies the number of tracks a unit for alternating blocks. The INIT
cannot clearly specify this value. The IDD ignores the specification for this bit. If the
value of the Active Notch in Page C is 0, the “Number of Logic Heads a cell” is
reported for the MODE SENSE and MODE SENSE EXTENDED commands.
If not, the total number of track of the zone which is specified as the Active Notch is
reported.
x Alternate sector count/zone
This parameter specifies the number of sectors per one cell as the number of spare sectors
secured for use as alternate blocks. In the IDD, this parameter indicates the number of
spare sectors secured in each cell. The maximum permissible value of this parameter
either the "number of physical sectors per track in the last cell - 1" or "24", whichever is
smaller. It is possible for the INIT to vary this parameter within a range of 0 to the
maximum permissible value. When a value which exceeds the maximum permissible
value is specified, the IDD performs rounding down of the parameter and sets a value
equal to this parameter's maximum permissible value. If the above rounding processing is
performed, a CHECK CONDITION status (RECOVERED ERROR [= 1] / Rounded
parameter [37-00] is reported for that command.
x Alternate track count / zone
This parameter specifies the area secured for alternate blocks as the number of tracks per
one cell. It is impossible to change this parameter. When a value other than zero is
specified in this field, the IDD performs rounding down processing of this parameter and
always sets this parameter value at zero.
x Alternate track count / drive
This parameter specifies the area secured for alternate blocks as the number of tracks per
disk drive. In the IDD, this parameter indicates the number of tracks in the spare area
secured as alternate cells. This value is fixed at a value that equals the number of tracks
per cylinder multiplied by the number of zones in the IDD. This parameter cannot be
changed by the INIT.
b. Parameters specifying track format (bytes 10, 11)
x Sector count/track
This parameter specifies the number of physical sectors per 1 track. In the IDD, the
number of physical sectors in a track is set unilaterally according to the data format
specified by the "Data Block Length" parameter in the block descriptor or the "Data byte
length/Physical sector" parameter in this page descriptor, so this parameter cannot be
changed. The IDD disregards the value specified in this field. This parameter indicates
the value of zone specified in Active Notch of Page C. If it is 0, this parameter indicates
the value in zone 0.