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Parameter Data Formats
4 - 16 C141-E167
c. Parameters specifying sector format (bytes 12 to 19)
• Data byte length/physical sectors
This parameter specifies the data length per 1 physical sector as the number of bytes. In the
IDD, the data byte length per 1 physical sector is the same as the data byte length in 1
logical data block. The INIT can specify the value of this parameter at 0 or 512 to 528
bytes (4-byte boundary).
If a value less than 512 bytes, the IDD sets a byte length of 512. If more than 528 bytes is
specified, the IDD performs rounding processing and sets a byte length of 528. If an odd
number of bytes is specified within the specified range, the IDD performs rounding up
processing. If the above rounding processing is performed, the IDD reports the CHECK
CONDITION status (RECOVERED ERROR [=1] / Rounded parameter [37-00] for that
command.
If 0 is specified in this parameter, the value calculated based on the value of the "Data block
length" in the block descriptor is used as this parameter value.
When both this page descriptor and the block descriptor are specified by the same MODE
SELECT command, and a nonzero value is specified in this parameter which differs from
the value in the "Data block length" parameter in the block descriptor, the value specified in
the block descriptor has priority.
• Interleave factor
This parameter field has meaning only with the MODE SENSE and MODE SENSE
EXTENDED commands. The interleave factor (in the IDD, this is always X '0001' :non
interleave) of the disk drive's current data format. The value specified in this field is
disregarded in the MODE SELECT and MODE SELECT EXTENDED commands.
• Track skew factor
This parameter indicates the number of physical sectors existing between the data block
with the highest order logical block address on a track and the data block with the next
logical block address on the next track of the same cylinder (track skew). This parameter
cannot be changed. The IDD disregards the value specified in this field and sets the
optimum track skew value in the specified data block length. See Chapter 3, "Data Format"
in the Product Manual for details about track skew. 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.
• Cylinder skew factor
This parameter indicates the number of physical sectors existing between the data block
with the highest order logical block address in a cylinder and the data block with the next
logical block address in the next cylinder (cylinder skew). This parameter cannot be
changed. The IDD disregards the value specified in this field and sets the optimum cylinder
skew value in the specified data block length. See Chapter 3, "Data Format" in the Product
Manual for details about cylinder skew. 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.
d. Parameters related to device type (byte 20)
• SSEC (soft sectoring)
When this bit is "1," it indicates that the data formatting method on the disk media is "soft
sectoring." However, since the IDD uses only the "hard sectoring" method (refer to
previously shown item b), this bit is disregarded. Furthermore, it is impossible to change
this parameter.