4.1 Control/Sense Commands

b.Block descriptor

The logical attributes of the data format on the disk media are described in the 8-byte long "Block descriptor."

Data block count

This field specifies the total number of logical data blocks (the block length is specified in "Data block length") allocated in the user space on the disk media. The maximum logical block address is a value with 1 subtracted from the value in this field.

If only the "Block descriptor" in this command is changed accessible data block count can be limited without formatting if "Data block count" value is within a "Cylinder count" value of page 4.

If zero is specified for the "Data block count," or when the block descriptor is not specified, the HDD retains its current capacity, if the block size has not changed. If the "Data block count" is set to zero and the Data block size has changed, the HDD shall set to its maximum capacity when new block size to be effect.

Data block length

This field specifies the byte length of a logical data block on the disk media.

The logical data block length and physical data block length are the same in the HDD. The data block length can be specified at 512 to 528 bytes (4-byte boundary).

If less than 512 bytes is specified in this field, the HDD performs rounding processing (there is a rounding processing report), setting the data block length at 512 bytes. If more than 528 bytes is specified, rounding processing is performed (there is a rounding processing report), setting the data block length at 528 bytes. If the block length is not 4- byte boundary, rounding processing is performed to change 4-byte boundary.

If zero is specified in this field, the value specified in bytes 12 and 13 (Data byte length/sector) of Page 3 (Format Parameter) is set. At that time, if Page 3 is not specified at the same time, the current value in Page 3 is used.

If the value set in this field differs from the value specified in bytes 12 and 13 (Data byte length/sector) of Page 3 (Format Parameter), the data block length in the block descriptor is set.

C141-C013

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Fujitsu MBA3147RC, MBC2036RC, MBC2073RC, MBA3300RC, MBA3073RC specifications Control/Sense Commands