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Byte Distance from the Index Format Defect Descriptor
Fig. 3.21 shows this description format of the defect descriptor. Defect descriptor in
this format specifies the cylinder number, head (track) number and byte distance to
the top byte of those data (8 bytes), of the data which includes defective bits, on the
disk media. One defect is treated as a defect with a length of 8 bytes (64 bits long).
Therefore, for defects with a length which exceeds 8 bytes, 2 or more defect
descriptors must be specified. When multiple defect descriptors are specified, the
cylinder number must be specified in the top position, the byte distance from the
index in the bottom position, and the defect positions listed in ascending order.
Note:
In order to specify an entire track as defective, X 'FFFFFFFF' must be specified
as the byte distance from the index to the defect position.
Bit
Byte
0
1
2
3
4
5
6
7
Figure 3.21 Defect Descriptor: Byte Distance from Index Format
7
6
5
Cylinder No. (MSB)
Cylinder No.
Cylinder No. (LSB)
Head No.
Byte distance from index to defect position (MSB)
Byte distance from index to defect position
Byte distance from index to defect position
Byte distance from index to defect position (LSB)
C141-E039-01EN
4
3
2
1
0
3 - 99
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