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Command Specifications
3 -
82
C141-E167
Bit
Byte
76543210
0 Cylinder No. (MSB)
1 Cylinder No.
2 Cylinder No. (LSB)
3 Head No.
4 Physical sector No. of defective block (MSB)
5 Physical sector No. of defective block
6 Physical sector No. of defective block
7 Physical sector No. of defective block (LSB)
Figure 3.15 Defect descriptor: physical sector address format
• Cautions in specifying the D list
The P List, containing defect position information, is always recorded on the IDD when it is
shipped from the factory. Also, information on defect positions for which alternate block
processing has been implemented during operation are recorded as the G List. The function
which specifies defect position information as the D List when the FORMAT UNIT command is
executed, is prepared mainly to specify initial defect position information of the disk media
which does not have the P List recorded on it. In the IDD, by specifying use of the P List and G
List, advance notice of the defect positions can be specified during initialization, so ordinarily, it
is not necessary to use the D List. When the D List is used for the IDD, caution should be
exercised in the follow points.
1. The maximum number of defective sectors (total amount of 'sector slip' and 'alternate
sectors') are calculated per :
a) Current condition of reallocated sectors:
(how many Slip Sectors have been allocated ? and so Alternate Sectors ? Since Defect
table entry for Slip and Alternate are different size.)
b) The maximum size of Defect Management Table (Fixed value)
c) Current allocation condition of 'sector slip'
(i.e. Up to 16 consecutive Slip Sector can be controlled by 1 Slip Defect entry. So the
necessary table size are varied not only the number of Defects but also the number of
consecutive Slips.)
Consequently, the concrete Defect numbers cannot be described though the IDD guarantees
12,000 Slip Sectors and 3,000 Alternate Sectors at minimum. If defect processing which
exceeds this limit is specified in the FORMAT UNIT command, that command is
terminated with a CHECK CONDITION status (HARDWARE ERROR [=4] / No defect
spare location available [=32-00]).
2. A defect descriptor specified as the D List are received normally if the specified defect
position information is within a range which does not exceed the disk drive’s physical