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BIT
BYTE
07
06
05
04
03
02
01
00
-------1------1------1------1------1------1------1-----
00
Format Option (00)
01
02
03
04
05
06
·07
08
09
10
(MSB)
(MSB)
-
-
-
-
-
-
-
-
- -
- -
-
Number of Spare Sectors
Length of
Defect List in Bytes
(aN)
Cylinder Number of Defect #1
Cylinder Number of Defect #1
Cylinder Number of Defect #1
Head Number of Defect #1
Bytes From Index
-
- - -
-
- -
-
-
-
-
-
Bytes From Index
-
-
-
-
-
-
-
-
- -
Bytes From Index
-
- - -
-
-
- -
-
-
-
-
Bytes From Index
8N-4
---------------------------------------------------------
to
Nth Defect
8N+3
---------------------------------------------------------
Figure 6-9.
Format Unit Data Block (Drive Formatting)
Byte 00
indicates
the formatting
option for
the drive.
00
indicates the entire unit is to be formatted;
01 indicates only
. the specified cylinder is to be formatted.
Byte 01 indicates the number of spare sectors to be allocated per
cylinder.
The number of spare sectors allocated must be the same
for every cylinder for single cylinder formatting.
A 00 in this
byte will result in no spare sectors.
If no spare sectors are allocated,
the defective sector pushdown
algorithm limits the number of
d~fects
to 128.
If bytes 2 and 3
specify more than 128 8-byte descriptors, a Bad Argument (24 H )
error will be posted.
If one or more spare sectors are
allocated, a number of sectors, up the total number of spares,
may be marked as defective.
The number of spare sectors allo-
cated on a cylinder must be less than the number of sectors on a
single track of the cylinder.
500504-00
6-15
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