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Bits 0,
2,
3,
and 4 indicate the presence and format of the
defect list.
The ACB-5500 only supports bytes from index format.
Bit 1 indicates whether a unique fill character is to be written
into the data fields during format.
Table 6-5 details the format
options provided by the FORMAT UNIT command.
Table 6- 5.
Format Options
Bit
Data
CmElt Format
Defect List
Fill Byte
4
3
2
1
0
0
0
0
0
0
No defect list
6C
H
0
0
0
1
0
No defect list
Value in Byte 02
1
1
1
0
0
Complete defect list in
6C
H
bytes from index format
1
1
1
1
0
Complete defect list in
Value in Byte 02
bytes from index format
Sector interleaving may be required because performance limita-
tions in the host.
The sector interleave number is equivalent to
the number of disk revolutions required to read or write a full
track of data.
The
10
fields will be interleaved as specified in byte 04 of the
COB.
The ACB-5500
controller does
not
require
interleaving
because of a high speed buffer control.
An interleave number of
1 results in sequential
10
fields being written on the disk.
Any
interleave number between 1 and the number of sectors per track
results in interleaved formatting. A 0 in this field will cause
the default interleave factor of 1 to be used.
Byte 3 must
always be zero.
The value in byte 4 must not exceed the number
of sectors per track minus one.
An error code of 24H (Bad Argu-
ment) will be returned if either of these rules are vlolated.
An example of an interleave number of 3 with 32 sectors per track
follows:
P -
F -
00 01 02 03 04 05 06
00 11 22 01 12 23 02
17 18 19 20 21 22 23
27 06 17 28 07 18 29
Physical sector count
07 08 09 10 11
13 24 03 14 25
24 25 26 27 28
08 19 30 09 20
P
=
F
=
Formatted logical sector locations
500504-00
6-11
12 13 14 15 16
04 15 26 05 27
29 30 31 32
31 10 21 32
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