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12.14 Initialize Device Parameters (91h)
The Initialize Device Parameters command enables the host to set the number of sectors per track and the number
of heads minus 1, per cylinder. Words 54-58 in Identify Device Information reflect these parameters.
The parameters remain in effect until following events:
- Another Initialize Device Parameters command is received.
- The device is powered off.
- Soft reset occurs and the Set Feature option of CCh is set instead of 66h.
Table 110 Initialize Device Parameters Command (91h)
Command Block Normal Outputs
Command Block Command Input
Register
7
6
5
4
3
2
1
0
Register
7
6
5
4
3
2
1
0
Data
-
-
-
-
-
-
-
-
Data
-
-
-
-
-
-
-
-
Feature
-
-
-
-
-
-
-
-
Error
-
-
-
-
-
-
-
-
Sector Count
V
V
V V
V
V
V
V
Sector Count
-
-
-
-
-
-
-
-
Sector Number
-
-
-
-
-
-
-
-
Sector Number
-
-
-
-
-
-
-
-
Cylinder Low
-
-
-
-
-
-
-
-
Cylinder Low
-
-
-
-
-
-
-
-
Cylinder High
-
-
-
-
-
-
-
-
Cylinder High
-
-
-
-
-
-
-
-
Device/Head
1
-
1
D
H
H
H
H
Device/Head
-
-
-
-
-
-
-
-
Command
1
0
0
1
0
0
0
1
Status
...See Below...
Error Register
Status Register
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
CRC UNC 0
IDN 0
ABT T0N AMN
BSY RDY DF
DSC DRQ COR IDX ERR
0
0
0
0
0
V
0
0
0
V
0
-
-
0
-
V
Output Parameters To The Device
Sector Count
The number of sectors per track. 0 does not mean there are 256 sectors per track, but there is no
sector per track.
H
The number of heads minus 1 per cylinder. The minimum is 0 and the maximum is 15.
Note:
The following conditions needs to be satisfied to avoid invalid number of cylinders beyond FFFFh.
(Total number of user addressable sectors)/((Sector Count)*(H+1)) = < FFFFh
The total number of user addressable sectors is described in Identify Device command.
176
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