IBM DTCA-24090 Hard Drive Specifications - Page 121

Initialize Device Parameters

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12.10 Initialize Device Parameters (91h) Command Block Output Registers Register 76543210 Data Feature Sector Count V V V V V V V V Sector Number Cylinder Low Cylinder High Device/Head 1 1DHHHH Command 10010001 Command Block Input Registers Register 76543210 Data Error Sector Count Sector Number Cylinder Low Cylinder High Device/Head Status ...See Below... Error Register 76543210 CRC UNC 0 IDN 0 ABT T0N AMN 00000V00 Status Register 76543210 BSY RDY DF DSC DRQ COR IDX ERR 000 0 V Figure 70. Initialize Device Parameters Command (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 reflects these parameters. The parameters remain in effect until the following events: Another Initialize Device Parameters command is received. The device is powered off. Hard reset occurs. Soft reset occurs and the Set Feature option of CCh is set instead of 66h. 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 condition needs to be satisfied to avoid invalid number of cylinder beyond FFFFh, which will cause performance degradation of the drive. (Total customer usable data sectors) / ((Sector Count)*(H+1)) → FFFFh The total customer usable data sectors are indicated at 3.1, " Logical Drive Format" on page 9, and related description is at 10.3.1, "Logical CHS Addressing Mode" on page 71. Command Descriptions 113

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12.10
Initialize Device Parameters
(91h)
Command Block Output Registers
Command Block Input Registers
Register
76543210
Register
76543210
Data
Data
Feature
Error
Sector Count
VVVVVVVV
Sector Count
Sector Number
Sector Number
Cylinder Low
Cylinder Low
Cylinder High
Cylinder High
Device/Head
1
1DHHHH
Device/Head
Command
10010001
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
0
0
0
V
Figure 70. Initialize Device Parameters Command (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 reflects these parame-
ters.
The parameters remain in effect until the following events:
Another Initialize Device Parameters command is received.
The device is powered off.
Hard reset occurs.
Soft reset occurs and the Set Feature option of CCh is set instead of 66h.
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 condition needs to be satisfied to avoid invalid number of cylinder beyond FFFFh,
which will cause performance degradation of the drive.
(Total customer usable data sectors) / ((Sector Count)*(H+1))
FFFFh
The total customer usable data sectors are indicated at 3.1, “ Logical Drive Format” on page 9,
and related description is at 10.3.1, “Logical CHS Addressing Mode” on page 71.
Command Descriptions
113