Initialize Device Parameters (91H); Figure 95. Initialize Device Parameters Command (91H) - IBM DTLA-305040 - Deskstar 41.1 GB Hard Drive Specifications

12.9 Initialize Device Parameters (91h)

Command Block Output
Registers
Register
Data
Feature
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Command
Error Register
7 6 5
CRC UNC 0
0 0 0

Figure 95. 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 reflect these para-
meters.
The parameters remain in effect until following events:
Ÿ Another Initialize Device Parameters command is received.
Ÿ The device is powered off.
Ÿ Soft reset/Hard reset has occurred 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. Zero does not mean there are 256 sectors per track,
but that there are no sectors per track.
H The number of heads minus 1 per cylinder. The minimum is 0 and the maximum is 15.
Note: The following conditions need to be satisfied to avoid invalid number of cylinders beyond FFFFh.
Ÿ (Total number of user addressable sectors)/((Sector Count)*(H+1)) = < FFFFh
Ÿ The total number of user addressable sectors is described in Identify Device command.
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
V V V V V V V V
- - - - - - - -
- - - - - - - -
- - - - - - - -
1 - 1 D H H H H
1 0 0 1 0 0 0 1
4 3 2 1 0
IDN 0 ABT T0N AMN
0 0 V 0 0
Deskstar 40GV & 75GXP hard disk drive specifications
Command Block Input
Registers
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
Status Register
7 6 5 4
BSY RDY DF DSC
0 V 0 –
125
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
see below
3 2 1 0
DRQ COR IDX ERR
– 0 – V