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DISK DRIVE OPERATION
SpinPoint V40 Product Manual
62
6.4.7 Idle (97h,E3h)
This command causes the drive to set BSY, enter the Idle Mode, clear BSY, and generate an interrupt. The
interrupt is generated even though the drive may not have fully transitioned to Idle Mode.
If the drive is already spinning, the spin-up sequence is not executed.
If the Sector Count register is non-zero, then the automatic Idle Mode sequence is enabled, and the timer
begins counting down immediately. If the Sector Count register is zero, the automatic power down sequence
is disabled.
After the drive enters Idle Mode, it automatically transitions to Standby Mode upon expiration of a
prescribed 1 minute spin-down timer.
Table 6-7 Automatic Standby Timer Periods
Sector Count Register Contents Corresponding Time-out Period
0 (00h) Timeout Disabled
1-240 (01h-FOh) (value * 5) seconds
241-251 (F1h-FBh) (value - 240) * 30 minutes
252 (FCh) 21 minutes
253 (FDh) 8 hours
254 (FEh) Reserved
255 (FFh) 21 minutes 15 seconds
6.4.8 Idle Immediate (95h,E1h)
This command causes the drive to set BSY, enter Idle Mode, clear BSY, and generate an interrupt. The
interrupt is generated even though the drive may not have fully transitioned to Idle Mode.
6.4.9 Initialize Device Parameters (91h)
This command enables the host to set the number of sectors per track and the number of heads minus 1, per
cylinder. Upon receipt of the command, the drive sets BSY, saves the parameters, clears BSY, and generates
an interrupt.
The only two register values used by this command are the Sector Count register which specifies the number
of sectors per track, and the Drive/Head register which specifies the number of heads minus 1. The DRV bit
designates these values to Drive 0 or Drive 1, as appropriate.