Idle (97H,E3H); Idle Immediate (95H,E1H); Initialize Device Parameters (91H) - Samsung WA31273A Technical Manual

6-4-5

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, 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 entered the Idle Mode, it automatically transitions to the Standby Mode
upon expiration of a prescribed 1 minute spin-down timer.
Sector Count Register Contents
1-240 (01h-FOh)
241-251 (F1h-FBh)
6-4-6

Idle Immediate (95h,E1h)

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.
6-4-7

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.
WA31273A / WA32543A / WA33203A / WA32163A / WA31083A / WA32162A 6-29
Table 6-7. Automatic Standby Timer Periods
0 (00h)
252 (FCh)
253 (FDh)
254 (FEh)
255 (FFh)
AT INTERFACE and ATA COMMANDS
Corresponding Time-out Period
Timeout Disabled
(value * 5) seconds
((value - 240) * 30) minutes
21 minutes
8 hours
Reserved
21 minutes 15 seconds