Specifications

A value of 0 in the Sector Count register means the drive is currently in,
or entering, Idle mode. A value of FF
H
in the Sector Count register
indicates that the drive is currently in, or entering, either Active mode or
Standby mode.
5.6.4 Idle Immediate command
This command (command code F8
H
) operates identically to the
ATA-standard Idle Immediate command, but has a different command
code.
5.6.5 Idle and Set Idle Timer command
This command (command code FA
H
) causes the drive to enter Idle mode
and sets the time limit for automatic entry to Idle mode. When the drive
receives this command, it asserts Busy in the Host Status register,
initiates entry into Idle mode, negates Busy, and generates an interrupt.
If the drive was already in Standby mode, the drive spins up to enter Idle
mode. The drive does not wait for the spinup to be complete before
generating the interrupt.
The Sector Count register is interpreted by this command as a time
interval in 100-msec increments to be used for automatic entry into Idle
mode. The time interval set by this command is the maximum time that
the drive remains in Active mode between future commands received
from the host. A value of zero in the Sector Count register disables the
timer used for automatic entry to Idle mode.
5.7 Seagate alternative power management com-
mands
An alternative set of power management commands were implemented
on some earlier Seagate drives. These commands are described below
and their operation is summarized in Figure 10. These alternative power
management commands are specific to the following Seagate drives:
Drive model Part number
ST9051A, ST9077A All
ST351A/X All
ST3120A 911003-0
xx
ST3096A 911008-0 xx
60 ATA Interface Reference Manual, Rev. C