Seagate ST9655 Series Product Manual page 15

ST9655 Family Product Manual, Rev. A 7
Reset or Soft Reset command from the host. After receiving a Soft Reset
command, the drive exits Sleep mode and enters Standby mode with all
current emulation and translation parameters intact.
Rest/resume commands. Some host systems reduce drive power
consumption by removing all power from the drive. Before shutting off
power, the host must save drive state information (including current
logical geometry, set feature parameters, cache status and task file
registers). After restoring power to the drive, the host restores the drive
to its prerest condition. This process is implemented using three com-
mands: Rest, Read Drive State and Restore Drive State. The Rest
command prepares the drive for a subsequent Read Drive State com-
mand. The Read Drive State command captures the state of the I/O
registers. The Restore Drive State command reads the drive state data
from memory and restores the drive state based on this data. These
commands are described in greater detail in section 3.3.3 on page 27.
Idle and standby timers. The drive sets the default time delay for the idle
timer at power-on. In most systems, you can set this delay using the system
setup utility. Each time the drive performs an Active function (read, write or
seek), the idle and standby timers are reinitialized and begin counting down
from their specified delay times to zero. If the idle timer reaches zero before
any drive activity is required, the drive makes a transition to Idle mode. If the
host has set the standby timer, the standby countdown continues. If the host
has not set the standby timer, the drive remains in Idle mode. If the standby
timer reaches zero before any drive activity is required, the drive makes a
transition to Standby mode. In both Idle and Standby mode, the drive
accepts all commands and returns to Active mode when disc access is
necessary.
Deferred spinup. ST9655 family drives may be factory-configured for
deferred spinup. If configured for deferred spinup, the drive does not spin
up immediately after power-on, but waits until it receives a command from
the host. At power-on, the drive posts a status of 80 and all master/slave
H
protocols are completed before the drive reports a status of 50 . After the
H
drive receives a command from the host, it executes the spinup/upload
process. If the host issues a soft reset before the drive spins up, the drive
responds normally, except that it does not spin up until it receives a
command from the host.