HGST TRAVELSTAR 80GN 30GB ATA5 08K0910 User Manual

Travelstar 80GN Hard Disk Drive Specification

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Load/Unload is a functional mechanism of the hard disk drive. It is controlled by the drive microcode. Specifically, 
unloading of the heads is invoked by the following commands.

Load is also invoked as the idle command.

The specified start/stop life of the product assumes that load/unload is operated normally, NOT in emergency mode.

When the drive power is interrupted with the heads still loaded, the microcode cannot operate and the normal 
5V power is unavailable to unload the heads. In this case, normal unload is not possible, so the heads are unloaded 
by routing the back EMF of the spinning motor to the voice coil. The actuator velocity is greater than the normal 
case, and the unload process is inherently less controllable without a normal seek current profile.

Emergency unload is intended to be invoked in rare situations. Because this operation is inherently uncontrolled, it 
is more mechanically stressful than a normal unload.

A single emergency unload operation is more stressful than 100 normal unloads. Use of emergency unload reduces 
the start/stop life of the drive at a rate at least 100 times faster than that of normal unload and may damage the drive.

The following are examples of such problems which can result when power is removed on most drives at an arbitrary 
time:

• Data is lost from the write buffer.
• If the drive is writing a sector, a partially-written sector with an incorrect ECC block results, 

the sector contents are destroyed, and reading that sector results in a hard error.

• Heads may land in the data zone instead of the landing zone depending on the design of the 

drive.

Standby

UL -> Comp.

Standby Immediate

UL -> Comp.

Sleep

UL -> Comp.

Soft Reset

Rdy (*1)

Hard Reset

UL -> Rdy

UL

= unload

Comp

= complete

Rdy

= interface ready

(*1)

Load/Unload condition is not changed by Soft Reset