Toshiba 4006GAH ユーザーズマニュアル

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9.5 Load/Unload 
 
  Be sure to issue and complete the following commands for unloading before cutting off the power 
supply. 
Following table shows the specification for normal load/unload cycles. 
 
Load/unload cycle (Times) 
Environment 
600,000 Room 
temperature 
300,000 
Operational temperature range 
 
Unload is executed by the following commands : 
 
Standby 
Standby Immediate 
Sleep 
Hard reset 
 
  Load/Unload is also executed as one of the idle modes of the drive. 
 
        If power is removed from the drive while the heads are over the media an Emergency   
Unload will take place.    An Emergency Unload is performed by routing the back-EMF   
of the spindle motor to the actuator voice coil.    An Emergency Unload is mechanically   
much more stressful to this drive than a controlled Unload.    The minimum number of   
Emergency Unloads that can be successfully performed is 20,000.    Emergency Unload   
should only be performed when it is not possible to perform a controlled Unload.