On Mon, 10 Sep 2012, Jon Elson wrote:
  Anyway, all drives that are supposed to be parked
can be assumed to handle
 it autonomously when power is removed, for nearly the last 20 years. 
 A very DANGEROUS assumption.
 My stuff is older than that. 
And mine... Some of my older (demountable :-)) hard drives do have
auto-parking on power down. With little NiCd batteries which are
connected to the positioner coil (via a switc hthat homes when the heads
are retracted) wo whip the heads off the disk when the mains fails.
  Hell, I have stuff in the back of my refrigerator
older than that. 
Photographic film?
-tony