[Fwd: ATENTION !!!!!!!virus]

Mike Bilow mikebw at bilow.bilow.uu.ids.net
Thu Nov 21 18:23:00 EST 1996



Albert Cahalan wrote in a message to Mike Bilow:

 AC> It is possible to low-level format a modern drive in such
 AC> way that the drive can only be reformatted by the factory.
 AC> Most IDE drives do not have enough accuracy to do a correct
 AC> low-level format. When a low-level format is done, the drive
 AC> can not be fixed without equipment at the factory.

Nearly all IDE drives made more recently than 1989 will accept and ignore
low-level formatting commands.  It was possible to destroy some of the very
early IDE drives, notoriously the 40 MB Seagate ST-157A, by low-level
formatting them, but this has not been possible for quite some time.  Among
other things, the cylinder-head-sector (CHS) geometry presented by all modern
IDE drives is a complete fantasy cooked up by the controller, since the media
actually has a variable number of sectors per track and low-level formatting is
a meaningless operation.  All IDE drives larger than 512 MB are incapable of
maintaining the CHS illusion, and they use Logical Block Addressing (LBA) so
that even the basic elements of track-by-track formatting are missing.

 AC> If the drive is large enough, you can move the heads in such
 AC> a way that the computer walks right off the table and
 AC> crashes to the floor. 

"Large enough" in this context is the size of a Volkswagen.
 
-- Mike





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