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From: ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.sys.mac.system
Subject: Re: HD disks failing at 800K format
Message-ID: <1991Apr12.122259.3412@waikato.ac.nz>
Date: 12 Apr 91 00:22:59 GMT
References: <51425@apple.Apple.COM>
Organization: University of Waikato, Hamilton, New Zealand
Lines: 24

I don't know who's right about which type of disk uses the stronger magnetic
fields, but I do know that, not only is it a bad idea to use a high-density
disk in a double-density drive, but you're also going to have problems
reformatting it in a high-density drive afterwards.

The solution is to put the disk through a bulk eraser (or close to some
other unshielded source of strong, oscillating magnetic fields) to
completely wipe any trace of the incorrect formatting.

Speaking of which, does anybody know of common, household items which can
work (or be adapted to work) as a bulk eraser? Say, if I wave a disk
about close to the compressor motor at the back of my refrigerator,
or even the motors in my washing machine--would that work?

Obviously, something that would only partially scramble the
magnetic fields on the disk wouldn't be good enough; it's got
to wipe it completely clean.

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 26" S, 175^ 19' 7" E, GMT+12:00
Scientists on the verge of breakthrough: a longer-lasting light bulb
that people _will_ have to keep on buying!