🚀 go-pugleaf

In article <1992Dec30.000429.24047@panix.com> schuster@panix.com (Michael Schuster) writes:
>I'd often wondered about the magnetic safety of mailing diskettes.
>Wondered how many diskettes that arrived unreadable were really
>due to exposure to magnetic fields during transit.
>
>Today in my mailbox was a post card from Pizza Hut. Taped to it was
>a magnetic sticker, suitable for posting on your refrigerator door,
>with the phone number of my local store.
...

Diskettes are not as sensitive to stray fields as you might have been
led to believe.  I just ran a quick experiment, using a large piece of
material similar to that from which those magnetic stickers are made.

A 3.5" HD diskette wiped thoroughly with the magnetic material was
still readable with NO errors or retries.  The disk was protected only
by the separation imposed by the thickness of its own plastic shell.

At the other end of the sensitivity spectrum, a 5.25" DD disk was
rendered totally unreadable by the same procedure.  However, repeating
the experiment with a single layer of corrugated cardboard (thin)
between the magnet and the disk left the disk still readable, again
with no errors or retries.

So, while it is advisable to minimize exposure to external fields, a
floppy disk protected by a disk mailer is likely to remain unscathed by
magnetic things that are likely to come into contact with it in the
mail.  Things like water and physical damage would seem to be the
greater danger.

(Interestingly, the steel hub of the 3.5" disk was magnetized pretty
strongly during the experiment.  I degaussed it later.)

Bob Nichols
AT&T Bell Laboratories
rnichols@ihlpm.ih.att.com