Re. Floppy disks and magnets

Subject: Re. Floppy disks and magnets
From: Geoff Hart <geoff-h -at- MTL -dot- FERIC -dot- CA>
Date: Mon, 14 Aug 1995 12:36:50 LCL

Mike Thompson asked about the dangers of X-rays and magnets to floppy
disks. Mike, this one raises lots of vocal opinions on both sides,
none with any really strong "scientific" evidence to back it up. For
your consideration, I offer the following:

1. A MacUser editor conducted a simple test with four high-density
disks a few years ago; after the first pass through the X-rays, one
disk was unreadable, and after four passes, not one was readable.
(Actual numbers differ... I'm doing this from memory.) Conclusion: it
was an old X-ray machine, and possibly poorly maintained. X-rays in
low doses won't harm magnetic media, but the electromagnetic fields
used to generate and control the X-rays surely can.

2. Another author has set diskettes on the top of monitors, has rubbed
them with speaker magnets and has had them X-rayed countless times
with no damage whatsoever. Similarly, _Toronto Computes_ has tested
diskettes atop the electric motors of the subway cars with no
discernible effect.

3. A friend lost data on a diskette subjected to the fields from one
of those magic wands they use to scan you for metal if you fail to
pass through the walk-through metal detector without a beep.

In short (all together now!): your mileage may vary. I err on the side
of caution, but there's considerable anecdotal evidence that it really
doesn't make any difference what you do to your floppies, so long as
you don't sit on them. Presumably the same applies to the much better
shielded hard disks on a laptop. Note, however, that you should still
ask security to check your laptop manually: I've seen so many bags
flung off the end of the conveyor past the X-rays (or crushed by other
bags) that I'd hold out for a manual check... and insist to see the
manager and ask for his written guarantee to pay for any damage if
they won't let you get away with a manual check.

--Geoff Hart @8^{)}
geoff-h -at- mtl -dot- feric -dot- ca

Disclaimer: If I didn't commit it in print in one of
our reports, it don't represent FERIC's opinion.


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