On 12 Jul, Simon Bains <[log in to unmask]> wrote:
> Can anyone on this list enlighten us with regard to the
> effect of magnetic security systems on CD-ROMs?
> Are they adversely affected by:
> - magnetic strips
> - sensitisers
> - security gates
> We have been assuming they should not be passed through the
> security gate, but have been tattling books accompanied by
> CD-ROMs. We are now being told that these magnetic strips
> also harm them.
Others more knowledgeable may be able to speak from experience, but as I
understand it: since CD-ROMs store data in the form of "pits" in a thin
metal film incorporated into a plastic disc, electromagnetic fields
(unless very strong) should have little or no effect (which would *not* be
true of magnetic media: floppy discs, audio or video tape, etc.).
> We have also been told that audio CDs are not affected in
> this way. Is this true? Are audio CDs and CD-ROMs different
> in this way?
Audio CDs and CD-ROMs store data in the same way, but CD-ROMs, I believe,
are more sensitive to *mechanical* damage (scratches etc.) than CD-ROMs
because audio CD players can "cover up" gaps by interpolating (the human
ear is very good at this, too!) whereas, unless error-correction is built
into the data on the CD-ROM, misread data cannot be corrected. So I
suppose CD-ROMs would be more sensitive than audio CDs to whatever
hypothetical damage might result from security devices.
Hope this helps. Now let's learn from the experts!
Cheers
Peter A
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