Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!rutgers!mtune!codas!burl!clyde!feg
From: feg@clyde.ATT.COM (Forrest Gehrke)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Filter on printer cable
Message-ID: <12657@clyde.ATT.COM>
Date: Fri, 21-Aug-87 10:20:00 EDT
Article-I.D.: clyde.12657
Posted: Fri Aug 21 10:20:00 1987
Date-Received: Sun, 23-Aug-87 08:22:27 EDT
References: <3732@ecsvax.UUCP>
Organization: AT&T Bell Labs, Whippany, NJ
Lines: 21
Summary: Magnetic fields and floppies

In article <3732@ecsvax.UUCP>, kotlas@ecsvax.UUCP (Carolyn Kotlas) writes:
> 
> We just got a new IBM Proprinter with a printer cable which has a small
> black box attached to the cable.  This is a "ferrite filter" which, upon
> opening it up to examine the contents, appears to be a weak magnet (it
> isn't strong enough to pick up paperclips).  Weak though it may be, can
> anyone tell us if this filter could damage floppy disk data?
  
If this is indeed a ferrite filter, it probably is there to filter out
any strong nearby radio frequency fields (which would mess up what the
printer is supposed to print).  Ferrites are not strongly magnetic and
unless you insisted on rubbing the surface of a floppy against it, the
data would remain intact.  Nevertheless you would be advised not to 
place floppies on the box containing this filter, as you would also
be advised generally not to allow floppies to lie on any magnetized
surface.  Floppies use a magnetic medium to record data in the form
of localized magnetic fields.  Changing these fields by bringing
a magnetic field close to the surface of a floppy will damage this
data.
 
Forrest Gehrke