bart at netcom.com
Sun Dec 20 09:53:45 PST 1992
In audio recording which uses magnetic media similar to disks
the only way to thoroughly erase a tape is with a so-called
bulk eraser. This applies a very strong a.c. magnetic field
and then is gradually withdrawn from the tape to allow the
residual magnetism to "follow the hysteresis curve" down to
zero. This would be difficult to apply to disks except floppies.
Consider also the technique used in the Norton Utilities
program "Diskwipe" which takes a /g switch which "Follows
certain government rules for wiping". I can't find the manual
but I think it specifies how many repetitions are used and
different values to write in each.
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