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From: fin%uf.msc.umn.edu@vma.cc.cmu.edu (Craig Finseth)
Newsgroups: comp.virus
Subject: Write protect tabs (was Re: CRC's)
Message-ID: <0005.8911172046.AA15647@ge.sei.cmu.edu>
Date: 17 Nov 89 15:51:38 GMT
Article-I.D.: ge.0005.8911172046.AA15647
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Approved: krvw@sei.cmu.edu


   kichler@harris.cis.ksu.edu (Charles Kichler) writes:

   ...

   Do you _know_ your write-protect tab really works?

   [Ed. This question was discussed a few times on VIRUS-L/comp.virus;
   the consensus was (after reviewing schematic diagrams) that the write
   protect mechanism on PCs (and clones thereof) and Macs is implemented
   in hardware and is thus not circumventable without hardware
   modifications.  Unless someone can produce a definitive, reproducable
   piece of code that can prove otherwise, lets all please consider this
   to be the case.]

I would like to confirm the "Ed." tack-on for IBM PCs, clones, and
Macs.  However, early Apple ][s *did* implement this feature in
software.

I don't know for sure, but believe that later (=current) Apple ][s,
Ataris, and Amigas perform this function in hardware.

Craig A. Finseth            fin@msc.umn.edu [CAF13]
Minnesota Supercomputer Center, Inc.    (612) 624-3375