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From: roman@sigma.UUCP (Bill Roman)
Newsgroups: net.micro.mac
Subject: Hardware Write Protect: Fact or Fiction?
Message-ID: <594@sigma.UUCP>
Date: Mon, 27-Jan-86 20:15:44 EST
Article-I.D.: sigma.594
Posted: Mon Jan 27 20:15:44 1986
Date-Received: Thu, 30-Jan-86 05:51:36 EST
Reply-To: roman@sigma.UUCP ()
Organization: Summation, Inc., Woodinville, WA, USA, Earth...
Lines: 37
Keywords: Larry Rosenstein, please respond


I, too, was upset to learn that it might not be possible to protect
my disks against being written on by software run amok, so I tried a
few experiments.

First, I observed that there is no visible LED above or below the
write-protect tab.  The location, close to the front of the disk
slot, would seem inappropriate for an optical sensor; it would be
too easily swamped by ambient light.

I tried inserting a disk with the tab in the "protect" position but
with an opaque card over the top of the disk blocking light from
passing through the hole.  The Finder (4.1) reported that the disk
was locked.

With the tab still in the "protect" position I covered the hole with
transparent (well, translucent) tape on the bottom side.  The Finder
then claimed the disk was unlocked.

I also tried but was unable to reproduce the reported behavior of
Finder 1.1g writing new file names on a locked disk.  My conclusion:
the write-protect interlock is mechanical, not optical.  Apple's
claim of a hardware protection system would seem to indicate that
our write protected disks really are safe.

I think we would all like the final, official word from Apple on
this matter.  In particular, before I spend my money on an upgrade,
are the 800k disks fully protected in hardware?

Larry Rosenstein, are you listening?
-- 
Bill Roman	{ihnp4,decvax,allegra,...}!uw-beaver!tikal!persci!roman

Summation, Inc, (formerly Personal Scientific Corporation)
18702 142nd Ave NE
Woodinville, WA 98072
(206) 486-0991