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From: labc-3dc@web-3c.berkeley.edu (Andy McFadden)
Newsgroups: comp.sys.apple
Subject: Re: write-protecting hard drives
Message-ID: <20314@agate.BERKELEY.EDU>
Date: 13 Feb 89 18:02:44 GMT
References: <890213043846.812082@DOCKMASTER.ARPA>
Sender: usenet@agate.BERKELEY.EDU
Organization: University of California, Berkeley
Lines: 24

In article <890213043846.812082@DOCKMASTER.ARPA> TMPLee@DOCKMASTER.ARPA writes:
>In response to my question about write-protection o fhard drives someone
>pointed out the protection bits in ProDos.  I'm afraid that without any
>address protection hardware they are useless -- any virus writer worth
>his salt would do direct block reads and writes, ignoring all of ProDos,
>which is why I was asking about a physical switch you could throw.

The point was, you could to some degree prevent viruses from attaching
themselves to your files.  Issuing ProDOS WRITE commands for a file is
*much* easier than writing the block, updating the system bit map, updating
the file's block list, updating the EOF, etc, etc...

The problem is, it can't prevent a virus from wiping out the drive (as you
point out) by doing direct block reads and writes.  There really can't be
a convenient way to do this unless HD manufacturers begin mounting switches
on the external portion.

What IS conceivably possible is to have two different copies of the ROMs,
only one of which (read/write, write only) is selectable at a time.  This
shouldn't be all that hard to do, assuming you are willing to risk your drive
in the interests of experimentation...

-- 
labc-3dc@widow.berkeley.edu (Andy McFadden)