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From: merlin@hqda-ai.UUCP (David S. Hayes)
Newsgroups: comp.sys.att
Subject: Re: Hard Disk for PC-6300
Message-ID: <119@hqda-ai.UUCP>
Date: Tue, 18-Nov-86 12:40:01 EST
Article-I.D.: hqda-ai.119
Posted: Tue Nov 18 12:40:01 1986
Date-Received: Tue, 18-Nov-86 21:28:50 EST
References: <8519PAX@PSUVMA>
Organization: Army AI Center, Pentagon
Lines: 39
Summary: Definitions of "plated" and "disk parking".

In article <8519PAX@PSUVMA>, PAX@PSUVMA.BITNET writes:
> My second question is terminology.  I've talked to some people, and they said
> I should look into "plated" disk drives, and ones that have "disk parking".
> These terms are foreign to me, so if you know what they are, please let me
> know.

Plated:
	Refers to thin-film plated platters.  This is a
method of depositing an extremely thin magnetic layer
onto the aluminum disk platters.  A thin-film platter
has a higher data capacity than an equivalent
conventional platter.  This is not really a user-visible
feature, other than through the higher capacity.

Disk Parking:
	On a winchester disk, certain cylinders are
reserved "landing areas" for the heads.  The head sits
over these cylinders when the drive is spinning up to
speed, or spinning down after being turned off.  Because
the drive is not operating at full speed, the heads will
actually be in contact with the platters during this
process.  These areas are subject to extra wear, from
physical contact with the heads, and cannot be used to
store data.

	The heads should be moved to the landing area
before powering down the drive.  On cheap drives, you
must run a program to do this.  More expensive drives do
this automatically.  Generally, these more expensive
drives also are better constructed, may have faster
access times, have better head positioners, braking
systems...

	If you opt for a drive without this feature, and
forget to run the parking program before shutting down,
you *WILL* damage your drive.  It may take several
occurrances before you start losing files, but every
shutdown without prior parking will decrease the
reliability of your drive.