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From: gaynor@armadillo.cis.ohio-state.edu (Jim Gaynor)
Newsgroups: comp.sys.mac.misc
Subject: Re: Formatting 800k as HD ?!?
Message-ID: <80967@tut.cis.ohio-state.edu>
Date: 29 May 90 14:16:24 GMT
Article-I.D.: tut.80967
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In article <7309@jarthur.Claremont.EDU> mwilkins@jarthur.Claremont.EDU (Mark Wilkins) writes:
>  Alright, two questions.
>
> 1) If formatting a DS/DD disk is so dangerous at high density, why don't
>ANY of the drives in the PC clone world check for the presence or absence of
>the hole used to indicate them?

	You are wrong.

	The old, "original" standard for HD disks and drives made no
distinction between DS/DD and HD diskettes.
	The current standard has HD disks with the "HD" printed on the
diskette, and the extra hole.

	IBM PS/2 machines, and some other clones use drives that were built
by the old standard, and do not detect for the extra hole (and therefore do
not check for HD disks, and will format DS/DD as HD)  Note that these drives,
since they lack the extra detection mechanism, are cheaper.
	Zenith PCs, and some of the other "high-end" clones, do use the drives
which check for HD disks, and therefore will refuse to format a DS/DD diskette
as a HD diskette.

> 2) Given (1), why is it that there have been no similar discussions of disk
>failure in the PC clone world, even among people who routinely buy DS/DD
>disks and format them at 1.4MB just because they've never been told any
>differently?

	Well, (1) is no longer a given.  There are two reasons for (2):
A)  The DOS formatting scheme marks off bad sectors.  Thus, an DS/DD diskette
formatted as HD may (and most times will) have bad sectors, but will still
be usable.
B)  Disks going "bad" for various reasons seems to be much more "accepted" in
the MS-DOS world than on the Mac side.  (This is only opinion here).  Note
the proliferation of programs such as Norton Utils, PC Tools, and Mace, whereas
equivalents in the Mac world are not as widespread, and are only recently
becoming high-sellers.

>  Note that the Apple 1.4 MB low-level encoding scheme is identical to that
>of an IBM PC floppy, but the hardware is much different.  If there is an
>answer to (2), it probably has to do with that.

	Yes, the hardware is different between an IBM drive and an Apple
drive - see my reply to (1).  I believe, however, that Zenith and Apple
use the same drive mechanism (but different controllers).  But this may
be false.

>  I agree with your statement 2 that mutilating a disk is a recipe for
>disaster.  However, nobody who advocates Apple's party line has ever
>given me an answer to these two objections.

	There, my friend, are your answers.

>  By the way, if you have any references to publicly available articles in
>engineering journals or the like which support Apple's official statements
>on the matter, I'm curious.

	Do you have access to similar materials supporting your claims of
"no difference" between types of diskettes?  I, at least, have the support
of diskette manufacturers, floppy drive manufacturers, and the producers of
both Macintosh and MS-DOS computers.

>-- Mark Wilkins

-=-
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