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From: rb@ccivax.UUCP (rex ballard)
Newsgroups: net.micro.amiga
Subject: Re: Use single sided disks at your own risk
Message-ID: <482@ccivax.UUCP>
Date: Fri, 14-Mar-86 18:54:45 EST
Article-I.D.: ccivax.482
Posted: Fri Mar 14 18:54:45 1986
Date-Received: Sun, 16-Mar-86 09:44:20 EST
References: <8603120813.AA03577@cory>
Reply-To: rb@ccivax.UUCP (What's in a name ?)
Organization: CCI Telephony Systems Group,  Rochester NY
Lines: 34
Summary: QC varies from maker to maker.

If any former Apple ][ or Atari-800 owners remember the old "Flippy Floppy"
hack, they might think that "Single Sided" 3 1/2" micro-floppies are
ok too.  This might be true in some cases but:

1 - Different manufacturers have different standards for "Failing" a 2-sided
disk.  Some consider one bit error in a double sided disk to be an error.
This is usually after several bit patterns are written.  Others consider
a number of sectors as a percentage of the "overflow track" capacity.  Some
allow even 50% of one track failure rates.  I got that word from a disk
salesman when I had a problem with the "flippys".

2 - Because the majority of micro-floppy sales are single sided, some lots
may be truly single sided.  If one side tests good, the other side isn't
even processed (the ferrite on the second side is just a "hedge" in case
the first side fails).  Minifloppies are usually processed first as
highest possible density and sorted down to lower levels as failures
occur.  In the case of some of the stricter makers, a single sided
single density mini-floppy may only have 5 bad sectors as a quad density
disk, but that's enough to fail them to single sided If its 3 adjacent
on side 2 and 2 adjacent on side one.

3 - In some cases, the lot is downgraded because a certain number of
disks "sampled out" and the remaining disks weren't further tested.
They may have been intended as 2 sided disks, but then were downgraded.
When this is the case, you may have a whole case of good diskettes
with only one that is really single sided.

In other words, there are pretty good odds that you could find a good
manufacturer of double sided disks that are labled as single sided
disks, but each disk is a gamble.  Maybe the odds are only one
in six of having one go bad.  Five people will say "they're great",
and wonder why that one guy is so paranoid.

6:1 is about the same odds as russian roulette, do you feel lucky :-).