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From: emjhm@uokvax.UUCP
Newsgroups: net.micro
Subject: Re: Floppy disk information request - (nf)
Message-ID: <3400044@uokvax.UUCP>
Date: Sun, 17-Jun-84 13:53:00 EDT
Article-I.D.: uokvax.3400044
Posted: Sun Jun 17 13:53:00 1984
Date-Received: Thu, 21-Jun-84 06:08:19 EDT
References: <9102@lanl-a.UUCP>
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Nf-ID: #R:lanl-a:-910200:uokvax:3400044:000:2638
Nf-From: uokvax!emjhm    Jun 17 12:53:00 1984

#R:lanl-a:-910200:uokvax:3400044:000:2638
uokvax!emjhm    Jun 17 12:53:00 1984

Double Density Single Sided disketts are manufactured form the same double
sided oxide coated Mylar ribbon.  Some manufacturers coat the oxide layer
with a non abrasive lubricant to reduce head wear which is more critical on
double sided (ie two heads) because of the hard surface on either side of the
diskette.  In other words, a DDSS diskette usually means that it has been
lot screened and certified to have no dropouts on one side.  It doesn't mean
that the other side is not just as good but rather that it has not been
certified.  Of course the lot screening doesn't guarantee that the certified
side is good either but the company that sells the didssketteses has guaranteed
that if you find a bad one, you can get it replaced.  Now as for making a
flippy diskette.  Most disketts are not really made properly to spin
backwards.  If you punch an index hole and write protect hole in the
jacket so that you can put the disk in upside down and record on the
other side of a singleon a single sided drive, this could cause the wiping action of
the fabric inside the jacket to release some of the oxide that it has
been cleaning from the diskette surface.  When this happens, you take the
chanced of getting some of this loose oxide picked up on the head and
cuausing dirty heads which can destroy disketts and decrease the life of
the heads.  On a single sided drive, the soft pad opposite the disk head
can also pick up some of the devrisbris and there is no effective way to
clean it so you have to partially dismantle the drive and replace the
pad if it gets dirty.  If you use a diskette which has both sides poillished
and coated with a silicone surface like scothScotch or Datalife Verbatim, you
will probably have no problems.  Even though it's probably not recommendsesd
to use both sides of a diskette, most people who have sidngle sided drives
punch the holes in the jacket and end up with twoice the capacity and have
relatively few problems despite the analytical rpoblemsproblems mentioned.  By
the way,  they used to manufacture foloppy disk drives which had two sets
of photocells for the index and write rprotect sensors so that you could
use both sides of a floppy diskette without punching the holes in the
jackett
I havent't heard of these kinds of drives mentioned for quite a qhilewhile.  I'm
not sure that it was because of problems like those mentioned before or
that the extra expense could probably but you a double sided drive uy you a double sided drive in
which case thae dual photocells were not needed.  Hope this helps...