Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!ames!hc!lanl!cmcl2!rna!amms4!hjg
From: hjg@amms4.UUCP (Harry Gross)
Newsgroups: comp.sys.ibm.pc
Subject: Re: make your own HD 3 1/2 in floppies
Message-ID: <563@amms4.UUCP>
Date: 14 Jul 89 19:34:46 GMT
References: <26260@amdcad.AMD.COM> <26262@amdcad.AMD.COM> <14333@dartvax.Dartmouth.EDU>
Reply-To: hjg@amms4.UUCP (Harry Gross)
Organization: Eagle Clothes, Inc., New York, NY
Lines: 41

In article <14333@dartvax.Dartmouth.EDU> genemans@mac.dartmouth.edu (Jan Genemans) writes:
	[stuff deleted regarding turning 760K's into 1.44M's]
>If anyone is going to try this, they should be forwarned.  I have used ~500
>disks in the 720k format with only 2 failures.  However, when I converted the
>disks into 1.44M with soldering a hole in them roughly one out of five disks
>had a failure, thus a ~5000% increase in disk failures.  If you insist on
>modifying the disks to a higher density than rated make sure that you backup
>*everything* or you might loose valuable data.  As for the 5.25" DS/DD format-
>ted as 1.2M DS/HD I had a failure rate of 50% or 5 out of 10 disk attempts.
>Other people might have different results, however, I strongly advise that
>this should not be done because of the headache of loosing data, even if it
>backed up.
>
>I suspect that the "coercivity of the coating" is different for the 1.44M as
>well as the 1.2M in comparison to the lower density disks.

I posted something on this a few minutes ago.  As far as I have been able to
determine, the only difference between the two diskettes it the use of the
flip side for data storage.  In all probability, the second side is perfectly
fine to use.  HOWEVER, there are no guarantees that the coating is 'computer
grade' on the flip side of a 720K diskette.  Most of the time, though, it works.

This 'trick' used to be used on CP/M (remember that? :-) systems to get double
sided diskettes out of single sided ones.  Sometimes, the second side didn't
have a coating at all.

Also, just as someone came out with a tool for notching a 5 1/4" floppy so that
you could flip it over and use the other side (like in an Apple, for example,
which ONLY has single sided drives), i have seen a tool advertised in
PC-MAGAZINE for punching out the necessary hole.  Using a soldering iron is
risky, as the excessive heat could damage the disk itself.  Also, just punching
a hole could leave little bits of plastic floating around.  The tool perportedly
avoids those problems.

Cheers

-- 
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