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From: tim@cit-vax.Caltech.Edu (Timothy L. Kay)
Newsgroups: comp.sys.ibm.pc
Subject: Re: new floppy format proposal
Message-ID: <4386@cit-vax.Caltech.Edu>
Date: Mon, 2-Nov-87 03:29:19 EST
Article-I.D.: cit-vax.4386
Posted: Mon Nov  2 03:29:19 1987
Date-Received: Thu, 5-Nov-87 23:20:41 EST
References: <4289@cit-vax.Caltech.Edu> <1155@cup.portal.com> <7735@steinmetz.steinmetz.UUCP>
Reply-To: tim@cit-vax.UUCP (Timothy L. Kay)
Organization: California Institute of Technology
Lines: 39
Keywords: high-density floppy

In article davidsen@crdos1.UUCP (bill davidsen) writes:
>|How about defining a new floppy format where the outside of the disk is
>|formatted high-density, and the inside is formatted low-density.  This
>|way, you should be able to comfortably and reliably pack about 800k-1000k
>|of data on the dirt-cheap floppies.  All you would need to do is rewrite
>|the DOS block device driver to recognize this special format automatically.
>
>High density diskettes have different coatings. The material used has a
>higher hysterysis (it is harder to magnetize and demagnetize). I doubt
>that a diskette which used one oxide on the inner tracks and one on the
>outer would be dirt cheap. Victor got the only free lunch there was,
>they pushed the outer tracks as hard as the inner.

Bill, I think you've missed the point.

Your comment about different coatings on the outside and inside of
the disks doesn't make any sense.  Consider an existing high-density
floppy.  The medium has to have the higher hysterysis so that it can
provide a higher *linear density* on the inner tracks.  However, because
the outer tracks are moving more quickly, their linear density is
much higher than necessary. 

Now consider a double-density floppy on a high-density machine.  The
effective linear density of the outer tracks is higher than that of
a high density floppy's inner tracks.  I was proposing that we do
just like they are doing on the Victor, but rather than increase the
speed of the drive on the outer tracks, we slow down the rate of the
bits being recorded when we get to the inner tracks.  (We do this by
switching the drive to and from high-density mode, which is something
the Victor machine couldn't do.)

This way, we could get more than a megabyte reliably on floppies that
cost $.25 each. 

Have I made myself clearer?

Is anybody interested in having such a device driver?

Tim