[Novalug] USB floppy, format to 1.722M?

Paul W. Frields stickster@gmail.com
Fri Jan 2 11:35:16 EST 2009


On Fri, Jan 02, 2009 at 11:11:01AM -0500, Ed James wrote:
> Richard
> 
> This seems to tilt the odds in favor of this working for me.  It also
> brings up the question for anyone to jump in here about...
> 
>     What determines if a laptop floppy drive can read a 1.772M floppy -
> the drive itself, the BIOS, or the Tom-code on the floppy?  And it
> feels odd that now that floppys are pretty much obsolete, I'm just
> now delving deep into how the suckers work.
> 
>     Note - I have other boxen with (probably) working floppy drives,
> but I don't have enough desk space to set another machine up.  I
> didn't wanna halt my working machine just bacause I'm seeing how
> long an uptime I can get outta it.

There's almost no floppy drive created in the last 12+ years that
can't read higher capacity floppy diskettes.  Microsoft, in fact, used
to send out MS Office on these types of diskettes, labeled as "DMF."
The extra capacity is created by fitting in 21 sectors per track,
which is simply a function of timing on the read heads.  (The other
method, jamming in 81-83 circular tracks on the diskette, is far less
reliable because it really does depend on significant motor
characteristics.)

I got my numbers wrong in my memory and hadn't double checked them --
it's actually 1.68 MB for these diskettes, or 21 spt * 2 sides * 80
tracks, or 3360 sectors, as opposed to the normal 2880.

-- 
Paul W. Frields                                http://paul.frields.org/
  gpg fingerprint: 3DA6 A0AC 6D58 FEC4 0233  5906 ACDB C937 BD11 3717
  http://redhat.com/   -  -  -  -   http://pfrields.fedorapeople.org/
  irc.freenode.net: stickster @ #fedora-docs, #fedora-devel, #fredlug
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