floppy media failure

Billy Pettit Billy.Pettit at wdc.com
Tue Apr 10 20:48:01 CDT 2007

Jules Richardson pondered:
... engage brain before posting :) I was thinking of lashing something up so

that the upper head wasn't in contact with the disk at all, reading the
surface, and only then reading the top. Thinking about it some more, the 
loading of the head against the surface on both sides is almost certainly 
critical, so this wouldn't work :(
Billy wrote:
The dual sided floppies offset the top head from the bottom to create a
tension path for the media.  This kept the media snug against the heads -
critical because floppy media is based on contact with the head.  Best way
to think of this an S shaped that is on its side.  The lobs are the two
heads and the line drawing the S is the media.  It is a very shallow bend
for the media.  Any other method would create a pinch effect that could be
deadly of the coating.
When the heads are unloaded, the media would float between them.  Loading
created the tension contour.  A lot of work was done with air bearing type
of read/write but it was not reliable enough to go into production.  The
media specs were too poor to give good snr with anything but contact
Contact recording was tried with hard drives a few times.  These were the
famous "tail draggers".  None of them ever achieved reliable enough
operation to survive long.


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