On Mon, 2 Sep 2002, tim lindner wrote:
  Did anybody ever market a floppy disk system that
communicated via
 RS-232? 
Yes, but, ...
Only one really "caught on"
Radio Shack "Portable Disk Drive" was sold for the Model 100.
It was serial, but not quite RS-232.  The first version was
Single-Density? on a 3.5" disk.