Hello Ernst!

  EdT> To write floppies I use dd(1):
     >
     > dd if=disk.image.filename of=/dev/fd0a bs=9216

dd was what I had in mind, but is fd0a the right device file
for a 3.5" DSHD diskette?  Perhaps there was just a physical
flaw on the disk when I tried that.  :-/

Regards,
  - Andy Ball