(UCSD P-system)
Many will disagree with me, but I feel that a floppy
based OS that can't
handle non-contiguous files is the worst product ever marked as being an
OS.
IIRC, RT11 (and thus PERQ interchange floppies, which have almost the
same filesystem) suffer from that problem. As does the HP LIF filesystem,
used on many of their machines.
-tony