The first attempt to use /dev/fd0 after using the (non-rewinding)
tape device gives an I/O error when trying to access the hardware.
If I eject the floppy and try again, it is then ok.
It appears to be the automatic media detection that's wrong,
because accesses to /dev/fd0H1440 work fine, even when /dev/fd0
gives errors. And, having used /dev/fd0H1440, /dev/fd0 is fixed.
My tape device is a Colorado Jumbo 250, and the floppy is a
standard 3.5" unit.
-- Peter Fox