Comment 2 for bug 447489

Incredible that this bug has remained open for 4 years.

The solution is simple--DOSemu running as a user doesn't have root permission to access a physical device.

You can fix this by

sudo chmod a+rw /dev/fd0

Note that you have to do this every time you reboot, as the device table is built fresh.

I can run BIOS-level floppy access just fine using this.