I’ve had floppies that weren’t usable and couldn’t be formatted under Windows, but would format and become usable under OS X. After that they were usable under Windows and NetBSD, and could even be re-formatted under Windows. All the systems used the same HW floppy disk which was a USB drive.
Formatting a real floppy or creating an on-disk image of a 2.88M floppy doesn’t seem to be all that straight-forward either. The only way I’ve been able to do it is under Windows (or MSDOS) making sure I had the right version of the MSDOS format utility. Some of the formatting and file structures used in Windows can also lead to other problems as well. For instance, it appears that the ExFAT format can be easily hacked to create disks which appear to have significantly more storage capacity then they actually contain. It’s easy to find devices on Amazon and eBay which claim to have 20, 30,60 TB of storage but in fact are built on a single 32 GB chip. One telltale sign of a fake device like this is when they say the device will become “damaged” if reformatted into NTFS, OS X or and Linux file structure. However the best way to determine if the device is fake is to run the “f3probe” utility on the device in question. (BTW - This would be a nice addition to pkgsrc.)
