5 1/4 floppies ... sniveling youngsters, now in MY early days I can remember 8 inchers....

I can also remember the difference between the 'hard hole sectors' and the single hole 'virtual sectors' floppies.... :-) they are not swappable....

as for getting the old HW to work on modern OSes, both 5 & 3 inchers should work on all MBs that have the 'floppy bus' HW plug as the Boot roms on all MBs (X86 compatible style PC) still recognise the drives, as they are part of the standard. They should work even on all versions of Linux, as they are part of the basic machine.