The main problem with the early Sony floppy drives were that they didn't have any way to rewind the floppies after reading. That wasn't a problem with the old 5.25" floppies which you could just turn over to use on the other side, but you couldn't do that with the new 3.5" floppies. They had to be manually rewound by rotating the platter with your thumb. Annoying with SD disks, and completely impractical with HD disks (which required twice as many revolutions to rewind fully.)