Before revision: Originally, the high-density modes for 3.5" floppy drives in Japan only supported a capacity of 1.2 MB instead of the 1440 KB capacity that was used elsewhere.books.google.com – Fix Your Own PC by Corey Sandler While the more common 1440 KB format spun at 300 rpm, the 1.2 MB formats instead spun at 360 rpm, thereby closely resembling the geometries of ether the 1.2 MB format with 80 tracks, 15 sectors per track, and 512 bytes per sector previously found on 5.25" high-density floppy disks or the 1.2 MB format with 77 tracks, 8 sectors per track, and 1,024 bytes per sector previously found on 8" double-density floppy disks.
After revision: Originally, the high-density modes for 3.5" floppy drives in Japan only supported a capacity of 1.2 MB instead of the 1440 KB capacity that was used elsewhere.books.google.com – Fix Your Own PC by Corey Sandler While the more common 1440 KB format spun at 300 rpm, the 1.2 MB formats instead spun at 360 rpm, thereby closely resembling the geometries of either the 1.2 MB format with 80 tracks, 15 sectors per track, and 512 bytes per sector previously found on 5.25" high-density floppy disks or the 1.2 MB format with 77 tracks, 8 sectors per track, and 1,024 bytes per sector previously found on 8" double-density floppy disks.