https://en.wikipedia.org/wiki/Commodore_1581
The Commodore 1581 is a 3½-inch double-sided double-density floppy disk drive that was released by Commodore Business Machines (CBM) in 1987, primarily for its C64 and C128 home / personal computers. The drive stores 800 kilobytes using an MFM encoding but formats different from the MS-DOS (720 kB), Amiga (880 kB), and Mac Plus (800 kB ...