The Commodore 1571 was Commodore's high-end 5¼" floppy disk drive. With its double-sided drive mechanism, it had the ability to utilize double-sided, double-density (DS/DD) floppy disks natively. This was in contrast to its predecessors, the 1541 and 1570, which could read or write such disks only if the user manually flipped them over to access the second side.
The Commodore 1581 is a 3½ inch double sided double density floppy disk drive made by Commodore Business Machines (CBM) primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM format different from both MS-DOS (720 KB), and the Amiga (880 KB) formats. It was released in the summer of 1987 and quickly became popular with bulletin board system (BBS) operators and other users.
