Source : Free On-Line Dictionary of Computing

Commodore 1571
     
         {Commodore Business Machines}'s "advanced" {disk
        drive} for the {C128}.  It was the double-sided version of the
        {Commodore 1570} disk drive but, unlike the 1570, worked quite
        well.
     
        The 1571 supported "{burst mode}" loading when used on a C128
        in native mode, which increased the transfer speed from 1541
        speed to about three kilobytes per second (about a 10-fold
        increase).  The 1571 could be told to emulate a {1541} for use
        with a {C64} or 1541 disks.
     
        Bugs in early releases of the 1571 {ROM} affected access to
        the second side of the disk.
     
        (1996-04-07)