Source : Free On-Line Dictionary of Computing

Commodore 1541
     
         The best know {floppy disk} drive for the {Commodore
        64}.  The 1541 was a single sided 160 Kb drive but converting to
        {flippy disks} would give another 160 Kb.
     
        The disk drive used {Group Code Recording} and contained a
        {6502} processor as a {disk controller}.  Some people wrote
        code for it to vibrate the head at different frequencies to
        play tunes.
     
        The transfer rate was about 300 bytes per second.  The 1541
        used a {bit-serial} version of the {IEEE 488} parallel
        protocol.  Some third-party speed-ups could transfer about 4
        kilobytes per second over the interface, and some "fast
        loaders" managed up to 10 kbps.
     
        The {Commodore 1570} was an upgraded 1541 for use with the
        {Commodore 128}.
     
        (2000-03-07)