The Free On-line Dictionary of Computing (30 December 2018):

Commodore 1541
1541

    The best known 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)