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

Commodore 64
C64

    (C64) An 8-bit Commodore Business Machines
   personal computer released around September 1981.
   Prototypes were (apparently) made before Christmas 1980 (and
   shown at some computer fair).

   The CPU was a 6510 from MOS Technology (who were a
   wholly owned subsiduary of Commodore at this time(?)).  The
   C64 had 64 kilobytes of RAM as standard and a 40-column
   text, 320x200 pixel display generating composite video,
   usually connected to a television.

   DMA-based memory expanders for the C64 (and C128) allowed
   128, 256, and 512 kb of RAM.  Several third party
   manufacturers produce accelerators and RAM expanders for the
   C64 and C128.  (Some, risking a holy war, compare this to
   putting a brick on roller-skates).  Such accelerators come in
   speeds up to 20MHz (20 times the original) and RAM expanders
   to 16MB.

   The C64's 1541 5.25 floppy disk drive had a 6502
   processor as a disk controller.

   See also Commodore 65.

   ["Assembly language programming with the Commodore 64", Marvin
   L. De Jong].

   (1996-06-05)