6502 

Commodore 64

In addition to the CPU, 
  System contained a 40-pin video processor. VIC II - MOS 6567/6569
    6567 - NTSC (U.S.)    6569 - pal (Europe)

    47 control registers.

    320x200 resolution. 40 characters x 24 lines

    Capable of text generation. 
      - ASCII code read from memory and graphic generated
    Supported bit level 16 color control based on reserved 16K block of ram.

    Capable of generating "Sprites" or Movable Object Blocks (MOB).
      Consisting of 24x21 dot array
      Once created, location specified by upper left corner(x,y).
      When moved (new x,y), VIC calculate location for all bits.
      If 2 MOBs intersect, VIC reports collision.

    Also handled DRAM memory refresh.

    Used bus mastering to access system memory during alternative half of
      clock cycle and could halt CPU to use additional clock cycles.

  Audio synthesizer  MOS 6581 SID
    Digital to analog decoders.

    3 tone Oscillators 0-4kHz
    4 wave-forms (triangle, saw-tooth, variable pulse, noise)
    3 envelope generators - shape of overall tone.  
    Programmable filter.

    2 analog to digital POT. (potentiometer)
      for Game paddles or other external controllers. 

    Random number generator. 

  Complex Interface Adapter 40-pin 6526 CIA
    Contained select-able multiplexer/de-multiplexer.
 
    Two 8-bit data-direction registers providing 
      16 individually programmable I/O lines.

    Handshaking. 

    2 16-bit interval timers (can be daisy-chained).

    24-hour clock with alarm.

    8-bit shift register for serial I/O (convert parallel to serial).