The VIC-II (Video Interface Chip II), specifically known as the MOS Technologies 6567/8562/8564 (NTSC versions), 6569/8565/8566 (PAL versions), is the integrated circuit chip responsible for generating composite video graphics and RAM refresh signals in the Commodore 64 and C128 home computers. The VIC-II, succeeding MOS' original VIC (used in the VIC-20), was one of two chips mainly responsible for the C64's success as the best-selling computer model of all time (the other was the SID sound chip).
One of the engineers working with the VIC-II was Robert Yannes, who also created the SID.
VIC-II features include:
- 16 KB address space for screen, character and color memory
- 320 × 200 pixels video resolution
- 40 × 25 characters text resolution
- three character display modes and two bitmap modes
- 16 colors
- concurrent handling of 8 sprites, each of 24 × 21 pixels
- movable video RAM address
- independent dynamic RAM refresh
- on-chip DMA
The VIC-II was programmed by manipulating its 47 control registers (up from 16 in the VIC), memory mapped to the range $D000–$D02E in the C64 address space. Of all these registers, 34 dealt exclusively with sprite control (sprites being called MOBs, from Movable Object Blocks, in the VIC-II documentation). Like its predecessor, the VIC-II handled light pen input, and the original PETSCII character set from 1977 was also retained, but now available on a similarly dimensioned display as the 40 column PET series.
The 8564/8566 VIC-II in the Commodore 128 had two extra registers, one for accessing the numerical keypad, and the other for toggling between a 1 MHz and a 2 MHz system clock; at the higher speed the VIC-II's composite video output was disabled, suggesting use of the C128's 80-column mode (via the 8563 VDC RGB chip) at that speed. Rather unofficially, the two extra registers were also available in the C128's C64 mode, permitting some use of the extra keys, as well as double-speed-no-video execution of some C64 BASIC programs.
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