Editing MOS Technology VIC-II (section)

==List of VIC-II versions {{anchor|versions}} ==
Commodore made many modifications to the VIC-II during its lifetime. ''[[Compute!'s Gazette]]''{{'}}s first issue, in July 1983, reported that there had already been eight since the Commodore 64's release in mid-1982.<ref name="halfhill198307">{{cite news | url=https://archive.org/stream/1983-07-computegazette/Compute_Gazette_Issue_01_1983_Jul#page/n41/mode/2up | title=Commodore 64 Video Update | work=Compute!'s Gazette | date=July 1983 | accessdate=6 February 2016 | author=Halfhill, Tom R. | pages=40}}</ref>

*[[NTSC]]
** MOS Technology 6566 &ndash; designed for [[static RAM|SRAM]]/non-[[multiplexer|muxed]] address lines (used in the [[MAX Machine]])
** MOS Technology 6567 &ndash; Original NMOS version
** MOS Technology 8562 &ndash; HMOS-II version
** MOS Technology 8564 &ndash; VIC-II E C128 version

*[[PAL]]
** MOS Technology 6569 &ndash; ([[PAL#PAL-B/G/D/K/I|PAL-B]], used in most PAL countries)
** MOS Technology 6572 &ndash; ([[PAL#PAL-N (Argentina, Paraguay and Uruguay)|PAL-N]], used in southern South America only)
** MOS Technology 6573 &ndash; ([[PAL#PAL-M (Brazil)|PAL-M]], used in Brazil only)
** MOS Technology 8565 &ndash; HMOS-II version for "C64E" motherboards
** MOS Technology 8566 &ndash; VIC-II E (PAL-B) C128 version
** MOS Technology 8569 &ndash; VIC-II E (PAL-N) C128 version

The earliest revision of the VIC-II was used in machines made during 1982 and early 1983; it had a ceramic shell for thermal reasons and generated 64 NTSC color clocks per line. These chips also did not output separated chroma and luminance signals. Later revisions had a lower cost plastic shell and 65 color clocks per line (for NTSC, 63 for PAL), as well as separated chroma and luminance, allowing for an early form of S-video. Several revisions were made chiefly in the interest of improving video output quality, which was poor on the early units, and eliminating a bug that would cause random pixels to appear on screen (a few early games intentionally exploited this for graphics effects that consequently did not work on later C64s). The 64 color clocks on the initial VIC-II was done with the intention of allowing NTSC artifact color in high resolution bitmap mode as the Atari 8-bit computers did, but that idea was quickly dropped.

Because it was necessary for cost reasons to switch to a plastic shell, overheating tended to be a problem with the VIC-II. This was for several reasons including the high density of the die relative to the process used, and its high internal speed (8&nbsp;MHz). Commodore tried an impromptu solution for this by using the aluminum [[RF shield]] as a heat sink (on NTSC machines; PAL machines were sold in countries with less restrictive RF interference standards than the United States and so only used aluminized cardboard), however it was not entirely effective at preventing overheating and chip failure.

The 85xx VIC-II used in C64Cs was made with the more modern 3.5 [[micrometre|μm]] HMOS process and requires only a single 5V power rail instead of the dual 12V and 5V rails of the 65xx VIC-II. These chips run significantly cooler and do not suffer from the overheating issues that affect the 65xx VIC-II.

Several revisions of 6569 exist: 6569R1 (usually gold plated), 6569R3, 6569R4 and 6569R5. The most common version of 8565 is 8565R2.