From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2003-04-29 14:12:43
On Tue, Apr 29, 2003 at 01:28:00PM +0200, Michael Huth wrote:
> AFAIK there are two major Versions of the VIC-II.
There are at least three major versions of the 6567. The 6567R56A
uses 64 bus clock cycles per line and draws 262 lines per frame. The
6567R8 and later consume 65 cycles per line and produce 263 lines.
Then there's the HMOS version of the NTSC VIC-II.
My measurements in http://www.funet.fi/pub/cbm/documents/chipdata/
(656x-luminances.txt) indicate that there are three versions of the
PAL VIC-II as well. The 6569R1 has five luminance levels (just like
the 6567R56A), while newer 6569 versions have nine.
If I remember correctly, none of the chips listed in the above document
suffer from the "sparkles" or produce strong vertical bars on the
screen. I don't have any C64 with a 85xx video chip, but I know the
phenomenon from the C128.
> there are some old ones with a 'better' red that's even readable on
> blue background.
Have you noted the video chip revisions?
> I do not know why this occurs, but I think it may be some internal problem
> with the pixel-clock-shifter delivering a wrong color signal?!?
Well, it looks like the register is shortly disconnected from the rest
of the chip. During that period, the rest of the chip sees a $ff value.
On the TED (the video chip of the C16, C116 and plus/4), the sparkles
are light green (also $ff).
Marko
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