From: Michael Huth (520052975648-0001_at_t-online.de)
Date: 2003-04-29 13:28:00
At 09:11 29.04.2003 +0200, you wrote:
>Seems this is the best place to discuss about hardware.
>I have noticed some sort of vertical lines on my
>new VIC. Well, if I check my old VIC, it also
>produces some lines, but they are almost unnoticable.
>I wonder what produces these? I have also noticed
AFAIK there are two major Versions of the VIC-II.
The old one has no vertical lines at all. It has a
quite unreadable red color on blue background. It also
produces no light-grey pixel if you change a register.
I checked several old ones and noticed that the red-color
varies a lot, there are some old ones with a 'better' red
that's even readable on blue background.
The newer Version has the vertical lines (i.e. brightness differences).
According to their periodicity, I guess it has something to do with
the phi/2-clock. Maybe some interaction within parts of the chip, since it
manages
the clock itself?!? (C= had such problems already before, f.e. with 6522 or
VDC)
The grey dot's always appear on a new VIC if you access a VIC-register.
It even works if you write f.e. to a register that does not change anything
on the screen, you'll get grey-dot-snow.
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?!?
Ciao....
...Micha
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