Questions about pal clocks

From: Jozsef Laszlo (
Date: 2001-11-22 15:01:32

Hi folks,

I have two questions about the clock generation in the C64.

1. The source Quartz for the PAL system is 17.73442 Mhz. If I replace
quartz with an 18.000 MHz one, will it work?
Theoretically it should but I'm not sure in it.

2. The VIC-II chip needs two input clocks: the color phase clock (this
is the
17.7Mhz I mentioned above), and the DOT clock. The 8701 generates both
them, the color clock is the same as the source clock, and the dot clock
the source*2/4.5 rate, which is approx 7.88 Mhz. So more or less the
color and the
dot clocks are synchronized. My question is: do they absoultely need
this sync?
I mean that if  drive the VIC-II with two independent clock sources, it
will  work or not?
(In theory the color generation is separated from the pixel generation
inside the VIC)

Does anybody have experiences in these topics?


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