Re: 6569 luminances

From: Gerrit Heitsch <>
Date: Wed, 12 Sep 2012 22:35:43 +0200
Message-ID: <>
On 09/12/2012 10:27 PM, wrote:
> On 2012-09-03, at 05:38, Segher Boessenkool wrote:
>>> It should be easy to come up with a circuit that does the same thing, take the crystal clock and divide by 2.25 (for PAL). The 8701 does that by doubling and then dividing by 4.5 (PAL).
>> Note it doesn't actually divide by 4.5; it divides unevenly.  The
>> datasheet shows how exactly (we have checked it with pictures of
>> the die, it does what the datasheet says).
> What does this exactly/practically mean? Will it matter if I somehow divide the xtal just by 2.25? Does one have to care about the relation of the phases of both outputs?

There was some reason why they didn't use 2 crystals in the C64 but had 
to have the color clock and the dot clock be related to each other.


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