Re: VIC-II and luma levels

From: Gerrit Heitsch <>
Date: Fri, 13 Jan 2012 18:05:50 +0100
Message-ID: <>
On 01/13/2012 04:00 PM, Segher Boessenkool wrote:
>> I know there is a major difference in the PAL version of the VIC-II
>> between the 6569R1 and all later versions. The R1 is only able to do 5
>> luma levels (1-4-6-4-1 number of colors per level) for the 16 colors
>> while the later versions are able to do 9 luma levels
>> (1-2-2-2-2-2-2-2-1). Some demos look quite odd on the R1.
> The LUM signal has an external pullup; everything inside the VIC-II
> does pulldown only.

Yes... And that pullup is integrated into the RF modulator. Which makes 
removing the modulator to improve picture quality a pain.

> The newer chips supposedly are nine levels, just like PAL; but indeed,
> when did they change from five?

I found this picture today while trying to do some further research:

 From this image is looks like they were still finetuning the resitor 
values after R3. Too bad the image doesn't contain values for the HMOS 

And here's some other information:

Why do I always come up with the proper google terms some hours after 
sending a mail out? :)


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Received on 2012-01-13 18:00:12

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