Re: Blurry picture

From: Gerrit Heitsch <>
Date: Thu, 17 Nov 2011 22:31:44 +0100
Message-ID: <>
On 11/17/2011 10:09 PM, Segher Boessenkool wrote:
>> The vertical stripes really depend on the chip run and are, from what
>> I have seen, more pronounced on the C128. I don't really notice them
>> on the C64 with 8565R2 I use most of the time.
> So what causes the stripes? They coincide with AEC/Phi2, but that doesn't
> mean it causes it. I don't see anything on the chip that could cause it,
> so maybe it is interference on the board?

Someone in the thread about the modulator removal mentioned that that's 
how the signal comes out of the chip, so it's likely not the board design.

Could it be possible that the power consumption of the VIC is not 
uniform with respect to AEC so that the resistance of the internal 
traces comes into play? Meaning one of the drivers in the chain for the 
luma signal has a power supply that fluctuates with the phase of AEC?

>> What I do notice are the grey dots of the HMOS-II VICs.
> That seems to be caused by the different boards, not the different VIC
> revision: the #CS signal is too early (relative to the data bus), which
> means that when you write a colour reg, it first gets written with all
> ones, getting the correct colour only later that same cycle. Delaying
> the #CS signal (adding a cap is enough) gets rid of the dots.

Maybe in a C64 or C128, but TED shows the same 'feature' and it handles 
its register decoding internally.


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Received on 2011-11-17 22:00:25

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