Re: Blurry picture

From: Gerrit Heitsch <>
Date: Mon, 14 Nov 2011 18:04:01 +0100
Message-ID: <>
On 11/14/2011 12:17 AM, Nate Lawson wrote:
> On Nov 12, 2011, at 9:30 PM, Segher Boessenkool wrote:
>>> Since the hsync/vsync signals on the VIC are driven by on-chip oscilators,
>> They are not; they are derived directly from the master clock, which is
>> externally generated.  There are no oscillators on the chip (well, the
>> 85xx versions have one for the back bias charge pump, but let's not count
>> that :-) )
> Sorry for the mistake. I think that may have been an earlier design I was remembering from Al Charpentier's notes about having to add a PLL to keep them in sync.

That was the VIC-II and all its derivates. In the end the decision to 
supply dot clock and color clock to the VIC-II independantly resulted in 
the need for the PLL and in the end gave us the little MOS 8701. Even 
though MOS reworked the VIC for the C128, the 8701 is still present there.


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Received on 2011-11-14 18:00:04

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