Re: Blurry picture

From: Gerrit Heitsch <>
Date: Thu, 17 Nov 2011 17:21:32 +0100
Message-ID: <>
On 11/16/2011 10:01 PM, Nicolas Welte wrote:

> IIRC, the SX64 has two separate crystals on a clock module
> daughterboard, with some TTL logic.

Anyone have a schematic for this board? The SX64 schematic up on doesn't include it.

> But I don't think the SX has bad video quality on it's video port. I
> think older C64 have a more blurry output and the new c64c and c128
> suffer from artifacts (vertical stripes).

Quite a bit of the blurry video of the older C64 is due to the 
modulator. There have been projects to get rid of it and replace it with 
just drivers for Chroma and Luma. That does produce a better image and 
also works for the 264 systems. There was even a further refinement to 
get rid of the vertical stripes for the 856x-VICs, it seems you can 
cancel them out to a large degree with some extra logic that uses the 
AEC signal.

The URL for the readers that speak German or just want to see the 
difference and the schematics:

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. What I do notice are the 
grey dots of the HMOS-II VICs.


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Received on 2011-11-17 17:00:09

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