Re: Tempest vector jitter.

Can you take a little movie of the effect with your digicam? It is hard to
imagine what you actually see so I'm not sure what to tell you to check...

But my guess is that is is a digital proglem, probably in the DAC's or
Vector counters... But I would really have to see what it's doing to make
sure. An anlog problem should look quite unrelated of what's exactly drawn,
and occur on multiple, random, (parts of) vectors. Vectors will look noisy
or warped.

Cheers,

Mendel

----- Original Message -----
From: "Alexander Glaser" <alex@galaga.org>
To: <mypearl@dds.nl>
Cc: "Alexander Glaser" <alex@galaga.org>
Sent: Sunday, January 29, 2006 7:36 PM
Subject: Re: VECTOR: Tempest vector jitter.

>
> Dear Mendel:
>
> On Jan 28, 2006, at 12:55 PM, Mendel Pearl wrote:
>
>> The distortion in the image link looks more like a digital problem than
>> analog jitter to me, are you sure your symtoms are alike (some vectors
>> go wild but others are okay) ?
>
> Thanks for the feedback. I guess that wouldn't be good news (having a
> digital instead of an analog problem), wouldn't it? (I just replaced the
> POKEY's a few weeks ago). Of course, the screenshot on the page is
> fabricated and the visual problems may indeed be somewhat different.
>
> But, yes, I think that only a few vectors jitter for a fraction of a
> second. In fact, I believe that only one vector jitters at a time
> (belonging to an arbitrary element of the playfield (blue tube, yellow
> shooter, text, etc.) ... Note also some "white dots" that may appear
> (also illustrated). Furthermore, in the picture I suggest that the jitter
> are zig-zag-lines, but they may actually be more "smoothly distorted" ...
>
> What should I look for when trying to narrow down the root of the
> problem. I assume changing the caps wouldn't be a bad idea anyway ---
> even if it ultimately doesn't solve my problem.
>
> Thanks again for looking into this ...
>
> Alex
>

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Received on Sun Jan 29 14:56:15 2006