Re: CIA old/new?

From: silverdr_at_wfmh.org.pl
Date: Mon, 4 Jan 2021 18:30:31 +0100
Message-Id: <87DC280D-0A01-47EF-ABD0-8D98ED271314_at_wfmh.org.pl>
> On 2021-01-04, at 17:19, Segher Boessenkool <segher_at_kernel.crashing.org> wrote:
> 
>> Not every detail in the design is clocked, some delays just happen because of 
>> gate propagation delays - and when the process changes, those delays may 
>> change as well.
> 
> Yup, exactly.
> 
>> The well known "grey dot" the new VICII produces are related 
>> to exactly the same thing.
> 
> But this isn't true at all.  You get the grey dot if *external* timing
> is off!  The difference isn't between VIC-II versions, the difference is
> between boards (and what PLA or PLA replacement is used on that).

Erm... are you sure? FWIW I tested a large number of combinations when developing the GreydotKilla switch for BeamRacer and a) it never happens on any NMOS VIC b) it happens on _some_ HMOS-II VICs, depending on the particular chip/batch and chip's temperature. Even on the same board. This also include boards like the "Reloaded MkII", BTW. While theoretically possible (I didn't check this) I would be a bit surprised if Jens dynamically adapted his PLA replacement timings to one or another VIC. I think gpz can comment on that.

-- 
SD! 
Received on 2021-01-04 19:00:55

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