Re: Blurry picture

From: Segher Boessenkool <*segher_at_kernel.crashing.org*> Date: Sat, 19 Nov 2011 12:51:27 +0100 Message-Id: <E44A969E-E94C-46CF-989C-90E084AFDCF3@kernel.crashing.org> · segher_at_kernel.crashing.org

> An 8500 will react slightly faster to AEC than a 6510, but that's  
> still
> not enough.  There are two big board differences as well though: the
> C64 has a 1.5kR pullup on R/#W, while the C64C has 3.3kR;

Two 3.3kR in parallel (from a resistor array).  So that's not it.

> and they use
> a very different PLA (or custom chip actually, for the C64C).  The  
> 82S100
> PLA used in the C64 has a propagation delay of typical 40ns, max.  
> 80ns.

The C64C uses a LH5062 Sharp CMOS part.  It might well be faster, but
who knows.

My current theory is all the components are just a little different,
and it all conspires to make R/#W or #CS too early :-)

Segher

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