Re: demo for 64

From: Segher Boessenkool <segher_at_kernel.crashing.org>
Date: Thu, 7 Nov 2019 05:10:26 -0600
Message-ID: <20191107111026.GY16031_at_gate.crashing.org>
On Thu, Nov 07, 2019 at 10:36:00AM +0100, silverdr_at_wfmh.org.pl wrote:
> > On 2019-11-07, at 09:33, Segher Boessenkool <segher_at_kernel.crashing.org> wrote:
> >>>> And there are some icing on the cake too - with one command we can turn on/off the annoying HMOS VIC "sparkles" w/o modifications to the board for example as well as enable "Lumafix". This with jumper though :-)
> >>> 
> >>> What does it do for the sparkles?
> >> 
> >> but with a flip of a bit we add a tiny delay to the R/_W line, which
> >> makes HMOS VIC output behave the same as NMOS one.
> > 
> > What I meant to ask (and failed horribly at :-) ) is how do you do that?
> > 
> > Perhaps I do just not know how this expansion works?  I assumed you keep
> > the original system (including ram, cpu, vic) intact, only adding some
> > cartridge or other plug-in; but maybe you don't.
> 
> CPU, RAM, etc. remains untouched. The expansion comes between the VIC and its socket. This means we have all VIC signals and we buffer/process the required ones. R/_W is one of those, which we have to handle anyway because we need it to communicate with the VIC. From there it was only a small step to have the sparkles annoyance fixed at will. 

Ah I see, a man-in-the-middle design, so this is straightforward to do.
Thanks for the explanation!


Segher
Received on 2020-05-29 23:29:57

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