Re: demo for 64

From: silverdr_at_wfmh.org.pl
Date: Thu, 7 Nov 2019 10:36:00 +0100
Message-Id: <4AEE3D31-A2DA-484B-87DB-399005A0B1B6_at_wfmh.org.pl>
> On 2019-11-07, at 09:33, Segher Boessenkool <segher_at_kernel.crashing.org> wrote:
> 
> On Thu, Nov 07, 2019 at 09:16:00AM +0100, silverdr_at_wfmh.org.pl wrote:
>>> On 2019-11-07, at 01:30, Segher Boessenkool <segher_at_kernel.crashing.org> wrote:
>>> On Wed, Nov 06, 2019 at 09:54:18PM +0100, silverdr_at_wfmh.org.pl 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?
>> 
>> By default it doesn't do anything because we want to keep the expansion
>> as "invisible" as possible
> 
> Sure, good design.
> 
>> 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. 

-- 
SD! 
Received on 2020-05-29 23:29:40

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