Re: Theorizing: what can be done with DOT clock signal present on C64 expansion port?

From: Claudio Sánchez <tokafondo_at_gmail.com>
Date: Sat, 6 Nov 2021 17:55:55 +0000
Message-ID: <ef7809f1-ef6b-fb04-ff90-d9e54ea13a29_at_gmail.com>
> If you can find a chip that needs 7.88mhz on pal and 8.18mhz on ntsc
> then sure, but you're then just using the DOT clock as a cheap way of
> getting a clock.

Well... at first it is. It's a cheap way of getting a clock.

phi2 pin is AFAIK a copy of what the 6510 gives out to the rest of the system, so when the 6510 gets halted by the VIC-II... is phi2 affected?

DOT clock is AFAIK a copy of what the VIC-II is given by the clock circuit or the 8701 chip, so it's not affected at all by the VIC-II dictatorship.

What would someone like to have constantly running at DOT speed no matter what happens inside the C64?

> 
> This used it for that exact reason
> https://retrotinker.net/cpm-card-with-8mhz-for-c64/
> 
> ~8mhz is kinda high for a sound chip though. Even 1mhz is incredibly
> high for producing sound in the human audible rangle.
> 
> On 06/11/2021 09:29, Claudio Sánchez wrote:
> 
>> Well... Not everything is digital sound. One thing for example could
>> be an external HQ sound generator chip, that could be based on
>> wavetable synthesis, that would work as the SID does, receiving just
>> data of the notes to be played and which sounds to produce. It could
>> use the DOT clock for its own inner workings.
>>
> 
Received on 2021-11-06 19:00:02

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