[Coco] overdrive ...

Kevin Diggs kevdig at hypersurf.com
Tue Apr 26 00:16:04 EDT 2005


KnudsenMJ at aol.com wrote:
> As a retired hardware designer, I agree that whatever scheme is used  between 
> the two CPUs, it will work better if the clocks are synchronized, so one  is 
> an integer multiple of the other.
> Otherwise, there will always be a "gray area" where some flip-flop is being  
> set by one side just as it is read by the other, and strange things will 
> happen  now and then.
> Also, synchronizing the clocks means that all noise and cross-talk events  
> will be repeatable, meaning you have a chance at debugging them.
> So your 68K sidecar should pick up the Coco's E/Q clocks and phase-lock to  
> them.
> (Running *almost exactly* the same frequency, so the two clocks "beat"  
> slowly, is guaranteed to stir up troubles -- so phase-lock 'em).
> And of course, with the 68K running at a harmonic of the NTSC frequency,  you 
> have the ability to run video hardware off the 68K side, if you ever want  
> fast graphics.
> --Mike K.

	A retired HW engineer huh. So acn you give me some pointers on how to 
do this PLL thing. Can you point me to an example? How much of a 
complication will the "double speed poke" be?


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