Monster 6502

drlegendre . drlegendre at
Sat May 28 20:19:59 CDT 2016

@Eric, All,

Light a candle for those in the dark..

If the min. clock speed is dictated by the ability of the gates to hold a
charge, as the bits rot away as charge drains (someone said "minimize
resistance to ground", but I believe they meant "maximize"?) , then what is
limiting the max. clock speed?

Is it just basic PCB stuff, like trace inductance, mutual / parasitic
capacitance, etc? Or are there other, more critical factors? I can't
imagine propagation delays could matter at these slow speeds.. requiring
meandering of traces and so forth.

On Sat, May 28, 2016 at 2:55 PM, Corey Cohen <applecorey at>

> > On May 28, 2016, at 1:31 PM, Eric Smith <spacewar at> wrote:
> >
> >> On Sat, May 28, 2016 at 5:31 AM, Corey Cohen <applecorey at>
> wrote:
> >> I can't wait to buy one!!!  I have a spare Replica-1 just waiting to
> hook up to a Monster 6502.
> >
> > It doesn't run at full speed. It presently runs in the tens to low
> > hundreds of kHz.  If a Replica-1 can be run slower than normal, that
> > might work.  Other common 6502-based micros, such as the Apple II or
> > Atari 400/800 will not work at low speed due to inherent timing
> > requirements related to video generation and DRAM refresh.
> >
> >> Just need to wire up a single step switch and this thing will be
> awesome!!!
> >
> > If you wire single-stepping using the RDY line, that should work,
> > though it will only single-step read cycles, not write cycles.
> >
> > You can't single-step the actual clock because it is dynamic logic.
> The replica-1 uses a propellor chip for video and static ram so I don't
> think it's that critical to timing.

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