Independent CPU/VIC-II setup

I've been thinking to put the VIC-II to work /independently/ of the CPU, and
I mean that the CPU won't get its clock from the VIC-II but from the clock
source itself.

I have a '816 CPU and the chips of a non working C64.

The idea is to have 64K of memory exclusive to the VIC-II mapped into the
memory address of the '816. The '816 would be running code outside of that
memory range, that would update the data that the VIC-II will use to render
the bitmap that will be used later to the final video output.

I know that in the C64 the VIC-II stops the CPU when needed to access the
memory to read the data. That should be still done in this setup, to avoid
bus contention -- or maybe a dual port RAM would be useful here, but out of
scope.

So help me with this:

my logical thinking says that if I run the '816 at ~8mhz or even ~14mhz (fed
by one of the clocks the VIC-II is also fed with), for everytime the VIC-II
does /one/ memory accesses, the '816 would be able to do eight or fourteen
times that memory accesses.

Is it like that?

Also, I'm thinking that a sort of address decoding mechanism could be used
in a way that the VIC-II would be only allowed to stop the '816 for its
additional fetches /when they both are accessing the same memory locations/,
but not when the '816 is somewhere else, like doing I/O or calculations in
some other memory space.

What do you think?



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