Re: 74ls612, clocking 6502and others...

From: Andre Fachat (
Date: 1998-04-23 14:11:31 wrote:
> > Hm. You should probably think of mapping the addresses $000000-$0fffff 
> > (1MByte)
> > with the MMU, i.e. with slow access. Then you can have some additional 
> > RAM in this space to replace the ROMs for example, which you couldn't do
> > otherwise (without sacrificing 8032 RAM for this purpose).
> I think you missed the point. A16-A23 of the CPU and those of the MMU are 
> placed PARALLEL! Which lines are active depends if the 65816 is in the area 
> $000000/$00FFFF or not. This means I can replace ROM with RAM form every other 
> big page I want.

Ok, I see now. But then the `normal', i.e. the fast 65816 memory 
would have to be able to handle a `slow' memory access, when the
MMU is used. 
But you use the 65816 with the same 1 MHz anyway, right?


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Andre Fachat, Institute of physics, Technische Universitšt Chemnitz, FRG

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