[Coco] What would a CoCo successor have to have as a minimum?

[Theodore (Alex) Evans]

If one wants to get pedantic, 8ns giving you 125MHz is only 4x faster 
than 25MHz, not 5x faster.  Of course it is still more than enough 
headroom for multiplexing the bus between video (accelerated or not) and 
the CPU especially since there is nothing stopping you from giving the 
video side 32 bit access even with no changes to the CPU.  The memory 
connection in a CoCo 3 to the GIME is 16-bit enough to get nearly the 
full bandwidth improvement, pure 8-bit access would have been barely 
fast enough for the video side of things alone leaving nothing for the CPU.

If we are modifying the 6x09 CPU, I would like to see support for 24 or 
32 bit addresses in the CPU and a true 16-bit ALU, and yes a wider data 
bus would be nice too.  To support all this there would have to be 
another CPU mode because at the very least it would mess up the stack.