[M100] Upgrade via System Bus ?

[Hiraghm]

Okay, so the system bus is used to connect to the DVI drive/video 
expansion, but what are its total capabilities?
In an earlier message I wished for a cpu/ram upgrade for the M100. On 
reading about the extRAM in Portable 100 issue November 1990 (page 17), 
I began to wonder if one of you hardware types could build a very small 
cpu/ram upgrade board that "takes over" for the CPU over the system bus.

Maybe this is how QUAD adds the banks of RAM, I don't know. That's why 
I'm asking, because I don't know.

Not only would such a hardware upgrade speed up and expand the 
capability of the M100 (would probably require a customized ROM via 
REX), but it would make CP/M or even a custom FreeDOS (except FreeDOS is 
32 bit :(  ) possible.