An example of Atmega128 and external memory:
The ideea is to use two Atmega128 microcontrollers and one memory. So called shared memory. The memory i will be using is called Dual-ported RAM. There are actually some chips that can implement this kind of memory. I will try to use 7025E or IDT7130.
This is block schem of the IDT7130:
And here is the general idea:
