Today I come or for those who will recognize my problem, I come back because I could not find a solution.
So for over 6 months I try to put in a microprocessor system a microcontroller between the processor and the SRAM. This not to build the capacity of the latter, but to be able to see and modify certain information.
For my solutions tested and without satisfactory result
At first, with the ATmega128 I got hooked on the address bus and the control bus, but the data bus crosses from one port to the other. Subsequently I made all the bus (address, data and control) by my Uc but this foid if I used an ATmega1280 but without success
I leave it to you