Hi Ivan,

the most difficult thing on your solution was the exact time point at which you switch from one memory to the other.

If you need never to switch by software, you can bring the CPU into the reset state, switch the memory area and the release the reset state, e.g. with 2 manual switches.

But if software allow to switch it was more difficult. E.g. mostly the current instruction fetch was damaged and where the program was continued was indefinite.
so you need additional hardware, e.g. latch the memory switching signal with ALE and guarantee, that the code sequence, which executed during switching was indentcal on both memory devices.

Thus why 99% of the developers prefer my solution.


Peter