I have taken over a design of which several thousands of boards are in the field. I need a bit more of RAM to solve some intermittent problems. I plan to pop a processor such as a RD2 in to gain this extra RAM. The external RAM is, of course, mapped from 0000. Has anyone developed a technique for keeping external and internal XDATA separate and - most importantly - have the compiler either do the switching of the control bit or at least scream blody murder if a location is accessed in the wrong state. Just special pre- or postambles such as EX... and XX... will not guarantee squat.

I will appreciate your insights

Erik