I will verify the clocking frequency of the oscillator and that spec'd by the 80C31. I am using one clock for two controllers, each on its own printed circuit board. One is the system controller and accesses external memory fine; it writes to a display and receives input from a keypad). The other will be a slave; it accesses its program code and operates from it except for the MOVX problem.

I thought I had looked at the clock but, as you probably well know, when things so fundamental don't work right you sometimes forget the simple things. Maybe it is that the two chips are of different specifications.

Thanks for the suggestions, Jeff Biss