hi,

By the way, Atmel has documented bug:
if during execution program from internal flash, you write to external data memory with MOVX then P0 outputs:
- A0...A7 (for ALE latch), then
- D0...D7 (data to be wrote with /WR), and then
- content of PCL for one oscillator clock, even if program memory is still internal executed.
Only after it, P0 comes to its original state (disables strong pull up/down output).

Unfortunately, this "feature" is not indicated in some datasheets however it presents.

Regards,
Oleg