Lower 32K seems protected/locked

[mwr07071]

This behavior just started as I was able to toggle in and run a test program at address zero two days ago.
I can still deposit bytes at upper 32K of memory addresses FF00 through FFFF. I can no logger deposit bytes at lower 32K of memory addresses 0000 through 00FF.

When I hit deposit, the selected bits flash very briefly on the data bus and then turn off.

Have I messed up a setting somewhere?

[mwr07071]

I forgot to flip configuration bit 11 back to zero after finishing playing with CPM!