In order to develop "understanding", at least one input channel must be available to provide something to understand. In order to ascertain that development, we require at least one output channel. Anything less and we are describing a pet rock. Language can be thought of as the rules of the communication.

The root question seems to be whether a machine can learn to communicate meaning and understanding over a bidirectional binary channel without previous training. I suspect that such communication can evolve. Some might look around and remark that it already has.