merlin:

Affordances

The “car stereo” in our Zipcar. Over 25 buttons and knobs—not including modes.

Tight.

I just finished reading _Design of Everyday Things_ by Don Norman again, and in it he said something about mapping, where if each button is limited in what function it does, and it maps one-to-one to features in the conceptual model, it’s a better design than something with fewer buttons but lots of modes. Also, affordances.