I would want a thermostat that does not connect to the internet or any wireless communication at all (with the possible exception of an outside temperature sensor if it cannot be connected with a wire; the one that the people installed (I did not have a say) does not have an outside temperature sensor), and does not have a lighted display or a colour display. I had thought to use Atmel AVR. However, to do that, I think that, first I would need test cases so that an emulator can be written.