I have a really good Panasonic Microwave. It was a top of the range model, and has buttons marked 'Potatoes' and 'Vegetables'.
If you put in a baking potato and tell it how much it weighs, the microwave will cook it, perfectly.
More intruiging tho', If you put in fresh veg such as carrots or brocolli, and press the vegetables button, it cooks them, perfectly. It doesn't need to know the weight of these, just whether they're fresh or frozen.
How does it know?
I've wondered for the 5 years we've had this wonderous machine (bought prior to the arrival of ds, couldn't afford such technology now! )