In some cars, the transmission lever cannot be moved in this position. If the steering wheel is applying pressure to the locking mechanism, the key might be hard to turn. If you do experience this type of condition, try moving the steering wheel to remove the pressure as you turn the key. All circuits are open, but the steering wheel can be turned and the key cannot be extracted. Current is supplied to all but the starter circuit.
Power is supplied to the ignition circuit and the starter motor only.
That is why the radio stops playing in the start position. This position of the ignition switch is spring loaded so that the starter is not engaged while the engine is running. This position is used momentarily, just to activate the starter. Power is supplied to all but the ignition and starter circuit. This allows you to play the radio, work the power windows, etc. while the engine is not running.