Is your question about unknown operations going on by default? It requires detailed knowledge of the programming language, and the device.
Example, how it decides whether a variable is stored as an integer or floating point, if not specifically dimensioned.
Whether arithmetic is done in floating point or fixed point or integer, based on what symbol you use for a math operation.
Whether it polls automatically and how often, to detect a keypress or mouse event.
Whether it polls automatically and how often, to notice if a peripheral was connected/disconnected.