The calibration procedure is still needed at some point, even under modern operating systems such as Windows XP. Usually, it consists of moving the joystick around all of its axes to measure the maximum axis excursion values, no matter if the joystick uses analog signals (from potentiometers) or digital signals (using microswitches or contacts). USB joysticks, on the other hand, do not need calibration. This is because USB sends digital signals.