The joystick is an input device that provides absolute position information. It is an additional supported input device and not a replacement for the mouse. For this chapter, the term joystick refers to any absolute position device; for example, a light pen, digitizing tablet, or touch screen could all use the joystick driver interface.
All joystick function calls are routed through the operating system. The operating system loads the joystick driver and passes application requests to it. The joystick driver must handle the standard tasks handled by all installable drivers, as well as the following joystick-specific tasks:
The joystick driver interface lets a driver to handle one or two devices. Each device can have one to three axes and one to four buttons. The IBMJOY joystick driver included with Windows can handle two joysticks, each with up to two axes and two buttons, or one joystick with up to three axes and four buttons. The joystick interface accommodates both analog and digital devices.