ABSTRACT
20.1 Introduction
Input devices provide a means of getting data into a computer system so that it may be subsequently used to control some aspect of either the system itself or an application running on that system. Human interface devices (HID) are the most common type of input device and, as the name implies, are used to enable the actions of a human operator to control some aspect of the system or application. Examples of HID devices include mice, keyboards, and joysticks. It should be noted that each of these devices, in their most general form, simply allow a human action to be sensed, communicated to the system, and used by that system in some way. This form holds true regardless of the specific human action being taken, the specific method of sensing that action, the specific communication methods involved, or the end-use of that action within the system. Thus, any human interface device follows the general form:
human action → sensing device → communication → system input → application/end-use action
