This guide describes how computers and other hosts interface to the Synaptics TouchPad. The first section describes the TouchPad generally, including operating modes, features, host interactions, and principles of operation, with many historical notes comparing older versions of the Synaptics TouchPad with the present one, version 4.5. (See page 4.) The Synaptics TouchPad family supports a variety of protocols for communicating with the host computer. The next few sections describe the available protocols: