3. USB 2.0

3.1 Presentation

USB 2.0 is compatible with previous versions of USB. USB 2.0 retains its principles, mechanisms and functions, while extending them to achieve high transfer rates.

USB 2.0 is 40 times faster than USB 1.x, with a gross data rate of 480 Mbit/s instead of 12 Mbit/s, and a maximum useful data rate of around 420 Mbit/s. Although maintaining backward compatibility with previous versions, USB 2.0 has features that set it apart, such as its bus cycle. In version 2.0, the hub also acts as an "adapter" between portions of the network compliant with version 1.x and others compliant with version 2.0. This last feature is very important, as it allows the two versions to coexist without wasting the possibilities of the more recent version.