USB Technology: Tom's Hardware Guide

All USB 2.0 hubs have at least one built-in transaction translator (TT) so that they can be downwards compatible. The TT automatically recognizes which USB category is connected on a particular port and translates any USB 1.1 signals to USB 2.0. It is a good idea to usie higher-quality USB hubs that have as many TTs as they do ports. No longer do the devices on the hub have to wait their turn for some free bandwidth; the TTs optimally embed all the separate data streams in the USB 2.0 data stream. According to the article LinXcel's multi-TT hub shines!