USB Hubs
Recently, we've been getting calls about some of our more popular USB hubs with questions regarding their backwards compatibility with older USB products. In case you didn't know, the whole older/newer question has to do with the newer USB 2.0 and the older USB 1.1 formats. The biggest difference between the two are their differences in bandwidth (how fast they can transmit data); USB 2.0 is capable of transmitting data at 480 megabits per second (Mb/s), while USB 1.1 is only capable of 12 Mb/s.
The problem is, when using a USB 2.0 hub with USB 1.1 devices, the older devices need what's called a transaction translator (TT) in order to communicate correctly. This is where we see difference in the capabilities of USB hubs. Let's say you have a hub that splits the USB port on you computer (host) into four USB ports, but it only has one TT. If you connect more than one USB 1.1 device, only one device will be able to communicate with the host computer at a time. If another USB 1.1 device is trying to communicate with the host, it will have to wait until the first USB 1.1 device is done communicating. This problem does not occur with USB 2.0 devices, because they do not need to go through the TT to communicate with the host, and skip this step altogether. Some USB hubs have multiple-TT's to get around this problem, though. A great explanation of this whole procedure can be found here. Check out the cool hubs we carry here and look for a review of all of them coming soon!
Sources: Tom's Hardware
