powered vs. powered hubs?
One important feature of USB is that the cables distribute power as well as data. This means that devices that use modest amounts of power don’t need separate power supplies. So few big power cubes at your wall outlet and fewer cords running across your desk. Still, the amount of power distributed over USB is limited. A unpowered (or self-powered) hub uses some of the power coming to it for it’s own operation, and passes the remainder along to devices plugged into it. This is OK for small hubs with low power devices plugged into it. A good example is this is a keyboard with an powered hub built-in. This has plenty of power for plugging in a mouse or track pad. Powered hubs have their own power supplies and can supply full power to all the devices that can physically plugged into them. Of course, you do have an extra wire and power block plugged into the wall. Some hubs can operate either way. If they don’t have their power supply plugged-in, they operate as an unpowered hub – with a li
