Image via WikipediaUSB, Universal Serial Bus. A USB port supports up to 127 periperal devices.
USB 1.1 supports 12-Mbps data transfer.
USB 2.0 supports transfer rates up to 480 Mbps.
Connecting a USB 2.0 device to a USB 1.1 port will slow the transfer rate to the level of a USB 1.1 device. It will also cause a number of problems and error messages.
Devices include printers, scanners, flash drives, external drives, digital cameras, PDAs, handheld devices, and PDA peripherals such as synchronization kits, charger kits, cradles, and adapter cradles.
If a USB device requires more power than a USB port can provide, it should be equipped with an AC/DC adapter and should draw power from a wall outlet.
If you have a USB 2.0 port, it is best to attach a printer to it instead of a parallel port. The USB port will be much faster.
A USB hub increases the number of USB ports on a computer. The hub plugs into the USB port on the computer, so the number of ports are actually minus one. For example, if you have a hub with four ports, there are actually three available.
There are bus-powered hubs and self-powered hubs. Self-powered hubs should be used for high-power devices such as cameras and external hard drives. Self-powered hubs draw power from an electrical outlet. Bus-powered hubs draw power from the USB bus. A keyboard and a mouse will work on a bus-powered hub. A low-powered device, such as a mouse or a keyboard, will work on a self-powered hub. However, high-powered devices will not work on a bus-powered hub. Bus-powered hubs power up to 100 MA per port, and self-powered hubs power up to 500 MA per port.
Error message: The Hub Doesn't Have Enough Power Available to Operate...