USB 1,1 is an external bus that supports rates of 12 data transfer of Mbps. A single port USB can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. The USB also supports to the Plug-and-Play installation and hot plugging.It began to be used in 1996, some manufacturers of computers began to include support for USB in its new machines. With the launching of iMac in 1998 the use of the USB extended. One hopes that it totally replaces the ports of series and parallels.