Universal Serial Bus(USB)

USB-

          Universal  Serial Bus

The Universal Serial Bus is the newer hardware interface standard that support low-speed device such as Keyboard mice and scanners as well as higher speed devices such as digital cameras.USB which is a serial interface provides data transfer speeds of up to 12 Mbps for faster device and 1.5 Mbps sub channel speed for lower speed device A newer version of the USB standard USB 2.0 supports up to 480 Mbps for data transfer speeds

How USB Works:-

          When a USB device is plugged into a USB port the host or the hub detects a change in the voltage on the interface .the host asks the new device to identify itself a process USB calls enumeration .The device replies with its types  its manufacture what it does and the amount of bandwidth it requires. The device is given an address code that identifies it uniquely from any other USB devices already on the bus. Each USB device attached to the bus even two of the exact same device gets a unique address ID so it can be referenced and addressed by the host.

                            

Feature of USB:-

          -The flexibility of Plug -and -Play device

-Standard connectors and cables with a wide verity of devices available including keyboard mice floppy drives hard disk drive. Zip code and Sass drives printer scanner, digital camera modem and hubs. Automatic configuration of devices when they are connected

          -How swapping USB devices can be connected and disconnected

          -The capability to support up to 127 devices on one channel