Universal Serial Bus (USB)
Universal
serial bus (USB) is an external peripheral bus standard designed to bring plug
and play capability for attaching peripherals externally to the PC. The bus
supports up to 127 devices simultaneously.
This Icon/ symbol is use to identify USB cables, connectors, hubs, peripherals.
USB conforms to Intel’s plug and play (PnP) specification, including “Hot” plugging, which means that devices can be plugged in dynamically without powering down or rebooting the system. Simply plug the device, and the USB controller in the PC detects the device and automatically allocates the required resources and drivers. USB supports following data transfer rate, depending on the amount of bus bandwidth a peripheral device requires.
§ 1.5 mega bits per second (Mbps) for devices, such as a mouse or keyboard, that do not required large amount of bandwidth.
§ 12 Mbps transfer rate for high-bandwidth devices such as modem, speakers, Scanners etc.
USB sends signals over simple four-wires the physically two series are specified for USB.
§ Series “A” connector is designed for devices in which the cable remains permanently attached, such as hubs, keyboard, and mice. The USB ports on most motherboards are normally a series “A” connector.
§ Series “B” connector are designed for devices that required data cable, such as printers, scanners, modems and telephones. The physical USB plugs are small and unlike a typical serial or parallel cable connector.
Note: Maximum cable length between two USB full-speed (12Mb/sec) devices is 5-Meters; while for lower speed (1.5Mbp/sec) devices are 3meters.
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| Types of USB Sockets Type A and Type B |
