| | | | Universal Serial Bus. Hardware interface that has become ubiquitous since it's introduction in the mix-1990s. USB software and drivers have been integrated into MS Windows operating systems from Windows 98 onwards. The USB interface was designed to allow for faster data transfer, Plug-and-Play operation and Hot-Swappable connection of peripheral devices to computers, as well as to help phase out older connections such as serial and parallel ports with their more fragile connector pins and the general requirement for adaptor cards or powering down the computer before connecting them. Many USB devices also operate without having to install specific drivers from the manufacturer. In addition, low-power devices are able to operate without the need for a separate power supply, drawing what they need through the USB connection. USB is a serial connection and can allow many devices to be linked together - indeed many devices now have their own built-in hubs to extend connectivity further. Up to 127 devices can be connected via a single USB port in theory. Modern PCs have a minimum of four USB ports at the back and also a number on the front panel to allow for easy access to connect devices such as digital cameras, card readers and PDAs. The first version of USB (1.0, 1.1) supports data transer rates of 1.5Mbps (Low Speed) and up to 12Mbps (Full Speed), while the much-improved USB 2.0 can operate at up to 480Mbps (Hi Speed). Not all devices can use the full bandwidth however and some fall back to the slower rate. Many input devices such as keyboards, mice etc still use the low speed 1.5Mbps. The USB connector itself has been specifically designed to be robust and to allow easy connection, with only moderate force needed to connect plug and socket and no screws or clips. | | | |
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