15 April 2010

What Is a USB Port?

Overview of USB Ports:
A USB port is a standard cable connection interface on personal computers and consumer electronics. USB ports allow stand-alone electronic devices to be connected via cables to a computer (or to each other).
USB stands for Universal Serial Bus, an industry standard for short-distance digital data communications. USB allows data to be transferred between devices. USB ports can also supply electric power across the cable to devices without their own power source.
Both wired and wireless versions of the USB standard exist, although only the wired version involves USB ports and cables.
What Can You Plug Into a USB Port?:
Many types of consumer electronics support USB interfaces. These types of equipment are most commonly used for computer networking:
  • USB network adapters
  • USB broadband and cellular modems for Internet access
  • USB printers to be shared on a home network

For computer-to-computer file transfers without a network, USB keys are also sometimes used to copy files between devices.
Multiple USB devices can also be connected to each other using a USB hub. A USB hub plugs into one USB port and contains additional ports for other devices to connect subsequently.
Usage Model:
Connect two devices directly with one USB cable by plugging each end into a USB port. If using a USB hub, plug a separate cable into each device and connect them to the hub individually.
You may plug cables into a USB port at any time regardless of whether the devices involved are powered on or off. However, do not remove cables from a USB port arbitrarily, as this can lose or corrupt data. Follow instructions provided with your equipment before unplugging USB cables.
Many PCs feature more than one USB port, but do not plug both ends of a cable into the same device, as this can cause electrical damage.
USB-B and Other Types of Ports:
A few different types of physical layouts exist for USB ports. The standard layout for computers, called USB-B, is a rectangular connection point approximately 1.4 cm (9/16 in) length by 0.65 cm (1/4 in) height.
Printers and some other devices may use smaller types of USB ports including a standard called USB-A. To connect a device having USB-B ports to a device with another type, simply use the correct type of cable with appropriate interfaces on each end.
Versions of USB:
The USB industry standard exists in multiple versions including 1.1, 2.0 and 3.0. However, USB ports feature identical physical layouts no matter the version of USB supported.
Alternative Technologies:
USB ports are an alternative to the serial and parallel ports available on older PCs. USB ports support much faster (often 100x or greater) data transfers than serial or parallel.
For computer networking, Ethernet ports are sometimes used instead of USB. For some types of computer peripherals, FIreWire ports are also sometimes available. Both Ethernet and FireWire can offer faster performance than USB, although these interfaces do not supply any power across the wire.
source : About.com

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