How Does a USB Port Work?

By Jack Gerard

Universal Serial Bus

The Universal Serial Bus, better known as USB, is a method of connecting peripheral devices to a computer so the computer can make use of them. USB is considered to be superior to older methods of connection in a number of ways, including the ease of the connection itself and the speeds at which data can be transferred between the peripheral device and the computer. The use of USB devices and USB ports allows for easy "plug and play" functionality, with an operating system identifying the device as soon as it's plugged, in instead of requiring you to attach the device while the computer is turned off. USB ports have become one of the most common methods of connecting peripheral devices to a computer, with everything from keyboards and mice to printers and game controllers making use of USB.

USB 1.0, 1.1, 2.0 and 3.0

The first type of USB port, known as USB 1.0, was introduced in 1996. This port was able to achieve a maximum transfer speed of 12 megabytes per second, and was not received well by the public at large. Two years later, USB 1.1 made changes to the way in which computers handled USB data (though it still retained the same transfer speed), and became the first type of USB port to become popular with computer manufacturers and the public at large. In 2000, USB 2.0 was released to the market and met with an even greater level of acceptance, due at least in part to the greatly increased data-transfer speed of 480 megabytes per second. USB 3.0 specifications were released in 2008, providing a huge speed increase over USB 2.0 with speeds up to 4.8 gigabytes per second (though the widespread consumer release of USB 3.0 devices was announced to be pushed back to the second half of 2009). All USB devices are backwards compatible with any USB port, though they are only able to transfer at the maximum speed of the port's version.

Transferring Data Via USB

Inserting the plug of a USB device into a USB port causes the computer's operating system to immediately search for a profile of the device in its drivers; if it cannot find the appropriate driver, you will have to install it (though it will be a one-time installation, since the computer will be able to recognize the device next time it is attached). Once the computer has identified the device and loaded the appropriate driver, data is transferred back and forth between the computer and the device at the maximum rate allowed by both the device and the USB port it is plugged into. In addition to commands and keystrokes from controllers, mice and keyboards, data can be sent to printers via USB, and entire files can be transferred to and from hard drives, USB flash drives and other storage devices at those same speeds.