Tech Talk 7-24-10

The Universal Serial Bus is very common today. Most desktop computers come with a few USB ports on the front with more on the back. The USB standard is now in its third version and firmly entrenched as a widely-used connection technology.

A seven-member consortium pioneered the USB concept in 1994. The group collectively made the decision to present the technology as open so any company could freely design USB products. Similar to the way IBM personal computers took off after IBM opened the technologies to others, USB technology took off and quickly gained widespread use.

The original design goal was to create a common physical port on the computer to act as an interface between the computer and a device. With a common port the designers envisioned the idea that adapter cards would no longer be needed. Another goal was to allow the port to accept hot-pluggable devices that could be simply plugged and unplugged from a running computer.

A USB cable carries both power and signals for a device. The flat and wide end that plugs into the computer is called the A-male connector; the end that plugs into a device is called the B-male or mini-B connector. The original implementation of USB transferred data at either 1.5 or 12 Mbps. The second version, referred to as Hi-Speed USB, transfers data at up to 480Mbps, which is about 40 times faster than the original version. The third and latest version of USB is called SuperSpeed USB. With USB III, data transfer speeds up to 3.2 Gbps are now achievable.

While faster speeds are good, I think a great feature of USB has been keeping the technology backward compatible. USB III ports are designed to be fast but still able to support older USB I and II devices.

Ron Poland is a professor in the Computer Information Systems AAS program at Clinton Community College. Poland is certified in computer repair and networking by the Computer Technology Industry Association (CompTIA). He is also a Cisco certified network assistant. Questions may be sent to him via e-mail at ron@ronpoland.com.

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