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CoolTechStuff: USB-?

Larry Mortimer, AIA lmort@kmort.com

Confused about USB (Universal Serial Bus) connectors and standards?  Here’s an explanation of the various USB connectors, standards and their capabilities. 

USB Connectors/Ports: Currently there are five basic types of physical USB connectors/ports (see Image 1).  USB-A, USB-B, USB Mini, USB Micro and the latest one USB-C.  The original USB connectors were the A and B plugs and receptacles.  The B connector was designed to prevent users from connecting one computer receptacle to another and accidentally creating a loop.  You will often see a cable with an A on one end and a B on the other used for printers. The Mini plugs and receptacles were added in April 2000 for smaller devices such as digital cameras, smartphones and tablets.  Micro-connectors came in January 2007 to accommodate integration into even smaller devices.  To further confuse things, the Mini and Micro connectors each have an A and B version and the Micro has an AB version.  The C connector came into use in 2014, and is a small reversible connector meant to replace the A and B connectors.

Adaptors can be used to connect one type of connector to another, and a hub can be used to increase the number of available ports.

USB Release Standards: Currently there are five major versions of the USB standards (protocols), USB 1.0, USB 1.1, USB 2.0, USB 3.0 and USB 3.1.  Each version has a different ability to communicate data and transfer power between computers and other devices (see Image 2).   All connectors/ports will not work with all standards (see Image 3).

Conclusion:  Although somewhat confusing, the USB protocol provides
a universal system to power our devices and allow them to communicate with each other.  The speed you experience will only be as fast as the slowest element in your system.  For example, a USB 2.0 device communicating with a USB 3.0 computer will only transfer data at 480 Mbit/s.  For that reason always purchase devices that use USB 3.0 or greater.

There is one last thing for Macintosh users.  In the last few years Macintosh computers have had both USB and Thunderbolt ports.  Thunderbolt (also known as Lighting) is a competing standard co-developed by Intel and Apple, but mainly used by Apple on Macs and iPhones.  Recent Macintoshes can accommodate either USB or Thunderbolt 3 standards by using USB-C connectors for both.  Rumors have it that Apple will ditch the Thunderbolt port on the upcoming iPhone 8 in favor of a USB-C port, and since some Android phones already use USB-C ports, USB will most likely be the winning standard (at least until the next standard comes along).

For More Information Than You Probably Want to Know Go To: en.wikipedia.org/wiki/USB

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