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Course 6: SuperSpeed USB 3.0

Chapter 1: Introduction/History

USB 3.0, also referred to as "SuperSpeed USB", is the latest and most advanced development of the Universal Serial Bus host adapter protocol to be promoted by the USB Implementers Forum (USB-IF)i. The new interface builds on the "universal" convenience offered by the USB standard, while delivering improved performance and data transfer speeds between USB 3.0-capable devices.

History of USB

Originally released in 19951, the initial USB 1.0 specification was a serial bus standard designed to provide a universal method of connecting computers to peripheral devices.

Unlike its serial and parallel predecessors, which used different connector types for different devices and often required users to install drivers and tweak device settings, the USB standard offered much simpler "plug and play" connectivity as well as the ability to "hot swap" devices without having to reboot the computer. USB 1.0 also eliminated the complicated installation procedures that were inherent to previous connection standards.

The first revision to the USB standard (USB 1.1) took place in 19982, at which time it gained broad consumer acceptance, partly due to the fact that popular operating systems such as Window® 95(SE) and Windows 98 offered USB support. At the time, USB offered theoreticalii data transfer rates ranging from 1.5 Mbps to 12 Mbps3, surpassing the existing bandwidth offered by standard serial (115 Kbps) and parallel (115 KBps) connections.

Universal Connectors

One of the distinct advantages of the USB interface was the standardized, easy-to-connect nature of the connectors.

The original USB standards (USB 1.0/1.1) as well as USB 2.0 used the same connector types: USB 'A', USB 'B', USB 'Micro' and USB 'Mini'. The following diagrams depict the various forms of USB connectors:

Figure 1: USB A-B cable

USB A to B Cable

Figure 2: USB A-Micro-B cable

USB A-Mini-B cable

Figure 3: USB A-Mini-B cable

USB A-Micro-B cable

USB 2.0

While common devices such as scanners, printers and PDAs (Personal Digital Assistants, also referred to as Palmtop computers in contemporary terms), could now be connected with greater ease, the range of devices that could be connected through USB expanded into different applications, such as external storage devices. Whereas the speed of USB 1.0/1.1 was sufficient for printers and scanners where performance speeds were dictated as much by mechanical operation as they were by throughput, the speed limitation of original USB standards made newer, more robust applications inefficient.

The need for improved data transfer speeds prompted the eventual release of the USB 2.0 (often referred to as "Hi-Speed USB") standard in April of 20004, which delivered 480 Mbps (theoretical burst rate) bandwidth – roughly 40x that of the original USB standard.

Based on the theoretical data transfer rate offered by the two standards, imagine transferring a 100MB5 file from an external hard drive enclosure to a computer:

  • Over a USB 1.0/1.1 connection: 100MB x 8 = 800Mb/12Mbps = 67 seconds
  • Over a USB 2.0 connection: 100MB x 8 = 800Mb/480Mbps = 1.7 seconds
1Seebach, P. (26 Apr 2005 , April 26). Standards and specs: the ins and outs of usb.
2Seebach, P. (26 Apr 2005 , April 26). Standards and specs: the ins and outs of usb.
3USB Definition. Pc magazine encyclopedia. Retrieved (2010, March 17) from http://www.pcmag.com/encyclopedia_term/0,2542,t=USB&i=53531,00.asp
4"Documents." USB.org. USB Implementers Forum, Inc., 27 April 2000. Web. 17 Mar 2010. http://www.usb.org/developers/docs/.
51 Megabyte (MB) = 8 Megabits (Mb). Thus, in this example, 100 MB = 800 Mb. The term Mbps refers to Megabits per second.

iThe USB Implementers Forum, Inc. is a non-profit corporation founded by the group of companies that developed the Universal Serial Bus specification, created to provide a support organization and forum for the advancement and adoption of Universal Serial Bus technology. StarTech.com is a member of the USB-IF.
iiTheoretical data transfer rates are for reference only, as an indication of the maximum data transfer rates under ideal operating conditions. During typical use, the actual transfer rate will be much less than in theory.

Next — Chapter 2: The Need for USB 3.0