Understanding USB
Confused about USB? It's understandable. Inconsistent terminology and some general misconceptions surrounding USB specifications are creating confusion in the marketplace. Just try and do a side-by-side comparison of USB products. It seems like everywhere you turn there's different USB jargon being used to describe the same specifications. It's downright frustrating. You'll find products described as USB compatible, USB 2.0, Hi-Speed USB, Full-Speed USB, USB 1.1, and just plain USB. So what do they all mean, and how do you know you're getting the product that makes the best sense for you?
Understanding the naming conventions
A fundamental problem with deciphering USB lies in the fast-and-loose way folks are using USB nomenclature. Putting it bluntly, many of the ways USB is being thrown around as product descriptions are just plain wrong. So we went straight to the source to set the record straight. Here are the proper uses of USB terminology, straight from the proverbial horse's mouth,
www.usb.org:
USB 2.0, Hi-Speed USB, and USB.
USB 2.0 is the most recent revision of USB specifications. It represents the evolution of USB from its introduction years ago from USB 1.0 (1.5Mbps, now often referred to as low-speed USB) to USB 1.1 (12Mbps, often referred to as full-speed USB) to the Hi-Speed USB of today, which is the most advanced evolution, with a data transfer rate of 480Mbps, up to 40 times faster than previous versions of USB.
So, to clarify, USB 2.0 encompasses all three target speeds of USB (480Mbps, 12Mbps, and 1.5Mbps). What this boils down to is that USB 2.0 is backward compatible with previous revisions of USB. You can use a USB device or peripheral in a USB 2.0 port, but your device will not run any faster than it was designed to. So use caution when you see a product described as USB 2.0 Full Speed, Full Speed USB, or USB 2.0, for example. As you can see, this terminology can be misleading to a consumer whose expectation is that a USB 2.0 product is, by definition, high speed.
Hi-Speed USB refers only to the 480Mbps portion of the USB 2.0 specification and the only correct usage of it is "Hi-Speed USB." As stated earlier, Hi-Speed USB can potentially achieve speeds up to 40X faster than USB. Hi-Speed USB is fully compatible with original USB.
USB refers only to the 12Mbps and the 1.5Mbps portions of the USB 2.0 specification. These portions, often referred to as full- and low-speed respectively, or USB 1.1 and USB 1.0 respectively, should today be referred to simply as "USB." USB is
compatible with the USB 2.0 specification, meaning it works with USB and Hi-Speed USB systems, cables, devices and peripherals, not that it runs at those higher speeds.
Understanding USB speeds
Ironically, the speeds associated with USB (480 Mbps, 12 Mbps, and 1.5 Mbps), refer to the theoretical maximum speed of the USB interface on a USB device or USB port and really have nothing to do with the device itself. The actual speed a USB-compliant device achieves is not necessarily the speed of the USB specification reflected in the product descriptions and marketing materials. Real performance of any given product is dependent upon how fast that product can run. The device can only achieve the theoretical speeds if it can keep up with the USB data transfer rate.
USB is good!
In spite of the potential for confusion, once you understand USB, it's easy to see how convenient it can make your life. It's an instant way to connect printers, scanners, digital cameras, PDAs, MP3 players — any USB-enabled device to your computer. And as more and more USB devices find their way to the marketplace, the more you need to know, so you can make choices that make sense. Because in today's ever-changing world of technology, knowledge is Crucial!
For more detailed information about USB, go to
www.usb.org