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Why USB 3.0?
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tomram486
Posted 2/4/2011 18:42 (#1593251 - in reply to #1592123)
Subject: Re: Why USB 3.0?


USB is next generation. This is for the transfer of larger files, say like moving 900 GB from one drive to another. I can't to see these ports on cheap computers. Remember always better and faster and cheaper.

Here are two questions/answers. Link for entire article: http://www.everythingusb.com/superspeed-usb.html

1. How does USB 3.0 achieve the extra performance?

USB 3.0 achieves the much higher performance by way of a number of technical changes. Perhaps the most obvious change is an additional physical bus that is added in parallel with the existing USB 2.0 bus. This means that where USB 2.0 previously had 4 wires (power, ground, and a pair for differential data), USB 3.0 adds 4 more for two pairs of differential signals (receive and transmit) for a combined total of 8 connections in the connectors and cabling. These extra two pairs were necessary to support the SuperSpeed USB target bandwidth requirements, because the two wire differential signals of USB 2.0 were not enough.

Furthermore, the signaling method, while still host-directed, is now asynchronous instead of polling. USB 3.0 utilizes a bi-directional data interface rather than USB 2.0's half-duplex arrangement, where data can only flow in one direction at a time. Without getting into any more technical mumbo jumbo, this all combines to give a ten-fold increase in theoretical bandwidth, and a welcome improvement noticeable by anyone when SuperSpeed USB products hit the market.


2. Isn't USB 2.0 fast enough?

Well, yes and no. USB 2.0 for many applications provides sufficient bandwidth for a variety of devices and hubs to be connected to one host computer. However, with today's ever increasing demands placed on data transfers with high-definition video content, terrabyte storage devices, high megapixel count digital cameras, and multi-gigabyte mobile phones and portable media players, 480Mbps is not really fast anymore. Furthermore, no USB 2.0 connection could ever come close to the 480Mbps theoretical maximum throughput, making data transfer at around 320 Mbps - the actual real-world maximum. Similarly, USB 3.0 connections will never achieve 4.8Gbps, but even 50% of that in practice is almost a 10x improvement over USB 2.0.

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