Feeds

Inside USB 3.0

What makes SuperSpeed tick

Build a business case: developing custom apps

Adaptive equalisation also helps the host cope with controlling one set of USB 3.0 ports nearby at the front of a PC and with those mounted on the backplane, much further away and so connected over a greater length of wire.

USB 3.0 SuperSpeed

The wire: what links one USB 3.0 device to another

SuperSpeed USB will be the first interconnect to use this kind of technology. Even HDMI, which can transfer data at up to 3.4Gb/s, doesn't rely on it. HDMI is the closest high-speed data transfer system to USB 3.0 in that connections likewise run over cables whose quality and length the standard has no control over.

Compare that to buses like Sata and PCI Express 2.0 - on which USB 3.0 is largely based - where the lane lengths, while not set in stone, can be assumed to be very short with well-defined signal attenuation characteristics.

The USB 1.1 and USB 2.0 specifications defined maximum cable lengths of 3m and 5m, respectively. USB 3.0 knocks the maximum back down to 3m.

USB 3.0 - Cable Profile

Inside a USB 3.0 cable

That said, since USB 3.0 is backward compatible with 2.0, connecting your current thin-wired mouse to a USB 3.0 port isn't going to be a problem. Indeed, as you'll see from the picture above, the USB 3.0 cable contains a separate USB 1.1/2.0 Unshielded Twisted Pair (UTP) cord - more on this crucial component later.

And the mouse's USB connector will still work too, mechanically and electrically. The basic USB 3.0 'Standard A' connector looks like today's big USB plugs - it's just longer, to accommodate five extra, rear-mounted pins which will mate up correctly in a standard USB 3.0 socket. Insert a USB 2.0 port instead, and the device will still work, just at the 'old' 480Mb/s speed.

Bus Architecture

SuperSpeed's Standard A port pair

Those extra pins provide a second ground connection, plus two pairs of lines, one for sending data the other for receiving it. Having separate wires for transmission and for reception means USB 3.0 links can be used to read and write data simultaneously - 'dual simplex' signalling, in the jargon, compared to USB 2.0's 'half duplex' operation. Previous versions of USB had two data wires, but they could only operate as uplinks or downlinks at any given time, not both.

Build a business case: developing custom apps

More from The Register

next story
iPad? More like iFAD: We reveal why Apple fell into IBM's arms
But never fear fanbois, you're still lapping up iPhones, Macs
Sonos AXES support for Apple's iOS4 and 5
Want to use your iThing? You can't - it's too old
You didn't get the MeMO? Asus Pad 7 Android tab is ... not bad
Really, er, stands out among cheapie 7-inchers
Apple winks at parents: C'mon, get your kid a tweaked Macbook Pro
Cheapest models given new processors, more RAM
4K video on terrestrial TV? Not if the WRC shares frequencies to mobiles
Have your say with Ofcom now, before Freeview becomes Feeview
Leaked Windows Phone 8.1 Update specs tease details of Nokia's next mobes
New screen sizes, dual SIMs, voice over LTE, and more
Microsoft stands on shore as tablet-laden boat sails away
Brit buyers still not falling for Windows' charms
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Backing up Big Data
Solving backup challenges and “protect everything from everywhere,” as we move into the era of big data management and the adoption of BYOD.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.