Feeds

Inside USB 3.0

What makes SuperSpeed tick

Choosing a cloud hosting partner with confidence

Since USB 3.0 incorporates USB 2.0, plugging a USB 3.0 printer into a USB 2.0 port on your PC will still work, but without the benefits of the faster bus. The USB 2.0 add-on doesn't even need to know the computer it's connected is a SuperSpeed device, it'll just work as if the PC has USB 2.0. Existing drivers will continue to work.

Bus Architecture

USB 3.0's dual-bus architecture

SuperSpeed USB has a dual-bus architecture to allow hosts to run USB 3.0 right alongside USB 2.0 - hence that USB 2.0 cable tucked inside the USB 3.0 cord. But while hosts and hubs will be able to operate USB 2.0 and USB 3.0 buses simultaneously, plug-in peripherals will not.

So there'll be no combining both buses to get an aggregate bandwidth of 5.4Gb/s.

However, it does mean that a brand spanking new netbook with USB 3.0 ports but running Windows XP as its OS won't lose USB functionality, only the SuperSpeed operation.

Running the USB 3.0 part independently of the USB 2.0 bus is necessary because the new bus uses different protocols, though it retains USB 2.0's data transfer types and pipe model to make it easier for driver writers to make use of existing code. SuperSpeed transmits data in packets, as USB 2.0 does, but this time devices explicitly route packets from the source to the target. Compare that to USB 2.0, which simply broadcasts all packets to all connected devices whatever they may be and whether they're the intended recipient or not.

The new approach has a couple of key advantages. First, it means you'll be able to connect many more devices: up to 127 of them chained in up to five tiers of hubs, each of which can drive up to 15 ports. Secondly, it makes for a far more power-efficient bus.

Packets are sent asynchronously and assembled into files at the end of their journey. Links in the route-chain are used only when they're needed. There's no need for devices to continually poll the link for incoming data.

Send a file to a USB Flash drive, and the packets will move from device to device down the chain according to a direct route encoded into the packets' headers. Each step of the journey is initiated at a signal from the host, which knows where each packet is coming from and where it's going.

USB 3.0 SuperSpeed

Hubs are more like routers in USB 3.0

The host is always part of the chain, so a packet sent from a connected camera to a Flash drive is routed first to the host and then out to the storage gadget.

Remote control for virtualized desktops

More from The Register

next story
NOKIA - Not FINNished yet! BEHOLD the somewhat DULL MYSTERY DEVICE!
N1 mini-'slab to plop into crowded pond next year
The Nokia ENIGMA THING and its SECRET, TERRIBLE purpose
Finnish firm coyly exposes mystery product – and WE NO what it is
Heyyy! NICE e-bracelet you've got there ... SHAME if someone were to SUBPOENA it
Court pops open cans of worms and whup-ass in Fitbit case
SLURP! Flick your TONGUE around our LOLLIPOP – Google
Android 5 is coming – IF you're lucky enough to have the right gadget
Nokia's N1 fondleslab's HIDDEN BRILLIANCE: The 'Z Launcher'
Sugarcoating Android's Lollipop makes tab easier to swallow
Space Commanders rebel as Elite:Dangerous kills offline mode
Frontier cops an epic kicking in its own forums ahead of December revival
prev story

Whitepapers

Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Choosing a cloud hosting partner with confidence
Download Choosing a Cloud Hosting Provider with Confidence to learn more about cloud computing - the new opportunities and new security challenges.
New hybrid storage solutions
Tackling data challenges through emerging hybrid storage solutions that enable optimum database performance whilst managing costs and increasingly large data stores.