Packets are held by each hub - now more like network routers than port duplicators - using a store-and-forward methodology which allows links to be deactivated when they're not in use. Links are deactivated by the device at the end of them if it's informed that no packets are pending. So devices which aren't involved in passing data can power down. USB 3.0 uses low-frequency pulses to allow one device to tell another that it needs to wake up.
NEC's µPD720200 USB 3.0 controller: first of many?
Devices may power down entirely, but USB 3.0 also allows them to switch themselves off bit by bit, powering down portions of their circuitry that are not in use. It's called a "function-level suspend" in the jargon.
USB 3.0 may not broadcast packets, but it does gain the ability to stream data. Built on the SuperSpeed equivalent of the existing bulk data transfer mode, streaming makes it easier for, say, a user to play a movie on a USB 3.0 device connected to his or her computer. Right now, that's done by essentially copying chunks of the file across the link. That's because the USB Mass Storage device class was originally designed with file stores in mind from which files would be copied back and forth rather than read directly.
Streaming addresses that by extending USB 3.0's Mass Storage technology to make it operate connected drives operate more like the host PC's own storage, eliminating or reducing the performance bottlenecks imposed by the current Mass Storage class. Making the data easier to get makes for a more efficient system that's less taxing to the hardware resources available.
Devices that draw their power from the bus now have access to current of at least 150mA - the "unit load" - with some 'configured' devices - ones that announce they're high-power peripherals - able to draw 900mA, 80 per cent than they could under USB 2.0.
That just leaves operating system support. Microsoft is keen on USB 3.0, an SuperSpeed will certainly be supported by Windows 7, though you may have to wait for Service Pack 1 for it. Support for Vista in due course is possible, but we suspect the drive to 7 will negate the need for it.
We can't see XP getting USB 3.0 code. By the time USB 3.0 ports are to be found in netbooks, they'll be running Windows 7 anyway.
Work is already under way to add USB 3.0 support to Linux, but it's the nature of the open source OS that this is likely to remain experimental for some time. The USB 3.0 spec is available, but Intel's reference design for USB 3.0 Host Controllers isn't, at least not without signing and NDA. That will change soon, we think, and work will progress, but it's going to take some time to adapt all the USB class drivers to tune them for USB 3.0.
Most of the way there: the SuperSpeed roadmap
As for Apple, it hasn't addressed the matter, but we'd say it's working on the technology, given its keenness on the Universal Serial Bus and general desire to be seen to be adopting technologies like this ahead of the curve.
But whichever OS you prefer, USB 3.0 is likely to take a while to bed down. Features may be initially absent, and devices may emerge that require code tweaks to be fully supported. We saw this in the early days of USB and we'll likely see it again. ®
Inside USB 3.0
@ Simon Ward & unexpected Bill
They should follow unreal tournaments announcements
I think it should go Monster Speed followed by Godlike
By the time USB 3.0 ports are to be found in netbooks, they'll be running Windows 7 anyway -NOT!
Windows 7 will not run on Netbooks - MS say Netbooks dont exist - especially the really fast ones running arm chips!
Whatever it is trying to be I'm fairly sure wireless is a much more sensible way to go - nothing new to do there - I don't want cables FULL STOP.
@Eddy Ito: connector standards
I think the reason for the backwards compatible connector is not for devices but for hosts.
Suppose USB3 has different connectors and suppose you are an OEM designing a netbook. There is only room for three ports. What combination do you choose? On one end of the spectrum will be power users who want to plug in loads of USB3 devices, and have hubs and adapters for any legacy USB2 devices, at the other end is the road warrior who has left his USB2 to 3 adapters at home and wants to plug in a USB2 mouse, thumb drive and printer.
With backward compatible connectors you don't have that dilemma. All the ports can be USB3 compatible (if the chipset allows it) and everyone is happy.
Regarding "What are they going to call USB4.0? 'Ludicrous Speed'?"
How about "On Speed"?
The only thing I want.
Is for a return to the original ethos of plug-and-play (and-unplug) and not what we have at the moment of plug-and-play then arse-about-stopping-the-device-waiting-a-bit-for-Windows-to-do-it's-thing-and-tell-you-it's-stopped-and-THEN-unplug.
It's not a lot to ask is it?