Have you spent too much time waiting for large files
to crawl between a computer and an external hard drive? Don't fret -- USB 3.0 has arrived. Not only can it move data faster
and provide more power, but it's compatible with USB 2.0 devices.
Developed by the USB Implementers Forum-(USB-IF), USB 3.0's SuperSpeed specification promises a theoretical top speed of 5Gbit/sec. versus USB 2.0's 480Mbit/sec.
The key to blending
old and new is NEC's μPD720200
controller chip. It has
the circuitry for USB 2.0 and 3.0 transfers inside and can use either, depending on what's plugged in. Right now, it's the
only game in town, but look for other companies, including Symwave, Fujitsu-and Via, to introduce their own USB 3.0 chips in the coming months.
The first round of USB 3.0 cards and
devices works with Windows Vista and Windows 7; Apple hasn't decided whether to support the new standard. The basic
software for USB 3.0 has been in the Linux kernel since
last fall, and the needed drivers are slowly coming out.
USB
3.0: The new speed limit
Introduction
What's
new in USB 3.0?
How
we tested
Buffalo
DriveStation
Seagate
BlackArmor PS 110
StarTech
SuperSpeed Docking Station
Lenovo ThinkPad W510
Conclusions
USB
3.0 Performance Chart
There are
already a few USB 3.0 devices available. To test them, I used a Lenovo ThinkPad W510 with USB 3.0 built in. I tried out a variety of new devices, including the Buffalo DriveStation USB 3.0 HD-HXU3 external hard drive; a StarTech SuperSpeed USB 3.0 to SATA Hard Drive Docking Station-in combination with my current Western
Digital WD Caviar Blue external drive; and a Seagate BlackArmor PS 110 USB 3.0 Performance
Kit, a portable hard drive
that includes its software on a USB 3.0 ExpressCard.
What's new in USB 3.0?
Unlike the change from USB 1.0 to USB 2.0, USB 3.0 brings
actual physical differences to the connectors. The flat USB Type A plug (that goes into the computer) looks the same, but
inside is an extra set of connectors; the edge of the plug is colored blue to indicate that it's USB 3.0.
On the other end of the cable, the Type
B plug (that goes into the USB device) actually looks different -- it has an extra set of connectors, so it looks a bit like
a USB plug that's been crimped a little ways down one end. There's also a new Micro Type B plug that has all its connectors
laid out horizontally.
The USB 3.0 plug has an extra set of connectors.
As a result, you
won't be able to fit a USB 3.0 cable into a USB 2.0 device. However, you will be able to plug USB 3.0 devices -- and cables
-- into your current computer; you just won't get the speed advantage. (Note: To get the most out of USB 3.0, the cable needs
to be less than about 9 feet long, down from the USB 2.0 16-foot limit.)
The reason for the new connector is that the USB 3.0
cable contains nine wires (four more than a USB 2.0 cable); eight carry data and one is used as a ground. Despite the increase
in wires, however, the cables should be no thicker than those used by USB 2.0. There will be a big difference in performance,
however. USB 2.0 is like a single-lane country road that needs to handle the morning-commute traffic in and out of L.A. There
are jams and slowdowns when too much data is going back and forth. With nine wires available, USB 3.0 has an additional two
lanes of traffic in each direction to smooth the flow between the computer and the device.
Unlike USB 2.0, which requires synchronous
transfers, where the data is asked for and then sent, the 3.0 host controller doesn't have to poll the USB device every time
it wants to send data. This streamlines the flow with high-speed asynchronous transfers.