USB 3.0: Everything You Need to Know
Within the past 14 years, the Universal Serial Bus (USB) has become the standard interface to connect devices to a computer. Whether it’s an external hard drive, a camera, the mouse, a printer, or a scanner, the physical connection to transfer data between devices generally is a USB cable. The interface is indeed universal.
USB technology has been under development since 1993. The first official definition, USB 1.0, was introduced in 1996. It provides a Low-Speed transfer rate of 1.5 Mbps for sub-channel keyboards and mice, and a Full-Speed channel at 12 Mbps. USB 2.0, which came in 2001, made a leap to Hi-Speed transfer rates of up to 480 Mbps. In 2010, USB 3.0 has finally hit the market.
So what can you expect from USB 3.0 and how will it affect you?
USB 3.0 Specifications
A number of changes have been implemented in USB 3.0 to satisfy the increased demands of external devices. Here is a quick USB technology overview:
- Transfer Rate
This new SuperSpeed interface provides realistic transfer rates of around 3,200 Mbps or 3.2 Gbps. The theoretical top signaling rate is at 4.8 Gbps.
- Data Transfer
USB 3.0 introduces full duplex data transfer. Two of five lanes are reserved for transmitting data, while another pair is dedicated to receiving data, meaning that USB 3.0 can read and write data simultaneously at full speed. Previous USB specifications did not support bi-directional data transfer.
The unit load has been increased to 150 mA and a configured device can draw up to six unit loads, which adds up to 900 mA. This exceeds USB 2.0 by 80% and leads to faster recharging or powering of more than four devices from a single hub. In addition, the minimum device operating voltage was dropped from 4.4 V to 4 V, which saves energy.
- Power Management
USB 3.0 suspends device polling, which is replaced by interrupt-driven protocol. As a result, idle devices won’t experience a power drain since a signal from the device is required to initiate data transfer. With USB 2.0 the host controller used to look for active transfers, slowly draining power. Briefly, USB 3.0 supports idle, sleep, and suspend states, as well as link-, device-, and function-level power management (Wikipedia).
- Physical Appearance
The above described specifications are also represented in the physical appearance of USB 3.0. While the cable was previously described to be thicker because it contains four more wires than USB 2.0, this appears not to be the case now. The plug, however, is a dead giveaway for USB 3.0. It contains an additional set of connectors, as illustrated in the image below.
The Good News
New technology is very exciting. But what does it mean? Will you still be able to use your old USB hardware? How will the new USB technology affect your everyday life? What are the benefits?
USB 3.0 is backwards compatible with USB 2.0. So whether you get a new USB 3.0 device or a new computer that supports USB 3.0, your old device will be able to communicate with the new interface. Naturally, it will do so at the old USB 2.0 speed. However, you won’t be able to use a USB 3.0 cable to connect a USB 2.0 device.
- Transfer Rate
Now I bet all this Megabit and Gigabit per second numbers sound impressive, but what does it actually translate to? Well, let me give you an example. With USB 3.0 you could transfer a 10 GB file from your computer to an external drive in approximately 25 seconds. With USB 2.0 this would take more than five minutes.
The devices that will benefit most from USB 3.0 are those that already outspeed USB 2.0, including HD webcams, Blu-Ray drives, or some external hard drives.
- Support by Operating Systems
Windows Vista, Windows 7, and Linux already support USB 3.0. Mac is expected follow. Given its age, Windows XP will probably not receive an update to support the new interface.
The Bad News
I was tempted to report that there is no bad news, but that’s not true. Let’s say bad news is minimal.
The maximum cable length USB 3.0 supports is reduced to approximately three meters, opposed to five meters with USB 2.0. However, using hubs, the maximum length can be extended to 18 meters.
- Speed Limit
Naturally, not all devices will be able to make use of the increased speed in USB 3.0. Magnetic hard drives for example, are limited by their RPM and the corresponding read/write speed. Hence, USB 3.0 will not unfold its full beauty until computers are equipped per default with faster hardware, such as solid state drives. But we all know how speedy progress is in the IT world. Give it a year or two and you will be able to fully benefit from USB 3.0.
Feel like you need more information? Computerworld has an excellent USB 3.0 review (USB 3.0: The new speed limit), including tests of currently available USB 3.0 hardware. Are you craving for even more in depth information? Check out this article at Tech Republic: 10 things you should know about USB 2.0 and 3.0. And have a look at Everything USB’s Super Speed USB 3.0 FAQ.
Now aren’t you looking forward to switching to USB 3.0? And if you have already been using a USB 3.0 device, please let the rest of us know how it feels!