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An In Depth Look at Intel’s Thunderbolt Technology

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SKYMTL

HardwareCanuck Review Editor
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As the computing market matures, digital distribution is quickly replacing the need for physical media and the need for quick access to these large networked files is becoming paramount. Most people these days just don’t have the time to wait around while a movie transfers from one device to another.

Another issue is that the sheer number of different connectors on modern PCs can quickly devolve into a confusing mess for many consumers. USB 2.0, USB 3.0, SATA, eSATA, Firewire, HDMI, DVI, Displayport and the list goes on. For file transfer alone there are numerous protocols, each of which supports different data transfer rates

Years ago Intel began developing what they hoped would become a standardized I/O technology which could replace a large number of these connector and cable formats while offering optimal performance for a media-hungry market. Their efforts ended up centering on a format dubbed Light Peak which used an optical connection to push bandwidth to unheard-of speeds.

Light Peak technology was first announced and demonstrated to the public in 2009 and has been gradually fine tuned on a number of fronts. Connectors have finally been chosen, file transfer protocols were decided upon and partners came on board. The end result is simply called Thunderbolt.

Thunderbolt will first be seen on Apple’s new line of MacBook Pro laptops where it will reside next to legacy USB ports and take will form of a mini DisplayPort connector. Announcements on the PC side of the fence likely won’t be making the rounds for a little while as OEMs and component manufacturers digest the technology and its associated costs. However, we do expect to see several devices supporting Thunderbolt to be introduced and available starting in Q2 2011.

It should be obvious by now that with Intel and Apple behind this technology, Thunderbolt should soon become a popular I/O format. This is why we are dedicating a quick article to explore its ins and outs of in a bit more detail.

 

SKYMTL

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Technology and Implementation

Technology and Implementation


For the time being, Thunderbolt will likely be used as a quick and easy way to connect to external storage devices but it also has the ability to run audio and HD video signals through its structure. The parallel compatibility for storage and display / audio standards is achieved by concurrently supporting both PCI Express and DisplayPort connection protocols. As we will see a bit later, both data and display signals can be sent and received at the same time through dual 10 Gbps channels.

One of the most important aspects of Thunderbolt is the fact that it isn’t considered a new protocol in any way, shape or form. In simple terms, it has been implemented as a blanket-type cover to allow existing protocols such as USB, SATA, DVI and DisplayPort to all operate under the same roof. This means it can pass signals for any of these standards over a single interface provided there is enough bandwidth on tap.


Since the current Sandy Bridge architecture’s Cougar Point PCH lacks native support for Thunderbolt compatibility, Intel has instituted a standalone host-side controller chip for its I/O operations. This approach may seem a bit ad-hoc at first glance but it allows for additional versatility and should allow manufacturers to easily implement add-in solutions for existing products.

We should also mention that while USB is an open format, Thunderbolt isn’t. This means companies who wish to implement Intel’s new technology will incur the cost of a controller chip and any potential royalties associated with it. Hopefully, the resulting price increases won’t be overly dramatic.


From a high level architectural standpoint, the Thunderbolt controller chip is installed in parallel with a motherboard’s chipset and will benefit from an x4 PCI-E 2.0 link with the PCH. In effect, this gives the controller a wide open 2 GB/s connection for data pass-through.

When video signals are processed through a dedicated GPU, HD content will be treated separately and won’t eat up any bandwidth between the controller and the PCH. This can be done since Intel has the option to output video signals from a stand-alone graphics card through the motherboard’s own display outputs (or in this case Thunderbolt) if necessary. If the on-die GPU is used, signals are once again passed through the PCH which will of course eat into the 2 GB/s of available bandwidth.

Think of this controller as a traffic cop that directs data towards the necessary pathways in order to speed up in-system communications.


Since Thunderbolt has the capability to both send and receive information, it was necessary to ensure that bottlenecks wouldn’t happen anywhere along the pipeline. To improve bandwidth transmission, Intel has implemented two duplex channels into the architecture and each channel provides full bi-directional performance. In layman’s terms this means the full 10 Gbps of bandwidth is available in both upstream and downstream directions while not being shared between multiple Thunderbolt ports.

With both PCI Express and DisplayPort standards being used, anything from monitors to external RAID arrays can be attached with the same type of cable.

There is however one small hitch to this whole setup. In order to support Thunderbolt, any device connected MUST have a proprietary controller chip built into its design. Could this lead to some companies being left out in the cold? More importantly, how will a proprietary controller affect the possibility of honest and fair competition?
 

SKYMTL

HardwareCanuck Review Editor
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Thunderbolt's Endless Possibilities

Thunderbolt's Endless Possibilities


Intel has designed Thunderbolt as a way to simplify things in a market that is highly fragmented as numerous protocols all vie for the limelight. They have also worked on expanding upon nearly every aspect of current connector and cable technology. From connectivity to performance to ease of use, what we have here could be considered a melting pot of things consumers have been asking for.


Instead of designing a one-off connector to go along with their proprietary technology, Intel has decided to use a standard mini DisplayPort format for their Thunderbolt devices.

It’s important to note that a Thunderbolt-certified cable is needed to transmit I/O data such as drive information to and from the controller. However, a standard DisplayPort cable can be used if the connector is only hooked up to a monitor or HDTV.


In terms of outright file transfer potential, there really isn’t a solution that comes close to the performance which Thunderbolt can achieve. Even the latest SATA 6G and USB 3.0 are simply left in Thunderbolt’s dust and to make matters every more interesting, Intel plans for speeds of up to 100 Gbps (12.5 GB/s) as this technology matures.

For the time being, both optical and copper connections are able to achieve the 10 Gbps speeds Intel has specified but the optical format will be able to transmit data over longer distances. Copper allows for support of bus-powered devices of up to 10W, has a maximum transmittal length of three meters and will be available immediately on any device supporting Thunderbolt.

According to our conversations with Intel, the optical version will be available later this year but naturally won’t feature any electrical current for powering external products.


Within the base specification for DisplayPort v1.2 there is a provision which allows for the daisy chaining of multiple displays onto one common interface. Intel has taken this to the next level by allowing for up to seven Thunderbolt-equipped devices to be strung together from a single port. Information packets can be transmitted alongside the HD audio and visual streams which DisplayPort natively handles.

The result (depending upon bandwidth requirements of course) can be a combination of up to two HD monitors and an additional five peripheral devices without having additional cable clutter coming from the back of your computer. Intel has also included other connection options such as hub-style star topologies and single cable tree layouts as well.

Since Thunderbolt is based off of a PCI-E protocol, several options can be created in order to offer a wide range of legacy support and additional compatibility. By using a PCI-E controller alongside Intel’s Thunderbolt controller, adaptors for almost anything from Firewire to USB to eSATA are a possibility.
 
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SKYMTL

HardwareCanuck Review Editor
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Montreal
Parting Thoughts

Parting Thoughts


Seeing a new technology bursting onto the market is always exciting. Intel seems to have developed Light Peak into something which could have a tangible impact upon the consumer market in the coming years but there are still a number of questions surrounding Thunderbolt. It’s will surely be implemented outside of Apple’s inner MacBook Pro circle sometime in the coming months but we’d love to see some additional products sporting Thunderbolt sooner rather than later.

The price points which supporting devices hit will be one of the determining factors to how quickly Thunderbolt achieves mass market acceptance but what we’re very concerned about is system builder integration. We have seen time and again that certain closed technologies like FireWire and Intel’s own WiDi have a much higher cost of implementation (through royalties and higher than expected controller costs) than most companies are willing to spend. As such, both faltered from the onset and more open yet less expensive technologies gained popularity. We honestly hope that type of situation isn’t repeated with Thunderbolt.


According to Intel, Thunderbolt will exist in parallel with USB 3.0 and will be complementary to it. From our understanding, this means Thunderbolt-supporting devices will offer more performance than their USB counterparts (which isn’t a stretch considering its projected transfer rate) but they will be saddled with a price premium as well.

We are still months away from seeing broad availability of Thunderbolt-supporting products and implementation on the PC front could be slow at first. From our understanding there could be some PCI-E add in cards available in the coming months (provided manufacturers can get around the need for a video signal) and Intel’s numerous hardware partners are hard at work on devices. Hopefully, we’ll see Thunderbolt make a splash in the market sooner rather than later.
 
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