An In Depth Look at Intelís Thunderbolt Technology

Author: SKYMTL
Date: February 24, 2011
Product Name: Intel Thunderbolt High Speed I/O
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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 isnít 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 architectureís 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 isnít. This means companies who wish to implement Intelís new technology will incur the cost of a controller chip and any potential royalties associated with it. Hopefully, the resulting price increases wonít be overly dramatic.

From a high level architectural standpoint, the Thunderbolt controller chip is installed in parallel with a motherboardís 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 wonít 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 motherboardís 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 wouldnít 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 laymanís 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?

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