Technology Brief Interconnect Technology Key Features 10Gbps bi-directional, dual channel data transfer Data & Video on single cable with Dual-protocol (PCI Express and DisplayPort) Thunderbolt Technology Daisy chain up to six devices 1 The Fastest Connection to your PC Compatible with existing DisplayPort devices Low latency with highly accurate time synchronization Uses native PCIe and DisplayPort protocol Thunderbolt technology is a transformational high-speed, dual software drivers protocol I/O that provides unmatched performance over current Power over cable for bus-powered devices I/O technologies with 10Gbps bi-directional transfer speeds. It (electrical cables only) provides flexibility and simplicity by supporting both data (PCIe) and video (DisplayPort) on a single cable connection that can daisy-chain up to six devices. Thunderbolt technology enables flexible and innovative system designs and is ideal for thin Some users need workstation performance but demand an profile systems and devices such as Ultrabooks. Ultrabook form factor. With Thunderbolt technology it is now possible to enable the thinnest and lightest laptops connected over a single cable to high performance storage, external media Key Thunderbolt Technology Benefits drives, multiple HD displays, HD media and editing systems as Thunderbolt technology dramatically increases the data well as legacy I/O hubs and devices. Giving users the ability transfer rate enabling faster backup, editing and file sharing, to have thin and light ultrabook systems but also the power, significantly reducing the time to complete key tasks. capability and expandability of a traditional workstation. Thunderbolt technology was specifically designed with Rethinking I/O inherently low latency and highly accurate time synchronization As every generation of information technology progresses, I/O capabilities. These features enable extremely accurate audio technologies evolve to provide higher bandwidth for getting and video creation, playback and editing that no other standard data into and out of computers. At its simplest, two discrete interconnect technology can match. types of I/O have resulted display (with formatted video and audio components), and data. Traditional approaches to this evolution have been to make an existing technology faster. Thunderbolt technology combines the next step in higher performance with the innovation of mapping two of the most fundamental I/O protocols at the heart of computing (PCI Express and DisplayPort), onto a single highly efficient meta- protocol, transmitting them over a single cable, and managing the traffic routing (supporting daisy chaining and hot-plugging devices) with intelligent hardware controllers. The choice of PCI Express was clear, providing for off-the-shelf controller use to attach to nearly any technology imaginable, and the choice of DisplayPort was equally clear for meeting the needs of the PC industry with capabilities like support for multiple HD displays, Figure 1. Thunderbolt cables expand a thin and light laptop to a high- and support for up to 8 channels of high-definition audio. resolution display and high-performance storage in a simple daisy chain. 1Protocol Architecture device. And an active optical cable provides for much greater Thunderbolt technology is based on a switched fabric lengths of up to 50m but does not provide power for bus- architecture with full-duplex links. Unlike bus-based I/O powered devices. architectures, each Thunderbolt port on a computer is capable of providing the full bandwidth of the link in both directions The Thunderbolt protocol physical layer is responsible for link with no sharing of band- width between ports or between maintenance including hot-plug detection, and data encoding upstream and downstream directions. The Thunderbolt to provide highly ef ficient data transfer. The physical layer has protocol architecture can be abstracted into four layers as been designed to introduce very minimal overhead and provides shown in Figure 2. full 10Gbps of usable bandwidth to the upper layers. The heart of the Thunderbolt protocol architecture is the Application-specic transport layer. Some of the key innovations introduced by the Protocol Stacks transport layer include: PCIe DisplayPort A high-performance, low-power, switching architecture. Common Transport Layer A highly ef ficient, low-overhead packet format with fl exible Electrical/Optical Layer QoS support that allows multiplexing of bursty PCI Express Connector and Cable transactions with isochronous DisplayPort communication on the same link. Thunderbolt technology Figure 2. Thunderbolt Technology Architecture. A time synchronization protocol that allows all the Thunderbolt products connected in a domain to synchronize A Thunderbolt connector is capable of providing two full- their time within 8ns of each other. duplex channels. Each channel provides bi-directional 10Gbps of band-width, as shown in Figure A. A The Thunderbolt DisplayPort and PCI Express protocols are mapped onto the connector is extremely small, making it ideal for Ultrabooks, transport layer. The mapping function is provided by a protocol plus it is enables connection to Thunderbolt products or to adapter which is responsible for ef ficient encapsulation of DisplayPort devices. Compatibility to DisplayPort devices is the mapped protocol information into transport layer packets. provided by an interoperability mode between host devices Mapped protocol packets between a source device and a and DisplayPort products if a DisplayPort device is detected, a desti- nation device may be routed over a path that may cross Thunderbolt controller will drive compatibility mode DisplayPort multiple Thunderbolt controllers. At the destination device, a signals to that device. Support for DisplayPort also enables protocol adapter recreates the mapped protocol in a way that is easy connectivity to other display types, such as HDMI, indistinguishable from what was received by the source device. with an adapter. The advantage of doing protocol mapping in this way is that Thunderbolt cables may be electrical or optical both use the Thunderbolt technology-enabled product devices appear as PCI same Thunderbolt connector. An active electrical-only cable Express or DisplayPort devices to the operating system of the provides for connections of up to 3 meters in length, and host PC, thereby enabling the use of standard drivers that are provides for up to 10W of power deliverable to a bus-powered available in many operating systems today. Figure 3. PCI Express* and DisplayPort transported between Thunderbolt controllers over a Thunderbolt cable. 2