3 Thunderbolt interface
3.1 Interface characteristics

Thunderbolt interface TB is an interface which brings to the world computer industry a number of new designs, solutions, features and enhancements. Thunderbolt interface is being developed in cooperation of Intel and Apple. The first prototype of the interface was presented to the public in 2009. It was called at that time as Light Peak. The first standardly produced device with Thunderbolt interface was in 2011 the notebook MacBook Pro of the firm Apple.

Difference of Thunderbolt interface compared with other interfaces is particularly in the structural design. It consists of a combination of two different interfaces - external PCI-E bus and port DP (Display Port). Communication is bidirectional and connection works in full duplex mode. The packets of both protocols are transmitted simultaneously over a single session. Thunderbolt controller multiplexes these packets at the transmitter side into a single data stream and the receiver at opposite side switches between the different protocols.

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Principle of communication on Thunderbolt interface

Advantage and objective of TB interface is a high-speed connection of various devices and support for multiple types of data transfers via one unified connector.

It was used a modified Mini DisplayPort connector for this purpose.

The TB interface exceeds standards such as eSATA, USB and Firewire With a theoretical transfer rate of up to 10 Gbit/s per channel. Its transfer rate is almost twice higher (depending on the specific hardware and software) in comparison with the bus USB 3.0 and requires less overhead. However, the real transfer rate is around the border of 6.4 Gbit/s per channel.

It can be connected to one TB connector up to seven TB devices. One TB port can also manage simultaneously transmit the data for two displays with DP ports in high resolution HD (High Definition).

Copper wires were in spite of initial plans of optical cables (technology of Silicon Photonics Link) used for data transmission and power supply.

The advantage of copper pairs is managing of sufficient transmission speed, cost price is in comparison with optical conductors substantially lower and it is possible to realize through them the power supply of the connected devices up to 10 W of power.

Their great disadvantage is limitation of cable length, which can be only up to three meters.

It is still counted with optical cables for the future use, especially due to their potential in the area of increasing of transfer rates up to values in the order of 100 Gbit/s and can be used much longer lengths of cables under constant transmission conditions.

Intel Corporation promises to transfer a two-hour video in Full HD resolution in 30 seconds, and transfer of records in MP3 format with time duration one year for 10 minutes.