Introduction

Thunderbolt (formerly known as “Light Peak”) is an external connection that allows 10 Gbps (around 1 GB/s) of data transfer in each direction. In this tutorial, we will explain everything you need to know about it.

The two main advantages of Thunderbolt are the use of the existing PCI Express and DisplayPort protocols and the use of an existing connector, the mini DisplayPort (mini DP). Because it uses existing protocols, it is not necessary to install an additional driver on your PC in order to use a Thunderbolt connection.

Figure 1: The Thunderbolt architecture

Thunderbolt can carry either computer data, using the PCI Express protocol, or digital video, using the DisplayPort protocol. This means that the other end of the cable can be attached to either an external storage device such as a DAS (Direct Attached Storage) box featuring a Thunderbolt port or to a video monitor with a Thunderbolt port. Since the cable can carry both video and data, the video monitor must have a Thunderbolt chip in order to capture the video data; regular monitors using a DisplayPort or a mini DisplayPort connector won’t work directly with Thunderbolt. It is possible that manufacturers will release an external box with a Thunderbolt controller in order to allow a Thunderbolt connection on regular video monitors.

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Figure 2: How Thunderbolt works

Cables and Connectors

As mentioned, the Thunderbolt connection uses a mini DisplayPort (mini DP) connector. In Figure 3, you can see a Thunderbolt port on a motherboard.

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Figure 3: Thunderbolt port on a motherboard

There are two types of Thunderbolt cables: electrical or optical. Electrical cables can be anywhere between 4 inches and 9.8 feet (10 cm to 3 m) long, while optical cables can be between 32.8 feet and 65.6 feet (10 m to 20 m) long. The use of one kind of cable or the other will depend on the cable length you want.

One advantage of the Thunderbolt connection is that both electrical and optical cables use the same connector type, the mini DisplayPort (mini DP). This is an electrical connector, so optical cables have circuitry at both ends to convert electrical signals into optical signals and vice versa. This circuit is available inside the rectangular box where the connector is attached. See Figure 6. Because of that, optical cables will not be inexpensive.

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Figure 4: Thunderbolt electrical cable

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Figure 5: Thunderbolt optical cable

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Figure 6: There is an electrical-to-optical converter inside these boxes