Apple Thunderbolt Connectivity and Compatibility



Apple’s Thunderbolt Interface

Apple has long since shown their propensity towards ignoring standards used by the rest of the computing industry. In most cases, they opt for developing breakthrough technology, rather than follow the pack. While they haven’t always been successful at this, most of the time they are.

Take interface connectors for example, while the rest of the computer world was turning to USB, Apple decided to come out with the FireWire connection; even though they had a hand in USB design. FireWire proved to be a faster interface, especially for video connections. In fact, it was so effective, that for the last several years, most of the computers sold have included FireWire connections.

It looks like Apple has done it again with the Thunderbolt connector. This joint venture, together with Intel, was aimed at creating the fastest I/O interface available. This single connection is capable of working with all peripherals; monitors, external hard drives and whatever else you might need to connect to your computer.

Thunderbolt Development

Thunderbolt was originally conceived as an optical connector. It was thought that in order to gain the type of speeds that were desired, copper wouldn’t work. However, they were able to gain those speeds with copper, so the design team abandoned fiber-optic in factor of lower-cost copper lines. This also made it possible to transmit power through the connector, rather than having a separate power connector.

The optical version of Thunderbolt is still on the drawing board. This will combine optical fiber for data communications, along with copper for power transmission, making it the first connector of its type.

Thunderbolt Connectivity

The Thunderbolt interface is built on the DisplayPort connector, albeit providing much more capacity than the old DisplayPort standard. Even so, it is fully backwards compatible, so that devices that were designed with a DisplayPort interface can be used with the new Thunderbolt.

The major difference that Thunderbolt provides is a blazingly fast connection; faster than anything else currently on the market. Part of that is that the Thunderbolt provides two separate I/O data channels in the same connector, each of which runs at 10 Gbps (gigabits per second). That makes Thunderbolt the only interface currently on the market, which can handle two separate data streams at a time.

In addition to the two channels, Thunderbolt multiplexes the data it is transferring, so that each channel can carry information to more than one device at a time. The interface is designed to allow connection with up to six Thunderbolt devices at a time. These can either be connected serially through a “daisy chain” or via a hub.

A single legacy Mini DisplayPort monitor can be connected as one of the devices as well, but it must be at the end of the daisy chain, as DisplayPort devices weren’t built for daisy chaining. So that monitor will break the chain if it’s not placed at the end.

The Thunderbolt interface also provides 10 watts of power to the devices connected to it, up from the 4.5 watts that USB 3.0 provides. This allows the manufacture of Thunderbolt devices which were impossible for USB, simply because of power limitations.

Thunderbolt Speed

Thunderbolt is by far the fastest interface currently on the market. The twin data channels each carry 10 Gbps of data in an input/output mode. That makes Thunderbolt 20 times faster than USB 2.0, and 12 times faster than FireWire 800.

This high speed makes it possible for Thunderbolt to be used with several high-capacity devices at the same time, another unique capability of the Thunderbolt interface. Speaking of which, this is the first time that video output and other peripherals are being run through the same interface. Even with the vast array of USB compatible devices on the market, there’s no way that they USB could support video monitors, nor has there ever been a video interface which could support other devices.

Thunderbolt Compatibility

As I’ve already mentioned, the Thunderbolt interface is directly backwards compatible with DisplayPort. However, it doesn’t directly connect with other devices which are not Thunderbolt compatible. That isn’t a problem though, as many manufacturers are producing adapters to go from the Thunderbolt connection to other display types and for video capture. However, there aren’t any adapters made yet for connecting other types of peripherals to Thunderbolt ports.

While the marketplace has been slow in doing so, there are some devices coming out which are designed as Thunderbolt compatible devices. Besides monitors, external drives are hitting the market, which take advantage of the great speed that Thunderbolt offers, in order to provide extremely fast data access times. These are typically SSD, rather than typical hard drives, as SSD provides much higher data seek and data transfer speeds than hard drives.


Rich Murphy