An overview of Thunderbolt Technology
The promise of Thunderbolt connectivity has been around for a couple of years now. Today, Thunderbolt is finally finding its way to the PC platform in the form of motherboards from ASUS and MSI. First unveiled as "Light Peak" at the Intel Developer Forum in 2009, the technology started out as a way to connect multiple devices to a system over a fiber optic cable (hence the 'light' in the name), though the final products have changed the implementation slightly.
The first prototype implementations actually used a USB-style connection and interface. It further required fiber optic cables. When it was renamed to Thunderbolt and then released in conjunction with a new lineup of Apple MacBook laptops, not only did the physical interface move to a mini-DisplayPort connection but the cable was made to use copper rather than fiber. Without diving too far into the reasons and benefits of either direction, the fact is that the copper cables allow for modest power transfer and are much cheaper than fiber optic variants would be.
Thunderbolt's base technology remains the same, however. It is a transfer standard that allows for 10 Gbps of bandwidth for each channel (bi-directional) and concurrently supports both data and display connections. The actual interface for the data path is based on PCI Express and connected devices actually appear to Windows as if they are internally connected to the system which can offer some interesting benefits – and headaches – for hardware developers. The display connection uses the DisplayPort standard and can be used along with the data connection without affecting bandwidth levels or performance.
For current Intel processor implementations, the Thunderbolt connection is supported by a separate controller chip on the motherboard (or a riser card) – and some routing is required for correct usage. The Thunderbolt controller does not actually include a graphics controller, so it must be fed an output from another graphics processor, obviously in this case directly from the Ivy Bridge / Sandy Bridge processors. In theory, these could be from other controllers, but with the ubiquitous nature of integrated processor graphics on IVB and SNB processors, this is going to be the implementation going forward according to motherboard and system designers.