New for Thunderbolt 2.0
September 2013, Intel Developer forum, San Francisco—Ben Hacker detailed the changes in Thunderbolt interfaces to address the need for higher transfer speeds. The Thunderbolt 2 doubles the throughput of the original Thunderbolt.
The base technology is designed to merge a number of traffic lines into a single cable that supports multiple protocols. It is designed to interface from PCs to high-speed peripherals like monitors, dock, and storage. The original spec called for a bi-directional, dual channel 10 Gbps per port interface. The interconnection is extendable by daisy-chaining end points.
The controller is a high-speed interface that can handle a mix of Display Port and PCIe devices. The active cables enable long cable runs, and optical cables are available for even longer runs. The connectors are specific to the Thunderbolt interface and are not interchangeable with similar types of cables, although the PCB connector is back compatible with mini-DisplayPort connectors.
The architecture makes the PCIe devices look like they are on the other side of a PCIe switch, and the DisplayPort looks like a repeater. The interface is managed in the controller hardware. Devices can be bus- or self-powered, but a bus powered device cannot share power with another device.
The latest controllers are available as single or dual port hosts/devices. The latest versions support 20 Gbps data transfers, and are showing up in a growing ecosystem of certified devices, including lower-priced cables and long optical cables. The interface is available on Mac and some PCs.
The way to get to 20 Gbps is to combine two 10 Gbps physical links into a single 20 Gbps logical interface. The Thunderbolt 2 with channel aggregation can support simultaneous 4k video file transfers and display, and the DisplayPort 1.2 handles 4k and multiple monitors.
The latest spec and associated devices are focused on 4k video storage and workflow support, such as PCIe SSDs with multiple Thunderbolt ports. New Windows software allows for device authorization by the user, control panel access to the Thunderbolt chain, and a topology view of connected devices. New device recognition allows the user to decide to choose from Do Not Connect, Connect Only Once, or Always Connect. The first device in a daisy chain is the gateway for all subsequent devices in that chain. Non-Thunderbolt certified for PC devices can be used with a PC.
