Thunderbolt is the brand name of a hardware interface for the connection of external peripherals to a computer. It was developed by Intel in collaboration with Apple. It was initially marketed under the name Light Peak and first sold as part of an end-user product on February 24, 2011.
Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into two serial signals and provides DC power via a single cable. Up to six peripherals may be supported by a single connector through various topologies. Thunderbolt 1 and 2 use the same connector as Mini DisplayPort (MDP), whereas Thunderbolt 3, 4, and 5 use the USB-C connector and support USB devices.
Description
Thunderbolt controllers multiplex one or more individual data lanes from connected PCIe and DisplayPort devices for transmission via two duplex Thunderbolt lanes, then de-multiplex them for use by PCIe and DisplayPort devices on the other end. A single Thunderbolt port supports up to six Thunderbolt devices via hubs or daisy chains; as many of these as the host has DP sources may be Thunderbolt monitors. A device with fewer than four PCIe lanes still qualifies as a Thunderbolt device but will not support the full capabilities and speeds of Thunderbolt.
A single Mini DisplayPort monitor or other device of any kind may be connected directly or at the very end of the chain. Thunderbolt is interoperable with DP-1.1a compatible devices. When connected to a DP-compatible device, the Thunderbolt port can provide a native DisplayPort signal with four lanes of output data at no more than 5.4 Gbit/s per Thunderbolt lane. When connected to a Thunderbolt device, the per-lane data rate achieves 10 Gbit/s and the four Thunderbolt lanes are configured as two duplex lanes, each 10 Gbit/s, comprising one lane of input and one lane of output.
Thunderbolt can be implemented on PCIe graphics cards, which have access to DisplayPort data and PCIe connectivity, or on the motherboard of computers with onboard video, such as the MacBook Air.
The interface was originally intended to run exclusively on an optical physical layer using components and flexible optical fiber cabling developed by Intel partners and at Intel's Silicon Photonics lab. It was initially marketed under the name Light Peak and, after 2011, as Silicon Photonics Link. However, it was eventually discovered that conventional copper wiring could furnish the desired 10 Gbit/s per channel at lower cost.
This copper-based version of the Light Peak concept was co-developed by Apple and Intel. Apple registered Thunderbolt as a trademark but later transferred the mark to Intel, which held overriding intellectual property rights. Thunderbolt was commercially introduced on Apple's 2011 MacBook Pro, using the same Apple-developed connector as Mini DisplayPort.
In January 2013, Sumitomo Electric Industries began selling optical Thunderbolt cables of up to in length in Japan, while in late September 2013, Corning Inc. started selling fiber-optic cables of up to in length in the United States.
History Introduction (2009) Intel introduced Light Peak at the 2009 Intel Developer Forum (IDF), using a prototype Mac Pro logic board to run two 1080p video streams plus LAN and storage devices over a single 30-meter optical cable with modified USB ends. The system was driven by a prototype PCI Express card, with two optical buses powering four ports. Jason Ziller, head of Intel's Optical I/O Program Office, presented the internal components of the technology under a microscope and the delivery of data through an oscilloscope. The technology was described as having an initial speed of 10 Gbit/s over plastic optical cables, alongside promising a final speed of 100 Gbit/s. At the show, Intel announced Light Peak-equipped systems would begin to appear in 2010, and posted a YouTube video showing Light Peak-connected HD cameras, laptops, docking stations, and HD monitors.
On May 4, 2010, in Brussels, Intel demonstrated a laptop with a Light Peak connector, indicating that the technology had shrunk enough to fit inside such a device, and had the laptop send two simultaneous HD video streams down the connection, indicating that at least some fraction of the software/firmware stacks and protocols were functional. At the same demonstration, Intel officials stated they expected hardware manufacturing to begin around the end of 2010.
In September 2010, some early commercial prototypes from manufacturers were demonstrated at the Intel Developer Forum 2010.
Thunderbolt 1 (2011) CNET's Brooke Crothers said it was rumored that the early-2011 MacBook Pro update would include some sort of new data port, and he speculated it would be Light Peak (Thunderbolt). At the time, there were no details on the physical implementation, and mock-ups appeared showing a system similar to the earlier Intel demos that utilizes a combined USB/Light Peak port. Shortly before the release of the new machines, the USB Implementers Forum (USB-IF) announced it would not allow such a combination port, and that USB was not open to modification in that way.
Other implementations of the technology began in 2012, with desktop boards offering the interconnection now available.
Apple stated in February 2011 that the port was based on Mini DisplayPort, not USB. As the system was described, Intel's solution to the display connection problem became clear: Thunderbolt controllers multiplex data from existing DP systems with data from the PCIe port into a single cable. Older displays using DP 1.1a or earlier must be located at the end of a Thunderbolt device chain, but native displays can be anywhere along the line. Thunderbolt devices can go anywhere on the chain. In that respect, Thunderbolt shares a relationship with the older ACCESS.bus system, which used the display connector to support a low-speed bus.
Apple states that up to six daisy-chained peripherals are supported per Thunderbolt port and that the display should be attached at the end of the chain if it does not support daisy-chaining.
In February 2011, Apple introduced MacBook Pro (13-inch, Early 2011), MacBook Pro (15-inch, Early 2011), and MacBook Pro (17-inch, Early 2011) featuring one Thunderbolt port. In May 2011, Apple introduced the iMac (21.5-inch, Mid 2011), featuring one Thunderbolt port, and the iMac (27-inch, Mid 2011), featuring two Thunderbolt ports. In July 2011, Apple introduced Mac Mini (Mid 2011), MacBook Air (11-inch, Mid 2011), MacBook Air (13-inch, Mid 2011), and Apple Thunderbolt Display, featuring one Thunderbolt port for daisy-chaining or other devices.
In May 2011, Apple announced a new line of iMacs that includes the Thunderbolt interface.
The Thunderbolt port on the new Macs is in the same location relative to other ports and maintains the same physical dimensions and pinout as the prior Mini DisplayPort connector. The main visible difference on Thunderbolt-equipped Macs is a Thunderbolt symbol next to the port.
The DisplayPort standard is partially compatible with Thunderbolt, as the two share Apple's physically compatible Mini DisplayPort connector. The target display mode of iMacs requires a Thunderbolt cable to accept a video-in signal from another Thunderbolt-capable computer. A DP monitor must be the last (or only) device in a chain of Thunderbolt devices.
Intel announced it would release a developer kit in the second quarter of 2011, while manufacturers of hardware development equipment have indicated they will add support for testing and development of Thunderbolt devices. The developer kit is being provided only on request.
In July 2011, Sony released its Vaio Z21 line of notebook computers that had a "Power Media Dock" that uses optical Thunderbolt (Light Peak) to connect to an external graphics card using a combination port that behaves like USB electrically, but that also includes the optical interconnect required for Thunderbolt.
Thunderbolt 1 ran at 10 Gbit/s, making it faster than USB at the time.
Thunderbolt 2 (2013) In June 2013, Intel announced that the next version of Thunderbolt, based on the controller code-named "Falcon Ridge" (running at 20 Gbit/s), is officially named "Thunderbolt 2" and entered production in 2013. The data rate of 20 Gbit/s is made possible by joining the two existing 10 Gbit/s-channels, which does not change the maximum bandwidth, but makes its usage more flexible.
In June 2013, Apple announced the Mac Pro (Late 2013) featuring six Thunderbolt 2 ports. In October 2013, Apple announced MacBook Pro (Retina, 13-inch, Late 2013), and MacBook Pro (Retina, 15-inch, Late 2013) featuring two Thunderbolt 2 ports. In October 2014, Apple announced Mac Mini (Late 2014), and iMac (Retina 5K, 27-inch, Late 2014) featuring two Thunderbolt 2 ports. In March 2015, Apple announced MacBook Air (11-inch, Early 2015), and MacBook Air (13-inch, Early 2015) featuring one Thunderbolt 2 port.
At the physical level, the bandwidth of Thunderbolt 1 is identical to that of Thunderbolt 2, which means Thunderbolt 1 cabling is compatible with Thunderbolt 2 interfaces. At the logical level, Thunderbolt 2 enables channel aggregation, whereby the two previously separate 10 Gbit/s channels can be combined into a single logical 20 Gbit/s channel.Apple (2013) "Thunderbolt". Apple. Retrieved February 4, 2014.
Intel says Thunderbolt 2 will be able to transfer a 4K video while simultaneously displaying it on a discrete monitor.
Thunderbolt 2 incorporates DisplayPort 1.2 support, which allows for video streaming to a single 4K video monitor or dual QHD monitors. Thunderbolt 2 is backward compatible, which means that all Thunderbolt cables and connectors are compatible with Thunderbolt 1.
The first Thunderbolt 2 product for the consumer market was Asus's Z87-Deluxe/Quad motherboard, announced on August 19, 2013,Walton, Jarred (August 19, 2013). "ASUS Introduces Z87-Deluxe/Quad: World's First Thunderbolt 2 Certified Motherboard". AnandTech. Retrieved December 28, 2013. and the first system released with Thunderbolt 2 was Apple's late 2013 Retina MacBook Pro, on October 22, 2013.Torres, Edwin (January 28, 2013) . MacRumors. Retrieved January 28, 2014.
Thunderbolt 3 (2015)
Thunderbolt 3 is a hardware interface developed by Intel. It shares USB-C connectors with USB, supports USB 3.1 Gen 2, and can require special active cables for maximum performance for cable lengths over 0.5 meters (1.5 feet). Compared to Thunderbolt 2, it doubles the bandwidth to 40 Gbit/s (5 GB/s). It allows up to four lanes of PCI Express 3.0 (32.4 Gbit/s) for general-purpose data transfer, and four lanes of DisplayPort 1.4 HBR3 (32.40 Gbit/s before 8/10 encoding removal, and 25.92 Gbit/s after) for video, but the maximum combined data rate cannot exceed 40Gbit/s; video data is prioritized and so uses all needed bandwidth, the remainder being available to PCIe. DP 1.2 support is mandatory, while DP 1.4 is optional. Other overheads are possible on PCIe data (1.5% of 128b/130b is also removed) and Thunderbolt 3 protocol (either optimise for speed or for latency), the last one gives only 21.6 Gbit/s to 25 Gbit/s. Thunderbolt 3 uses 64b/66b encoding after that, which means the real rate is bigger than 40 Gbit/s, 2 times 20.625 Gbit/s.