|Produced||February 24, 2011–present|
|Length||3 meters maximum (copper)|
|Width||7.4 mm male (8.3 mm female)|
|Height||4.5 mm male (5.4 mm female)|
|Daisy chain||Yes, up to 6 devices|
|Audio signal||Via DisplayPort protocol or USB-based external audio cards. Supports audio through HDMI adapters.|
|Max. voltage||18 V (bus power)|
|Max. current||550 mA (10 W max)|
|Bitrate||10 Gbit/s per channel (20 total.)|
|Protocol||4× PCI Express 2.0, DisplayPort 1.1a|
|Pin 2||HPD||Hot Plug Detect|
|Pin 3||HS0TX(P)||HighSpeed Transmit 0 (positive)|
|Pin 4||HS0RX(P)||HighSpeed Receive 0 (positive)|
|Pin 5||HS0TX(N)||HighSpeed Transmit 0 (negative)|
|Pin 6||HS0RX(N)||HighSpeed Receive 0 (negative)|
|Pin 9||LSR2P TX||LowSpeed Transmit|
|Pin 10||GND||Ground (reserved)|
|Pin 11||LSP2R RX||LowSpeed Receive|
|Pin 12||GND||Ground (reserved)|
|Pin 15||HS1TX(P)||HighSpeed Transmit 1 (positive)|
|Pin 16||HS1RX(P)||HighSpeed Receive 1 (positive)|
|Pin 17||HS1TX(N)||HighSpeed Transmit 1 (negative)|
|Pin 18||HS1RX(N)||HighSpeed Receive 1 (negative)|
|This is the pinout for both sides of the connector, source side and sink side. The cable is actually a crossover cable, it swaps all receive and transmit lanes, e.g. HS1TX(P) of the source is connected to HS1RX(P) of the sink.|
Thunderbolt (codenamed Light Peak) is a hardware interface that allows for the connection of external peripherals to a computer. It has a transfer speed of 10 Gbit/s per channel over copper wire and 20 Gb/s per channel using optical cabling. It uses the same connector as Mini DisplayPort (MDP). It was released in its finished state on February 24, 2011.
Thunderbolt combines PCI Express (PCIe) and DisplayPort (DP) into one serial signal alongside a DC connection for electric power, transmitted over one cable. Up to seven peripherals may be supported by one connector through various topologies.
Thunderbolt was developed by Intel with technical collaboration from Apple. It was commercially introduced on Apple's 2011 MacBook Pro, using the same Apple-developed connector as Mini DisplayPort, which is electrically identical to DisplayPort, but uses a smaller, non-locking connector. Though the Thunderbolt trademark was registered by Apple, full rights belong to Intel which subsequently led to the transfer of the registration from Apple to Intel.
Thunderbolt controllers multiplex one or more individual data lanes from connected PCIe and DisplayPort devices for transmission via one duplex Thunderbolt lane, then de-multiplex them for consumption 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 single legacy 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 4 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 becomes 10 Gbit/s and the 4 Thunderbolt lanes are configured as 2 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 new 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. The Intel technology at the time was logically marketed under the name Light Peak, after 2011 referred to as Silicon Photonics Link. However, it was discovered that conventional copper wiring could furnish the desired 10 Gbit/s Thunderbolt bandwidth per channel at lower cost. Optical Thunderbolt cables were announced in mid April 2012 by Sumitomo Electric Industries.
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.
At the show, Intel claimed that Light Peak-equipped systems would begin to appear in 2010. A YouTube video simultaneously published by Intel also showed Light Peak interfacing with HD cameras, laptops, docking stations, and HD monitors. Jason Ziller, Head of the Intel Optical I/O Program Office also demonstrated the internal components of the technology under a microscope and the sending of data through an oscilloscope.
On 4 May 2010, in Brussels, Intel demonstrated a laptop with a Light Peak connector, indicating that the technology had shrunk small 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 said they expected hardware manufacturing to begin around the end of 2010.
Copper vs. optical 
In 2009, Intel officials said the company was "working on bundling the optical fiber with copper wire so Light Peak can be used to power devices plugged into the PC." In 2010, Intel said the original intent was "to have one single connector technology" that would allow "electrical USB 3.0 […] and piggyback on USB 3.0 or 4.0 DC power." Light Peak aimed to make great strides in consumer-ready optical technology, by then having achieved “[connectors rated] for 7,000 insertions, which matches or exceeds other PC connections,” “cables [that were tied] in multiple knots to make sure it didn't break and the loss is acceptable” and “you can almost get two people pulling on it at once and it won't break the fibre,” predicting that “Light Peak cables will be no more expensive than HDMI.”
In January 2011, Intel's David Perlmutter told Computerworld that initial Thunderbolt implementations would be based on copper wires. "The copper came out very good, surprisingly better than what we thought," he said. A major advantage of copper is the ability to carry power. The final Thunderbolt standard specifies 10W DC on every port. See comparison section below.
Intel and industry partners are still developing optical Thunderbolt hardware and cables. The optical fiber cables are to run "tens of meters" but will not supply power, at least not initially. They are to have two 62.5-micron-wide fibers to transport an infrared signal up to 100 metres (330 ft). The conversion of electrical signal to optical will be embedded into the cable itself, allowing the current MDP connector to be forward compatible, but eventually Intel hopes for a purely optical transceiver assembly embedded in the PC.
Market introduction 
It was rumoured that the early-2011 MacBook Pro update would include some sort of new data port, and most of the speculation suggested 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 using a combined USB/Light Peak port. Shortly before the release of the new machines, the USB-IF announced they would not allow this, stating that USB was not open to modification in this way.
However, in July 2011 Sony released its Vaio Z21 line of laptop with a “Power Media Dock” that uses the optical iteration of Thunderbolt to connect to an external graphics card using a combination port that behaves like USB electrically but also includes the optical interconnect required for Thunderbolt. Other implementations of the technology have begun in 2012, with desktop boards offering the interconnect now available.
In spite of these comments and speculation, Apple's introduction came as a major surprise when it was revealed that the port was based on MDP, 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, have to be located at the end of a Thunderbolt device chain, but native displays can be placed anywhere along the line. Thunderbolt devices can go anywhere on the chain. In this respect, Thunderbolt shares a relationship with the older ACCESS.bus system, which used the display connector to support a low-speed bus.
Apple explained that 6 daisy-chained peripherals are supported per Thunderbolt port, and that the display should lie at the end of the chain.
In February 2011, Apple introduced its new line of MacBook Pro laptop computers and announced the technology's commercial name would be Thunderbolt, with these machines being the first to feature the new I/O technology.
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 MDP 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 MDP connector. The Target Display mode on iMacs requires a Thunderbolt cable to accept a video-in signal from another Thunderbolt-capable computer. DP monitors must be the last (or only) device in a chain of Thunderbolt devices.
Intel announced that a developer kit would be released in the second quarter of 2011, while manufacturers of hardware development equipment have indicated they will add support for the testing and development of Thunderbolt devices. The developer kit is being provided only on request.[needs update]
Peripheral devices 
While Apple released their first computer to feature the interface in early 2011, it took some time for peripheral devices supporting the Thunderbolt interface to hit the marketplace, with initial ones not starting to hit retail stores until late 2011. Storage manufacturer Promise Technology was the first company to release large-sized RAID storage devices, with their Pegasus R4 (4 drive) and Pegasus R6 (6 drive) enclosures, however they were reasonably expensive for the average consumer. Additionally, mass floods in Thailand —where much of the world's supply of HDDs were made— heavily reduced hard drive production, so along with many products on the market generally, following the initial release, retail prices also increased further, contributing to a slow take-up of the devices.
It also took some time for other storage manufacturers to release products, with most focusing on smaller storage devices, with speed being the goal rather than large-scale storage needs. Many of these devices were under 1 TB in size, with some also featuring an SSD for fast external data access rather than a standard HDD, mainly aimed at the professional user. Backwards compatibility with non-Thunderbolt equipped computers was also an issue, as most storage devices only featured two Thunderbolt ports for daisy-chaining up to six devices together from a single Thunderbolt port.
As of late 2012, very few other storage devices offering larger, double-figure TBs of storage, have started to hit the market, with Sonnet Technologies, Inc. releasing high-end expensive professional units, and Drobo offering 4- and 5-drive enclosures, the latter featuring their own BeyondRAID proprietary data-handling system.
Other companies have focused on offering interface solutions, allowing older, usually slower, interfaces to be routed through a single Thunderbolt connection, meaning just one Thunderbolt wire had to be connected to the computer rather than many wires for each interface. Similarly, early-on in July 2011, Apple released an updated monitor, Apple Thunderbolt Display, which featured many older interfaces, including gigabit Ethernet, effectively making it the first product to be able to be used as a hub for this purpose.
Since Thunderbolt extends the PCI Express bus, which is the main expansion bus in current systems, it allows very low-level access to the system. PCI devices need to have unlimited access to memory, and may thus compromise security. This issue exists with many high-speed expansion buses, including PC Card, ExpressCard and FireWire.
An attacker could, for example, maliciously configure a Thunderbolt device. On connecting to a computer, the device, through its direct and unimpeded access to system memory and other devices, would be able to bypass almost all security measures of the OS and have the ability to read encryption keys or install malware.
A number of Intel processors since the introduction of the Nehalem microarchitecture (that is, a number of CPU branded Core i5, Core i7, or later) support VT-d, an IOMMU implementation. This allows the operating system (OS) to isolate a device in its own virtual memory address space (in a manner analogous to the isolation of processes from one another using the MMU). Devices could thus be prevented from having access to unauthorized parts of the memory space. However, this feature isn't generally used except for its initial purpose of giving guest virtual machines passthrough access to specific host hardware.
In June 2011, the first two meter Thunderbolt cable from Apple cost US$49.00. As an active cable, it includes circuitry inside the connectors. The cable has five wires: one for management and two uni-directional pairs, one for incoming and second for outgoing traffic.
In the third quarter of 2012, other manufacturers started to release cables of varying length up to the maximum supported length of 3 meters, whilst some who were releasing storage enclosures started to include a Thunderbolt cable with their devices.
In January 2013, Apple reduced the price on their 2.0 meter cable to US$39.00. Apple also announced availability of a shorter 0.5 meter cable for US$29.00.
|82523EF||4||15×15||3.8W||Light Ridge||Q4 2010|
|82523EFL||4||15×15||3.2W||Light Ridge||Q4 2010|
|L2510||2||15x15||???||Eagle Ridge||Q1 2011|
|L2310||2||8x9||1.85W||Eagle Ridge (SFF)||Q1 2011|
|L2210||1||5x6||0.7W||Port Ridge||Q4 2011||Device Only|
|L3510L||4||12×12||2.8W||Cactus Ridge||Q2 2012|
|L3310||2||12×12||2.1W||Cactus Ridge||2012||Host Only|
|L4510||4||12×12||???||Redwood Ridge||2013||DP 1.2|
|L4410||2||10×10||???||Redwood Ridge||2013||Host Only|
|???||???||???||???||Falcon Ridge||2014||20 Gbit/s speed|
Power capabilities versus other interfaces 
Thunderbolt is intended as, and functions as, a unifying interface for mobile, laptop and desktop devices to prevent more proliferation of cables and connectors for displays and storage. Its power characteristics reflect this. The power, at 10 watts, improves on USB 3.0's 4.5 watts, but is not beyond the ability of a laptop or tablet to power. While it could not displace power over Ethernet (at 30 watts per port or more) or FireWire (40 watts per port) due to this low wattage and short expensive cables, its higher data rate may give it advantages in some applications until powered 10GbE or 100GbE are more common.
The origin and announced intent to continue work on a fiber optic interface reduces interest somewhat in a powered device market as a metal-augmented fibre cable can not carry power for distances greater than extant powered data cables. The announced 4.5 watt USB 3.0 power level for the fibre cable would not be enough to run most existing 10 watt Thunderbolt devices. Accordingly there is risk of the market splitting (as it did with USB 2.0 and 3.0) into low-power devices (under 4.5 watts), two of which could be chained on a Thunderbolt port, mid-power devices (under 10 watts) which would monopolize the port, and higher-power devices (over 10 watts) which would require external sources of power to function.
See also 
- Computer bus
- Optical interconnect
- Parallel optical interface
- Optical communication
- Interconnect bottleneck
- Optical fiber cable
- DisplayPort / Mini DisplayPort
- IEEE 1394 (FireWire)
- USB 3.0
- Lightning Bolt
- Apple Thunderbolt Display
- List of computer peripheral bus bit rates
- List of Thunderbolt compatible devices
- List of device bit rates
- "Thunderbolt™ Technology". Intel. Retrieved June 28, 2011.
- "Apple Updates MacBook Pro with Next Generation Processors, Graphics & Thunderbolt I/O Technology" (Press release). Apple. February 24, 2011. Retrieved August 17, 2011.
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- "Thunderbolt Device Driver Programming Guide". Apple. Retrieved December 21, 2011.
- https://en.wikipedia.org/wiki/USB_2.0 Read Comparisons with other connection methods - Thunderbolt
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- "Light Peak: Overview". Intel. Retrieved June 29, 2011.
- "White Paper: The 50G Silicon Photonics Link". Intel. Retrieved June 29, 2011.
- Sumitomo Electric Launches Optical Thunderbolt Cable Samples http://global-sei.com/news/press/12/prs045_s.html
- Patel, Nilay (September 24, 2009). "Video: Intel's Light Peak running an HD display while transferring files... on a hackintosh". Engadget. AOL. Retrieved February 25, 2011.
- Jason Ziller (January 26, 2010). Intel Light Peak Interconnect Technology Update (YouTube). Intel. Event occurs at 1:20. http://www.youtube.com/watch?v=nfGevFIVKw4. Retrieved February 23, 2011.
- Shiels, Maggie (September 25, 2009). "Future is TV-shaped, says Intel". BBC News. Retrieved September 27, 2009.
- Light Peak to Connect Consumer Devices at Record Speed on YouTube
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- Shah, Agam (January 8, 2011). "Intel says Light Peak interconnect technology is ready". Computer World (International Data Group). Retrieved February 23, 2011.
- "IPtronics Develops Components for Light Peak Technology" (Press release). IPtronics. October 1, 2009. Retrieved April 5, 2011.
- Clarke, Peter (October 1, 2009). "IPtronics, Avago chip in to Intel's optical interconnect". EETimes. Retrieved October 1, 2009.
- Metz, Cade (February 24, 2011). "Intel: 'PC makers took the light out of Light Peak'". The Register (Situation Publishing). Retrieved February 25, 2011.
- Jason Ziller (January 23, 2010). Light Peak to Connect Consumer Devices at Record Speed (YouTube). Intel. Event occurs at 1:13. http://www.youtube.com/watch?v=izNoF1SWtSg. Retrieved February 23, 2011.
- Crothers, Brooke (February 19, 2011). "New high-speed connection tech due from Apple". CNet News (CBS Interactive). Retrieved February 25, 2011.
- Kim, Arnold (February 19, 2011). "Apple to Introduce Light Peak (High Speed Connection Technology) Soon?". MacRumors. Retrieved February 25, 2011.
- Smith, Mat. "ASUS and MSI launch Thunderbolt motherboards, tie for first place".
- "Thunderbolt: Next-Generation high-speed I/O technology". Apple. February 24, 2011. Retrieved February 25, 2011.
- "Apple Announces New iMac With Next Generation Quad-Core Processors, Graphics & Thunderbolt I/O Technology". Apple. Retrieved 10 May 2011.
- "iMac (Mid 2011): Target Display Mode does not accept video over a Mini DisplayPort cable". Apple. July 14, 2011. Retrieved July 17, 2011.
- Shah, Agam (April 12, 2011). "Intel to Open up Thunderbolt Development This Quarter". PC World (PCWorld Communications). Retrieved April 13, 2011.
- Holland, Colin (April 12, 2011). "LeCroy lines up armada for Thunderbolt testing". EE Times Products. UBM Electronics. Retrieved April 18, 2011.
- registration required for developer information
- Graham, Robert (February 24, 2011). "Thunderbolt: Introducing a new way to hack Macs". Errata Security. Retrieved March 5, 2011.
- Foresman, Chris (June 30, 2011). "The technology inside Apple’s $50 Thunderbolt cable". Retrieved July 2, 2011.
- "Thunderbolt interface rattles placid PC landscape". July 3, 2011. Retrieved March 29, 2013. "The five-wire assembly uses one wire each for the four 10-Gbit/s links (two in and two out) and the fifth for management traffic.""
- van Beijnum, Iljitsch (June 20, 2012). "Hands-on: Apple's Thunderbolt Gigabit Ethernet adapter". Ars Technica.
- Gurman, Mark (January 10, 2013). "Apple slashes price on Thunderbolt cable, releases additional shorter model". 9to5mac.
- Nilsson, LG. "Intel cans 3.4W TDP Cactus Ridge Thunderbolt chip". VR-Zone. Retrieved March 30, 2012.
- Nilsson, LG. "Thunderbolt roadmap unveiled, new features coming to Apple et al". VR-Zone. Retrieved July 24, 2012.
- Chen, Monica. "Intel to release new Thunderbolt chip in 2Q13". DIGITIMES. Retrieved July 24, 2012.
- Nilsson, LG. "Intel finally shipping 2nd gen Thunderbolt controllers, just in time for new Macs". VR-Zone. Retrieved August 14, 2012.
- Shimpi, Anand. "New Thunderbolt Controllers (DSL4510/4410) and Future 20Gbps Falcon Ridge TB Controller Announced". AnandTech. Retrieved April 8,2013.
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