Thunderbolt gearing up to stick around

Apple's last major connectivity advancement was in the late '90s with FireWire, which was used as a replacement for the SCSI bus on Mac systems; however, the licensing and complexity of the port made it a less attractive option than alternatives like USB for many device manufacturers, especially given the ease of implementation and eventual speed of USB 2.0. While FireWire has extended beyond its initial 400Mbps speeds to offer 800Mbps, and potentially up to 3,200Mbps, in the face of current alternatives the technology does not seem to be advancing much beyond its current implementations.

Given the relatively slow adoption of FireWire, its lack of competition with USB 2.0, and its potentially bleak future, people may wonder how long Thunderbolt will be around and whether it will catch on or follow in FireWire's footsteps, especially given competition with technology like USB 3.0. Luckily, given some of its advancements and recent news on upcoming features just announced at the Intel Developer Forum (IDF), Thunderbolt looks promising enough to be around for a while.

Thunderbolt is Intel's new connectivity option that Apple has adopted for use in its entire Mac lineup. Unlike USB, FireWire, Ethernet, and other port options, Thunderbolt extends the system's entire PCIe (PCI Express) bus, enabling a developer to attach practically any PCIe technology to the port.

As with any connection technology, its future ultimately lies in whether or not peripheral devices are created for it, so obviously the first concern people have had is whether or not device manufacturers will jump on board and supply Thunderbolt options for their products. Currently there are a handful of devices for Thunderbolt, and unlike current USB and FireWire options, it's a full and versatile range of devices, which shows great potential for the technology.

Shortly after Thunderbolt's introduction in Macs, Promise Technology was the first out the door with its Pegasus line of RAID drives that offer exceptionally fast transfer speeds. Since then, we have seen the announcement and release of numerous other devices, including Aja Video Systems' Io XT, Blackmagic Design's Intensity and UltraStudio 3D audio and video interfaces, Apple's Thunderbolt Display, and Promise's SANLink Fibre Channel interface.

Beyond interfaces, perhaps the biggest potential for Thunderbolt comes with its ability to extend the PCIe bus to external chassis and adapter devices. These include Sonnet Technologies' RackMac mini Xserver and Magma's ExpressBox1, which allow full-size PCIe cards to be used with the systems, but in addition Sonnet has released its Echo ExpressCard adapter that allows ExpressCard/32 cards to be used in any Mac with a Thunderbolt connection.

In addition to these audiovisual, storage, and chassis devices, other companies have stepped forward to announce products as well. Belkin has an upcoming Thunderbolt Express Dock interface that will allow audio, Ethernet, USB and FireWire ports to be attached to a Thunderbolt Mac; Seagate is creating a Thunderbolt adapter for its GoFlex line of hard drives; and Matrox is releasing Thunderbolt adapters for its various MXO2 audio and video interfaces. Beyond these options, Canon, LaCie, Iomega, Adobe, and Western Digital have all apparently shown interest in developing devices and technology to work with Thunderbolt.

This is all great news for Thunderbolt, but it gets better. The current implementations of Thunderbolt in Macs are likely plenty for most people; however, there are some limitations to Thunderbolt that Intel has in part addressed at IDF.

In its current implementation, Thunderbolt offers one bus at 10Gbps speeds that allows for eight devices connected in series, with up to two of them being DisplayPort devices (in other words, displays like Apple's Thunderbolt Display). At IDF, Intel discussed the upcoming Cactus Ridge controller, in which it is promising some modest advances. The first is that the devices will offer up to four channels, each independently supporting the same 10Gbps speeds with two DisplayPort links on up to eight devices per channel. The second major advancement that Cactus Ridge brings is that it will be available for Windows PC manufacturers to implement in their systems, and currently Acer and Asus have jumped on board to have systems out with Thunderbolt next year. This is exciting news for the technology, as it helps further cement its use in the PC industry, rather than it being solely a Mac connectivity option.

Unfortunately, not all PC manufacturers are on board, with major players like Dell and HP so far having no plans to use Thunderbolt. In addition, some companies like Sony are experimenting with their own Thunderbolt implementations that threaten to fracture the technology into multiple proprietary implementations rather than the standard that Apple and Intel have been pushing. It is expected that companies will initially experiment with the technology and wait to see whether it will catch on, but hopefully sooner or later (as was the case with FireWire) we should see Thunderbolt make its way into more manufacturers' devices as a cross-platform standard that everyone can use.

In terms of the speed and extendability of Thunderbolt, currently cables are made of copper wiring, but even with active electronics to help propagate the signal, the cables are limited to a couple of meters in length. This may be enough for most purposes, but many have wondered about the use of fiber optics, since Thunderbolt (originally code-named Light Peak for its use of optical connections) was developed to take advantage of fiber-optic cabling. Intel claims that optical Thunderbolt cables may be out by as early as next year; however, there may be delays and others have suggested that practical use of optical cables may be years away.

Optical cabling offers the potential for greater speeds and longer distances between devices; however, despite this potential the Thunderbolt controllers will be limited to 10Gbps for a while, meaning the only benefit of optical cables would be their lengths. Currently the 6-foot length of copper cables is likely plenty for most Thunderbolt uses, especially since devices can be daisy-chained together if needed. This means that in a chain of eight Thunderbolt devices the last one in line can be sitting over 40 feet away from the computer. Granted, with optical cabling this distance could be greatly extended, but as it stands this would be the only benefit of using optical cables. In addition, optical cables would have much higher prices than the current (and already expensive) copper cables that go for $49 from the Apple Store.

This limit to 10Gbps for at least a few years is actually good news for early Thunderbolt adopters, because their first-generation implementations will not be immediately left behind thanks to a faster second or third revision of the technology, as has happened in the past (the iPhone being one example). The current 10Gbps speed should accommodate Thunderbolt devices for years to come, and spur the development of many 10Gbps devices. The only major difference between current and newer Thunderbolt systems will likely be that newer systems will have more Thunderbolt connections.

A last point that has been brought to my attention is that some people who own older Macs without Thunderbolt ports are wondering whether there will be ways for older systems to take advantage of the technology. As MacFixIt reader "Paul" recently wrote in asking: "I keep seeing Thunderbolt mentioned...How do I connect or access this port on my 3-year-old iMac?"

Thunderbolt being based on PCIe and DisplayPort technology means it may be technically feasible to put a Thunderbolt controller on a PCIe bus (especially through a special video card) and thus enable it to be added to an existing Mac that contains PCIe expansion slots; however, there could be compatibility issues and other limitations with such a setup. Unfortunately, this type of implementation would be the only way to get a Thunderbolt connection into a Mac that does not currently have one, and therefore systems such as the iMac and Mac Mini that do not have expansion slots would not be able to accommodate such an expansion. It is also highly unlikely that a Thunderbolt add-in card for Macs will be created, so for the foreseeable future the only way to take advantage of Thunderbolt is to purchase a new system that comes with it.

Finally, if you currently own a Thunderbolt-equipped Mac, be sure to keep your system fully updated for optimal performance of your Thunderbolt setup, especially during these initial deployment phases in which drivers and firmware are being updated. While tests have shown that current performance differences between operating systems (SL and Lion) are minimal, this may change in the future as drivers mature. Additionally, firmware updates have been issued to address compatibility problems, so be sure to apply them to your systems, especially if you use Thunderbolt connections.

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