One by one the barriers to mobile computing have been falling. In the early days you could move to a notebook but you'd give up a lot of CPU, GPU and I/O performance. SSDs really fixed the storage performance issue (2.5" hard drives are horrendously slow compared to their 3.5" counterparts), power gating and turbo boost helped address the CPU problem and I wouldn't be too surprised to see companies have another go at external GPU solutions for those who need the added graphics horsepower.

The idea of external GPUs brings up the current limitation we face in this mobile transition. Although being more mobile is great, we still want the best of both worlds: great performance when we're at a desk, and great battery life when mobile. Enabling the former is going to require new technologies as well as new high speed interfaces.

Intel has been at the forefront of many of the successful high bandwidth interfaces in the evolution of the PC industry. Will Thunderbolt be another feather in its cap? In February we got the first Thunderbolt enabled MacBook Pros and just last week Promise shipped the first Thunderbolt enabled storage device. It's time to put the two together.

Thunderbolt Recap

At the beginning of this year Intel, alongside Apple, finally introduced a productized version of the interface we'd previously only known as Light Peak. Given that the first instantiation of this interface used traditional copper wires and not an optical interface, Apple and Intel branded it Thunderbolt.

Thunderbolt Controller IC on 15" 2011 MacBook Pro - Courtesy iFixit 

The interface is royalty free, although Intel is the only company that makes Thunderbolt controller needed to support the interface. There's no word on the cost of the Thunderbolt controller. Thunderbolt isn't an Apple exclusive, however we won't see PCs ship with the high bandwidth copper interface until 2012 at the earliest.

Thunderbolt is a high speed, dual-channel serial interface. Each channel is good for up to 10Gbps of bi-directional bandwidth (20Gbps total) and with two channels a single Thunderbolt link is enough for 40Gbps of aggregate bandwidth.

Thunderbolt can carry both PCIe and DisplayPort signaling. Apple claims that one of the channels is used for DisplayPort while the other is used for PCIe. DisplayPort interface support extends to the connector, which is physically compatible with a standard mini-DisplayPort connector. DisplayPort support is key as it allows video to be carried in addition to data, potentially allowing for some interesting use as a single cable docking solution for notebooks.

In addition to carrying up to 40Gbps of total bandwidth, a single Thunderbolt cable can also deliver up to 10W of power to connected devices.

Each Thunderbolt port can drive up to 7 daisy chained devices, although all devices must share the 40Gbps (up/down) bandwidth to the host.

There's an obvious comparison to USB 3.0 which currently tops out at 5Gbps, however even it offers only 1/4 of the total available bandwidth of the Thunderbolt PCIe channel (not to mention its inability to carry DisplayPort).

The Pegasus: Hardware


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  • repoman27 - Saturday, July 09, 2011 - link

    OK, I recognize that most A/V equipment isn’t refreshed as often as PCs are, but the industry started the switch to digital display interfaces 12 years ago. If you really can’t part with your equipment that predates DVI, you can pick up an Apple mini DisplayPort to VGA adapter for $29, or a generic one for $5. It’ll fit in your pocket, and yes it will work with the Thunderbolt equipped Macs. And hey, now that you’ve got an analog signal, it’s no problem to use a passive adapter to convert to s-video or composite video, and then you can attach it right to your RF modulator and drive any TV made since 1941. Complete backwards compatibility for under $15 that will fit in your pocket (although you’ll probably need cargo pants for the RF modulator.)

    If you can confine yourself to connecting to displays manufactured in the last 10 years or so, you can get an Apple DisplayPort to DVI adapter for $29, or a generic one for $5. It’ll fit in your pocket, and yes it will work with the Thunderbolt equipped Macs. Combine that with a DVI to HDMI cable for an additional $2, and now you can connect to any display with a digital interface except those requiring dual-link DVI. If you want audio as well as video over HDMI, you can get a mini DP to HDMI adapter such as the super slick Griffin GC17096 with Audio and DVI for $27, or go generic for far less.

    The only cumbersome and expensive conversion on the newer Macs is when you absolutely have to go the dual-link DVI route. This requires an active adapter that has to regenerate the video signal. The apple version will run you $99 (see, those TB cables aren’t so expensive after all). However, Thunderbolt may actually allow for cheaper and more elegant solutions due to sufficient power being available on the port. Then again, dual-link DVI only displays are cumbersome and expensive in and of themselves, so it shouldn’t matter too much to those who actually own one.

    The whole point of Thunderbolt is that it’s NOT yet another connection, it’s a radical extension of the capabilities of one you already have—the video out port. The only digital display interfaces that are even remotely as versatile, capable or compact as mini DP are mini/micro HDMI, but their consumer electronics heritage presents some drawbacks for PC applications. Not to mention that it is the packetized nature of the DisplayPort protocol itself that allows it to be combined with PCIe on a single link to create Thunderbolt. VGA ports are literally 8 times the size of mini DP ports and DVI are larger still. By forcing those who need to connect to 10 year old equipment to carry a $5 adapter in their pockets when they might need to do so, manufacturers are able to give everyone an additional 15 minutes of power when running on battery.
  • darwinosx - Friday, July 08, 2011 - link

    Hardly anyone uses projectors so VGA ports should only be on business class laptops. Reply
  • Zok - Friday, July 08, 2011 - link

    Can't say I agree with you there. Despite being issued a corporate laptop, I use my personal one for most of my work, including (VGA-requisite) projector presenting. Reply
  • cacca - Friday, July 08, 2011 - link

    some questions:

    Does USB 3 port do the same?

    Does the PCI-E external do the same?

    Does External SATA do the same?

    Thunderbolt is just another PROPRIETARY standard that competes with others.

    It reminds me RAMBUS.

    were cost and compatibility matters. Is faster but....

    We will ever seen a review of something from Intel that points out the shortcomings?

    or this place is ADDtech instead of anandtech?
  • André - Friday, July 08, 2011 - link

    Rest assured that USB 3.0 does NOT in any way or form do the same as Thunderbolt.

    The protocols are very different, as in, USB 3.0 nearly doesn't support any and Thunderbolt being an extension of a 4 x PCI-Express slot does support heaps of features, like Target Disk Mode, S.M.A.R.T.-status, Native Command Queuing, daisy-chaining (with very low latency) making it ideal for many professional applications (Audio/Visual devices), bi-directional bandwidth, DisplayPort, 10 Watt of power and native software driver support.

    Just to name a few.

    External SATA doesn't do the same either.

    Thunderbolt is a multi-purpose connector, not limited to only storage or transfer of files.

    If you for a minute think that USB or E-SATA does the same as Thunderbolt, then you need to educate yourself.

    It has the potential to replace all other external connectors. One cable to rule them all, instead of legacy cables that clutter up the backside of your computer and collect dust.
  • Anato - Friday, July 08, 2011 - link

    And one controller (maker) to rule us all. Thats a big problem in PC, but not necessarily in Mac. Reply
  • Jaybus - Sunday, July 10, 2011 - link

    Not really. Light Peak is essentially protocol agnostic. It tunnels PCI-E. The PCI-E-to-whatever bridge is built into the cable and/or dongle. In other words, a USB 3.0 adapter/hub that plugs into a Light Peak port is possible and even likely.While Intel may control the Light Peak controller, which will no doubt be integrated into motherboard chipsets, I don't think that will give them a monopoly on the bridge chips that make LP actually useful. Reply
  • Exodite - Friday, July 08, 2011 - link

    Cue 'potential'.

    It's not hard to foresee another Firewire or mini-DP in the making, or a Beta if you prefer going old-school.

    Coupling Light Peak technology with mini-DP was a mistake. The technology is new, unproven and offers precious few usage scenarios with non-existent device support. Piggy-backing it on mini-DP, which suffer from pretty much exactly the same issues, won't help adoption rates.

    Choosing USB over mini-DP as the 'legacy' interface would have been a much better choice.
  • André - Friday, July 08, 2011 - link

    Except that the USB connector is only allowed to be used as an USB connector.

    DisplayPort is also vastly superior to any other display cable standard, so I cannot see the problem in that regard. Mini-Display is already shipping in millions and millions of computers, as well as Mini-DisplayPort. The same can be said by Thunderbolt, even though it is only Apple who have fully embraced the technology.

    As a professional in the audio/visual segment I can hardly see the problem with it being a repeat of FireWire, because my market usually adopts the better technology despite of a small price increase. Of course, it helps that we only use Apple computers to begin with and have already ditched all the back-alley, legacy connectors.
  • Uritziel - Friday, July 08, 2011 - link

    Heh, yet another continuation of the myth that media professionals only use macs... Reply

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