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
Comments Locked


View All Comments

  • Conner_36 - Friday, July 8, 2011 - link

    Or even in the office, to able to take your entire project and move between the rooms carrying ALL of the data? That's unheard of!

    From what I understand with HD movie editing I/O is the bottleneck.

    All we need now is an SVN hardware device with thunderbolt to sync across multiple thunderbolt RAIDs. Once thats out you could have a production studio with some real mobile capabilities.
  • Exodite - Friday, July 8, 2011 - link

    I wager pretty much any usage scenario can come up with a high-performance 12TB storage solution for significantly less than 2000 USD.

    You're right though, it's definitely not the solution for me.

    Or anyone I know, or am likely to ever know. *shrug*
  • Zandros - Friday, July 8, 2011 - link

    What happens if you try the Macbook Pro -> Pegasus -> iMac in Target Display Mode -> Cinema Display connection chain?
  • Focher - Saturday, July 9, 2011 - link

    Pretty sure the DP monitor has to be the last device in the chain. Maybe that is just a current limitation because there are no Thunderbolt displays.
  • Zandros - Monday, July 11, 2011 - link

    AFAICT, the iMac is a Thunderbolt display, since it does not support Target Display Mode from Display Port sources with Display Port cables.
  • tipoo - Friday, July 8, 2011 - link

    Is there a way to make it shut off the drives after idling for a while?
  • piroroadkill - Friday, July 8, 2011 - link

    But when you saw the file creation maxed out at 9TB, on 10TB array..

    Since.. uh, Snow Leopard, Apple changed file and drive sizes to display decimal bytes as used by the manufacturers, which is the same as the 10TB array.
    However every other thing ever reports in binary bytes, such as windows describing "gigabytes" even though it means gibibytes in reality.

    Ugh, anyway, what I'm trying to get at is that maybe you did infact fill the array. That said, the thing shouldn't have fucked up..
  • CharonPDX - Friday, July 8, 2011 - link

    If I had way too much money, my usage model for Target Display Mode would be to use the iMac as a Virtual Machine host/server, connected to either a second iMac or a MacBook Pro as a dual-screen workstation.

    With the minimum 27" iMac, you're basically buying a 27" Cinema Display plus a $700 Mac mini-on-steroids. If you want a second Apple display for your iMac or MacBook Pro, and want a Mac Mini to use as a server, that is an excellent value to instead just get a second iMac. (That value may drop depending on the next Mac Mini update, of course.)
  • etamin - Friday, July 8, 2011 - link

    in the block diagram on the first page, why is the Thunderbolt Controller connected to the PCH thru PCIe rather than to the processor? I thought PCIe connections came off the processor/NB?
  • repoman27 - Sunday, July 10, 2011 - link

    The lanes that come off the processor/NB are usually used for dGPU. On the new MacBook Pros, Apple borrowed four of them for the Thunderbolt controller. Apparently on the new iMacs, however, they decided to give all 16 lanes from the CPU to the graphics card and pulled four from the PCH instead.

Log in

Don't have an account? Sign up now