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I've recently been reading about new peripherals for the Mac (such as this). I'm very attached to using an external display, but since the DisplayPort is now combined with Thunderbolt, how is it expected that we use an external display and a device?

As I understand it, Thunderbolt supports daisy chaining up to 7 devices, but it would appear that the display/device doesn't support this. Are we going to start seeing ThunderBolt "hubs" anytime soon, or am I asking this question too early?

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3 Answers 3

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Thunderbolt is different than other connectors in that there are two 10 Gbps signals multiplexed on one physical connector/cable assembly. The DisplayPort signal will go down the chain of devices uninterrupted so the full DP bandwidth will get to the monitor that will ultimately end up at the end of the device chain. Of course new display hardware could be released to add a hub / further Thunderbolt connections - but existing DP monitors should work as described.

All the rest of the devices will share in the PCIe bandwidth - sort of like how existing system boards have multiple PCI slots operating at full speed. Until vendors start shipping real devices with hubs and connectors - we are limited to speculation and browsing the engineering/marketing materials released by Intel and Apple.

From what I've read, the initial devices will be like FireWire devices - two Thunderbolt ports per device - one to the computer and one for the next device to connect down the chain. The bi-directional, hot-pluggable, dual-channel cables with substantial bus power means the best aspects of FireWire could be commonplace as a much more powerful standard for years to come.

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I don't know enough about Thunderbolt to say if hubs are possible. If devices are given an ID for their location in the daisy chain line SCSI was, this is probably impossible. Imagine this: your computer is device zero, your external SSD RAID is device 1, your hub is device 2, and your monitors are both device 3. Your computer could get very confused.

I think we'll see Thunderbolt devices come out designed to be daisy-chained. All the devices at the Intel keynote were daisy-chainable (correct me if I'm wrong) and I think that'll just be the Thunderbolt culture, like FireWire.

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As it is right now, you would daisy-chain 6 or 7 Thunderbolt devices and hook your display on the end of the chain. The mini-DisplayPort compatibility is available down the whole chain.

(And yes, there will probably be Thunderbolt hubs, eventually. I propose we call them "Thunderhubs" to save on some typing.)

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Using those devices I linked to, no one says there has to be another "input" on the device. What is to stop a company from making a device that can't be chained to? –  vcsjones Apr 14 '11 at 0:19
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Nothing is there to stop them. –  Jason Salaz Apr 14 '11 at 0:28
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@vcsjones Just like FireWire: it's great if they do, it's possible that they won't, and hopefully they will. Have you ever seen a FireWire hub? (I actually have one, but I nearly never use it. Nearly all my FireWire stuff has a hub in it.) –  CajunLuke Apr 14 '11 at 0:34

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