3 ms·

Thunderbolt runs over USB-C, as well as DisplayPort. USB 3.1 features re-configurable lines that can negotiate almost any protocol. [1] [2] [1] http://www.anan

Thunderbolt runs over USB-C, as well as DisplayPort. USB 3.1 features re-configurable lines that can negotiate almost any protocol. [1] [2] [1] http://www.anandtech.com/show/8558/displayport-alternate-mode-for-usb-typec-announced http://www.anandtech.com/show/8558/displayport-alternate-mod... [2] http://www.anandtech.com/show/8539/usb-power-delivery-v20-and-billboard-device-class-v10-specifications-finalized http://www.anandtech.com/show/8539/usb-power-delivery-v20-an...

afandian 12y ago
I've not read those docs (sorry) but what if I want to run DisplayPort for my monitor and simultaneously plug in an external USB drive? Can a single line switch between protocols?
- mmastrac 12y ago
  Yes you can. IIRC you can run USB3.x-speed devices and one alt-mode over a single line.
- lsaferite 12y ago
  They will be able to MUX two DP lanes onto two of the USB SS lanes and keep one for USB 3.1 as well. Also, there are dedicated wires for USB 2.0 as well that are separate from the SS lanes.
djrogers 12y ago
Displayport != Thunderbolt. Displayport is a protocol that can run over a thunderbolt port, but the thunderbolt spec includes much more than that. I don' believe we'll be seeing the 40Gbps PCI extension that is today's thunderbolt over USB 3.1.
- ajross 12y ago
  You're getting too tied up in brand identity and going too far in the other direction. What we call "Thunderbolt" is effectively an evolution of the DisplayPort PHY (which already supported graphics streaming of course, and also encapsulated USB transfers) with protocol extensions to do more PCI-like transactions. And the USB 3.1 "SuperSpeed+" PHY is a 10Gbps thing that is very comparable to Thunderbolt electrically and would be expected to evolve similarly. You're right that USB lacks the PCI framework (which many of us view as a feature). But DP/Thunderbolt similarly lacks a cabling standard with the sophistication of USB: no charging, not reversible connectors, no OTG-style switching of host/guest mode. Apple had a choice of supporting both connectors, or giving up "PCI madness" or "nice cables" to get just one. They picked USB.
  - mikeash 12y ago
    That's all well and good, but the question was whether it supported actual Thunderbolt, to which the answer given was "yes" but the actual answer appears to be "no." Supporting something like Thunderbolt is nice, but not exactly the same. It's not about "brand identity," it's about "does this equipment I have work with this machine?"
    - ajross 12y ago
      That's hardly unique to this situation though. It doesn't support Firewire or eSATA or VGA or ethernet or AppleTalk or Centronics parallel either. Life moves on, and this is hardly a company gripped by concerns for backwards compatibility.
      - mikeash 12y ago
        You seem to have confused "Is this the end of Thunderbolt as well?" with "I hate Apple forever for changing things." It's a simple question with a simple answer. (Yes.)
      - zoul 12y ago
        Life moves on, but Thunderbolt is such a new interface to be obsoleted.
    - lsaferite 12y ago
      Just to clear up the FUD, the Type-C connector supports 'Alternate Modes.' This allows manufactures to implement chips that can MUX different signal types onto the USB cable SS lanes. There are 4 SS lanes that can be reassigned and either 2 or 5 additional wires that can also be used depending on if it's a cable or dock connection. So, can the Type-C connector support Thunderbolt? Yes. Does the Type-C connector currently support Thunderbolt? No. Will someone add Thunderbolt over Type-C? Maybe. I've only heard of PCIe over Type-C (via the spec docs) and DP over Type-C (from the VESA guys).
      - mikeash 12y ago
- lsaferite 12y ago
  So, in alternate mode all 4 SS lanes can be reassigned. Each lane is doing 10Gbps right now from what the specs say. You could do PCIe over this and they even use PCIe as an example in the Type-C spec documents.
lsaferite 12y ago
Just to clarify what you said, Alternate Mode allows two directly connected devices to negotiate what the SS lanes and a few other wires are used for. The signaling that happens over the wires after negotiation is totally outside of the USB spec as the signals are simply MUXed onto the wires. In theory you could MUX anything over the wires as long as the signaling parameter fell within the specs defines for the cabling.

afandian 12y ago

I've not read those docs (sorry) but what if I want to run DisplayPort for my monitor and simultaneously plug in an external USB drive? Can a single line switch between protocols?

mmastrac 12y ago
Yes you can. IIRC you can run USB3.x-speed devices and one alt-mode over a single line.
lsaferite 12y ago
They will be able to MUX two DP lanes onto two of the USB SS lanes and keep one for USB 3.1 as well. Also, there are dedicated wires for USB 2.0 as well that are separate from the SS lanes.

djrogers 12y ago

Displayport != Thunderbolt. Displayport is a protocol that can run over a thunderbolt port, but the thunderbolt spec includes much more than that. I don' believe we'll be seeing the 40Gbps PCI extension that is today's thunderbolt over USB 3.1.

ajross 12y ago
You're getting too tied up in brand identity and going too far in the other direction. What we call "Thunderbolt" is effectively an evolution of the DisplayPort PHY (which already supported graphics streaming of course, and also encapsulated USB transfers) with protocol extensions to do more PCI-like transactions. And the USB 3.1 "SuperSpeed+" PHY is a 10Gbps thing that is very comparable to Thunderbolt electrically and would be expected to evolve similarly. You're right that USB lacks the PCI framework (which many of us view as a feature). But DP/Thunderbolt similarly lacks a cabling standard with the sophistication of USB: no charging, not reversible connectors, no OTG-style switching of host/guest mode. Apple had a choice of supporting both connectors, or giving up "PCI madness" or "nice cables" to get just one. They picked USB.
- mikeash 12y ago
  That's all well and good, but the question was whether it supported actual Thunderbolt, to which the answer given was "yes" but the actual answer appears to be "no." Supporting something like Thunderbolt is nice, but not exactly the same. It's not about "brand identity," it's about "does this equipment I have work with this machine?"
  - ajross 12y ago
    That's hardly unique to this situation though. It doesn't support Firewire or eSATA or VGA or ethernet or AppleTalk or Centronics parallel either. Life moves on, and this is hardly a company gripped by concerns for backwards compatibility.
    - mikeash 12y ago
      You seem to have confused "Is this the end of Thunderbolt as well?" with "I hate Apple forever for changing things." It's a simple question with a simple answer. (Yes.)
    - zoul 12y ago
      Life moves on, but Thunderbolt is such a new interface to be obsoleted.
  - lsaferite 12y ago
    Just to clear up the FUD, the Type-C connector supports 'Alternate Modes.' This allows manufactures to implement chips that can MUX different signal types onto the USB cable SS lanes. There are 4 SS lanes that can be reassigned and either 2 or 5 additional wires that can also be used depending on if it's a cable or dock connection. So, can the Type-C connector support Thunderbolt? Yes. Does the Type-C connector currently support Thunderbolt? No. Will someone add Thunderbolt over Type-C? Maybe. I've only heard of PCIe over Type-C (via the spec docs) and DP over Type-C (from the VESA guys).
    - mikeash 12y ago
lsaferite 12y ago
So, in alternate mode all 4 SS lanes can be reassigned. Each lane is doing 10Gbps right now from what the specs say. You could do PCIe over this and they even use PCIe as an example in the Type-C spec documents.

lsaferite 12y ago

Just to clarify what you said, Alternate Mode allows two directly connected devices to negotiate what the SS lanes and a few other wires are used for. The signaling that happens over the wires after negotiation is totally outside of the USB spec as the signals are simply MUXed onto the wires. In theory you could MUX anything over the wires as long as the signaling parameter fell within the specs defines for the cabling.