iMac USB Hi-Speed Bus vs SuperSpeed Bus

Discussion in 'iMac' started by Solomani, Feb 26, 2014.

  1. Solomani macrumors 68030

    Solomani

    Joined:
    Sep 25, 2012
    Location:
    Alberto, Canado
    #1
    I was wondering if someone can help explain the following to me.

    Looking at my late-2012 iMac (21.5" quad-core i7) System Information, the hardware lists 4 USB ports in the following order:

    USB 3.0 Hi-Speed Bus
    USB 3.0 SuperSpeed Bus
    USB Hi-Speed Bus
    USB Hi-Speed Bus

    My first question is, does the hardware system info above imply that I have two USB 3.0 ports and the other two are older USB 2.0 ports? I wasn't aware that Apple mixed and matched USB ports.

    And what is the difference between a USB 3.0 Hi-Speed Bus and a USB 3.0 SuperSpeed Bus? Is one better than the other?

    Just some USB questions that I never really paid attention to before. Maybe it might make a difference if I knew which is the best iMac USB ports to plug in something (like charging my iPod Touch or iPad or synching via USB).
     
  2. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #2
    Superspeed is 5.0 Gbit/s
    HiSpeed is 480 Mbit/s

    The one that says USB 3.0 Hi Speed Bus probably means it sees a USB 3 controller in a slower device. The ones that just say USB Hi-Speed Bus probably have USB 2 devices connected.

    If you list what's connected to each port, you might get a better answer.
     
  3. Solomani thread starter macrumors 68030

    Solomani

    Joined:
    Sep 25, 2012
    Location:
    Alberto, Canado
    #3
    That's only partially true. When I listed the above hardware profile, I only had a single USB device attached, which was an Apple Extended USB Aluminum Keyboard (using the USB 2.0 specification) attached to USB port #4, which is one of the USB Hi-Speed Bus ports.

    The other 3 ports have nothing plugged into them. Very odd.
     
  4. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #4
    I forgot how OS X lists USB devices. (I haven't had to check System Information on my system in quite a long time.) I'd have to see a listing with devices plugged in to give an accurate answer, possibly from more than one configuration of devices.
     
  5. DeltaMac, Feb 26, 2014
    Last edited: Feb 26, 2014

    DeltaMac macrumors 604

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #5
    I think you can test this.
    Connect a USB 3.0, SuperSpeed device to one of the built-in ports, then refresh the USB page of System Information.
    What does that page report for the SuperSpeed connection?
    Eject the device, and move the USB to another port, then refresh the page to update the list. What do you see now?
    Do the same for each of the ports.
    Now, if you have them available, connect true USB 3.0 devices to all ports at the same time, then refresh the page again. (you can't do this with a USB keyboard, obviously, unless the keyboard is a USB 3 model, I don't know if those exist yet)
    Are ALL ports showing as SuperSpeed devices?

    I think you will find out that the connection speed is determined by the device connected to the port, and not the port itself (your Mac doesn't know what you will connect prior to the connection, only after.)
     

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