How does CalDigit Dock get HDMI signal?

Discussion in 'Mac Accessories' started by phositadc, Mar 9, 2014.

  1. phositadc macrumors 6502

    Dec 9, 2012
    I see the CalDigit dock has two Thunderbolt ports and an HDMI port. I understand that one of the CalDigit Thunderbolt ports is connected to your Mac laptop, leaving one free for a display (or anything else).

    If you want a second display, the CalDigit has an HDMI output. But how does that HDMI output get a signal? Is it essentially the equivalent of a USB to HDMI adapter, and the display connected to it might therefore have some lag in certain applications? Or is it an actual native HDMI port somehow?

    I'm not very knowledgeable about this stuff, and I don't understand how the CalDigit is getting an HDMI signal to output to a display, when the only thing connected from the Mac laptop to the CalDigit is a single Thunderbolt cable.

    Anybody know? Thanks.
  2. FrancoisC macrumors 6502a


    Jan 27, 2009
    Montreal, Qc
    Thunderbolt is basically a mix of PCI express + displayport, and displayport can be converted to pretty much anything, including HDMI.
  3. phositadc thread starter macrumors 6502

    Dec 9, 2012
    Interesting, thanks for the reply. So say you have a late 2013 Macbook Air that has only 1 Thunderbolt port and zero HDMI ports. You connect it to a CalDigit via the Thunderbolt port. Say you connect two displays to the CalDigit--one via Thunderbolt, and one via HDMI. Is the one connected via HDMI essentially a native HDMI connection? Or is it more like a daisy chained Thunderbolt display?
  4. phositadc thread starter macrumors 6502

    Dec 9, 2012
    I think I found the answer at

    It looks like it would be like a Thunderbolt to HDMI connection. So if you are using a computer with support for only one Thunderbolt display (such as Macbook Air), you cannot use both the Thunderbolt port AND the HDMI port for displays. You would have to use either the Thunderbolt port OR the HDMI port, and then a USB port via USB-to-HDMI adapter for the second display.

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