I have a setup of a MacBook Air (2013), an iMac (2009), and a regular external monitor. I’m able to connect either the iMac or the monitor to the MacBook and use them as an additional screen. Is there way though to connect both of them at once, so that I have two external monitors managed by the MacBook? Obviously, the MacBook only has one Thunderbolt port, but there’s an extra one available on the iMac. Any way to utilise it in this case?

  • What cable are you using to connect the 2013 MacBook Air to the 2009 iMac. This is what I'm trying to work out.
    – user59299
    Commented Oct 11, 2013 at 12:30

2 Answers 2


Short Answer

Yes, but you need a USB display adapter (any DisplayLink adapter, like this one should do) for your MacBook Air, the iMac can’t do passthrough.

Longer Answer

The 2009 iMacs don’t have Thunderbolt, only mini-Displayport. Even the later iMacs with Thunderbolt can’t do passthrough with their second Thunderbolt ports. Therefore you need a second display connection on the source Mac. Since the MBA only has one, you’ll need to use a USB-based adapter. There are many options, pretty much all of them using the DisplayLink technology. It works well for 2D stuff, but don’t expect to do any gaming or other 3D work on it.

  • I am also trying to use a 27" imac (late 2009 model) as an external display with a 2013 macbook air, but with no success so far. I've purchased a MiniDisplay Port to MiniDisplay Port cable, but that doesn't seem to work for me. According to your post, you succeeded to use a 2009 imac as an external monitor. Could you please collaborate how you achieved this?
    – mrcrazylee
    Commented Jun 17, 2014 at 20:56

This is now possible on macOS Monterey 12.4 and the Universal Control feature.

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