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Swaamedic Author

Level 1

4 points

How to use an iMac as a second display?

I'm trying to use my older iMac 2012 (running Catalina) with a thunderbolt connection as a second display for my 2020 iMac running BigSur. I've connected the two and the F2 does not work. (I've tried all the F2 simple fixes, different keyboards etc). The older Mac will be recognized by my MacBook Air (2018) and work as a monitor (So I know my USB-C to thunderbolt adapters, all $100 worth, are good) but my new iMac running BigSur will not detect it. Has my old Mac become useless and obsolete now?

Thanks,

iMac Line (2012 and Later)

Posted on Dec 13, 2020 3:55 PM

Top-ranking reply

Malcolm J. Rayfield

Level 7

23,059 points

Posted on Dec 13, 2020 8:37 PM

Use your iMac as a display with target display mode - Apple Support

"You can connect any of these older iMac models to another Mac from 2019 or earlier for use as an external display."

Also:

"Target display mode requires macOS High Sierra or earlier on the iMac used as the external display. It does not work with macOS Mojave or later."

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How to use an iMac as a second display?

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