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Hi, how do I connect a 2020 iMac to a 2009 iMac? I want to use the 2009 iMac or 2012 Macbook Pro as a second screen.

I have a thunderbolt wire, but the iMac 2020 don't have a port for the thunderbolt anymore. What kind of adapter do I need? How do I connect them? So that I will only use one keyboard and one mouse for all of them.

iMac 27″, macOS 10.12

Posted on Sep 29, 2023 8:34 PM

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Posted on Sep 30, 2023 12:14 AM

Your welcome. You can moves files from one computer to the other. That is Sharing. Information on Sharing can be found by clicking


.Set up file sharing on Mac - Apple Support



an even easier method is to setup iCloud on both computers , please click


Set up iCloud Drive - Apple Support



5 replies

Sep 30, 2023 2:16 AM in response to fitzdarcy

27" Late 2009 iMacs don't have Thunderbolt. They have Mini DisplayPort – which is an advantage when it comes to Target Display Mode, because it means you don't need Thunderbolt input, just regular Mini DisplayPort input. If that was the end of the story, all you'd need is a USB-C to Mini DisplayPort adapter cable - the same type of adapter you might use to connect to a modern standalone monitor.


Unfortunately, Apple put restrictions on the other device after the fact. It now must be a Mac that was introduced in 2019 or earlier and that is running macOS Catalina or earlier. Both restrictions lock out your M1 iMac. I suppose you could try using a USB-C to Mini DisplayPort cable and TDM, but there's no guarantee that it would work. (If it did, a future system update might break it out from under you.). Most likely result is you'll wind up with a spare cable that you or someone else could use to connect to a real display.


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


People with iMacs made between 2011 and mid 2014 are in a much worse boat. Those Macs have Thunderbolt, and require Thunderbolt input (probably for technical reasons). Connecting a modern Mac with a Thunderbolt 3 / 4 port (USB-C connector) to an ancient one with a Thunderbolt 1 / 2 port (Mini DisplayPort connector) would set you back about $80 for specialized Thunderbolt hardware ($50 TB3-to-2 adapter + $30 TB1/2 cable).


Since none of the iMacs that support TDM have resolutions higher than 2560x1440 pixels, and monitors have come down in price a lot, spending $80 on specialized Thunderbolt hardware to try to use an ancient TDM-equipped iMac in a now-unsupported way isn't particularly attractive. Not compared to putting the $80 towards a new monitor that has the same or better size/resolution, and that probably has more years of life left before it fails.




Hi, how do I connect a 2020 iMac to a 2009 iMac? I want to use the 2009 iMac or 2012 Macbook Pro as a second screen.

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