Target Display Mode - iMac 2012 and Macbook Pro 2020

Not all 2020 MacBook Pros have a silicon M1 processor, some have Intel. I think this "No 2020, No Big Sur" is empirical data since I have not seen any flat-out statement from Apple about Intel Macs, just Use external monitors with your Mac - Apple Support about silicon. However, since Apple has archived the article Use your iMac as a display with target display mode - Apple Support that indicates this is not a feature that is currently supported by any hardware Apple still supports (i.e., anything less than 5 years old).

This could only be done with a very few and very specific older iMacs and support was very limited. Read this topic for a 2021 perspective on this: https://discussions.apple.com/thread/252271436?answerId=254300142022#254300142022

and this 2021 post by Allan Jones about software limitations:

https://discussions.apple.com/thread/252344497?answerId=254428494022#254428494022

and read about Screen sharing https://support.apple.com/guide/mac-help/share-the-screen-of-another-mac-mh14066/mac

I don’t know if this helps or hinders, but I am using a 27” iMac mid-2010 as my display for a 2020 M1 Mac Mini using Big Sur, and connecting the two up with a Morphie USB-C to Mini Display Port cable

https://www.apple.com/shop/product/HN8B2ZM/A/mophie-usb-c-cable-with-mini-displayport-connector

Everything seems to be working relatively OK though I appreciate it isn’t true Target Display Mode, it’s pretty darn close as I’m using the iMac as a target display for the M1 Mac Mini!

Details of the configuration and caveats are here https://discussions.apple.com/thread/252582193 but essentially, the iMac is booted up in High Sierra 10.13.6, the the cable connected to the Mac Mini as it is booting up.

The iMac has the display set to sleep as ‘Never’, and likewise on the Mac Mini but the screen saver works ok but there maybe an impact on the environment and a dent in the wallet over a year!

Anyways, it does show that there is at least one configuration possible out there for the good ol’ mid-2010 iMac 27” to cling onto, which allows it to be used with the latest Adobe upgrades and at M1 speeds.

As for the OP, I suppose it depends upon the MacBook Pro’s thunderbolt connection which may need an adapter at the other end for the 2012 iMac if it doesn’t have the Mini Display Port, but there maybe an appropriate Morphie cable to suit. It would be useful to know, because this and similar questions are cropping up regularly.

I hope this helps, and good luck!

This is not Target Display Mode like the OP needs.

2009 and 2010 iMacs use a different system for TDM than the newer Macs, which allows newer Macs to use these older Macs as displays.

I am glad you got it working, but it is different than the OP's situation.

Cheers,

Jack

Appreciated, and acknowledged in the reply, but I’m not getting Target Display Mode as described in the support material either.

For instance, the F2 do not work to switch screens; have to disconnect the connecting Morphie cable, lightly touch the power button on the back of the iMac and tap the iMac keyboard a couple of times before the iMac screen comes back on. Only then can I see the Mac Mini screen after reattaching the cable.

Whatever the result is far from ideal but for the most part it’s working well. The point being, there are some situations where the documentation or (lack of) spirit and poor intention from Apple to stop such wonderful functionality are not totally accurate, so may be worth a try for the OP or any others asking similar questions and find the thread. Despite Apple’s apparent intentions, the door does not seem to be completely shut! :-)

Hi spammy_CA,

I'm sorry, but 2020 Macs and macOS Big Sur are not compatible with Target Display Mode. It won't work, unfortunately.

Cheers,

Jack

Unfortunately, even if you downgraded, it is still a 2020 Mac, and 2020 Macs are not compatible, even with Catalina.

Cheers,

Jack