Unfortunately it appears that an i. Mac running Catalina can no longer function in TDM. A Catalina mac can use the display an i. Mac with an older OS that is set to TDM (something I do daily with my Catalina MBP to my High Sierra i. Mac). I don’t know if this is lack of support in Catalina itself or if installing Catalina updates firmware and that kills support.
The next thing we wanted the answer to was; which Mac models can I install macOS Catalina on?
You can install mac. OS Catalina on any of these Mac models. This list will be updated as other compatible models become available. If you’re using one of these computers with OS X Mavericks or later, you can install mac, and os catalina.
Does Target Display Mode work with MBP 2020 13”+ iMac 27”?
According to what Apple Support told me today after some tests with them (and chasing them for a couple of weeks), Target Display Mode does NOT work with MBP 2020 13” + i. Mac 27” late 2013.
Another frequently asked query is “Does the 2020 iMac support Display Port and Thunderbolt?”.
We can dig a little deeper. so, it seems to support display port, but not thunderbolt., both i Macs worked fine in target display mode as a dual setup with my 2017 Mac. Book Pro 13″, but not the 2020.
This begs the inquiry “Can I use a Thunderbolt cable with the new MacBook Pro 13?”
If the other Mac uses Thunderbolt 3, you can use the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with your [genuine Thunder, and bolt] cable. That’s a genuine Thunder. Bolt cable, right, not just a Mini Display, and port cable? Both are Apple issued, the cable and adapter. It works fine from the 2017 Mac. Book Pro 13, just not the new 2020 model.