I have a 27” iMac late 2013, and I would like to use it as my secondary monitor to my MacBook Pro 2020. I noticed there is no HDMI cord in the back of the iMac. I do have a multiport adapter for a HDMI cord for my MacBook, but nothing for the iMac.
Which cord should I use to connect them?
iMac 27″, macOS 10.15
Although that iMac supports Target Display Mode using Thunderbolt input, Apple placed restrictions on the video source. Your MacBook Pro was released after 2019. and so is too new to use any iMac (including your iMac) as a Target Display.
See the bad news here: Use your iMac as a display with target display mode - Apple Support
That iMac is far too old to act as an AirPlay Receiver for AirPlay to Mac. (Note that even where supported, AirPlay would provide lower quality than a hardware-supported connection to a real monitor.)
See the bad news here: Continuity features and requirements for Apple devices - Apple Support
Although that iMac supports Target Display Mode using Thunderbolt input, Apple placed restrictions on the video source. Your MacBook Pro was released after 2019. and so is too new to use any iMac (including your iMac) as a Target Display.
See the bad news here: Use your iMac as a display with target display mode - Apple Support
That iMac is far too old to act as an AirPlay Receiver for AirPlay to Mac. (Note that even where supported, AirPlay would provide lower quality than a hardware-supported connection to a real monitor.)
See the bad news here: Continuity features and requirements for Apple devices - Apple Support
In short, what Servant of Cats is saying (and I agree 100%) is you cannot use your iMac as an external display for the MBP. If the MBP needs an external display, please simply buy one. Why,
Using iMac as second monitor for MacBook pro
