Imac 2010 as second screen for macbook 2015
Hello I have an old 2010 imac and I want to use it as a second screen for my 2015 macbook pro. I have connected from the HDMI on the macbook to the mini display port on the imac but can't get the imac to switch to target mode. Command + F2 is not working and neither is Fn +command + f2. Do I need a different cable (I.e. Thunderbolt to Thunderbolt)?