using a 2009 bricked iMac as an external display with windows I have a late 2009 21.5" iMac. It has a mini display port. Its hard drive has been formatted, and I haven't re-installed OSX yet (and don't want to if I don't have to).

I'd like to use the iMac as an external display for a windows PC that has a display port.

Before I buy a mini-display port to display port adapter. How can I tell the requirements for this iMac to support target display mode?
This is pretty easy. No iMac other than some 27 inch models work in target display mode. Not all 27 support it, but some do.  No other size iMac and no other Mac period support target display mode. 


https://support.apple.com/en-us/HT204592


Even the 2009 models 27 inch iMac won’t target display mode - Can I use my early 2009 iMac as an external screen?