Imac as a monitor

[drmajor]

My Imac's HD is dead. I was playing with it- can it be used as a monitor for my Macbook?
I connected Mini-Display cable- nothing.
Imac boots to Apple screen- which goes nowhere.

I plan to replace HD in Imac- just playing with it.

 

[redheeler]

Nope. Target Display Mode only works when the iMac is booted into MacOS.