Q: Does the 21.5" iMac support TDM or not?

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Thunderbolt 21'5-inch iMacs support Target Display mode, but Late 2009 and Mid 2010 21'5-inch iMacs don't support Thunderbolt. See > http://support.apple.com/kb/PH11302

To use the 21'5-inch iMac as an external display, simply connect it with a Thunderbolt cable to another Mac with Thunderbolt, and press Command and F2 keys on your iMac to enable Target Display

The article mentions the iMac with Thunderbolt, and then it mentions the 27-inch iMac with Mini DisplayPort, which are the Late 2009 and Mid 2010 computers. As I told you, Mid 2011 and Late 2012 21'5-inch iMacs have Thunderbolt, so they support Thunderbolt. Have a look at this forum.

leona0123 wrote:

 

I was told that if I connected the two computers, that I would only be able to transfer data between them, and the displays would not be connected in any way.

You can connect a Thunderbolt Mac to the Thunderbolt iMac for both things, but you need to follow additional steps:

• To enable Target Display mode: press Command and F2 keys on the iMac.
• To enable Target Disk mode (transfer files between Macs without Migration Assistant): hold the T key while your iMac or the other computer is starting

You are welcome

does target display mode work on iMac late 2009 21.5 inch

Just throwing my input in.  My 2011 21.5" iMac, which is running OS X 10.6.8, supports target display mode just fine via thunderbolt cable.  I too was confused after being told both that it did and didn't, but it works.

I have a late 2009 iMac 21.5", you can use it as a display on any Mac that has a Thunderbolt or MiniDisplay (dedicated older port), its the cable or adapter that would make the connection. I use the Mini DisplayPort to Mini DisplayPort cable to make the connection. (Apple no longer carries) but you can grab you one from Amazon, I have a Belkin cable that I got when I first got that iMac. The newer Macs that have the Thunderbolt port on it, would use a the same cable except you plug it into the Thunderbolt port which is backward compatible with Mini Display Port. Per Use your iMac as a display with Target Display Mode - Apple Support the only exception is the iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays. So the store would have been correct on the 2015 21.5" models. Grab a refurb if that's your ultimate goal from the Apple Online Store.

tammylig wrote:

... So the store would have been correct on the 2015 21.5" models. Grab a refurb if that's your ultimate goal from the Apple Online Store.

You may have missed the fact that this thread is over 2 years old.

Actually tthere's two new responses on here sorry though didn't mean to offend you replying to the newest questions

hi. i know this thread is old but i have just seen you replied recently, so i was hoping you could help.

i also have a late 2009 21.5 inch imac which i´d like to use as target display for a new macbook pro, and i got a Mini Display Port to Mini Display Port cable to connect the two, but when i press F2 on the imac nothing happens.. can you tell me what you did to make it work? i read everywhere that its only possible with the 27 inch late 2009 imacs, but you seem to have done it with the 21.5 inch.. thanks

I just bought one and its not working either.. I bought the port after reading Apple's site and saw "2009 iMac works" and thought it would work - but then I went back and saw it only says for the 27 inch - I'm guessing it might be due to it having a better processor? Perhaps it worked for the other 2009 person because theirs was upgraded? I wish I knew how to get it to work

I am in the same situation as you are and beckcarioca. Has it finally worked for you? That is successfully use the late 2009 iMac 21.5" as external display to MacBook Pro using MDP-MDP cable?

You may have already read Use your iMac as a display with Target Display Mode - Apple Support, Apple is VERY clear which iMacs support TDM. Unfortunately no 21.5" iMac from any year (so far) supports it.