rMBP using iMac as external display in Target Display Mode - with lid closed?

[jennyp]

Right now I have a mid-2011 iMac, and next to it an ageing mid-2009 MacBook Pro.

I'm looking to buy a new rMBP when they get updated, and I thought when I do, I'd be able to use the iMac as an external display in Target Display Mode.

I saw a YouTube video showing how to do this, but I can't seem to find out if it's possible to do this with the rMBP lid closed (aka "clamshell mode'). Would that be possible?

Thanks!

 

[whlabus]

I can't see why it wouldn't. OS X should just treat it as it would any other external display, allowing you to extend the desktop, mirror it, or close the notebook lid and use it as the sole display. One thing to note is that I'm fairly certain only the 27" iMac can be used as an external display, the 21.5" cannot.

 

[simonsi]

I can't see why it wouldn't. OS X should just treat it as it would any other external display, allowing you to extend the desktop, mirror it, or close the notebook lid and use it as the sole display. One thing to note is that I'm fairly certain only the 27" iMac can be used as an external display, the 21.5" cannot.

My 2011 iMac 21.5" can be used as a target display using a TB cable. I think there are model year dependencies for both being and able to use a target display iMac.

 

[Mooseiah]

There may be a workaround for it, but with just factory programs you need to have it plugged into the power adapter for it to not shut itself off when you close the clamshell Works perfect as long as it's plugged in though.

 

[jennyp]

I should have said that the iMac is the 27 inch.

Thanks for the info. I get the impression I can do it, as long as the rMBP is connected to power. That's great

 

[SVTmaniac]

Connected to power, and an external keyboard, mouse and display attached. That's the requirements for clamshell mode. Any of those are taken away and it will just go to sleep when you close the lid.

 

[qtx43]

Connected to power, and an external keyboard, mouse and display attached. That's the requirements for clamshell mode. Any of those are taken away and it will just go to sleep when you close the lid.

To prevent sleeping, you might try opening a terminal and typing:

caffeinate -i read

I think that should work, haven't tried it with an external display. Then to go back to normal, go to the terminal and type some input and return (or control-C).

 

[defboob]

Yep you definitely can. I have a 2009 iMac 27 and a new rMBP 13" - using a miniDisplayPort cable works great, it switches over right away, and you can close the lid just fine. the screen flicks off and back on quickly when you do it, but then it's fine.

Also you don't even need an external keyboard, just a mouse will work too - however that doesn't make much sense...but it still works.

 

[jg321]

I should have said that the iMac is the 27 inch.

Thanks for the info. I get the impression I can do it, as long as the rMBP is connected to power. That's great

As has been said, TDM doesn't change anything, it's the clamshell requirements that determine this, which are power and keyboard/mouse. I use both a cMBP 13" and an rMBP 13" hooked up to a 21.5" late 2013 iMac in this way.

TDM is great in principle, but has the following drawbacks for me:

1) Using the iMac kb/mouse on the laptop is a bit of a faff. I'm currently achieving this in a similar manner to the "bash script" at the bottom of http://wherenow.org/imac_target_display_bluetooth_keyboard_mouse/

2) It's flakey. CMD+F2 often needs to be pressed like 5 times. If the iMac locks itself you have to type your password in blind to press CMD+F2 (or use Screen Sharing). Pulling the cable doesn't help either, screen just stays black. Disabling auto-lock just isn't an option for security reasons.

Overall, it feels very half-assed and not very "Apple" in my opinion. It should either work properly and efficiently or not be an option.

To prevent sleeping, you might try opening a terminal and typing:

caffeinate -i read

<snip>

Not certain on this one, but I assume this won't stop the physical hardware action of putting the computer to sleep. Could be wrong though, but you're gonna need power/kb/mouse anyway if "docking up", so likely not needed.

 

[jennyp]

Using the iMac kb/mouse on the laptop is a bit of a faff. I'm currently achieving this...

@jg321 - Thanks for those points ... presumably I can just plug in my spare Apple keyboard & mouse into the rMBP to use those whilst displaying on the iMac?

 

[jg321]

@jg321 - Thanks for those points ... presumably I can just plug in my spare Apple keyboard & mouse into the rMBP to use those whilst displaying on the iMac?

Yeah if you have two sets then you're fine. Trying to share them is a pain though!