Michael Olivero
The official blog of Michael Olivero, Software Architect & Humble Entrepreneur

Thunderbolt and MiniDisplay Mac Compatibility 101

Thursday, 21 July 2011 19:05 by Michael Olivero

I have a MacBook Air 2010 model with the mini display port.  At the office we recently ordered an iMac with the thunderbolt port.  On occasion, I want to use my MacBook Air at the office so I was exploring the option of using the iMac 27 as an external monitor via the thunderbolt port.

The latest macs, both the 2009-2010 models using mini display ports as well as the 2011 using the thunderbolt ports support a feature referred to as "Target Display Mode".  In essence, when properly cabled with either of the two cables, hitting Command/F2 will enable it.

The main question is, what are all the possible combinations?  Meaning, here I am with a mini display port MacBook Air and an thunderbolt iMac 27", do they communicate?  Turns out no, a mini display port cannot target a thunderbolt machine (or monitor) as a target display.   So a little frustrated, I went to them Apple store to sort things out and the Apple employee was super friendly on testing all the combinations with a new thunderbolt MacBook Air and cables I had just bought.  Here are the results:

SourceDestinationCable UsedResultDestination iSight Camera works
MBA Mini Display Cinema Display (Mini Display) Integrated Mini Display Cable Worked Fine Yes
MBA Thunderbolt Cinema Display (Mini Display) Integrated Mini Display Cable Worked Fine Yes
MBA Mini Display iMac 27" Mini Display Mini Display Cable  Worked Fine No, MBA prevails
MBA Mini Display iMac 27" Mini Display Thunderbolt Cable Did Not Work NA
MBA Mini Display iMac 27" Thunderbolt Mini Display Cable Did Not Work NA
MBA Mini Display iMac 27" Thunderbolt Thunderbolt Cable Did Not Work NA
       
MBA Thunderbolt iMac 27" Mini Display Mini Display Cable Worked Fine MBA Prevails
MBA Thunderbolt iMac 27" Mini Display Thunderbolt Cable Did Not Work NA
MBA Thunderbolt iMac 27" Thunderbolt Mini Display Cable Did Not Work NA
MBA Thunderbolt iMac 27" Thunderbolt Thunderbolt Cable  Worked Fine NO, MBA Prevails

One thing to note, when using target display mode and mirroring, the resolution will default to the lowest resolution device. In my case, I had a MacBook Air resolution displayed on the iMac 27 which didn't look great for extended reading. There are two ways to achieve target display native resolution. One way is to close the MacBookAir and tap on the mouse to wake it up. When it wakes up, it will adjust to the target display resolution. With the Thunderbolt MBA, you will need to have the magsafe power plugged in. I am not sure if this is required also for the Minidisplay MBA.

The second way entails setting up a second monitor side by side (uncheck mirroring). The problem here is, if you want to ignore the MBA's monitor and solely use the target display, the dock and menu bar are annoyingly on the MBA monitor making it very cumbersome to work. We accidentally came across a nifty solution by trying out various options. We discovered, just like you can move the orientation of the second monitor, you can move around the menu strip too. So while viewing the monitor orientation window, click and drag the little white strip above one of the monitors and drag it to the other. This in essence moves the doc and menu over to the target display monitor. At this point, you can either dim the brightness of the MBA and you are all set to go.  Thanks!

 

Unfortunately WordPress didn't make it convenient for migrating blogs out of their system.  As a consequence, I'm linking to the original posting for this topic so others can have access to the comment history.  Moving forward I will be updating this blog.

http://mike952.wordpress.com/2011/07/21/thunderbold-and-minidisplay-mac-compatibility-101/