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Thunderbolt backward compatible with Mini DisplayPort

Codpeace

Codpeace

macrumors regular
Original poster
May 13, 2011
160
101
NYC
Hi all,

There are a lot of questions flying around about what is/isn't possible w/r/t the new iMac being used as a display for other devices, being used with multiple displays, etc.

Everymac says that Thunderbolt is backwards compatible with MiniDisplayPort. See:
"This model is equipped with Thunderbolt ports rather than a Mini DisplayPort. Thunderbolt is backwards-compatible with Mini DisplayPort-equipped displays as well as adapters that are compatible with Mini DisplayPort (DVI, VGA, dual-link DVI and HDMI). ..."
http://www.everymac.com/systems/app...minum-27-inch-mid-2011-thunderbolt-ports.html

So if you could do something on a 2010 iMac, why would you not be able to do it with the new 2011 iMac? Is the compatibility statement false?

I honestly don't know, because I have never owned a Mac. Looking to buy one soon, though, so I am trying to learn as much as possible to smooth my transition from PC.

Thanks.
 
Any mDP to something adapter will work but from what I have heard, something to mDP adapters don't (note the order). That means, you can connect monitors to the iMac using mDP adapters but you cannot use the iMac as a screen with mDP adapters. That is what I have heard, although I'm not 100% if that is correct.
 
Hellhammer said:
Any mDP to something adapter will work but from what I have heard, something to mDP adapters don't (note the order). That means, you can connect monitors to the iMac using mDP adapters but you cannot use the iMac as a screen with mDP adapters. That is what I have heard, although I'm not 100% if that is correct.
Click to expand...

I don't think that's true, since the 27" iMac apparently supports target display mode, which would require a [something] to mDP adaptor. But of cause, not all Macs support target display mode.

As far as I understand it, Thunderbolt is compatible with everything that mDP works with, as the mDP standard is part of Thunderbolt. The thunderbolt part comes in for specific thunderbolt accessories, for example hard drives, daisy chained displays, but obviously those accessories aren't available yet.
 
seb-opp said:
I don't think that's true, since the 27" iMac apparently supports target display mode, which would require a [something] to mDP adaptor. But of cause, not all Macs support target display mode.

As far as I understand it, Thunderbolt is compatible with everything that mDP works with, as the mDP standard is part of Thunderbolt. The thunderbolt part comes in for specific thunderbolt accessories, for example hard drives, daisy chained displays, but obviously those accessories aren't available yet.
Click to expand...

The 2011 iMacs support target display mode, but only when the machine being connected is also running Thunderbolt (so as it stands right now, another 2011 iMac or a 2011 MBP).
 
peskaa said:
The 2011 iMacs support target display mode, but only when the machine being connected is also running Thunderbolt (so as it stands right now, another 2011 iMac or a 2011 MBP).
Click to expand...
If this is true, then the statement that TB is backwards-compatible with mDP is false, no?
 
Codpeace said:
If this is true, then the statement that TB is backwards-compatible with mDP is false, no?
Click to expand...

Semantics. The Thunderbolt port is backwards compatible with MDP if you're going one way (ie: connecting MDP display to TB) but not the other. So strictly speaking it is backwards compatible, just not 100%.
 
An odd choice of connectors

It's really odd to me that Apple went with a connector that they have been using for display ports with Thunderbolt. If nothing else, it just creates far too much confusion, and to many questions about stuff like this. I love Apple, but this was truly a perplexing decision.
 
I assume that a simple hdmi / VGA / dvi cable TO Thunderbolt cable probably won't do then, if they existed? Do you think you will need some kind of convert box to be a be able to connect other devices to the Thunderbolt port on the iMac?
 
With a real Target Dispaly Mode and support for industry standard ports, there would have been a 27" standing on my desk by now.

Oh, who am I kidding, it will be there anyway, it would only have been an easier decision.
 
Richdmoore said:
I read on here that the thunderbolt equipped imacs, target display mode only works when both computers have thunderbolt. I will look for an official apple reference.
Click to expand...

Yeah, target display mode appears to need thunderbolt on both sides. I can confirm it wouldn't work hooking my non-thunderbolt macbook pro up to my thunderbolt iMac 27". Its possible I was screwing something up, but I followed the directions pretty close. And I suspect an adapter to make this work would be pricey, since it probably needs to talk the full thunderbolt protocol now.

But iMac driving out seems fine - both my apple dual-link adapter and my monoprice single-link adapter the same as on my laptop. So seems fully compatible in that direction.
 
The reason the 2011 27" iMac won't accept video inputs the way most consumers would appreciate is a combination of protocol differences and that Apple purposefully retards their products.
 
Codpeace said:
If this is true, then the statement that TB is backwards-compatible with mDP is false, no?
Click to expand...

My guess is that target display mode is either an optional part of the spec or an Apple specific addition to the spec. So the Thunderbolt ports on the new iMacs could be fully compatible with the mDP spec, but not support additional functionality from previous Apple implementations of mDP.

Here's hoping for adapters (or possibly a software update?) to allow mDP->Thunderbolt target display mode, though.
 
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