MacBook (Retina, 12-inch, Early 2015) Target Disk Mode

I find the terminology "full featured" confusing, but I think they just mean a USB-C to USB-A/C cable that supports data (the included one is just power).

Unless I'm missing something, this should do the trick.

@brysontyrrell Yes, that's the implication - the support page indicates that the included cable is only useful for charging, which I find consistent with their vision for the device (you don't connect to things with cables, save for charging). Selfishly, I wish the included cable was also good for data, because I don't have any USB-C cables lying around...

But how could they add to their billions if they gave stuff away.

Am I correct in thinking that - since virtually every other Mac supports Target Boot Mode over FireWire or Thunderbolt, but not USB - connecting an older Mac in Target Boot Mode to the new MacBook is going to be impossible? Say, for purposes of using Migration Assistant to bring data from the old system to a new MacBook?

Target Disk Mode will work over USB-C
https://support.apple.com/en-us/HT204360

"USB Target Disk Mode
Your MacBook supports USB Target Disk Mode when you use it with a compatible, full-featured (“super speed”) USB-C cable. Note that the USB-C Charge Cable (included with MacBook) does not support USB Target Disk Mode.
To enable Target Disk Mode, hold down the T button on your keyboard while starting your MacBook. Then connect the USB-C cable. Use a full-featured USB-C to USB-C cable to connect to another MacBook, or a full-featured USB-A to USB-C cable to connect to a Mac with standard USB-A ports."

@HCSTech Sorry, maybe I confused my description - I don't mean booting a MacBook into Target Boot Mode and connecting it to an older Mac. I'm curious about booting the MacBook normally, and attempting to connect an older Mac in Target Boot Mode to the MacBook: MacBookPro(in TBM)----->MacBook12"

This is the opposite situation than what is described in the Apple support article: MacBook12"(in TBM)------>MacBookPro

I'm aware of only one Mac - the very first MacBook Air - that supports Target Boot Mode over USB.

@brysontyrrell It looks like the monoprice cable you linked to is 2.0....despite being listed as both 2.0 and 3.1 in the description. There is now a note in the reviews from monoprice confirming this. Here's a couple I've seen that should work:

-Aukey
-Belkin (not yet available)

And now... Thunderbolt 3.0/USB-C
http://www.macnn.com/articles/15/06/02/new.protocol.also.makes.passive.thunderbolt.cables.possible.128860/

@Chris_Hafner Wow that sounds very promising. Some additional reading:

Intel
Wired

I just bought one of these thinking I could use it for target disk mode with the 12" MacBook but it doesn't work, can't figure out why..the USB 3.0 A has the SS on it..

https://www.addoncomputer.com/product/USBC2USB3A1MB

so if you need this cable make sure that the description of the product calls out that it works with the 12" MacBook in Target Disk Mode, like this one that I've confirmed works:

https://amzn.com/B00YT688U0

And I can confirm that this Belkin model works:

Belkin USB-C to USB-A

@stevewood does it work both ways, i.e. also having the USB-A machine being in target disk mode?

@alizbazar sorry, I cannot confirm as I am no longer in that role to be able to test.