Anyone figure out how to connect Apple Thunderbolt Display to DisplayPort or Mini-DisplayPort?

Discussion in 'Mac Accessories' started by themp, Feb 7, 2016.

  1. themp Contributor


    Jun 18, 2011
    Anyone figure out how to connect an Apple Thunderbolt Display to a computer with DisplayPort or Mini DisplayPort? (or a computer with anything besides Thunderbolt?)

    Bought a Thunderbolt Display a while back and my wife thought she'd be able to use it with her work PC laptop... but I haven't been successful in getting it to work. I think its an HP EliteBook 840. She's ready to kill me. Has an adapter been created for this yet or am I hosed?
  2. waw74 macrumors 68030

    May 27, 2008
    sadly, even though they are the same connector, it won't work, as it's a completely different protocol.

    unless you can return the monitor, and get one with MDP, i think the following link might be your only help
  3. priitv8 macrumors 68040

    Jan 13, 2011
    The compatibility works exactly the other way around - on the output side, not input side.
    If you plug DP device into TB port, the controller will recognise it and switch the output into DP mode.
    Not so with TB input plugged into DP output.
    Nor will TB input try to adapt to other outputs, as display is just one possible use of the port/protocol.
    TB is essentially PCIe so actually generic expansion port.
  4. campyguy macrumors 68040

    Mar 21, 2014
    Portland / Seattle
    You're basically hosed. That display will work with TB cables and TB ports (from a Mac or maybe a TB card in a Windows PC). There's a bit more to it with that display than just plugging in a cable, and please ignore priitv8's input here as it's just wrong...

    TB combines power, PCIe, and DP 1.1a. The combination of a Mac and a TB display also involves muxing/demuxing video signals - the Mac muxes the video and the display demuxes the video - DP doesn't "do" that. DP is a subset of TB 1/2, as is PCIe, but there's more going on between a Mac and TB display than that...

    Also, so much of the nifty stuff in the TB display are controlled in Apple's OS - Windows drivers for the TB displays don't exist...

    Go grab a lid from one of your garbage cans - you're gonna need it when she starts throwing shoes at you... :p
  5. priitv8, Feb 8, 2016
    Last edited: Feb 8, 2016

    priitv8 macrumors 68040

    Jan 13, 2011
    What is exactly wrong here?
    To begin with, mDP and TB, despite sharing same connector, use different pinouts. Hence, pins are muxed and how else could a MacBook draw anything on a mDP display connected to it's TB port, than recognising a mDP device and reconfiguring it's pin layout? Please explain that.
    mDP pinout | TB pinout

    Also, when I said TB is essentially generic expansion port, I meant that it is not just display port, rather an extension of CPU external bus. That's why you can also connect things like eGPU-s and disk drives etc to it.
    Your explanation of transport packet muxing is correct, of course. But it's not just that.

    So, basically - TB port will take (magically) a mDP display and still display an image. Since mDP display knows nothing about TB, it must be the computer, that adapts. And that's what I mean by "compatibility works the other way around".
    A mDP port will not take a TB dsiplay, PCIe expansion box or storage device.
    Actually, Apple could have also provided ATD compatibility with mDP ports, had they chosen to allow for the display to also act as mDP device towards the computer (eg via a configuration setting or separate port)
  6. campyguy macrumors 68040

    Mar 21, 2014
    Portland / Seattle
    IMHO, you're missing my point. The OP has a Windows PC box (a laptop) to connect to a TB display - it's not going to happen. My point with your post is you offered that "TB is essentially PCIe so actually generic expansion port" - which is not true, not by a long shot, especially given the two devices the OP wants to connect - a laptop pushing DP and a display that requires a TB connection, keeping in mind that the EDID data negotiation (over DP protocol) isn't going to happen either as that's partly how Apple designed its TB display.

    Basically, a Windows PC isn't going to be able to negotiate an EDID data connection, a mux/demux connection, or a power connection (DP doesn't convey power either). I'm describing a connection between a Win PC and an Apple TB display, that it's not going to happen, and that you are - IMHO - describing "theory" and that you're wrong in your assumptions that the two devices "should" be able to connect and negotiate a connection. Also, TB and DP aren't necessarily compatible - TB 1/2 is DP 1.1a compatible, years behind the current DP 1.2/1.2a/1.3 that's shipping in current Macs and PCs.

    As for muxing, with the Apple TB display, yes, it is just that. That display includes hardware that demuxes a muxed video signal, terminates a DP 1.1a video signal that has been muxed, and remuxes a video signal for the next video device in the DP chain (if there is one). The Apple DP display can pass on a DP 1.1a video channel - but only if it's been sent to it over a TB cable.

    I'm not describing a TB port or a DP port. The Win PC the OP is describing has a DP port - it's not compatible with an Apple TB display between it and a computer. The Apple TB display requires a TB port AND a TB cable, carrying a TB 1/2 signal to the display. Send a DP signal to an Apple TB display and it's a paperweight.
  7. priitv8 macrumors 68040

    Jan 13, 2011
    Well, I see your point. I just was talking about the general background why OP's idea was not going to work. Not the particular pair of mating connectors (s)he has in hands.
    In my opinion, it is always better to understand the ground principles, rather than just know the facts.
    PS I've never assumed ATD (in its current incarnation) would work with mDP port. But I still say the TB port (in general, I also assume on Win PC-s) has been made to be backward compatible with a DP display. Nothing more, nothing less.
    PPS Apple could have made its ATD also compatible with DP-only computers, but it didn't. Probably for other reasons, than technical.
  8. mo_macs_mo_problems macrumors newbie

    Feb 28, 2016
    I believe my question was answered in the above discussion, but I was hoping to get a confirmation.

    I have an older generation iMac with a mini displayport connection, and a newer generation iMac with Thunderbolt connections. Is there any way to connect the two iMac's and use the older generation iMac as a second monitor?

    To throw an extra wrench into things, I have installed Windows 7 on both computers using bootcamp, and I am on the Windows side most of the time.
  9. JTToft macrumors 68040

    Apr 27, 2010
    Aarhus, Denmark
    - Sure you can. Just connect the two with a Mini DisplayPort cable and hit Cmd + F2 on the older iMac.
    The other way around will not work, though.
    I have no clue on the Windows aspect.
  10. mo_macs_mo_problems macrumors newbie

    Feb 28, 2016
    Thanks for your help!

Share This Page