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Definition: Target Display Mode


An iMac feature that lets the screen function as an external monitor for another computer. Thunderbolt-based iMacs starting in 2011 can only be a Target Display Mode (TDM) screen for computers connected via Thunderbolt. Previous Mini DisplayPort-based iMacs could serve as an external screen if connected via Mini DisplayPort, as well as Thunderbolt, HDMI and DVI with the appropriate adapter cables. See Target Disk Mode.