A black box was a device which recorded the movement of a vehicle. If the vehicle crashed, the black box could be used to find out what happened.
Ships during the Dark Times, such as the Infinite, used data chips as a black box. (TV: The Infinite Quest)
In the 21st century, the Sycorax used stone spheres as black boxes. (COMIC: The Widow's Curse)
The Rokathia black box was used by the Rokathia. They were intelligent and telepathic, allowing them to control people into sending a message. (COMIC: Opera of Doom!)
In the 51st century, ships used Home Boxes. If something went wrong on the flight, the Home Box was ejected and returned home with the flight details. (TV: The Time of Angels)