Data chip

Data Chips were a means of flight recording developed during the Dark Times. They functioned like black boxes, allowing people to trace the ships. This required advanced technology, since the chips were older than most species' histories.

The spacecraft Infinite had four data chips. Each was a small disk with an infinity symbol on it. Each would allow the owner to find the next data chip. When they had all four, they could find the Infinite. After the Infinite was destroyed, its chips were scattered around the universe. Eventually, Baltazar, Capitan Kaliko, Meregrass and Gurney were each able to obtain a data chip by their time at Volag-Noc. Using the Doctor to track them, Baltazar killed the other three and took their data chips. (DW: The Infinite Quest)