A prioritron

On entering 's TARDIS control room, the Eighth Doctor noted that the a prioritron, the randomiser and the safety locks were still operational. (AUDIO: The Castle of Kurnos 5)

Behind the scenes
In philosophy, something can be known without sense experience, coming before experience, as contrasted with  knowledge, which is gained through interaction with the world. These terms are central to Immanuel Kant's pursuit of synthetic a priori knowledge, a priori knowledge which is not based on the meaning of the words in the statement. (e.g. "All bachelors are unmarried" would not qualify.)

Etymologically, the suffix -tron refers to an instrument or device, things one would typically use in the formation of a posteriori knowledge, rather than a priori.