Telector screen
From Tardis Wiki, the free Doctor Who reference
The telector screen was a device which was, for a period of time, present in the Doctor's TARDIS. It took the form of a small screen and measured the ship's current position.
On one occasion, the First Doctor noted to his companions, Ian Chesterton and Barbara Wright, that the device was not working properly. Upon exiting the ship, the group discovered that this was in result of the team shrinking to the size of insects. (COMIC: Dr Who in "Lilliput")
After demonstrating the TARDIS's dimensional transcendentalism, the Doctor turned to the telector screen as he noted that the crew would meet with countless adventures as they traversed space time. (COMIC: The Secrets of the Tardis)
