The Type 1 TARDIS (also known as the Type One) was an early prototype created by the elders of ancient Gallifrey. It was poorly designed, dangerous to operate and difficult to start. Some of them had minds of their own, with a history of escaping and roaming the universe. (PROSE: Heart of TARDIS)
After being marooned on ancient Gallifrey, the Eleventh Doctor sought out supplies to repair his TARDIS, only to be drafted by Rassilon into helping develop the Type 1s after he had calmed down one of the ships. Though the Doctor attempted to extradite himself from the testing, he was eventually assigned to take the ship he'd calmed down on its first flight through the Time Vortex. Though the Doctor intended to use the Type 1's parts to repair his own ship, a leftover dimensional bubble caused the Type 1 to panic during dematerialization with both her and the Doctor being considered lost. The Type 1 survived the trip but wound up in the Void.
The Doctor's companion, Alice Obiefune, refused to believe the Doctor was dead and sought out a Type 1 who also believed her sister ship had survived. The two left Gallifrey to search only to wind up crashing on an oceanic planet. With the Type 1 beyond repair, Alice was forced to call the Doctor for a lift.
Content with the peace of the Void, the Type 1 refused to return. Unable to work the controls, the Doctor wired himself to the TARDIS via the telepathic circuits to try and convince her to return to N-Space via his memories of its wonders. The Type 1, however, perceived the universe as a chaotic place, and sought to end it, taking on the imperative of "Silence Will Fall". To that end, it used the Void to generate anti-time energies to destroy the universe via white holes. When the other Doctors were drawn into the rift however, the twelve of them were able to convince the Type 1 to stop its efforts by linking the telepathic circuits of their TARDISes to the Type 1. Through this, the Type 1 was able to reevaluate her initial perception of reality and jettisoned all that she had consumed. Despite this, she still desired peace and remained in the void. As the universe returned to normal, the Twelfth Doctor, the only one to retain any memories of the events, told Bill and Nardole about the Type 1. (COMIC: The Lost Dimension)