Inspired by the success and limitations of the Navigator program, the Type 51 was equipped with a Cybernetic Personality Matrix Interface. The original hope was, with the aid of a Symbiotic Bypass, to create a TARDIS that could function autonomously without any crew at all. This would have removed the need for Time Lords to participate in the purely observational journeys that make up the majority of off-world travel. While this goal was abandoned in the design phase the programmers still hoped to create a TARDIS that could function as a fully interactive 3-dimensional and 5-dimensional life-form. To this end, the matrix was programmed to replicate Gallifreyan mental and emotional responses.
The CPM Interface was able to verbally interact with the operators and acts as a liaison with the Sentient Matrix in the TARDIS's Protyon Core. The CPMI is capable of controlling all the TARDIS's functions (assuming the Automatic Systems Override hasn't been thrown). The interface was not carried over to later models of TARDIS because there was a basic design flaw in the system that caused the CPMI to develop new, disruptive, personalities. This was caused by the engineered brain's inability to understand the subtle block-transfer processes holding the TARDIS together. A visit to a Gallifreyan Repair Center was often necessary to reset the personality. Another minor oddity of the interface is that it can often be heard faintly whispering when the Type 51 is talking to another TARDIS.
- The Type 51 was the first and last TARDIS to have the Cybernetic Personality Matrix Interface as a standard component.
- Most of the production run was scrapped.
- The remainder were removed from the registry and put to use by Interventionists of the CIA.
The following color code is used:
- Black: For information from the TV Series, including Dimensions in Time, and 1996 TV Movie.
- Blue: For information from the Novels and Audios including Target, Virgin, BCC, and Big Finish.
- Green: For information from 'licensed' reference sources such as the Technical Manual, Doctor Who Magazine, and the Role Playing Games.
- Red: For information from unofficial sources -The Faction Paradox series, behind the scenes interviews, author's speculation, and popular fan belief.
The TARDIS Technical Index is copyright Will B Swift.