The Matrix, in the long-running British science fiction television series Doctor Who, is a massive computer system on the planet Gallifrey that acts as the repository of the combined knowledge of the Time Lords. Background The Matrix is first introduced in the 1976 serial The Deadly Assassin, twenty-three years before the release of the film The Matrix, six years before William Gibson's 1982 "Burning Chrome", eight years before Gibson's novel Neuromancer and years before the advent of virtual reality in the 1980s. It is one of the locations for a battle between the Doctor and Chancellor Goth, the titular assassin. Most of Part Three of the serial is spent inside the virtual reality of the Matrix where the Doctor battles an agent of the Master. The serial also explains that if a person dies while linked to the Matrix, he dies in the real world as well. Access to the Matrix is obtained through an apparatus connected to or enclosing the head of the user or, physically, via Doors into which the user walks. The Matrix functions as a simulated reality, the physical laws of which an advanced user may bend or break. Full access to the Matrix is given only to the President of the High Council of Time Lords through the use of the Crown of Rassilon, but limited access to its contents is guaranteed to other Time Lords. The Keeper of the Matrix holds the Key of Rassilon that grants access to the Seventh Door, which was thought legendary until the Doctor used the Key to access it in The Ultimate Foe. The Matrix is part of the Amplified Pana tropic Computer Network, or APC Net, which contains the biological imprints (or bio-data extracts) of all Time Lords as well as the memories of dead Time Lords, storing them in an extradimensional framework of trillions of electrochemical cells. It also receives input from sensors contained in the TARDIS time machines piloted by Time Lords. As a result, the Matrix is not only a record of the past but can actually predict the future as well. The amount of knowledge in the Matrix, though vast, is not complete, and can be tampered with if given the right amount of access. The unauthorised extraction of a Time Lord's bio-data from the Matrix is an offence tantamount to treason (Arc of Infinity). In The Trial of a Time Lord, evidence