Switch room
From Tardis Wiki, the free Doctor Who reference
Within the Time Sceptre, the switch room was the lower half of a TARDIS control room. (REF: The Visual Dictionary (2007 edition) [+]Loading...{"var":"2007 edition","1":"The Visual Dictionary"})
In some TARDIS designs, a switch room was located underneath a TARDIS control room as the hub of the vehicle's operation. It contained a combination of semi-organic, fibre-optic, metallic, and acoustic circuitry extending down from the TARDIS console, connecting it to the rest of the TARDIS via dimensional bridges and transdimensional links. In the Time Sceptre, the switch room completed the central sphere of which the control room was the top half.
There were steps leading from the Tenth Doctor's control room so that he could access the switch ropm. (REF: The Visual Dictionary [+]Loading...["The Visual Dictionary (2007 reference book)"])
