A Mainframe is a device that is linked to a teleporter and functions as a pad on which the teleported subject lands. It appears in the maps Der Riese, Kino der Toten, Moon, The Giant, Revelations and Classified. After a teleporter is used, all players who used it will return to the mainframe. In several maps, the player is required to re-link the teleporter with the mainframe.
In Der Riese and The Giant, the mainframe is in the courtyard, at the spawn. To use one of the three teleporters, the player has to approach it and return to the mainframe in a limited time to create a link. Once all three teleporters are linked to the mainframe, the Pack-a-Punch will open. In The Giant, an easter egg involving the mainframe triggers a laser from the giant robot's head, uncovering a Perk-a-Cola machine (Either Stamin-up or Deadshot daiquiri).
In Kino der Toten, a mainframe is located in the spawn lobby, to which the player gets after teleporting to the Pack-a-Punch room and passing through an intermidate room such as Samantha's Room in the house. Each teleportation requires the player to establish a link with the mainframe
In Moon and Classified, a mainframe can be found in Groom Lake, unlike other mainframes, it is also used to teleport and does not act only as a receiving pad. A similar mainframe can be found in Moon's Griffin station. Some Classified's Documents detail the attempts of Schuster to establish a link to Griffin station for the Americans, however the devices in question are referred to as teleporters and not mainframes.
- Radios in Der Riese and Moon show that both Maxis and Richtofen's team and Schuster's and Richtofen's team work on teleporters have used the mainframe technology.
- During Classified's intro cutscene, a mainframe can be seen in Shangri La. However, such a mainframe is not located in the map itself in-game.
- Several mainframes appear in the icon for the achievement I've seen some things... which was added to Kino Der Toten with Zombies Chronicles.