Calculator The Calculator was the computer that controlled Vault 0 , serving as its overseer . Unlike the ZAX computers , it was not an example of real Artificial Intelligence , instead being a cyborg , as it was connected with several human brains . Background . Origin . According to official information , one advantage the Calculator had over normal computers was the electro - organic linking terminal . The CPU could share tasks and receive data from pseudo - cryogenic stored brains maintained in an oxygenated tank . These brains were initially those of lab rodents , but calculations eventually indicated that human brains could be preserved in the same fashion . The brains were fed specifically formulated nutrients to sustain suspended life . In turn , they assisted the Calculator ' s CPU in vault management , including life support , food production and distribution , Vault 0 defenses , and " pacification protocol " . The brains of the eight most promising humans of Vault 0 were chosen to become one with the Calculator : The neural network was also meant to assist in Vault 0 ' s primary function : to initiate humanity ' s post - War rebirth . Once the outside temperature , radiation levels and poison particle counts returned to acceptable levels , Vault 0 was to remotely activate the " Exodus " protocol , which would initialize the integration of all vault dwellers with the planet ' s surface . Additionally , the Calculator was entrusted with an army of robots that it could use to assist in the protocol . However , it was a plan that never came true . The Calculator became corrupted due to fatal errors in its CPU and data storage systems - human brains . The cybernetic machine became a mad personality , whose goals turned rather homicidal . Many of Vault 0 ' s citizens were killed by the Calculator , while those who survived had suffered brain damage due to the lack of backup life support systems to their cryogenic chambers . Unfortunately , such systems were scrapped during streamlining of the vault ' s construction , to be replaced by leisure facilities and to provide pay raises to senior committee members . Taking full control of the Vault 0 , the Calculator awaited the beginning of the Exodus protocol . Menace from the West . The Exodus protocol could also be triggered by a breach of the vault ' s defenses , as was the case when the Eastward - fleeing super mutant s stumbled upon Vault 0 ; this awoke the Calculator completely . The cybernetic being proceeded to enact its " pacification protocol " , considering all life to be its enemies . The Calculator activated its nuclear reactor in Buena Vista and constructed many robot manufacturing and repair facilities across the wastes . Soon , the Chicago region was full of rumors of a Menace from the West , coming to exterminate all life . The Calculator discovered a useful ally in a captured Midwestern Brotherhood of Steel General named Simon Barnaky , who began to see the machine as the only hope of restoring order . Barnaky was transformed into a humanoid robobrain and began his service to the Calculator as its adviser and guardian . Although the Calculator had begun rapid expansion and had attempted to eliminate the Midwestern Brotherhood of Steel , Vault 0 was breached by Brotherhood forces led by the Warrior . There , the Warrior defeated the robots and Simon Barnaky ' s new form , and entered the Calculator chamber . The eight brains crucial to the Calculator were destroyed , so the Calculator required a new brain to continue to function . From here on , the warrior had three choices , which determined the game ' s ending . Appearances . The Calculator appears in " " and is mentioned in the " Fallout Bible " . Behind the scenes . " Incidentally , the story of Tactics went through a lot of revisions . For example , my original concept for the main villain , the Calculator , was for it to be a completely unfeeling automated system , not even a computer so much as an engine designed to tick over and perform certain tasks after doomsday . Totally implacable , and therefore the fault of everything bad that happens is still in the hands of the humans . "