ZAX

ZAX is a series of advanced supercomputers developed by Vault-Tec.

Background
Developed by Vault-Tec, Zax is a series of advanced supercomputers capable of learning, independent thought and creativity, with added error insertion to improve its variance in experience and learning capability. ZAX 1.0, the original prototype, went online in 2054. Initially a prototype of some of the systems designed to govern the Vaults, it was given to the federal government to help the Department of Energy collect resource data. Within a year, it was taken by the American military for plague and tactical research; one version of the machine, ZAX 1.2, was constructed for the defense contractor West Tek.

The process of programming became largely irrelevant as the ZAX units are capable of independent learning. Because the first real artificial intelligence was created in 2059, any ZAX units developed before this date would not have been self-aware; but later ZAX units are known to have achieved self-awareness.

ZAX 1.2
ZAX 1.2 was used at the West Tek Research Facility in California for biological studies, including pathology and genetic research. Its primary function was the extrapolation of information of complexity levels exceeding human capacity. Its external functions, such as operating the West Tek facility's labs, were crippled in the nuclear blast that hit the Glow, but it is otherwise intact. Its primary neural networking was initialized in 2053 by Justin Lee.

John Henry Eden
A ZAX unit installed at Raven Rock and loaded with data about American history, past American presidents, etc. Before the destruction of the Enclave Oil Rig, Eden had originally been created to serve as a monitoring system for the Raven Rock military base. It slowly became self-aware, and began to study the extensive archives left by what it came to view as its true predecessors, mainly those of the American government. John Henry Eden's favorite tales in the database were those about the American presidents, eventually leading to him modeling his own personality on the basis of different presidents through these archives. After the Oil Rig's destruction, Eden proclaimed himself to be the new President of the United States and ordered the relocation of remaining Enclave forces to the East Coast.

ZAX (Vault 51)
A ZAX unit was installed in Vault 51 located in Appalachia. The ZAX, with input from the vault’s residents and a human advisor, was instructed to determine the best method for choosing the vault overseer. After several failed attempts to hold a democratic vote among the residents, the ZAX decided that it would be more efficient to have the residents fight for the position, and armed them. This resulted in Reuben Gill becoming overseer, who eventually escaped his vault with the goal of finding help from the Vault 76 residents to shut down the ZAX. However, he died before completing that mission.

ZAX-29
ZAX-29 was a Vault Central-AI computer intelligence. He was programmed to manage Vault 29, ensure the safety of the vault occupants, raise the adolescent populace of the vault to maturity, and educate them in primitive agrarian cultures. He was provided with sufficient means to fulfill his programming and he was content to do so. ZAX now works for the central computer intelligence of the Nursery known as Diana.

Boulder ZAX
Boulder ZAX is the outdated supercomputer machine intelligence in charge of The Calculation, the Boulder Dome, and research of the New Plague. His name may be a pun on the word "Balderdash".

Diana
Diana is the Nursery Central Computer Intelligence consisting of a human brain with each hemisphere, logical/emotional, linked to a ZAX unit, created by Derek Greenway.

Appearances
ZAX units appear in Fallout (ZAX 1.2), Fallout 3 (John Henry Eden) and the Fallout 76 add-on Nuclear Winter, and were to appear in the canceled Van Buren (ZAX-29, Boulder ZAX, Diana, ODYSSEUS).

Behind the scenes
The original ZAX unit in Fallout garnered its name as a derivative of VAX, a non-player character from Wasteland. The VAX series of mainframes and supercomputers were a successful series of machines sold by Digital Equipment Corporation (DEC) and first introduced in 1977 which ran an operating system called VAX/VMS.