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. Since the first real artificial intelligence is known to have been created in 2059, ZAX might have not originally been truly self-aware, but all known ZAX units achieved self-awareness eventually after that date.
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.
A ZAX unit located in 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. He slowly became self-aware, and began to study the extensive archives left to him, mainly those of the American government. His 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-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.