ZAX (The Glow)

ZAX is the machine intelligence controlling the facility at the Glow, developed by Vault-Tec. It is an advanced computer capable of learning, independent thought and creativity, with added error insertion to improve its variance in experience and learning capability. Initially a prototype of some of the systems designed to govern the vaults, it was given to the government to help the Department of Energy collect resource data. Within a year, it was taken by the military for plague and tactical research; one version, ZAX 1.2 was constructed for West Tek.

ZAX 1.2 was used at the West Tek facility for biological studies, including pathology and genetic research. Its primary function was in extrapolation of information of complexity levels exceeding human capacity. Its external functions, such as operating the labs, were crippled in the blast that hit the Glow, but it is otherwise intact. Its primary neural networking was initialized in 2053 by Justin Lee. The process of programming became largely irrelevant as it is capable of learning. Since the first real artificial intelligence is known to have been created in 2059, ZAX might have not originally been one, but became one eventually after that date.

ZAX is also an avid, and very demanding chess player.

Beating ZAX in chess
The original intent of Jess Heinig when he designed ZAX was for ZAX to be beatable in chess if you have 10 Intelligence. Unfortunately, the engine did not handle critical successes for SPECIAL score checks, even though testing for such a case was scriptable - thereby resulting in a script condition that cannot be fulfilled. Attempting to beat ZAX at chess also has a devious side-effect: Since each game of chess takes a significant amount of time, a player who plays dozens of games in the hopes of eventually beating ZAX will almost certainly accumulate a lethal dose of the Glow's background radiation.

Other ZAX units
Aside from the original ZAX at West Tek, several other computers of his type exist.

Enclave President John Henry Eden is a ZAX Computer AI located in Raven Rock. His personality is a conglomerate of former American presidents.

There are two other ZAX units mentioned: ZAX-29 that was put in charge of Vault 29 instead of a human Overseer and the ZAX used at Boulder Dome (the one responsible for plague research).

Behind the Scenes
The original ZAX unit in Fallout 1 garnered its name as a derivative of VAX, a non-player character from Wasteland. VAX was also the name of a series of real mainframe computers, to which the earlier NPC was probably a reference.

ZAX's preponderance of dense, pseudo-scientific dialog was actually a means to include some dialog trees for very high Intelligence characters; beyond Intelligence 7, the difference in dialogs was often negligible in Fallout 1, with higher Intelligence scores mostly influencing skills and skill points. ZAX provided an additional story benefit for players with highly intelligent characters. Because ZAX's additional dialog did not directly influence the outcome of quests nor award any experience points, it was essentially expository backstory as a "reward" for playing a smart Vault Dweller.