A weapon that has been rebuilt twice: once 2000 Years Ago and again very recently, it is a Mobile Suite originally designed from 12,000 Years Ago or more specifically from the Reign of Ancient Atlantis where Newtypes formerly ruled, its Operating System is: Generational Unilateral Neurons-link Dispersive Automatic Manoeuvre Module.
12000 Years Ago
During the Era of the Atlantis Empire, Newtypes and Technology Ruled a large portion of the world and held dominion over a massive amount of Earth's Territory, therefore a mighty Force was built with the (unnamed original form of) the Revelation acting as the Cornerstone. Powered by a Creation Particle Reactor and an Emergency Nuclear Nozzle (due to it being a Prototype), it easily held peace and order over the Empire while being based at Atlantis, however after Humanity (later known as the "Naturals") infiltrated the Main Creation Reactor on the Underside of the Floating Island their less than intelligent expertise caused Atlantis to sink to the waves with the surviving Newtypes hiding Atlantis away; cloaking its location and technological wonders from the rest of the world.
2000 Years Ago
Andras Casaba, the last of the Newtype Royal Line looked for a way in which Newtypes could resist against the growing disgust of the Naturals and their insatiable Greed, like the Newtype Nobility he sought a way in which the Newtypes could once again rise to prominence as leaders of the Human Race. Andras sought Atlantis in secret and built a small hidden base on the moon (later unknown as the Lorentz Crater) from where he could continue his search, there he built a Supercomputer to help with his search and later updated it with Atlantis born technology, the Revelation which went by its previous name also was brought to the moon to be rebuilt with present electronic equipment.
Andras knew that he may not succeed at "World War 3" let alone survive, so he mated with the La Flaga Noble Family much to his lover's annoyance, despite the success of his Organization he eventually disappeared leaving a paramilitary weapons development Corporation in control of Lorentz Crater. This would become the first neutral nation outside of the Earth Sphere where it would retain its neutrality (since most of its Inhabitants were Newtypes) in return for building revolutionary weapons, including this were Linear Cannons and even the Earth Alliance Ships.
Rebuilt as a G-Weapon
It is unknown how the Revelation was born other than its predecessor was taken apart and rebuilt into a Aegis-designed G-Weapon, it was designed as a Trial System for the later G-Weapon as well as a means to test Newtype-type Technology, however this failed as the Genetic Outline of its predecessor still kept a lock on the advanced O.S. therefore only the (believed to be deceassed) Andras Casaba could undo the lock.
Salvaging of Heliopolis
After Heliopolis was destroyed by ZAFT and the Archangel's prepared flight from the area, the Revelation Gundam was brought aboard the Varda where it returned to the hands of the (now Immortal Researcher and Advisor) Andras Casaba whom undid the lock and did minor upgrades to the computer system including adding a Prototype 360-degree panoramic cockpit based off those seen in the GAT-X106 and GAT-X104, later the lock was restablished by Andras except Krane's Biometrics were included in the lock as though he were predicting the damage to Krane's Custom CGUE Assault at Artemis.