Repositories of knowledge are libraries that download the entire knowledge bank of the Ancients into the brain of a person; however the knowledge is far too vast for the Human brain to comprehend at its current evolutionary level, so much so that the mind of the person exposed to the data within will slowly degrade after being exposed, until the brain can no longer function. (SG1: "The Fifth Race", "Lost City, Part 1", "Lost City, Part 2")
Each Repository possesses an interface that allows it to transfer knowledge directly into the mind of the user. Once the interface has established a direct link to the mind of the recipient, the device downloads all of the knowledge contained within. The entire process only takes a few seconds and likely drains a large amount of power. (SG1: "The Fifth Race", "Lost City, Part 1")
The interface itself consists of a metallic circle with a dark window in the center. When activated, the device extends to encompass the user's head while the knowledge is transferred, although there have been cases where the device does not grip the head.
The two main theories are that the user either requires the Ancient Technology Activation gene (further evidence provided by prototype Lantean technologies in both SG-1 and Atlantis), or the device has programmed biological criteria.
Only the Repository's interface has been shown; it is suggested but left unclear as to whether or not there is a larger structure behind the interface, which contains the information itself and supplies the necessary power (since SG-1 has considered taking a Repository with them, the total size of the equipment is probably not enormous, and Adria was able to fit one onto the wall of an Ori warship easily enough). (SG1: "Lost City, Part 1", "The Shroud")
A similar repository found in Atlantis possessed a conventional user interface for selective usage, rather than a neural interface. One hypothesis can be suggested in that even though one could gain access to the knowledge, the use of the neural interface has dire consequences for those not ready to possess it, and thus this could possibly be considered a security measure.
- "You cannot even begin to comprehend the extent of what was unfolding in O'Neill's mind. Our scientists, long ago, extracted parts of the Ancient library of knowledge and learned much from it. But we have been studying it for as long as I can remember, and we have barely scratched the surface."
The Ancients were among the most advanced races in the universe and their Repositories contain the most up-to-date knowledge they possessed before they ascended to a higher plane of existence, which far surpasses that of every other encountered race in the universe in its scope (except for the Ori, who have also ascended).
The vast amount of knowledge the device contains will kill the recipient if their brain is unable to fully absorb it (such as the brain of a normal Human), despite the fact that the knowledge unfolds gradually. When Colonel Jack O'Neill used two such devices, once by accident, the information slowly and inevitably took over his mind. While he was able to build many advanced technologies, such as a power generator that allowed the Earth Stargate to dial an eight-chevron address and a weapon capable of defeating any Replicator, it also caused his brain to slowly degrade, eventually rendering him unable to speak any language apart from that of the Ancients. This degradation would have eventually led to his death had the knowledge not been removed in time, both times by the Asgard. (SG1: "The Fifth Race", "New Order, Part 2")
While possessing the knowledge of the Ancients O'Neill was also able to heal Bra'tac, who was severely injured by Ronan, one of Anubis' many spies; however he was left in a weakened state as his brain was already dying from the knowledge it contained. This healing ability exhibited by O'Neill indicates that the device vastly increases the brain activity of the recipient, to the point where they are able to ascend if they so choose. (SG1: "Lost City, Part 2") (SGA: "Tao of Rodney")
Thousands of years ago the Asgard managed to download only a small amount of the information within a Repository to their own computers to learn from the knowledge within. They have learned much, but the amount of information contained within even that small portion was so great that they had only begun to scratch the surface of what they had downloaded by the time the Asgard became extinct. Although it should be noted that the collective knowledge of an entire race who's fairly advanced or more is quite overwhelming, Thor speculated that the amount of knowledge contained in a Repository is so vast that it could very well be truly infinite. Even though the Asgard studied the Repository, they were so advanced in their own right so they didn't need the help of other races to develop incredible technology which, when they committed mass suicide, rivaled the Ancients' most up-to-date pre-ascended technology, and to some extent even surpassed them. The knowledge contained in the Repositories is so vast, that when Thor decided to use the knowledge to try to build a weapon capable of destroying the Replicators, he chose to risk using Colonel Jack O'Neill to do it, stating that while it would be impossible to search for what they needed if they simply downloaded the Repository into his ship's computer, O'Neill's conscious mind could hopefully access the knowledge and give them what they need. Despite being in stasis and connected to the ship's computer, Thor's theory was right. (SG1: "New Order, Part 2", "Unending")
While humans are unable to handle the knowledge stored in the repository, as shown with Jack O'Neill they are able to at least subconsciously access the knowledge contained in it and use it for various purposes. The one using the knowledge like this doesn't consciously know what they're doing and can't even consciously control their actions during this time. However, O'Neill proved at least somewhat capable of controlling what he wanted to find when connected to Thor's ship's computer as shown when he told Teal'c, Doctor Daniel Jackson and Thor that he knew what they needed and to let him get to work and then told them to wait because he wasn't done yet. Getting the knowledge removed causes the person to lose all memory of the time they possessed it, but according to Thor, their memories will eventually return. (SG1: "The Fifth Race", "Lost City, Part 1", "Lost City, Part 2", "New Order, Part 2")
The first encounter with an Ancient Repository was during SG-1's visit to the planet they had designated P3R-272, where Colonel Jack O'Neill accidentally activated the device. Upon returning to Stargate Command, O'Neill began to develop strange technologies such as a power generator, added new Gate addresses to the Dialing computer as well as the ability to dial eight symbol addresses, came up with blueprints for the Dial Home Device and instructions to fix one frozen in mid-dial and lost the ability to speak English. The other team members discovered that the knowledge in his brain was far too powerful for it to handle and that his body wouldn't be able to handle the stress. Luckily, his subconscious mind realized the danger he was in and directed him to another galaxy, where the Asgard were able to remove the information before he died. The Asgard then informed him of the Alliance of Four Great Races and that the Tau'ri were well on their way to becoming a part of it before sending O'Neill home. (SG1: "The Fifth Race")
Five years later, in March 2004, SG-2 located another Repository on P3X-439; however, Anubis was aware of its existence as well. SG-1 attempted to remove the Repository and bring it back to Earth to safely store the data before Anubis could use the knowledge in the Repository for his own purposes. While a Tau'ri team was searching for the repository Anubis attacked the planet, which left O'Neill no choice but to download the information into his mind again.
Fearing what the Tau'ri would now be capable of doing should they have time to utilize the information, Anubis sent a fleet of 30 ships on an immediate course for Earth to destroy his enemies. Using the knowledge in his mind O'Neill located an Ancient outpost in Antarctica, and used the weapons platform containing thousands of Drone weapons to destroy Anubis' fleet. During this time O'Neill was able to lead the team to Proclarush Taonas, upgrade a Tel'tak's hyperdrive from interstellar to intergalactic, heal a mortal wound and modify a set of Transportation rings to emit a beam of energy to drill a hole through a mile of ice. Afterwards, O'Neill had to put himself in a stasis pod to escape death. A few weeks later, Major Samantha Carter and Teal'c attempted to seek out the Asgard using the Tel'tak that O'Neill modified using the Ancient knowledge. Thor later linked O'Neill's mind to the computer of his ship to create a weapon to use against the Replicators, and again the information was removed at the last second. O'Neill successfully created the Replicator disruptor, but retained no memory of what it was or his actions since he downloaded the database though Thor said his memory would return. (SG1: "Lost City, Part 1", "Lost City, Part 2")
A variant of the Repository of knowledge was discovered in Merlin's tomb. When used in conjunction with a Molecular construction device, the device allowed one to visualize a program or machine, and then create it. This version of the Repository was interactive, and not only sent information, but also received it. It could also encode the DNA and the consciousness of an individual and download it into another persons brain and then return the altered brain to a previous state after a certain amount of time had passed. Returning to the previous state of mind before being downloaded into the persons mind was a safe guard put in place by Merlin himself. (SG1: "The Quest, Part 2", "The Shroud")
The formerly ascended Ancient would interface with the device and use two rods that slid out at the bottom of the device, where he was then able to create any object at the molecular level with a great deal of concentration. Merlin used his Repository to recreate the Sangraal as much as he could and then transferred both his memories and quasi-ascended powers to Dr. Daniel Jackson when he was too weak to continue (even programming a failsafe into this transfer that erased the modifications made to Jackson's mind and body to compensate for the weaknesses of human physiology). The device was then moved aboard an Ori warship and used by Jackson to complete the Sangraal, which was then used to eliminate the Ori in their home galaxy. (SG1: "The Quest, Part 2", "The Shroud", "The Ark of Truth")
- Main article: Destiny interface chair
The Ancient starship Destiny possesses a much older version of the Repository of knowledge encountered by SG-1. It is part of the Destiny database and can be transferred to a user through the ship's interface chair, but access to it through standard control consoles is blocked by the database's security lockouts. Although the contents of the data it transfers are unknown, aside from that they contain the master code, it is believed to be far less than the newer versions seen in the Milky Way. Dr. Nicholas Rush suggested that because of this, its effects may be less damaging to humans. While this theory may be entirely correct, the older method of data transfer used by the interface chair can leave an unevolved human in a deep coma which can take months to recover from (assuming full recovery is ever possible), and for that reason the Destiny expedition is under strict orders not attempt to download the database or use the chair for any other purpose. To date, only two people have used the repository, Jeremy Franklin and Rush, though the latter was using a different method of data transfer than that normally used by the interface chair. (SGU: "Life", "Justice", "Human", "Subversion")