The Destiny interface chair is a device that was created by the Ancients and installed on Destiny. It appears to serve similar functions to the Repository of knowledge and Control chair units that have been seen in various other locations once controlled by the Ancients, and may be an earlier version of the same technology.
This unit predates the later versions of the Repository of knowledge and Control chair devices, possibly by millions of years. The device, located aboard Destiny, is a chair and contains electrodes placed either side of the user's head which facilitate transfer of information to the brain, and from the brain to the ship's computers. The electrodes do not normally puncture the skin during operation, but the seizures induced in some cases can cause the user's head to cut itself on them. The chair can perform a variety of different functions - some, such as the transfer of the Destiny database into a human mind, were already programmed by the Ancients before the arrival of the Destiny expedition. Others, such as the "lucid dream" state it can induce, was the result of Tau'ri modifications to both the hardware and software of the chair. (SGU: "Sabotage", "Human")
Because this technology predates the creation of the Ancient Technology Activation gene, or at least the widespread use of it as a security measure, the device appears to work with any human. It does, however, present significant safety risks to non-Ancients - especially when using Ancient programs written for use on their own kind.
Unlike later Ancient Neural interface devices, which were widely used but performed only fixed functions, the Destiny neural interface chair is a versatile tool to be controlled and monitored by experts. It can perform a large variety of functions on an individual's brain and mind, functions still being discovered by the Destiny expedition. Whilst the Ancients left many programs in the Destiny database, some were unsuitable for the human brain, so the Tau'ri have both written software for and physically modified the chair to allow it to better work with their own kind.
This program was written by the Ancients and instructs the chair to download the Destiny database into the mind of its user. Curiously, the Destiny master code is not required to perform this function, despite the database being protected by it when accessed through normal consoles. Jeremy Franklin's personality, however, changed considerably after his use of the chair, and he became reluctant to share any of Destiny's secrets with Dr. Nicholas Rush. This may be an equivalent security precaution, programmed into him by the chair. (SGU: "Justice", "Hope")
This program, in its original Ancient form, is unsuitable for use by normal humans; their brains cannot handle the rapid transfer of information. The only known human user of the program, Franklin, was left in a comatose state for months - though he did partially recover. This may suggest that the Destiny database does, in fact, contain a manageable amount of information - unlike the later Repository of knowledge which the Asgard believe would overwhelm and kill any normal human.
The Tau'ri modified the chair slightly, in pursuit of the master code, adding information buffers and some software to allow the user to receive information slowly in the form of a lucid dream. The information in the database was not transferred in a manner which could be easily interpreted by the user, however, and it only provided a small clue as to the nature of the master code when used by Rush.
Similar to the functions of the Control chair, the Destiny interface chair allows control of the ship's systems via mental commands. It appears as though the master code is not required for this function either, despite navigation controls, amongst many others, being protected by the code when accessed via consoles. It should be noted, however, that the only user of this program, Jeremy Franklin, may already have known the code when using the chair, and this may have allowed him access to more systems than would otherwise have been possible.
Uploading of human mind
Ancient programming in the chair allows it to upload an entire human mind into the Destiny database, where it can then be run by the ship's computers. This process, for unknown reasons, appears to wipe the mind from the chair's user as well. In cases where more than one mind occupies the same body, however, individual minds can be selectively uploaded, leaving others intact. This program, despite its Ancient origin, appears to be harmless to even normal humans.
- Main article: Destiny simulation program
After a human mind has been uploaded into the ship, it can be placed in one of Destiny's apparently perfect simulations - where it will be given a virtual body and be literally unaware of any differences. This is dangerous, however, as the process of uploading and re-downloading a mind is complex and the potential exists for many problems to occur. (SGU: "Seizure").
It is unknown if the chair can create a true virtual simulation inside the user's brain, without uploading their mind to the ship. Considering the ability of the ship-wide neural interface to perform such a function whilst a user is asleep, it is likely that the neural interface chair can do the same if programmed correctly.
Rush stated that the chair could be used to cure the Nakai pathogen which was given to Chloe Armstrong while she was held on one of their ships. He said this was possible because the chair would destroy any non-human parts of her which it detected. It is unknown specifically what he was referring to - he could have meant either infections in the body or, more likely, alterations to the brain. Either way, the chair was unsuccessful in curing Chloe entirely: her body still continued transforming and she continued to gain access to more and more Nakai knowledge. She did not, however, suffer the effects of the infection's mind-control anymore, suggesting that Rush may have selectively targeted that aspect of the pathogen, whilst leaving its knowledge intact. (SGU: "Pathogen")
The chair was found aboard Destiny by a team, led by MSgt. Ronald Greer and monitored via Kino by Dr. Nicholas Rush. Upon entering the room, Dr. Boone activated a console and the device sprang to life; the bindings closed at the ankle and wrist positions and the neural electrodes swung down and protruded to where a person's head would be if the chair was occupied at the time. Rush quickly advised the team not to touch anything and went to the location himself to investigate further.
Later, Colonel Everett Young was informed of the discovery and he decided the device was too dangerous to be used. Despite Rush's insistence that the device is not as dangerous as those used by Colonel Jack O'Neill, he was not willing to sit in the chair himself until he was sure it was safe. Greer volunteered to sit in the chair if it meant saving the rest of the crew, but he respected Young's order not to. (SGU: "Life")
Though the order stood that the device was not to be used, Young relinquished command of Destiny to Camile Wray when he became the prime suspect in the murder of Sgt. Spencer, at which time Wray granted Rush a science team, dedicated to researching the device. Late one night, while working alone, Jeremy Franklin sat in the chair. When he was discovered by Eli Wallace five minutes later, he was convulsing and the chair's electrodes had cut into the sides of his head, drawing blood. Eli was unable to deactivate the device himself, so he desperately called for help. Rush, Young and Lt. Tamara Johansen arrived at the scene and the chair soon deactivated. Franklin's convulsions eventually stopped, but he then went into a catatonic state. Wray ordered T.J. to administer a high dose of Lorazepam, though it apparently didn't have any immediate effect. (SGU: "Justice")
Some time later, the expedition developed modifications to prevent the transfer of data from overwhelming the user, giving them access via lucid dreaming. Rush sat in the chair in an attempt to find the Destiny master code, it helped him to narrow it down, using 46 as a base. Unlike with the first test, Rush suffered no damage other than two nosebleeds and a minor cardiac event. (SGU: "Human")
In a desperate attempt to save Destiny from an attack, Young decided to use the chair to bypass the damage which was keeping Destiny from jumping to FTL. Franklin, who seemed to be snapping out of his catatonic state, managed to vocalize that he'd like to do it. He was allowed to take Young's place. When Franklin used the chair, he began lowering the temperature in the room for some reason, and ordered everyone to leave. He successfully bypassed the damage and took the ship to FTL. Strangely, when Young came back to check on Franklin, the chair was empty and Franklin was nowhere to be found. Rush later revealed that Destiny downloaded his consciousness into the ship's mainframe. (SGU: "Sabotage", "Hope")
When Chloe Armstrong was infected with the Nakai pathogen, Rush suggested that a few seconds in the chair would be sufficient for its Ancient programming to purge any non-human elements to cure her. Rush knew that the chair did not cure her entirely, but it does appear to have reversed the mind-controlling effects - at least temporarily - so that she can appear cured to the rest of the crew. (SGU: "Pathogen")
After traveling back in time and accidentally killing Colonel David Telford, a future version of Dr. Nicholas Rush decides he has nothing left to lose and to use this chair on a Destiny that is falling into a star in order to get the knowledge of the Ancients before he dies. With the help of his past self, he succeeds, but dies in the chair when Destiny disintegrates inside the star. (SGU: "Twin Destinies")
After Ginn and Dr. Amanda Perry resurface in Chloe's body, Rush decides to use the chair to download their conciousnesses into Destiny's mainframe like the ship did with Franklin. Due to a choking incident in which Ginn re-experinces her death at the hands of Simeon while the download takes place, there's a power surge which shuts down the database and affects systems all across the ship including the instruments TJ is using to complete a kidney transplant. The download is successful however and Ginn and Perry are able to interact with Eli, TJ and Rush. (SGU: "Hope")
In an interview on the MGM official Stargate website, Brad Wright notes that both this chair and the newer Repository of knowledge are harmless to Ancients, but because they were in a more evolved state than Humans (even when constructing Destiny) the information and the method of transfer can cause far more damage to our brains.  The original screen used chair now permanently resides in the Corporate offices of Stingray Auto Repair in Seattle.