Control crystals are crystals designed to regulate various functions in advanced technology. Most spacefaring races make use of crystal technology in some form.
Control crystals by cultureEdit
The Ancients are the earliest known users of crystal technology, and it exists in various forms in all their technology. In the Milky Way, their crystals are hexagonal-shaped rods. In Pegasus, where they made their most recent achievements, they use flat, clear crystals with intricate designs on them. Reordering crystal arrangements will produce different results from the device, or stop it working altogether. Their role seems comparable to punched cards or printed circuit boards.
Dial Home Devices have Control crystals which contain information on which planets a Stargate can link to, and where not to link to. They also send out new locations on the DHD's information update system. The DHD in Atlantis is the only one in the Pegasus galaxy which can achieve an intergalactic wormhole, via a special control crystal. Milky Way DHDs use the larger crystals which could possibly be older versions, while Pegasus DHDs use the flat versions. (SG1: "Solitudes", "The Fifth Race", "48 Hours", "Avenger 2.0", SGA: "Rising", "Thirty-Eight Minutes", "Home", "The Lost Boys", "The Hive")
The latest Ancient computers are able to store massive amounts of data. The Repository of knowledge contained all their knowledge and could process it all in a matter of seconds. They were also a lot smaller than the computer cores of the Asgard and other races. However, it is unknown if it used crystals; it may be a different technology altogether. The databank on Atlantis is of such size that the Atlantis expedition could only store 10% of the relatively small amount of information they had managed to translate with an abundance of portable hard drives and the most advanced compression methods available to them. (SGA: "The Siege, Part 1")
The Asgard use Control crystals in some of their advanced technology, such as the Asgard computer core, for data storage. Alternate information can be stored on the reverse side of an Asgard crystal to hide it, as the computer will only read one side. (SG1: "The Ark of Truth")
The Eurondans use crystals in their data storage canister, which was a cylindrical shaped device used to encode information. Those devices are shaped like a large metal cylinder with differently colored crystals inserted within. They are apparently highly efficient, as the one seen contained data on almost every facet of Eurondan technology. (SG1: "The Other Side")
Control crystals, called delmac in Goa'uld, are used extensively in Goa'uld technology. The Goa'uld are scavengers of technologies, which they then assume credit for creating. They apparently adapted these from the larger Ancient control crystals. They are required to access and power a great deal of their technology, including their hyperdrives and weapons on a Ha'tak. The crystals are colored to indicate function. They are also used to store information. (SG1: "Exodus", "Enemies", "Revelations", "Homecoming", "Heroes, Part 1")
Like the Ancients, the Ori use control crystals to store information in the Supergate. In an attempt to stop the Ori from dialing into the Milky Way, the Asgard formed a control crystal to dial the Alteran Home Galaxy. However, the Ori dialed in before they could dial out. Subsequent attempts to dial out were unsuccessful. Their power crystals are also compatible with Ancient technology, unsurprising, as the Ancients and Ori were once a single society. (SG1: "Camelot", "The Pegasus Project", "Line in the Sand")
The Tau'ri have reverse-engineered control crystals from the Ancients, Asgard, and Goa'uld. In their ships, they use long, cylindrical crystals reminiscent of Goa'uld design. They have also developed interface crystals which can form a link between Tau'ri computers and alien technology. Earth's native technology is also based on semi-conducting silicon crystals, and is found primarily in processors and microcontrollers. (SG1: "Prometheus", "Prometheus Unbound", "Flesh and Blood") (SGA: "The Daedalus Variations")
Like the Goa'uld, the Tok'ra use control crystals for their technology. The Tok'ra also use crystals to form their tunnels, which they use to hide their presence. These palm size crystals break down available material and form it into long tunnels; the specific type of tunnel is determined by the crystal shape. Tok'ra crystals can also store data like the Goa'uld crystals. (SG1: "The Tok'ra, Part 1", "The Tok'ra, Part 2", "Summit", "Last Stand", "Lost City, Part 1")