Data crystal chip

A data crystal chip is a file storage and transfer device akin to 21st-century memory cards. Data crystal chips are often used to store data that cannot be sent via wireless transmissions because of the data's sensitive or complex nature. They are used by the UNSC to store navigation data, weapons data, and strategic and tactical intelligence. Data crystal chips can also be used to house the Riemann matrix of an artificial intelligence construct, even one of starship-grade.

With the Mark V and subsequent versions of the MJOLNIR Powered Assault Armor, a data crystal chip containing an AI matrix can be inserted into the Spartan wearer's neural interface; this allows the AI and Spartan to synchronize on a mental level, coordinating the supersoldier's reflexes to an even greater degree. An armored matrix may be used to transport and protect an AI's data crystal chip; this is often done when no holotank is available.

Trivia
Though Cortana's data crystal chip is featured prominently in Halo: Combat Evolved, Halo 3, and Halo 4, her method of transfer varies between each game. In Halo: Combat Evolved, Cortana's matrix is transferred only when the chip is directly inserted into an access port. In Halo 2, Cortana is capable of transferring from the MJOLNIR Mark VI's gauntlets to any electronic system in close proximity without using the chip. The chip returns in Halo 3, though Cortana is seen transferring herself remotely to and from the device, much as she did via the suit's gauntlets in Halo 2. Halo 4 reintroduces the direct-insertion system from Halo: Combat Evolved, despite Cortana having upgraded the suit since the events of Halo 3. This may be do to Cortana's deteriorating state of rampancy, as at one point she mentions being "unable to move on her own".

List of appearances

 * Halo: The Fall of Reach
 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: First Strike
 * Halo 3
 * Halo: Reach
 * Halo: Fall of Reach
 * Invasion
 * Halo: Combat Evolved Anniversary
 * Halo 4
 * Halo 5: Guardians