From Halopedia, the Halo wiki
Kalmiya was created by Dr. Catherine Halsey for the primary purpose of testing experimental software and techniques that would be incorporated into Cortana. Entering service in 2537, Kalmyia was decompiled, edited, and reconstructed by Dr. Halsey several times, prolonging her lifespan far past that of most "smart" AI. Despite the fact that Kalmiya was destroyed during the Fall of Reach, Blue Team discovered some of her subroutines surviving within the ruins of CASTLE Base in 2559. These remnants guarded a vault holding material that was later used to create the AI known simply as "the Weapon."
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