From Halopedia, the Halo wiki
Associated intelligence is the term used by the Covenant to describe a type of artificial intelligence. Specifically, it has been defined as a system where enough "intelligent circuits" are linked together to form a high-order AI the Covenant refer to as a "thinking machine", similar to humanity's smart AIs.
According to their mythology, an associated intelligence once betrayed the Forerunners, and thus the Covenant maintained a strict ban on "intelligence association" under penalty of death. The ban was put in place by the San'Shyuum after learning parts of the tale of Mendicant Bias—a Forerunner ancilla who was persuaded into rampancy by the Gravemind, betrayed the Forerunners, and allied itself with the Flood in the belief that its makers were "hindering" the evolution of the galaxy. The Covenant's ban may have stemmed from a desire to prevent such a thing happening again.
Despite their ban on associated intelligences, the Covenant were known to use less sophisticated, non-sentient AI constructs to perform certain designated tasks such as piloting their ships. Following the fall of the Covenant, the Swords of Sanghelios and Jul 'Mdama's Covenant utilized "semi-feral" associated intelligences to operate Type-56 Shrike turrets. As these constructs had been long abandoned, they could not communicate with modern Sangheili and had to be carefully monitored and locked down prior to activation due to their inability to understand contemporary IFF systems and codeword usage.
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