memory core

Tali'Zorah nar Rayya: I tracked a patrol of geth to an uncharted world. I waited for one to become separated from its unit. Then I disabled it and removed its memory core.

Captain Anderson: I thought the geth fried their memory cores when they died. Some kind of defense mechanism.

Shepard: How did you manage to preserve the memory core?[…]

Tali'Zorah nar Rayya: According to the memory core, the Reapers were a hyper-advanced machine race that existed 50,000 years ago.