Mem chips are an advanced technology used for holding the all the data of an individual's brain.
Background
Created before the Great War, the data it held could be implanted into a robot or synth, however it is unknown if it could be implanted into humans or animals. In 2276, Horace Pinkerton stole a mem chip from Vault 112[1], and used it in his mind wipe of A3-21, making A3-21 to believe it was a human named Harkness.[2]
Appearances
Mem chips are mentioned only in Fallout 3.