Cores (also referred to as Spheres, Personality Cores/Spheres, or Aperture Science Artificial Personality Constructs) are machines designed to house advanced artificial intelligence, mostly unique for their ability to express emotions. Cores generally come in two varieties: Spherical and Input. Spheres are the standard form, used as a standalone body for Personality Constructs and in android bodies like Atlas'. Input Cores, by contrast, are elliptical in shape, and are used for the Turrets and in android bodies like P-Body's. Spherical Cores who do not have limbs are generally attached to management rails in the Aperture Science computer-aided Enrichment Center.
https://theportalwiki.com/wiki/Cores