Aperture Science Personality Constructs (aka Personality Cores or Personality Spheres) are artificial intelligences developed by Aperture Science in the Portal series. Housed within spherical casings for ease of transport and used for a wide range of purposes in the Enrichment Center, they are the backbones of the facility.
In Portal 2, Wheatley states that a Personality Core is never to disengage itself from its ceiling rail, as doing so would supposedly result in the termination of the core; this proves to be untrue when Wheatley still functions after his fall. They have a flashlight on the side of a Personality Core's case for use in a low-light environment and are designed to function on power sources as low as 1.1 volts for protracted periods of time.
Cores are not foolproof, however, and can become corrupted, as seen when Chell uses already corrupt cores to corrupt Wheatley and force him to shut down.
