The Infernal Machine (1974)

a huge and bizarre spaceship lands on the surface of the moon. the inhabitants of alpha receive a communication from an entity that identifies itself as gwent and that requires a delegation of land-based aboarders. john koenig, dr. russell and professor bergman go on an exploration, but once inside, they discover only an old man, companion. gwent is nothing but the ship itself, the worst side of companion that has designed and built the indestructible machine with the sole intent of preserving its personality. when companion dies, gwent demands new servants and alan carter's efforts to free his companions are worth nothing.