see Memory Alpha. The Star Trek Concordance refers to the device as the "Berserker"; The Monsters of Star Trek also used the berserker moniker in describing the weapon.
"Fred Saberhagen... was best known for his Berserker series, in which self-replicating robotic probes, a doomsday device left over from a vast interstellar conflict, are programmed to destroy all organic life... The series was an obvious influence on television's Star Trek, in an episode called The Doomsday Machine." Michael Carlson, "Obituary, Fred Saberhagen", The Guardian, Thursday 19 July 2007