The fifth incarnation of the multitronic computer system, tested by Dr. Richard Daystrom in 2268 as his latest try at surpassing his own breakthrough duotronic system.

Like its predecessor models, this version carried a fatal flaw — Daystrom's use of his own neural engrams to make the leap in artificial intelligence required for the operating system to fully emulate a human mind.

Initially successful in a test aboard the U.S.S Enterprise, the M-5 caused the deaths of hundreds during combat trials and nearly caused the destruction of its test ship when it refused to surrender. Depending on Daystrom's sense of morality having survived the engrammatic impression, Enterprise's Captain James Kirk persuaded the unit to shut itself down when it was shown in a different vein that it had committed murder.