Transwarp computer

From Memory Alpha, the free Star Trek reference

The transwarp computer was a computer control device associated with experimental transwarp drive technology aboard the USS Excelsior, circa 2285.

While assigned as Chief Engineer of the Excelsior, Commander Montgomery Scott sabotaged the ship's transwarp computer. This would later disable the Excelsior and prevent it from pursuing the stolen USS Enterprise. (Star Trek III: The Search for Spock)