A diagnostic computer was a type of computer that could be found on starships to detect the power levels of systems. One was present on the Millennium Falcon, but was disabled in 3 ABY by a seismic charge fired by Boba Fett's ship. Lando Calrissian, with the help of his his old friend L3-37, one of the droid brains of the Falcon, was able to fix the diagnostic computer.