April 2, 2004: For a long time is was said, only half in jest, that you built a new warplane by finding the most powerful engine you could and then building an airplane around it. That has changed in the last two decades. The engine and the airframe are now easy, the software to make everything work together is the hard part. The F-22 software comprises some two million lines of source code (the text and numbers that are converted, or "compiled', into computer readable instructions). This code is complex, and it must work reliably for long periods of time,...