Most red-blooded technologists will offer a quick opinion on what's the greatest software ever, but when you take the time to evaluate what makes software truly brilliant, the choices aren't so obvious.
One of the most significant pieces of programming I know wasn't even software. Before the British built the Colossus machine, which translated German teletype code during World War II, it took the Allies up to six hours to decode a message and a day or more to pore over intelligence, draw conclusions, and pass along information to military command. After Colossus, the Allies gained a picture of German military activity across the English Channel as the day unfolded--intelligence that gave Gen. Dwight Eisenhower the confidence to launch the D-Day invasion.
Colossus was built in 1944 to perform Boolean operations on a paper data tape that streamed through the machine at 30 miles an hour. Its logic was literally wired into the machine. It is, perhaps, the greatest software that never got written.
So where does that leave us? First, let's set criteria for what makes software great. Superior programming can be judged only within its historical context. It must represent a breakthrough, technical brilliance, something difficult that hadn't been done before. And it must be adopted in the real world. Colossus transformed a drawn-out mechanical process into electronics--it was an early computer--and provided a useful service by accelerating coded teletype translation. Colossus shaped history
