Big Computer Rules The World

Whe I was younger I saw a film in which a crazy meglomaniac computer took over the world by taking control of the worlds nuclear missiles. No, it was well before Terminator and War Games. All I remember was that it was very bleak and had a wonderful un-Hollywood ending. Ever since I've been trying to find out what that film was (not trying awfully hard, but thinking about it now and again sort of trying.) And guess what? I've found it, whilst reading an essay entitled Does Visual Studio Rot the Mind? (which is only of interest if you (a) know what Visual Studio is and (b) Actually use it.).

The answer.....?