Here's a nice infographic: https://medium.freecodecamp.org/the-biggest-codebases-in-his.... Unix 1.0 (1971) has a third of the number of lines of code as the average iPhone app. I know LOC is a very poor proxy for complexity, but I have a hard time believing that 70s engineers could replicate the functionality of Google's 2 billion LOC with tools like ed.