From Bjorn Freeman-Benson’s talk Airplanes, Spaceships, and Missiles: Engineering Lessons from Famous Projects
Bjorn is discussing the ferrite core memory of the Apollo guidance system.
These are very, very robust memory systems. … But the problem is that they actually have weight to them. Core memory actually weighs a bunch, so when you’re writing your program for the lunar module … every line of code that you wrote had a consequence in weight. And you could measure how heavy your code was at the end of a compile line. … It’s an interesting analogy to keep in mind because in fact even today our code has weight. It doesn’t really have physical weight … Our code has psychological weight because every line of code we write has to be maintained. It has to be supported. It has to be operated.