Today I learned that hand-crafted memory for computers exist and were a thing during the US space program. This early form of RAM, also known as “magnetic core memory” is made an incredible amount of thin wires that are woven together and using super tiny magnetic “cores” or rings, that have a directional magnetic field going one way or the other. And an electronic current that pulses through this memory, allows to reverse the direction of the magnetic field and this way change a bit from 0 to 1. One of the memory units in the Saturn V had 114688 bits (14 Kibibytes) on it, and the entire navigation system was running 6 of them in total, but in 2 computers doing the same calculations, means the entire programming of the navigation system had to fit it into 42 Kibibytes. The more interesting part is, that each of them was hand made and each of those 6793008 bits were placed onto those woven structures by a person with an incredible amount of patience and skill.

I came across this by watching a semi-random YouTube video about the Saturn V mission that contains an interview with one of the engineers from back then. I highly recommend to have a look at it.