Core memory
Memory made of rings on wire, hand-woven under a microscope — and the reason a crash dump is still called a core dump.
Each bit was stored in a small ferrite ring magnetised one way or the other. The rings were threaded onto a grid of wires, and sending current through one row and one column at once flipped an individual ring. The technology dominated computer memory from the mid-1950s to the early 1970s.
Two properties defined the era. The memory was non-volatile — its contents survived a power loss, which made it possible to dump the whole memory image after a crash, hence core dump. And reading was destructive: reading a ring cleared it, so the machine had to write the value straight back. The weaving was done by hand, often by women with textile backgrounds; the Apollo computer's memory was literally woven.