Inside the 128KB magnetic core memory from a 1980 Space Shuttle lab

Before silicon took over spaceflight, 128 kilobytes of memory meant magnetic rings and conduction-cooled circuit boards.

A high-resolution visual teardown reveals the inner mechanics of a magnetic core memory module from a 1980 Spacelab computer. The reusable laboratory flew inside the Space Shuttle's cargo bay using three French-built Mitra 125 MS minicomputers—one for lab systems, one for payload experiments, and one as a backup.

Why it matters: Core memory stores each bit in a tiny ferrite ring. Engineers wired the cores in a grid, sending half the current needed to flip a bit down one horizontal wire and half down a vertical wire. Only the ring at the exact intersection got enough magnetic force to change state.

Know this: Reading core memory destroys the stored data. To keep the computer functioning, every single read cycle immediately triggers an automatic rewrite cycle to put the bit back.

Not bad for a storage system that took up a full third of the computer's chassis.