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   Tom Lyon ✅ (aka_pugs@mastodon.social)'s status on Thursday, 19-Feb-2026 10:41:12 JST Tom Lyon ✅

   Before transistors, relays were widely used in telephony switches. They were much slower, but much more reliable than vacuum tubes.

   This 1951 booklet, "NO. 5 CROSSBAR" from Bell Labs describes the bad-ass mainframe of relays. Lots of photos and diagrams.

   https://drive.google.com/drive/folders/1UBnLJIzYjpGu1401I6F3lDa9fWiXSBu5?usp=sharing