Delete comment from: Ken Shirriff's blog
It's interesting that the separate '1' and '0' serial lines concept lives on to this day in the Weigand protocol for building access-control interfaces. Originally designed to read the presence or absence of a "Weigand wire" embedded in parallel tracks in a swipe card, it is still used to link numerical keypads, RFID tag readers, and even biometric scanners to building security systems. So the original Weigand-card-reader cables installed in a building built in the 1970s can still be re-used for modern security devices, just like re-purposing 25-pair key telephone system wiring for modern digital PBXs, then 10BASE-T Ethernet, which is still sufficient for VOIP Phones. Old cables die hard, especially when you need to pay union electricians to pull new ones.
Dec 14, 2021, 7:01:27 PM
Posted to Inside a transistorized shift register box, built in 1965 for Apollo testing