I used these in an early job to track vacuum tube information and stock.<p>This is also a good article on them by Kevin Kelly
<a href="https://kk.org/thetechnium/one-dead-media/" rel="nofollow">https://kk.org/thetechnium/one-dead-media/</a><p>This is the culmination of a rat hole run that started with how Unix did spell in 64kb -> Bloom filters -> Zatocoding (where I went "I used that!") to Edge-notched-cards then the KK and Hackaday articles.<p>Another hour lost, thanks Hacker News.