JR writes in -
I thought this was a cool story that didn’t get wide pickup. I like #9 especially: IBM SELECTRIC TYPEWRITER… Because the Selectric coupled a motor to a mechanical assembly, pressing different keys caused the motor to draw different amounts of current specific to each key. By closely measuring the current used by the typewriter, it was possible to determine what was being typed on the machine. To prevent such measurements, State Department Selectric typewriters were equipped with parts that masked the messages being typed.