My computer still makes a “beep” every time it starts up to let me know that it is “good to go”. Then again, my computer is custom-built and I know every part down to the last wire in it.
The click when somebody hangs up on you.
In the summer of ‘65 our highway construction field office had a Telex installed.
I loved the urgent clatter of incoming messages.
Leading edge, at the time. ;^)