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Original telephone keypad layouts researched by Bell Labs in the 1950s.
https://diqn32j8nouaz.cloudfront.net...s_fullsize.jpg
More:
https://mrserge.lv/assets/human-fact...phone-sets.pdf
Previously:
https://www.homemadetools.net/forum/...805#post220441
https://www.homemadetools.net/forum/...786#post220373
https://www.homemadetools.net/forum/...569#post212444
https://www.homemadetools.net/forum/...090#post187756
https://www.homemadetools.net/forum/...435#post189090
That's really interesting. One of those things you don't even think about. The original DTMF touch tones were created by mixing eight different frequencies, with each button representing a mix of two tones. The mixing happens in a grid that lines up with they key layouts for IV-A and VI-A (which are identical). On the early phones it would have been way easier to just run horizontal and vertical wires matching the frequency mixing. All those other layouts would have complicated the phone design. Bet the bean counters made the final decision on which keypad layout was the winner.
https://en.wikipedia.org/wiki/Dual-t...gnaling#Keypad
There used to be a a thing called "phone phreaking." It was started by a guy named John Draper who found that blowing a small toy whistle from a Captain Crunch cereal box into a phone receiver would get free calls on payphones. It's a pretty interesting rabbit hole that involves a lot of figures like Steve Wozniak.
https://www.youtube.com/watch?v=ugTKmveF2G4
Another video. The history of it all is pretty interesting.
https://www.youtube.com/watch?v=HDh_XRTpXxI
Even if you only drink "regular" coffee you are consuming a higher quality of coffee than from decades ago. Most of it then was Robusta. Most of what is available today is Arabica, usually considered to be superior to Robusta. So if you're old like I am and you hated coffee when you were a kid, you may like it better now. Or maybe not.