I'm thinking of the Chatterbox in Ocean City, NJ, for instance. Grace Kelly used to be a waitress.
https://www.tastingtable.com/1203923/best-diners-in-new-jers...
Also, the Bendix Diner is closed, likely permanently, because of fire code violations.
While it’s possible that Unicode was also conceived at a diner, you’re likely thinking of UTF-8. Unicode was from a decade earlier.
I would not make a good fact-checker :(