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Low water marks

This is a list of the earliest use of each of the terms or concepts listed, as currently known. This list is only a personal memo and is neither exhaustive nor definitive: it will be revised as earlier examples are discovered or indeed rediscovered.

Term Oldest usage
Buckling rubber sleeve 1967, US patent 3465099 (granted 1969 to Friden, owned by Singer), used on optical beam keyboard
1970, US patent 3767022 (granted 1973 to the Singer Company), “Return spring key stem boot” (same design as above but given its own patent)
Mechanical 1971, Electronic Engineer magazine’s “this is your keyboard reference”
N-key rollover 1971, Electronic Engineer magazine’s “this is your keyboard reference”
Optical beam keyboard 1951: Calculator, US patent 2641753 (granted 1953 to Monroe)
1960: Alphanumeric keyboard, US patent 3032163 (granted 1972 to Invac)
Tactile feedback 1970, US patent 3644855 for Cherry reed switches (as “tactile feel”)
1970, US patent 3767022 filed by Singer, as “breakaway feel”