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.
|Buckling rubber sleeve||1970, US patent 3767022 (granted 1973 to the Singer Company), “Return spring key stem boot” (used on optical beam keyboard)|
|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”); as “breakaway feel” in US patent 3767022 (also 1970)|