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 | 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) |