As Don Hopkins sort-of says—the original chording keyboard (and most later units) just had you inputting a binary number, which would be added to 64 to get an ASCII codepoint. No attempt was made to optimize for letter frequencies in English at this stage of design—A was one key (00001) but E was two (00101).

Engelbart's style of chording keyboard barely escaped the Anglosphere. But a related invention, the stenographic keyboard, did; these are used for court reporting and live television captioning. They introduce a very different strategy for inputting text—operators of these input one full syllable at a time, phonetically, and the machine interprets the pronunciation according to a dictionary; thus in English the most common errors are homophones, which can be revised later from context. It requires quite a lot of training and practice to be proficient with them, and they are extremely language-specific.