Keyboard input devices, methods and systems

A keyboard for inputting graphical indicium representations of language characters formed from one or a combination of character units, the keyboard comprising a plurality of keys, each key having at least one unit associated therewith but with selected keys, at least, having two or more units associated therewith, the two or more units all being different and each forming at leas a part of a character, a key mapping for each key whereby selection of a key generates a mapped value of a unit associated with the selected key, the mapped value having a relational correlation with one or more relevant characters, and selection of one or more further keys which are associated with the same or other units provide further mapped values consistent with at least one of the relevant characters such that a character that is unique to the selected key or combination of keys is determined, the keys being so arranged on the keyboard that visually similar units are associated with the same of adjacent keys, and units which usually form left, right top or bottom character parts are associated with keys generally located in physically similarly related positions on the left, right, top and bottom, respectively, of the keyboard.