28. An information signal generator operable in at least four information levels, comprising: A. shift means operable to select any one of said information levels; B. a keyboard operable to select desired information, incorporating twelve keys arranged in a four by three matrix wherein each number of from 0 to 9 is individually selectable by operation of a corresponding individual key of the twelve keys when the first information level is selected and wherein the letters from A to Z are divided into first, second and third mutually exclusive groups, each group having less than thirteen letters, wherein each letter of the first group of letters is individually selectable by operation of a corresponding individual key of said keyboard when the second information level is selected, wherein each letter of the second group of letters is individually selectable by operation of a corresponding individual key of said keyboard when the third information level is selected, and wherein each letter of the third group of letters is individually selectable by operation of a corresponding individual key of said keyboard when the fourth information level is selected; and C. a signal-generating circuit responsive to simultaneous operation of the shift means and the keyboard for generating a signal corresponding to the information represented by operation of the selected key of the keyboard and the selection of an information level by operation of the shift means.
32. An information generator as defined in claim 28, wherein said keyboard further incorporates additional keys representing punctuation symbols.