Abstract: According to the present invention, a hand-held portable transmitter is provided which is capable of communicating with a variety of different message receiving hosts. The transmitter is provided with a technique for generating waveforms to communicate with foreign message receivers over a communication channel by using a lookup table and software implementation in combination with a telephone interface circuit. Also provided is a versatile encoding protocol in which a message is optionally converted to a four-bit, five-bit, or six-bit sequence, or to a sequence of variable-length bit-strings, the converted message is queued and regrouped as four-bit nibbles, and the nibbles are communicated by DTMF tones.

Abstract: An electronic dictionary has a keyboard for entering words, which words are displayed along with a set of synonyms divided into subsets, each subset having a displayed common core meaning. The original word entered by the user for which synonyms and related words are sought is put into a history list. The user can select any of the synonyms or any of the words from the core meaning presented, or can independently enter any desired word and add those entered words to the history list. In this fashion, the user can build up a history list which can be reviewed by the user and any word in the history list re-accessed, so that the user can track through the history list and explore any desired complex arrangement of concepts, ideas, and relationships. As the history list becomes full, the earliest additional entry words are deleted in sequence.