Double Input–Single Output Systems
All of the Boolean logic gates with double inputs and a single output are discussed. The specific types discussed are AND, OR, NOR, NAND, INHIBIT, XOR, XNOR, IMPLICATION, TRANSFER, NOT TRANSFER, PASS 0 and PASS 1. These are driven by a variety of inputs: cationic, anionic and neutral chemical species, biochemical entities and light dose. Redox inputs are also applied chemically or electrochemically. In suitable situations, pairs of chemical inputs are classified according to their distinguishability and connectivity as well. Some of these open up chemical logic phenomena which have no physical counterpart in electronics. Though the emphasis throughout is on molecular phenomena which can be taken to the single-molecule situation in favourable cases, molecule-based materials also provide a rich source of double input-single output logic. Some of these involve behaviour which is characteristic of the material concerned.