DESCRIPTION
The HEF4556B is a dual 1-of-4 decoder/demultiplexer. Each has two address inputs (A0 and A1), an active LOW enable input (E) and four mutually exclusive outputs which are active LOW (O0 to O3). When used as a decoder, E when HIGH, forces O0 to O3 HIGH. When used as a demultiplexer, the appropriate output is selected by the information on A0 and A1 with E as data input. All unselected outputs are HIGH.