TheLSTTL/MSI SN54/74LS139 is ahigh speed Dual 1-of-4 Decoder/Demultiplexer. The device has two independent decoders, each accepting two inputsand providingfour mutually exclusive active LOW Outputs. Each decoderhas an activeLOW Enable input which can be used as a data input fora 4-output demultiplexer. Each half of theLS139 can be used as a function generatorproviding all four minterms oftwo variables.