Dual 2-Line To 4-Line Decoder / Demultiplexer in DIP-16 Package.
The SN74HC139N contains two two-to-four decoders with one active low output strobe G. When the outputs of one channel are gated by the strobe input, they are all forced into the high state. When the outputs are not disabled by the strobe input, only the selected output is low while all others are high.

