Quad 2:1 multiplexer for 5V logic buses
The Texas Instruments SN74AHCT157N is a 4-channel 2:1 multiplexer from the 74AHCT logic family, in a 16-pin DIP through-hole package. It selects one of two 4-bit data sources onto a common output bus under control of a single select line.
Output drive and fan-out
Each output can sink or source 8mA (typical) — enough to drive three or four standard LSTTL loads or a single 74AHCT input with margin. If you are driving a heavily loaded bus or a long backplane trace, plan a buffer stage; the 8mA rating is the limit per pin.