A multiplexer or data selector, is a combinational circuit having multiple input line, select lines and one output line. Further, multiplexers integrated circuits are having ENABLE input, which has to to be activated to perform the multiplexer operation. In multiplexer depending upon select lines the binary data present on inputs is passed to the output line.
If there are n select lines, then the maximum input lines are 2^n and the multiplexer is referred to as a 2^n-to-1 multiplexer or 2^n ×1 multiplexer. Figure below show the block presentation and truth table of 4-to-1 multiplexer.
Figure below shows the 8-to-1 multiplexer Integrated circuit of TTL family 74151. This Integrated circuit has active LOW
ENABLE input and gives complementary outputs.
Figure below shows the 16-to-1 multiplexer Integrated circuit of TTL family 74150. This multiplexer has active LOW ENABLE input and active LOW output.