Verilog and VHDL generally use more complex logic than the four-value logic system, with various strengths of logic zero and one so that weak effects such as pull-up resistors and weedy pass transistors can be modelled.

This enables a net-resolution function to be applied when a net is driven by more than one source. For instance, an equal drive-strength one and zero will resolve to an X but the stronger will win when strengths are not matched.

The pass transistor is a cheap (in area terms) and efficient (in delay terms) form of programmable wiring, but it does not amplify the signal.