==Wire and Pin Values (Level & Strength)==
Each wire or each device pin has both a logic level & a strength that together make its value at any instant of time. [[B2RF.Spice A/D]] supports 3 signal levels and 4 signal strengths, giving a total of 12 different values. The possible logic levels are high (1), low (0), and indeterminate (x). The possible strengths are strong (s), resistive (r), high impedance (z), and initial unknown (?), in order by their strength, from strongest to weakest. If one pin of a wire is generating a strong-high signal and the other pin is generating resistive-low, then the strong level will dominate, and the result will be a strong-high wire value.
The value that a pin propagates can differ from the value of the wire it is attached to if the wire is also attached to other pins which are propagating different values. In this case, the wire must resolve the competing values to come up with a single wire value. An indeterminate level resolved with anything else is indeterminate. An initial unknown level resolved with any other level is set equal to the other level. A high resolved with a low results in indeterminate. Pins will propagate indeterminate levels when there is not enough information at the inputs of a device to generate known outputs.