Logic and Colors in Logicly
Signal is represented in Logicly using colors. Wires connecting objects, and some objects themselves, may change color on the editing surface when pins change state or when a connection is created or removed.
Blue means that the signal is in the high state (true).
White means that the signal is in the low state (false).
Gray means that the signal is in the high impedance state (hi-Z).
Red means that the signal is in an error state.
High Impedance (hi-Z) and Error states
The simulator assumes that all input pins start out in an high impedance (hi-Z) state before the signal begins propagating. If you prefer to work strictly with high (true) and low (false) values only, you may change the default float signal to high or low in your document settings.
In the real world, if a gate's input pin is left "floating" (unconnected), it could pick up noise from the surrounding environment and change state unexpectedly. In other words, at any given moment, the simulator can't necessarily be sure if an unconnected input pin should be interpreted as a high or low signal. With this in mind, some components may output an error state if they receive a high impedance (hi-Z) signal.
There are a couple of ways to avoid propagating a high impedance (hi-Z) signal:
For the mathematically inclined, here's the truth table that Logicly uses:
|A||B||A OR B||A AND B||NOT A|