One of the exercises in university was to output a truth table for the gate, which takes an input
t, and returns
t ^ t, where ^ is a xor gate.
Now if t = 1 or t = 0, the output is always 0. Furthermore, even if the input is t = X (don't know), the output is still 0.
What I am not sure is the answer in case an input is Z (high impedance).
My guess would be that the output is also Z, because the output wire is not driven by anything. Could anyone confirm / deny this?
Also, any other examples using other gates (such as AND / OR) and Z values would be appreciated.