Value Set:
---> Four values to model the functionality
Value level--------- Condition in hardware circuits
0 ------------- > Logic zero, false condition
1 ------------- > Logic one, true condition
X ------------ > Unknown logic value
Z ------------- > High impedance ,floating state
---> Four values to model the functionality
---> Eight strengths of real hardware
1 ------------- > Logic one, true condition
X ------------ > Unknown logic value
Z ------------- > High impedance ,floating state