1. Static Hazard :
Static hazard occur in combinational circuits and can be eliminated by using redundant gates. Static hazard is further classified as:
1. Static-1 hazard 2. Static-0 hazard
2. Dynamic hazard :
When the output changes several times then it should change from 1 to 0 or 0 to 1 only once, it is called dynamic hazard. Dynamic hazard occur when the output changes for two adjacent input combinations while changing, the output should change only once. But it may change three or more times in short intervals because of different delays in several paths. Dynamic hazards occur only in multilevel circuit.
Difference between Static and Dynamic Hazard :
|STATIC HAZARD||DYNAMIC HAZARD|
|Static hazard occur when an input changes and it causes the output to change at the same moment before output becomes stable.||Dynamic hazard occur when output changes for two adjacent inputs while the output should change only once.|
|Static hazard occur in combinational circuits.||Dynamic hazard occur only in multilevel circuits.|
|Static hazard is easy to resolve.||Dynamic hazard is complex to resolve.|
|It can be eliminated by using redundant gates.||Removal of static-1 hazard ensures no occurrence of dynamic hazard.|
|Static hazard is further classified as Static-1 and Static-0.||Dynamic hazard is not further classified.|
|It causes temporary false output value.||It results in a transition to a wrong stable state.|
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