Multiple choice assembly

What is the value of over flow (O) flag after the instruction: SUB AX,AX





    

      
    
            
  1. 
              
    Set
    
    
            
    2. 
            
  2. 
              
    Cleared
    
    
            
    3. 
            
  3. 
              
    Unknown
    
    
            
    4. 
            
  4. 
              
    none of the above
    
    
            
    5. 
      

    


    

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        B
        Correct answer
      

        

          Explanation
          

            
The instruction 'SUB AX, AX' performs a subtraction of a register from itself (AX - AX), which always results in zero. Since 0 - 0 does not cause an arithmetic overflow (the result fits in the destination), the Overflow (O) flag is cleared (0).


          

        

    

  



          

      
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