126. How many address lines are used to identify an I/O port in the peripheral I/O device?

1. 1. 8

   
   
   

   2. 4

   
   
   

   3. 16

   
   
   

   4. 2

   
   
   

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   2

   Correct Option: D

   2

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127. The first two instructions of an interrupt service subroutine are PUSH B, PUSH PSW. What will be the next instance?

1. 1. POP PSW

   
   
   

   2. HLT

   
   
   

   3. POP B

   
   
   

   4. None of these

   
   
   

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   POP PSW

   Correct Option: A

   POP PSW

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128. Microprocessor is an in-sequence device, which powerful category of instructions breaks this sequence?
     

1. 1. Data transfer Instⁿ

   
   
   

   2. Arithmetic Instⁿ

   
   
   

   3. Logical Instⁿ

   
   
   

   4. Branch control Instⁿ

   
   
   

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   Branch control instructions

   Correct Option: D

   Branch control instructions

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129. Specify the number of times the given loop will count— LOOP:
     

     MVI	B, 64 H
     DCR	B
     JNZ	LOOP

1. 1. 101

   
   
   

   2. 100

   
   
   

   3. 65

   
   
   

   4. Infinite

   
   
   

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   Infinite

   Correct Option: D

   Infinite

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130. What is the total delay for executing the following program?

     MVI	C, FFH
     DCR	C
     JNZ	LOOP

1. 1. 1.8 ms

   
   
   

   2. 1.5 ms

   
   
   

   3. 2.0 ms

   
   
   

   4. 2.5 ms

   
   
   

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   1.8 ms
   Clock frequency, f = 2 MHz
   

   =	1	=	1	× 10-6 = 0.5 μs
   	f		2

   
   Time period to execute,
   MVI = 7 T-states × 0·5
   T = 3·5 μs
   Time Delay = T × Loop T-states × N10
   = 0·5 × 10^–6 × 14 × 255
   = 1785 μs ≈ 1·8 μs

   Correct Option: A

   1.8 ms
   Clock frequency, f = 2 MHz
   

   =	1	=	1	× 10-6 = 0.5 μs
   	f		2

   
   Time period to execute,
   MVI = 7 T-states × 0·5
   T = 3·5 μs
   Time Delay = T × Loop T-states × N10
   = 0·5 × 10^–6 × 14 × 255
   = 1785 μs ≈ 1·8 μs

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