| 61. | Suppose a processor does not have any stack pointer register. Which of the following statements is true? |
| a. | It cannot have subroutine call instruction |
| b. | It can have subroutine call instruction, but no nested subroutine calls |
| c. | Nested subroutine calls are possible, but interrupts are not |
| d. | All sequences of subroutine calls and also interrupts are possible |
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Answer: (a).It cannot have subroutine call instruction
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| 62. | Given the following Karnaugh map, which one of the following represents the minimal Sum-Of-Products of the map?
 |
| a. | xy + y'z |
| b. | wx'y' + xy + xz |
| c. | w'x + y'z + xy |
| d. | xz + y |
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Answer: (a).xy + y'z
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| 63. | A processor needs software interrupt to |
| a. | test the interrupt system of the processor |
| b. | implement co-routines |
| c. | obtain system services which need execution of privileged instructions |
| d. | return from subroutine |
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Answer: (c).obtain system services which need execution of privileged instructions
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| 64. | A CPU has two modes-privileged and non-privileged. In order to change the mode from privileged to non-privileged |
| a. | a hardware interrupt is needed |
| b. | a software interrupt is needed |
| c. | a privileged instruction (which does not generate an interrupt) is needed |
| d. | a non-privileged instruction (which does not generate an interrupt is needed |
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Answer: (b).a software interrupt is needed
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| 65. | Consider the following circuit with initial state Q0 = Q1 = 0. The D Flip-flops are positive edged triggered and have set up times 20 nanosecond and hold times 0. Also, consider the following timing diagrams of X and C; the clock period of C <= 40 nanosecond. Which one is the correct plot of Y?
  |
| a. | a |
| b. | b |
| c. | c |
| d. | d |
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Answer: (c).c
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| 66. | Which is the most appropriate match for the items in the first column with the items in the second column:
X. Indirect Addressing I. Array implementation Y. Indexed Addressing II. Writing re-locatable code Z. Base Register Addressing III. Passing array as parameter |
| a. | (X, III) (Y, I) (Z, II) |
| b. | (X, II) (Y, III) (Z, I) |
| c. | (X, III) (Y, II) (Z, I) |
| d. | (X, I) (Y, III) (Z, II) |
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Answer: (a).(X, III) (Y, I) (Z, II)
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| 67. | The 2’s complement representation of (−539)10 in hexadecimal is |
| a. | ABE |
| b. | DBC |
| c. | DE5 |
| d. | 9E7 |
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Answer: (c).DE5
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| 68. | Consider the circuit shown below. The output of a 2:1 Mux is given by the function (ac' + bc). Which of the following is true?
 |
| a. | f = x1'+ x1x |
| b. | f = x1'x2 + x1x2' |
| c. | f = x1x2 + x1'x2' |
| d. | f = x1 + x2' |
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Answer: (c).f = x1x2 + x1'x2'
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| 69. | Consider the circuit given below with initial state Q0 =1, Q1 = Q2 = 0. The state of the circuit is given by the value 4Q2 + 2Q1 + Q0.
Which one of the following is the correct state sequence of the circuit?  |
| a. | 1,3,4,6,7,5,2 |
| b. | 1,2,5,3,7,6,4 |
| c. | 1,2,7,3,5,6,4 |
| d. | 1,6,5,7,2,3,4 |
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Answer: (b).1,2,5,3,7,6,4
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| 70. | Consider the following data path of a simple non-pilelined CPU. The registers A, B, A1, A2, MDR, the bus and the ALU are 8-bit wide. SP and MAR are 16-bit registers. The MUX is of size 8 × (2:1) and the DEMUX is of size 8 × (1:2). Each memory operation takes 2 CPU clock cycles and uses MAR (Memory Address Register) and MDR (Memory Date Register). SP can be decremented locally.
The CPU instruction “push r”, where = A or B, has the specification M [SP] How many CPU clock cycles are needed to execute the “push r” instruction?  |
| a. | 1 |
| b. | 3 |
| c. | 4 |
| d. | 5 |
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Answer: (b).3
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