A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

11. Serial access memories are useful in applications where
a. Data consists of numbers
b. Short access time is required
c. Each stored word is processed differently
d. None of these
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Answer: (d).None of these

12. The essential difference between traps and interrupts is
a. traps are synchronous and  interrupts are synchronous with the program
b. traps are synchronous and  interrupts are asynchronous with the program
c. traps are synchronous and  interrupts are asynchronous with the I/O devices
d. None of these
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Answer: (b).traps are synchronous and  interrupts are asynchronous with the program

13. The size of the ROM required to build an 8-bit adder/subtractor with mode control, carry input, carry output and two's complement overflow output is given as
a. 2^16 x 8
b. 2^18 x 10
c. 2^16 x 10
d. 2^18 x 8
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Answer: (b).2^18 x 10

14. A specific editor has 200 K of program text, 15 K of initial stack, 50 K of initialized data, and 70 K of bootstrap code. If five editors are started simultaneously, how much physical memory is needed if shared text is used?
a. 1135 K
b. 335 K
c. 1065 K
d. 320 K
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Answer: (c).1065 K

15. A hierarchical memory system that uses cache memory has cache access time of 50 nano seconds, main memory access time of 300 nano seconds, 75% of memory requests are for read, hit ratio of 0.8 for read access and the write-through scheme is used. What will be the average access time of the system both for read and write requests ?
a. 157.5 n.sec
b. 110 n.sec
c. 75 n.sec
d. 82.5 n.sec
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Answer: (a).157.5 n.sec

16. For switching from a CPU user mode to the supervisor mode following type of interrupt is most appropriate
a. Internal interrupts
b. External interrupts
c. Software interrupts
d. None of the above
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Answer: (a).Internal interrupts

17. In a dot matrix printer the time to print a character is 6 m:sec., time to space in between characters is 2 m.sec., and the number of characters ina line are 200. The printing speed of the dot matrix printer in characters per second and the time to print a character line are given by which of the following options?
a. 125 chars/second and 0.8 seconds
b. 250 chars/second and 0.6 seconds
c. 166 chars/second and 0.8 seconds
d. 250 chars/second and 0.4 seconds
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Answer: (c).166 chars/second and 0.8 seconds

18. Match the following 8085 instructions with the flags:
 
a. XCHG i. only carry flag is affected.

b. SUB ii.  no flags are affected.

c. STC iii. all flags other than carry flag are affected.

d. DCR iv. all flags are affected.

code:
a  b  c   d
a. iv  i   iii  ii
b. iii  ii   i  iv
c. ii  iii   i  iv
d. ii  iv   i  iii
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Answer: (d).ii  iv   i  iii

19. How many times will the following loop be executed?

          LXI    B, 0007 H
LOP: DCX  B 
          MOV  A,B
          ORA  C
          JNZ   LOP
a. 05
b. 07
c. 09
d. 00
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Answer: (b).07

20. Specify the contents of the accumulator and the status of the S, Z and CY flags when 8085 microprocessor performs addition of 87 H and 79 H.
a. 11, 1 ,1 ,1
b. 10, 0 ,1 ,0
c. 01, 1, 0, 0
d. 00, 0, 1, 1
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Answer: (d).00, 0, 1, 1

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