Code: DC14                                                                             Subject: SYSTEM SOFTWARE &

Time: 3 Hours                                                                                        OPERATING SYSTEMS

Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1       Choose the correct or best alternative in the following:                                         (2x10)

a. Virtual memory is

(A)  simple to implement                     

                   (B)  used in all major commercial operating systems

(C)  less efficient in utilization of memory                                                                          

                   (D)  useful when fast I/O devices are not available

b. Relocation bits used by relocating loader are specified by

(A)  Relocating loader itself                 (B)  Assembler or Translator

(C)  Macroprocessor                           (D)  Both (A) and (B)

             c.   Resolution of externally defined symbols is performed by

(A) Linker                                          (B) Loader

(C) Compiler                                       (D) Editor

             d.   Relocatable programs

(A)  cannot be used with fixed partitions

(B)  can be loaded almost any where in memory

(C)  do not need a linker                    

(D)  can be loaded only at one specific location

             e.   Page stealing

(A) is a sign of efficient system           

(B)  is taking page frames other working sets

(C)  should be the tuning goal

(D)  is taking larger disk spaces for pages paged out

             f.    The total time to prepare a disk drive mechanism for a block of data to be read from is its

(A) latency                                        

(B)  latency plus transmission time

(C)  latency plus seek time

(D)  latency plus seek time plus transmission time

g.   To avoid race condition, the maximum number of processes that may be simultaneously inside the critical section is

(A)  zero                                             (B) one

(C)  two                                              (D) more than two

             h.   The memory allocation scheme subject to “external” fragmentation is

(A) segmentation                                (B) swapping

(C) pure demand paging                      (D) multiple fixed contiguous partitions

             i.    Page fault frequency in an operating system is reduced when the

(A)  processes tend to the I/O-bound

(B)  size of pages is reduced

(C) processes tend to be CPU-bound 

(D) locality of reference is applicable to the process

             j.    In which of the following page replacement policies Balady’s anomaly occurs?

(A) FIFO                                           (B)  LRU

(C)  LFU                                             (D)  NRU

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Describe language processing activities?                                                             (8)

b.   Explain the criteria to classify datastructures used for language processing?          (8)

  Q.3     a.   Explain macro definition, macro call and macro expansion?                                 (6)

             b.   What are the advantages of code optimization? Explain optimizing transformations?             (10)

Q.4     a.   Explain the following terms

(i)   Translated address

(ii)  Linked address

(iii) Load address

                  Explain the relationship amongst these.  (6)

             b.   What are the functions of passes used in two-pass assembler? Explain pass-1 algorithm?                (10)

Q.5     a.   What is a text editor?  Explain in brief the different kinds of text editors.              (8)

b.   What datastructure is used by an operating system to keep track of process information?                (4)

c. What is an I/O buffer?  What are the advantages of buffering?                             (4)

  Q.6     a. Categorize the CPU scheduling algorithms? Explain non-preemptive algorithms?                 (4)

             b.   Differentiate between Batch Operating System and Time Sharing Operating System?                      (6)

     c.   What is file sharing?  List the popular file sharing modes.  Also list the dynamic file sharing semantics of Unix.                                                           (6)

Q.7     a.   What is a Deadlock? Write an algorithm for deadlock detection.                         (8)

             b.   Develop a regular expression for

                   (i)   Integer

                   (ii)  Real number

                   (iii) Real number with optional fraction

                   (iv) Identifier                                                                                                      (8)

Q.8     a.   What is critical section problem? Give two solutions for critical section problem?                (8)

             b.   Explain difference between Security and Protection? Describe the scheme of capability lists to implement protection?                                          (8)

Q.9     a.   Explain with the help of examples FIFO and LRU page replacement algorithms?                 (10)

             b.   Explain interprocess communication through messages.  What implementation issues arise in such communication?                                   (6)