Code: DC-14 Subject: SYSTEM
SOFTWARE & OPERATING SYSTEMS 
Time: 3 Hours Max. Marks: 100
NOTE: There are 9 Questions in all.
· Question 1 is compulsory and carries 20 marks.
· 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. Which of these is not a part of Synthesis phase
(A) Obtain machine code corresponding to the mnemonic from the
Mnemonics table
(B) Obtain address of a memory operand from the symbol table
(C) Perform LC processing
(D) Synthesize a machine instruction or the machine form of a constant
b. The syntax of the assembler directive EQU is
(A) EQU <address space> (B) <symbol>EQU<address space>
(C) <symbol>EQU (D) None of the above
c. The following features are needed to implement top down parsing
(A) Source string marker
(B) Prediction making mechanism
(C) Matching and Backtracking mechanism
(D) All of the above
d. A macro definition consists of
(A) A macro prototype statement (B) One or more model statements
(C) Macro preprocessor statements (D) All of the above
e. The main reason to encrypt a file is to ______________.
(A) Reduce its size (B) Secure it for transmission
(C) Prepare it for backup (D) Include it in the startup sequence
f. Which of the following is not a key piece of information stored in single page table entry assuming pure paging and virtual memory
(A) Frame number
(B) A bit indicating whether the page is in physical memory or on the disk
(C) A reference for the disk block that stores the page
(D) None of the above
g. A UNIX device driver is
(A) Structured into two halves called top half and bottom half
(B) Three equal partitions
(C) Unstructured
(D) None of the above
h. The following is not a layer of IO management module
(A) PIOCS (Physical Input Output Control System)
(B) LIOCS (Logical Input Output Control System)
(C) FS (File System)
(D) MCS (Management Control System)
i. Which amongst the following is not a valid page replacement policy?
(A) LRU policy (Least Recently Used)
(B) FIFO policy (First in first out)
(C) RU policy (Recurrently used)
(D) Optimal page replacement policy
j. Consider a program with a linked origin of 5000. Let the memory area allocated to it have the start address of 70000. Which amongst the following will be the value to be loaded in relocation register?
(A) 20000 (B) 50000
(C) 70000 (D) 90000
Answer any FIVE Questions out of EIGHT Questions.
Each question carries 16 marks.
Q.2 a. Differentiate between
(i) Problem-oriented and procedure-oriented language
(ii) Dynamic and static binding
(iii) Scanning and parsing (6)
b. Define Grammar of a language. Identify the different classes of grammar. Explain their characteristics and limitations. (10)
Q.3 a. Enumerate the data structures used during the first pass of the assembler. Indicate the fields of these data structures and their purpose/usage. (8)
b. What is an assembly language? What are the advantages of assembly language? Explain the different kind of statements used in assembly language. (8)
Q.4 a. What is macro-expansion? List the key notions concerning macro expansion. Write an algorithm to outline the macro-expansion using macro-expansion counter. (8)
b. What is a heap? Name and explain the popular techniques to identify free memory areas as a result of allocation and de-allocations in a heap. (8)
Q.5 a. Suppose that a process scheduling algorithm favors those processes that have used the least processor time in the recent past. Why will this algorithm favor /IO-bound processes, but not starve CPU-bound processes? (6)
b. Why is segmented paging important (as compared to a paging system)? What are the different pieces of the virtual address in a segmented paging system? (6)
c. List one advantage and one disadvantage of having large block size. (4)
Q.6 a. Suppose two processes enter the ready queue with the following properties:
Process 1 has a total of 8 units of work to perform, but after every 2 units of work, it must perform 1 unit of I/O (so the minimum completion time of this process is 12 units). Assume that there is no work to be done following the last I/O operation.
Process 2 has a total of 20 units of work to perform. This process arrives just behind P1.
Show the resulting schedule for the shortest-job-first (preemptive) and the round-robin algorithms. Assume a time slice of 4 units of RR. What is the completion time of each process under each algorithm? (8)
b. What are threads? Why are they required? Discuss the differentiate between Kernel level and user level threads? (8)
Q.7 a. Consider the following segmented paging memory system. There are 4 segments for the given process and a total of 5 page tables in the entire system. Each page table has a total of 8 entries. The physical memory requres 12 bits to address it; there are a total of 128 frames. (8)
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Segment Table |
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0 |
0x73 |
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0x25 |
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0x85 |
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0x0F |
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0x17 |
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1 |
0x2C |
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0x2D |
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0x31 |
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0x3D |
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0x00 |
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0 |
0x3 |
2 |
0x05 |
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0x1E |
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0x01 |
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0x5D |
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0x0D |
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1 |
0x1 |
3 |
0x17 |
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0x5A |
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0x1F |
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0x1E |
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0x66 |
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2 |
0x0 |
4 |
0x57 |
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0x0F |
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0x09 |
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0x6C |
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0x62 |
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3 |
0x4 |
5 |
0x1A |
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0x7A |
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0x0A |
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0x2F |
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0x50 |
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6 |
0x4B |
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0x2B |
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0x1A |
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0x78 |
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0x32 |
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7 |
0x11 |
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0x6C |
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0x32 |
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0x7B |
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0x11 |
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0 |
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1 |
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2 |
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3 |
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4 |
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Page Tables |
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physical memory; address=12 bits |
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(i) How many bytes are contained within the physical memory?
(ii) How large is the virtual address?
(iii) What is the physical address that corresponds to virtual address 0x312?
(iv) What is the physical address that corresponds to virtual address 0x1E9?
b. What is swapping? Does swapping increase the Operating Systems’ overheads? Justify your answer. (8)
Q.8 a. Suppose there are 2 copies of resource A, 3 copies of resource B, and 3 copies of resource C. Suppose further that process 1 holds one unit of resources B and C and is waiting for a unit of A; that process 2 is holding a unit of A and waiting on a unit of B; and that process 3 is holding one unit of A, two units of B, and one unit of C. Draw the resource allocation graph. Is the system in a deadlocked state? Why or why not? (8)
b. Draw the state diagram of a process from its creation to termination including all transitions, and briefly elaborate every state and transition. (8)
Q.9 a What are capability based computer systems? How they are different from conventional computer system. (4)
b What is buffering of records?
Explain how is file processing using n buffers achieved. (6)
c Explain in brief the various techniques that can be employed to protect the user files. (6)