Note: Attempt five questions in all including Q.No.1 which is compulsory. Select one
question from each unit.
Q1. Answer the following: (2.5x10=25)
(a) Explain process states with the help of a diagram.2.5
(b) Explain thrashing.2.5
(c) Write Linux commands to display currently running processes, terminate a
process, execute a command in background, display all jobs created, bring a job in
foreground.2.5
(d) Differentiate between I/O bound and CPU bound processes.2.5
(e) Explain the working modes of vi editor.2.5
(f) What is PCB? State the contents of PCB.2.5
(g) Distinguish between internal and external fragmentation.2.5
(h) What is Starvation and Aging?2.5
(i) What is Belady's Anomaly?2.5
(j) What is Swapping in OS?2.5
UNIT-I
Q2. (a) What is an Operating System? State the functions of
an Operating System.6.5
(b) Define the essential properties of the following types of Operating
Systems:6
I. Batch II. Time Sharing III. Real Time
OR
Q3. With the help of diagram, explain the architecture of
LINUX operating system.7.5
(b) State and explain the Basic Directory Structure of Linux OS.5
UNIT-II
Q4.(a) What are the criteria for CPU scheduling?5
(b)Consider following processes with length of CPU burst time in
milliseconds:7.5
Process
Burst Time
Arrival Time
P1
5
0
P2
10
2
P3
2
4
P4
1
7
All process arrived in order p1, p2, p3, p4.
(a) Draw Gantt charts illustrating execution of these processes for FCFS,
preemptive SJF and round robin (quantum=3).
(b)Calculate waiting time for each process for each scheduling
algorithm.
(c)Calculate average waiting time for each scheduling algorithm.
OR
Q5. (a) Explain the terms relating to IPC - i) Critical Section ii)
Race Condition6.5
(b) Explain Semaphores and its types.6
UNIT-III
Q6. (a) What is deadlock? List and explain conditions for the
deadlock situation and various ways for deadlock prevention.7.5
(b) Consider the following snapshot of a system:5
Threads
Allocation
Max
Available
A
B
C
D
A
B
C
D
A
B
C
D
T0
6
0
1
2
4
0
0
1
3
2
1
1
T1
2
7
5
0
1
1
0
0
T2
2
3
5
6
1
2
5
4
T3
1
6
5
3
0
6
3
3
T4
1
6
5
6
0
2
1
2
Answer the following questions using the Banker's algorithm:
a. Find the total number of resources of type A, B, C, D.
b. What is the content of the matrix Need?
c. Is the system in a safe state? If it is, find the safe sequence.
OR
Q7. (a) Explain the concept of Contiguous memory allocation.
Consider free memory holes of sizes 40K, 5K, 28K, 15K, 27K are available. The processes of size 29K, 12K,
25K, 28K is to be allocated. How are the processes placed in first fit, best fit, worst fit? Which algorithm
makes the most efficient use of memory?6
(b) Explain the concept of demand paging. Consider the following page reference
string: 7, 2, 3, 1, 2, 5, 3, 4, 6, 7, 1, 0, 5, 4, 6, 2, 3, 0, 1, and assume 4-page frames.6.5
Explain the following page replacement algorithms of demand paging and compute the
number of page faults for each algorithm.
i. LRU replacement
ii. FIFO replacement
iii. Optimal replacement
UNIT-IV
Q8. (a) Explain any three schemes for defining the logical
structure of a directory also state the operations that could be performed on directories.6.5
(b) Compute the total head movements according to FCFS, SCAN, and C-SCAN HDD
Scheduling.6
Queue: 98, 183, 67, 122, 14, 124, 95, 37
Head starts at 35
OR
Q9. (a) Current permissions of file demo.txt are "rw-r-xr--". Using
both relative and absolute mode, specify the 'chmod' expression required to change the permissions as
follows:6
i. rwxrwxrwx
ii. r--r--r---
iii. --- --- ---
iv. rwxr-xr-x
(b) Explain the various types of files in Linux and the file Permissions applied to
protect the file.6.5