Download 1 - Erode Sengunthar Engineering College

NOORUL ISLAM COLLEGE OF ENGINEERING
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
TWO MARKS , 16-MARKS QUESTIONS FOR UNIT-I
Date : 20.07.2004
TWO MARK QUESTIONS:
1.Define the functions of OS?
Main functions of OS:

process management

Memory management.

Device or I/O management.

File management.
Other functions of OS:
 Implementing the user interface
 Sharing network among users
 Preventing users from interfering with one another.
 Allocating the users to share data among users.
 scheduling resources among users.
 Facilitating input and output.
 Recovery from errors.
 Accounting for resource usage.
 Organizing data for secure and fast access.
 Facilitating parallel operations.
 Handling network connections.
2.What are the goals of OS?
Primary goal :
 To make a system convenient to use.
 It provides an environment , within this environment other programs can
do useful work.
Secondary goal :
 Efficient operation of the computer system.
3.Define SPOOLING with diagram?
SPOOLING : Simultaneous Peripheral Operation Online
It keeps both CPU and I/O devices working at much higher rates.
Disk
Card
Reader
CPU
Printer
Card reader read the input , it is kept on the disk. , when the job or process is executed , the
necessary or essential details are obtained from disk When job needs to print the output then the
line of output is copied to buffer , and is written to the disk. Then it copies next line and so on.
When the job is completed , output is printed This is called Spooling.
4.Write demerits of BOS?
 Non-Interactive operating system.
 It takes long turn around time.
 Programs should be debugged dynamically
 While the program is in execution , we can’t modify the program to study the
behavior of program
 Output will display only after completion of all processes in that batch.
5.Define virtual memory?
When the program’s memory size is larger than available physical memory size then , we
need virtual memory. Here the job or process to be executed that may not be completely in
primary memory, but partial portion of the process or job may be in secondary memory. It
requires CPU scheduling scheme , job synchronization , job communication also jobs should not
get stuck in deadlock.
6.Differentiate TCS & LCS ?
LCS
1.Each processor has its own
local memory
2.Each processor can
communicate with other all
through communication lines
TCS
1.Common memory is
shared by many processors
2.No need of any special
communication
lines(telephone lines)
7.Mention the reasons why distributed systems are more important?
i.
Resource sharing : If number of different machines or sites are connected to one
Another , then a user at one machine may be able to use the
Resources available at another machine.
ii.
Computation speedup : Distribute the work into many machines or sites . so each
Part of a work is run concurrently on different machines .
iii. Reliability : If one machine fails in a distributed system , then the remaining
Machines will not stop its processing , but it continues its working
iv.
Communication :
8.Compare different types of Multiprocessing systems?
ASYMMETRIC
1.Working of OS is based on
Master-Slave relationship
2.Each processor is assigned with a
specific task. Master processor
controls the system , schedules and
allocates work to the slave
processors.
3.Example : Sun OS version 4
SYMMETRIC
1.Each processor concurrently
runs a copy of the OS
2.Many processes can run
simultaneously
3.Example : Windows NT , OS/2,
UNIX , Solaris
9.Give minimum four examples of Real time operating system?
 In ISRO fuel injection systems , speed adjustment.
 Scientific experiments
 Medical Imaging systems , Industrial control systems.
 Weapon systems.
 Robotics.
10.Compare Hard RTOS and Soft RTOS ?
Hard RTOS
1.Time delays are not allowed
2.It assures critical tasks must
completed on time
3.All delays in the system should be
bounded
Soft RTOS
1.Time delays are allowed
2.Very critical tasks gets more
priority ever other tasks and
retains it until it completes.
3.All delays in the system
should be bounded
11.What is the need of mode bit ? In which architecture this mode bit is not applicable?
To protect OS from user programs , and from shared resources , hardware support is
essential. It is given by mode bit. This bit is added to the hardware of the computer to indicate
the current mode
If Mode bit=1User mode
Mode bit=0Monitor mode (supervisor mode , privileged mode system mode)
User programs will be executed on user mode.
System programs , System calls , Interrupt Service Routine are executed in favor of monitor
mode
In 8088 architecture it is not applicable.
12.What do you mean by Command Interpreter?
It is interface between user and operating system. To get the next command statement
and to execute commands , command interpreter is needed. In MSDOS , UNIX command
interpreter is as a program that will run when a job is initiated or when a user first logs on.
13.Name different kinds of services provided by OS?
 Program execution.
 I/O operation.
 File system manipulation.
 Communication.
 Error detection
 Resource allocation.
 Accounting.
 Protection Or security.
14.what is meant by mechanism and policy?
Mechanism determines how to do something ;
Policies determines what will be done ;
Policies are likely to change in the underlying mechanism. A general mechanism
would be more desirable. A change in policy would then require redefinition of only certain
parameters of the system. If in one computer system , a policy decision is made that I/O intensive
programs should have priority over CPU-intensive ones, then the opposite policy could be
instituted easily on some other computer system if the mechanism were properly separated and
were policy independent.
15.Draw simple structure of UNIX operating system?
The users
The Shells and commands , compilers , interpretor , system libraries
System call interface to the Kernel
Signal
File system
CPU scheduling
Terminal handling
Swapping block
Page replacement
Character I/O
I/O system
Demand paging
System terminal drivers
Disk and tape drivers
Kernel Interface to the hardware
Terminal controllers
Device controllers
Memory controllers
Terminals
Disks& Tapes
Physical memory
16.What is called Microkernel& give its usage & Give 2 example of it.
It removes non-essential components from the Kernel and implementing them as system
and user level programs. So small kernel is achieved called microkernel.It is a small privileged
Os , that provides process scheduling , memory management and communication services and
relies on other processes to perform some of the functions associated with the OS kernel.
Examples:Tru64 UNIX (Digital UNIX) , QNX
17.Name the set of system calls used to manage the devices and process control?
System calls for process control:
 end , abort
 load execute
 create process , terminate process
 getprocess attributes , setprocess attributes
 wait for time
 waitevent , signalevent
System calls for Device management
 get device attribute , set device attributes
 requestdevice , releasedevice
 read , write , reposition
 logically attach or detach devices.
18.What is web clipping?
A normal PC has 21 inches , but handheld devices had 3 inches , so reading e-mail ,
browsing web pages must be condensed onto smaller displays. A small subset (portion) of a web
page is displayed on the handheld device is called web clipping.
19.Define parallel cluster ? give 2 examples of parallel cluster?
Multiple hosts are allowed to access the same data on the shared storage. It is difficult to
achieve. Each machine has full access to data in database.
Example : Oracle’s Parallel Cluster Server in a version of oracle’s database which is designed to
run on parallel cluster.
20.Compare multiprogramming and multiprocessing operating systems?
Multiprogramming
1.Only one Processor is there.
2.programs which are ready to be
executed are in main memory.
3.It executes only one process at any
time
4.It increases CPU utilization .
Multiprocessing
1.More than one processor will be there
2.It increases throughput , reliability
3.It executes more than one process at
any given time.
4.It also increases CPU utilization .More
than one processors shares computer
memory , computer bus , clock ,
peripheral devices
21.Describe graceful degradation of machines?
In multiprocessor systems , failure of one processor will not affect the whole system. The
function or work of failed one is takeover by other processors , so system gets slow.(i.e)If 10
systems are then , if one fails then workload of this failed processor is handled by 9 systems.
Now the overall performance of 9 systems are reduced by 10%.it is called graceful degradation.
22.Differentiate turnaroundtime and responsetime?
Turnaroundtime
1.Interval between the time of submission of a process , to
the time of completion.
2.Time spent waiting to get into memory + waiting in the
ready queue + executing on the CPU + doing I/O .So the
turn around time may be large value in certain cases.
Responsetime
1.Time interval between submission of the
process and first response produced for that
process.
2.If the response time is very low , then
performance is very good.
23.What is distributed lock manager?
Instead of improvements in distributed computing , most systems do not offer general
purpose distributed file systems .therefore , most clusters do not allow shared access to data on
the disk. For this , distributed file systems , must provide access control and locking to the files
to ensure no conflicting operations occur. It is called distributed lock manager.
24.Mention primary advantages of virtual machines?
First , by completely protecting system resources , the virtual machine provides a robust
level of security.
Second , the virtual machine allows system development to be done without disrupting
normal system operation.
25.What is JVM?
Java provides a specification for Java Virtual Machine(JVM).Java objects are specified
with the class construct. For each java class the java compiler produces an architecture-neutral
byte code output.(.class file run on any implementation of the JVM).
JVM is an specification of abstract computer. JVM consists of class loader , class verifier
, java interpreter. The class loader loads .class files from both the java program and the java API
for execution by the java interpreter. Then class verifier checks that the class file is valid java
byte code and also it ensures that the byte code does not perform pointer arithmetic , which
could provide illegal memory access. Then it is run by java interpreter. The JVM automatically
manages garbage collection.
16-mark questions :
1.a.Explain in detail about hardware protection , with necessary diagrams?
b. Explain Layered approach of system structure
2. Explain the following briefly
i Multiprocessing systems
ii Clustered systems
iii Desktop systems
iv Multiprogrammed systems
(10)
(6)
(16)
3.i Explain layered approach of system structure?
ii Describe the concepts of virtual machines in detail?
(6)
(10)
4.a.Explain system calls in detail ?
b Describe various system services of operating system in detail
(10)
(6)
5.i Briefly explain system components in detail?
ii Explain design and implementation of system in detail?
(6)
(10)
6.i.Explain virtual machines in detail ?
ii Explain how the Time sharing operating system works?
(12)
(4)