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16th February 2016, 02:14 PM
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Re: Operating System Notes For UGC Net

Hello sir, I want notes of UGC NET examination one of the subject is computer science. In the computer science operating system is a topic of computer science. Please provide me notes if you have? Other wise give me some question of operating system for UGC NET?
  #3  
16th February 2016, 02:14 PM
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Join Date: May 2012
Re: Operating System Notes For UGC Net

I was founded operating system syllabus from UGC NET blog spot. Syllabus of operating system is very lengthy so here I’m provides you here. But I’m giving you overview and some basic detail of operating system notes.

What is an operating system? Hard to define precisely, because operating systems arose historically as people needed to solve problems associated with using computers.
Much of operating system history driven by relative cost factors of hardware and people. Hardware started out fantastically expensive relative to people and the relative cost has been decreasing ever since. Relative costs drive the goals of the operating system.

In the beginning: Expensive Hardware, Cheap People Goal: maximize hardware utilization.
Now: Cheap Hardware, Expensive People Goal: make it easy for people to use computer.

In the early days of computer use, computers were huge machines that are expensive to buy, run and maintain. Computer used in single user, interactive mode. Programmers interact with the machine at a very low level - flick console switches, dump cards into card reader, etc. The interface is basically the raw hardware.

Problem: Code to manipulate external I/O devices. Is very complex, and is a major source of programming difficulty.
Solution: Build a subroutine library (device drivers) to manage the interaction with the I/O devices. The library is loaded into the top of memory and stays there. This is the first example of something that would grow into an operating system.

Because the machine is so expensive, it is important to keep it busy.

Problem: computer idles while programmer sets things up. Poor utilization of huge investment.
Solution: Hire a specialized person to do setup. Faster than programmer, but still a lot slower than the machine.
Solution: Build a batch monitor. Store jobs on a disk (spooling), have computer read them in one at a time and execute them. Big change in computer usage: debugging now done offline from print outs and memory dumps. No more instant feedback.
Problem: At any given time, job is actively using either the CPU or an I/O device, and the rest of the machine is idle and therefore unutilized.
Solution: Allow the job to overlap computation and I/O. Buffering and interrupt handling added to subroutine library.

Some questions of Operating System For UGC Net:

1. If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 67.
A. 239
B. 310
C. 321
D. 325


2. Which of the following memory allocation scheme suffers from external fragmentation ?
A. Segmentation
B. Pure demand paging
C. Swapping
D. Paging


3. Consider a system having m resources of the same type. These resources are shared by 3 processes A, B and C which have peak demands of 3, 4 and 6 respectively. For what value of m deadlock will not occur ?
A. 7
B. 9
C. 10
D. 13


4. Pre-emptive scheduling is the strategy of temporarily suspending a running process
A. before the CPU time slice expires
B. to allow starving processes to run
C. when it requests I/O
D. to avoid collision


5. Resources are allocated to the process on non-sharable basis is
A. mutual exclusion
B. hold and wait
C. no pre-emption
D. circular wait


6. In round robin CPU scheduling as time quantum is increased the average turn around time
A. increases
B. decreases
C. remains constant
D. varies irregularly


7. Pool based allocation of memory achieves better usage. Memory can be preempted from inactive programs and used to accommodate active programs. This is called
A. Preemption
B. Swapping
C. Spooling
D. Scheduling


8. Which of these is an example of a virtual resource?
A. Print server
B. Virtual machine
C. Virtual memory
D. All of the above


9. Which concept explains the working of an Operating System?
A. It is event driven
B. It is object oriented
C. It is procedure based system software
D. It is a collection of procedures that interact with each other


10. Which of these is/are the desirable features of an Operating system
A. Extensible
B. Portable
C. Reliable
D. All of the above


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