Operating System FAQ
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This article discuss about some of most frequently asked questions about Operating System....

1.What you mean an operating system?write the name of one operating system?   

An operating system (OS) is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system. A user cannot run an application program on the computer without an operating system, unless the application program is self booting.Android, iOS, Linux, Mac OS X, all of which have their roots in Unix, and Microsoft Windows.

2.List out Operating System functions?
  • Resource allocation
  • Accounting
  • Protection and Security
  • File-system manipulation
  • Communication

3.What are the user operating system interfaces? Give one example?
  • Command Interpreter
Eg:UNIX,Linux systems ,there are several different shellsa user may choose from including the Bourine shell,C shell, etc..
  • Graphical User Interface
Eg; Common Desktop Environment ,X-windows systems.

4.Define System Calls?What are they?
System calls are interface to the services made available by an operating system.Different types of system calls are listed below

  • Process control
  • File Management
  • Device Managemennt
  • Information Maintanance
  • Communication

5.What are the operating system operation?

  • Process Creation
  • Process Termination

6.Define Process?
A process is a program in execution.

7.Discuss process state?
  • Running:-Instructions are being executed.
  • Waiting:-The process is waiting for some events occur.
  • Ready:-The process is waiting to be assigned to a processor.
  • Terminated:-The process has finished execution.

8.Discuss Operating system services.

There are two sets of operating system services
  • One set is for user services
  • Another is for system services 
  • User services
  • User Interface
  • Command Line Interface
  • Graphical User Interface
  • Batch Interface
  • Program Execution
  • I/O Operation
  • File System Interface
  • Communication
  • System services

9.Different Types of schedulers?
  • Long term schedulers
  • Short term schedulers
  • Medium term schedulers

10.What is race condition?

Several process access and manipulate the same data concurrently and the outcome depends on the particular order in which the access take place is called a race condition.

11.Define Critical Section?

Consider a system consisting of several process,each having a segment of code called critical section.Execution critical section is mutually executive.

12.What are critical section solutions?

  • Mutual Exclusion
  • Progress
  • Bounded Waiting

13.what you mean by semaphore?What are they?

A semaphore is an integer variable that, apart from initialization,is accessed only through two standard atomic operations:wait and signal.
Semaphore Types
  • Binary Semaphore
  • Counting Semaphore

14.What are the scheduling criterias?

  • CPU utilization
  • Turn around time
  • Throughput 
  • Waiting time
  • Response time

15.Define Busy waiting,Spin lock?

In semaphore, the main disadvantage of the mutual exclusion solutions presented so far is that they all require busy waiting.This type of busy waiting wastes CPU cycles.A semaphore that loops is called spinlock.

16.Discuss different types of operating system?

  • Real-time
A real-time operating system is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main objective of real-time operating systems is their quick and predictable response to events.

17.Discuss the structure of an operating system ?  

An operating system consists of many parts. One of the most important components is the kernel, which controls low-level processes that the average user usually cannot see: it controls how memory is read and written, the order in which processes are executed, how information is received and sent by devices like the monitor, keyboard and mouse, and decides how to interpret information received from networks. The user interface is a component that interacts with the computer user directly, allowing them to control and use programs. The user interface may be graphical with icons and a desktop, or textual, with a command line. Application programming interfaces provide services and code libraries that let applications developers write modular code reusing well defined programming sequences in user space libraries or in the operating system itself. Which features are considered part of the operating system is defined differently in various operating systems. For example, Microsoft Windows considers its user interface to be part of the operating system, while many versions of Linux do not.
18.What you mean by deadlock?

The system is in deadlock state because each process holds a resource being requested by the other process neither process is willing to  release the resource it holds.

19.What are the deadlock characterization?

  • Mutual Exclusion
  • Hold and wait
  • No preemtion
  • Circular wait

20.Define thread?

The process model discussed so far has implied that a process is a programmatic perform a single thread of execution.

21.Write down deadlock prevention methods?
  1. Elimination of mutual exclusion
  2. Elimination of hold and wait
  3. Elimination of no preemtion
  4. Elimination of circular wait

22.What is Safe state?

When a process an available resource,system must decideif immediate allocation leavesthe system in a safe state.

23.What is inter process communication?

Process executing concurrently in the operating system is independent processes,if it cannot affect or be affected by the other processes executing in the system.There are two fundamental models of inter process communication:
  • shared memory
  • message passing

24.What is Buffering?

Whether the communication is direct or indirect,messages exchanged by communicating processes reside in a temporary queue.Queue of messages attached to the link;

25.Define fragmentation?

Fragmentation is a phenomenon in which storage space is used inefficiently,reducing capacity  and in most cases performance.The term is also used to denote the waited space itself.

26.What is compaction?
The techinique of relocating all occupied areas of memory to one end of the memory so as to get one large block of free memory space is called compaction.

27.Define paging?

In Computer operating systems,Paging is one the memory management schemes by which a computer can stored.The word 'Paging' means that this page describes the page and lists other pages  on the web where you can find additional information.

28.What you mean by scheduling?

Scheduling is the process of deciding how to commit resource between a variety of possible tasks

29.Different types of scheduling?
  • Primitive Scheduling
  • Non Preemtive Scheduling

30.Examples of primitive scheduling and non primitive scheduling?

Primitive Scheduling-Round Robin
Non primitive Scheduling-First-come First Served(FCFS)

31.Define multitasking?
In a computer operating system,multitasking is allowing a user to perform more than one computer task.

32.Define multithreading?

Multi threading is the ability of a CPU to executive several threads of execution apparently at the same the same time.

33.Define multiprogramming?

The execution of two or more programs by a single computer.

34.What is process affinity?

Processor affinity is a modification of the native central queue scheduling algorithms in a symmetric multiprocessing.

35.What you mean by Load balancing?

Load balancing is a computer networking methodology to distribute workload across multiple  computers or a computer.

36.Define synchronization?

Synchronization is the process by which Data protection Manager (DPM) tranfer data changes.It is a timekeeping which requires the coordination of events to operate a system in a unison.

37.Define Starvation?

A state of extreme hunger  resulting from  lack of essential no variants over a prolonged period.

38.What is segmentation?

Segmentation is a Memory Management technique in which memory is divided into variable sized chunks.

39.File  Management system?

The system that an operating system or program uses to organize..

40. List out File attributes?

  • Name of the file
  • Identifier
  • Type
  • Size
  • Protection information

41.Write two types of file types and usal extention?
  • object-obj,o
  • text-txt,doc

42.List out file operations?
  • Creating a file*Writing a file
  • Reading a file
  • Repositioning a fil
  • Deleting a file
  • Truncating a file

43.Define Backup?

To making copies of data so that these additional copies may be used to restore the original after a data loss event.These additional copies are typically called"backup".

44.What is thrashing?

Thrashing is situation where large amounts of  computer resources are used used.

45.Define kernel?

In computing, the kernel is the central component of most computer operating systems;it is a bridge between applications and the actual data processing done at the hardware level.

46.Implementation of virtual memory?
  • Demand Paging
  • Demand Segmentation

47.What all are Memory Management Schemes?

  • Contiguous 
  • Non contiguous
  • Single partition allocation
  • Multiple partition allocation
  • paging
  • Segmentation

48.Define Data?

Data is information that has been translated into a form that is more convenient to move or process.

49.Define Virtual Memory?

Virtual Memory is the separation of user logical memory from physical memory.

50.Discuss methods for handling Deadlock?

  • Ensure that the system will never enter a deadlock.
  • Allow the system to enter a deadlock state and then recover.
  • Ignore the problem and pretend that deadlock never occur in the system;used by most operating systems,including UNIX.


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