Computer Awareness - SPLessons

Computer Operating System

Chapter 3

SPLessons 5 Steps, 3 Clicks
5 Steps - 3 Clicks

Computer Operating System

Computer Operating System

shape Introduction

Computer Operating System (OS) is an interface between the user and computer hardware and other software. It is the collection of programs that helps the user to manage the computer hardware.The software that allows computer users to run applications with the hardware.

shape Concepts

  • OS is the most important program that runs on a computer. Every computer must have an operating system to run other programs and applications.

  • An operating system performs such tasks like memory allocation, controlling input &output devices.

  • Without OS computer doesn’t work. There are many OS’s on which it can perform different tasks Windows OS, mac OS, and Linux.


Types of operating systems
Based on different uses and nature of operating systems are classified into several types:

  1. Single and multi-tasking: A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program parallel. This is done by sharing processor to multiple processes at the same time.

  2. Single and multi-user: A single-user operating system is a system in which only one user can access the computer system at a time. On the other hand, a multi-user operating system allows more than one user to access a computer system at one time.

  3. Distributed: A distributed operating system connects a group of different computers and makes them appear to be a single computer. When program may be run on any computer in the distributed system and access data on any other computer. All these computers connected by the networking.

  4. Network Operating system: A network operating system includes special functions for connecting computers and devices into a local-area network (LAN). Some operating systems, such as UNIX and the Mac OS, have networking functions built in.

  5. Real-time Operating Systems: are very fast and quick respondent systems. These systems are used in an environment where a large number of events (generally external) must be accepted and processed in a short time. Most of the time, processes remain in primary memory in order to provide a quick response.

  6. Mobile Operating system: A mobile operating system (OS) is software that allows smartphones and other devices to run applications and programs. Examples of mobile device operating systems include Apple iOS, Google Android BlackBerry OS, Nokia’s Symbian etc.


Functions of Operating Systems
Some important functions of operating system are


  1. Program execution: OS acts as an interface between application software and the hardware. It allocates the memory and other resources which need to execute the program.

  2. Interrupts: It is a type of signal from the computer when it requires the operating system to stop the process and it says what to do next to complete the process. There are two types of Interrupts software interrupts and hardware interrupts

  3. Memory Management: It is the most important task in the operating system. It keeps track of each and every memory location, either it is allocated to some process or it is free. It checks how much memory is to be allocated to processes. It tracks whenever some memory gets free or unallocated then it updates the status.

  4. Virtual memory: Virtual Memory is a space where large programs can store themselves in form of pages while their execution and only the required pages are loaded into the main memory. This technique is useful when large virtual memory is required for user programs when a very small physical memory (hard disk memory) is there.

  5. Networking: Modern operating systems are supporting different types networking protocols. This means when different computers running different operating systems can participate in a common network for sharing resources such as printers, scanners, files.

  6. Security: OS security refers to required steps or measures used to protect the OS from threats, viruses, worms, malware or remote hacker intrusions. OS security takes care of all preventive-control techniques, which safeguard any computers data or information are being stolen, edited or deleted if OS security is compromised.

  7. Disk access and file system: Access to data stored in the disk is a major feature in all operating systems. Computer store data in disk using files, which are structured in a specific way in order to allow faster access, higher reliability and give the better experience to the user.

  8. Input/output management: OS manages I/O devices and makes the I/O process effectively. OS accepts the input from the input devices and stores in the main memory, asks to process it and finally, the provides the results to the output devices for output.

  9. Time Sharing: Every time CPU tries to manage the time. It shares the resources to all the processes which are currently running. Distributes the time to the one which is on high priority.

shape Questions

1. Which of the following is/ are the part of an operating system?

  1. Kernel services
  2. Library services
  3. Application level services
  4. All of the above

Answer: D

2. Which is a large operating system core provides a wide range of services?

  1. Multilithic kernel
  2. Macro kernel
  3. Micro kernel
  4. Monolithic kernel

Answer: D

3. A direct method of deadlock prevention is to prevent the occurrences of_______

  1. Mutual exclusion
  2. Hold and wait
  3. Circular waits
  4. No preemption

Answer: C

4. The methods or algorithms which are used to increase the performance of disk storage sub-system is called ___________

  1. Disk performing
  2. Disk scheduling
  3. Disk storing
  4. Disk extending

Answer: B

5. ________ is the time required to move the disk arm to the required track.

  1. Seek time
  2. Rotational delay
  3. Latency time
  4. Access time

Answer: A

6. The different types of tables maintained by the operating system are_______

  1. memory, logical, I/O file
  2. Memory, I/O, file, physical
  3. Memory, I/O, file, process
  4. Memory, logical, I/O, physical

Answer: C

7. ___________is an example of an operating system that supports single user process and single thread.

  1. UNIX
  2. MS-DOS
  3. OS/2
  4. Windows 2000

Answer: B

8. Name the latest introduced operating system.

  1. Windows XP
  2. Vista
  3. Windows 7
  4. Windows 10

Answer: D

9. Which one is the first program that is loaded into computer’s main memory, when a computer is switched on?

  1. Hardware
  2. Application Software
  3. Operating System
  4. I/O system

Answer: C

10. An error in hardware is detected

  1. by the compiler
  2. by the operating system
  3. by the compiler
  4. None of the above

Answer: D

11. Which of the following is a UNIX shell?

  1. Bounce shell
  2. Korn shell
  3. C shell
  4. All of the above

Answer: D

12. Which one of the first operating system?

  1. UNIX
  2. LINUX
  3. Windows XP
  4. DOS

Answer: A

13. When was Windows XP released?

  1. October 25, 2001
  2. November 25, 2000
  3. June 23, 2008
  4. November 20, 2001

Answer: A

14. In which only one user can access the computer system at a time?

  1. Single-user
  2. Multi-user
  3. Multi-tasking
  4. Single tasking

Answer: A

15. Binding of instructions and data to memory addresses can be done at:

  1. Compile time
  2. Load time
  3. Execution time
  4. All of the above

Answer: D

16. The address generated by the CPU is referred to as _______.

  1. Physical address
  2. Logical address
  3. Reference address
  4. Memory address

Answer: B

17. The base register is also known as _____.

  1. Basic Register
  2. Regular Register
  3. Relocation Register
  4. Deallocation Register

Answer: C

18. The size of the process is limited to the size of______

  1. Physical memory
  2. External storage
  3. Secondary storage
  4. None of the above

Answer: A

19. The main memory accommodates

  1. Operating system
  2. CPU
  3. User process
  4. All of the above

Answer: A & C

20. MS-DOS operating system is a

  1. Time-sharing operating system
  2. Single-user operating system
  3. Multi-user operating system
  4. Real-time operating system

Answer: B