Class 8th / 9thComputer Science notes

Chapter # 2

A: Short Answers to the Questions.

Q1: Why operating system is important software for a computer give any five reasons.

A: Operating system is an important software for computer because in controls and runs all the activities of computer system it is also known as System software following are reasons due to which computer is an important software for computer.

  • It manage all the process inside computer.
  • It manages all the resources of computer.
  • It manages memory and memory allocation.
  • It manages input/output devices connected to computer.
  • It manages/ organize all the files stored in computer.
  • It manages user accounts and users.

Q2: Give any three objective of operating system.

A: Main objectives of operating system is given below.

Main objective of operating system is management it manages all the resources of computer and also users and requests of users that’s why it is also called resource manager. It manages CPU input/ output devices memory and internet to be used in more efficient and convenient way. It also provide a platform for application software to run without operating system we cannot use computer.

Q3: Mention few disadvantages of DOS.

A: DOS is not a user friendly operating system is it has no graphical user interface. It is a character based interface so user must have to remember all the commands as well as the syntax of theses commands which is a difficult task. It is a single user and single task operating system. It is not convenient as a Graphical user interface.

Q4: Name two operating system which are used in modern mobile.

A: following are operating system used in modern mobiles.

  • Android Operating system(Google)
  • IOS IPhone operating system (Apple)
  • Blackberry Operating system.(Blackberry)
  • Microsoft operating system (Microsoft Phones former Nokia)
  • Bada Operating system( Samsung Electronics)

Q5: what difficulties a student may face if he/she is not familiar with the operating system of a computer?

A: As we know that to run any machine we must have knowledge about that machine that how it works/operates same case is with computers student must know about the operating system because computers run on operating system to run the computer if he/she have no knowledge about the operating system then he/she cannot give commands to computer to perform certain tasks like office automation operating system installation and other application software’s installation.

Q6: Define UNIX and Windows operating systems.

A: UNIX is a multi-user command line interface operating system was developed to run on main frame computers. It can handle multiple users at the same time and allow users to concurrently access the resources and run multiple programs at the same time. At first it was command based but GUI was also introduces late.

Windows is the most popular operating system used today in modern computers mainly microcomputers, it is very flexible reliable and easy to use it was developed by Microsoft some version of windows operating system are 95,98,2000,millinum,XP,2007, windows 8 and windows 10. It is also a multi task but single user operating system.

Q7: Differentiate between multi-user and single user operating systems/

A: Operating system which can be used by a single user at a time is known is single user operating system.

  • User can login through his/her login credentials to use single user operating system.
  • It easy to use and its resources are not shared like CPU memory and input/output.
  • It is used on microcomputers or personal computer.
  • It is multi task operating system and user can run many program at the same time.
  • It requires less computing power and memory and that’s why it is cheap.

Examples are DOS, Windows and MAC etc.

Operating system which can be used by many user at a time is known as multi-user operating system.

  • It is normally centralized computer many users can login at the same by using their login credentials.
  • Its resources are shared with many users using the computer at the same time.
  • It is used in mini computers and main frame computers.
  • Administrator control the privileges to user to access the resources user can also communicate with each other.
  • It require more powerful CPU memory and hard drives.
  • It support multi-programming and time sharing.

Examples are Windows NT, UNIX and Linux.

Q8: What is meant by managing data and why is it important?

A: Data management mean to sort or organize data which is stored in the computer hard drive USB or secondary storage. We manage data to access it or find certain data easily as we have different types of data so to store same type of data we create folders and sub folders for that. In graphical operating systems a file management tool provide us the facility to easily create folders sub folders copy move delete update or sort data.

Q9: What is meant by resources of computer?

A: In computing, a system resource, or simply resource, is any physical or virtual component of limited availability within a computer system. Every device connected to a computer system is a resource. Like processor memory and devices connected to computer.

Q10: What types of problems may a student face if no antivirus is installed in his/her computer system.

A: Anti-virus is a software which protect the computer from viruses or malwares. If there is no Anti-virus installed virus can easily attack the system and damage the data databases programs or the computer. It can also delete the entire hard drive or malfunction the devices connected to computer it can copy itself to other programs.

See next page for Long Q/A

Long Answers to the questions.

Q1: Explain the main functions of operating system.

Ans: Main functions of operating system are given below.

  • Process management
  • Memory management
  • Input output management
  • File management
  • Resource management
  • User management

Process management: Process management is an integral part of any modern-day operating system (OS). Process is a program in execution and multiple programs are running concurrently. The OS must allocate resources to processes, enable processes to share and exchange information, protect the resources of each process from other processes and enable synchronization among processes.

Memory management: Memory management is the functionality of an operating system which handles or manages primary memory and moves processes back and forth between main memory and disk during execution. Memory management keeps track of each and every memory location, regardless of either it is allocated to some process or it is free. As we know that we have limited memory and large programs that’s why memory management is very important.

Input/output management: Operating system control and manages all the operations of input/output devices connected to computer with the help of input/output controller. I/O devices are the pieces of hardware used by a human (or other system) to communicate with a computer. For instance, a keyboard or computer mouse is an input device for a computer, while monitors and printers are output devices.

File management: It’s a part of operating system that manage organize or store data and keeps the track of computer files and folders we can classify computers files as programs images documents videos. All the operation performed on these files are control by the operating system such as editing deletion updating coping moving etc.

Resource management: Resource management is the dynamic allocation and de-allocation by an operating system of processor cores, memory pages, and various types of bandwidth to computations that compete for those resources. The objective is to allocate resources so as to optimize responsiveness subject to the finite resources available. Operating system automatically allocate resources like memory input/output device CPU to process in execution.

Users’ management: Operating system manages all the users accounts created in operating system. It is an important feature which keep secure the computer system when a user is created by the administrator operating system issue user name password for that user. Operating system give full access to administrator and administrator can provide full of limited access to other user’s operating system keep separate different users and their data one user cannot access the data or program installed by the other user until permission is granted same-wise one user cannot delete the program installed by the other user. User can login to operating system by using their user name and password.

Q2: Describe the following computer interfaces.

  1. Command line interface
  2. Graphical user interface
  3. Menu driven interface

Ans: 1) Command line interface: A CLI (command line interface) is a user interface to a computer's operating system or an application in which the user responds to a visual prompt by typing in a command on a specified line, receives a response back from the system, and then enters another command, and so forth. Example of CLI are DOS and UNIX.

2) Graphical user interface: Graphical user interface or GUI is a type of interface provided to users in which user interact with operating system through windows icons menus or lists. It is a type of user interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation, instead of text-based user interfaces.

It is much easier to use because we don’t need to memorize any commands it allows us to run different programs at the same time as well as switch between them but it require more memory and resources as compare to command line interface.

Examples are windows, MAC and Linux

3) Menu driven interface: menu-driven interface is an interface consisting of a series of screens which are navigated by choosing options from lists, i.e. menus. Users select option from every screen and every option run different command. It is much easier than command line interface. It is used in some programs and applications and other devices like mobile phones and iPod.

Two common operating systems are Novell’s Netware, and ProDOS.

Q3: Describe the following types of operating systems.

  1. Batch processing system
  2. Time sharing system
  3. Real-time system

Ans: 1) Batch-processing system: Batch processing is a technique in which an Operating System collects the programs and data together in a batch before processing starts. Computer loads the programs one by one after the completion of the other task. Batch processing is used where large amount of data processing is required it has improved the functionality of computers because there is no much interruption or switching from users occur.

Example of batch processing system is credit card billing system all the data of the credit card holders is collected and held until processed as a batch at the end of billing cycle.

Another example of batch processing is students’ report card generation.

2) Time sharing system: Time-sharing is a technique which enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multiprogramming. Processor's time which is shared among multiple users simultaneously is termed as time-sharing.In time sharing system multiple users use the same computer concurrently.

The operating systems used in in minicomputers and mainframe computers support time sharing system. Time sharing system are used in organizations like airline. Bank hotel university database organizations or small business.

The Multicast & UNIX operating systems are time sharing Operating Systems.

Example of time sharing system is NADRA and Passport offices in Pakistan.

3) Real time system: A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time applications that process data as it comes in, typically without buffer delays. Processing time requirements (including any OS delay) are measured in tenths of seconds or shorter increments of time. This type of operating system are used to control industrial processes government tasks and process where quick responses are required. Like military air force emergency response units and disaster management.

Real time system is used in cities traffic system space monitoring system and radarsurveillance.

Q4: Write notes on Macintosh and Linux operating system.

Ans: Macintosh operating system: Mac OS is the computer operating system for Apple Computer's Macintosh line of personal computers and workstations. It was developed by by Apple Corporation in in 1984 A popular feature of its latest version, Mac OS X, is a desktop interface with some 3-D appearance characteristics.

It is used in IPhone IPod IPad and Apple TV

Linux operating system: The Linux open source operating system, or Linux OS, is a freely distributable, cross-platform operating systeminvented by Linus Torvalds in 1991. It is based on UNIX that can be installed on PCs, laptops, netbooks, mobile and tablet devices, video game consoles, servers, supercomputers and more.Torvalds started the development on Linux OS system and its foundation and programmers around the world helped him to improve it.

Top release of Linux OS includes Debian Ubuntu Fedora Red Hat and open SUESE.

Q5: Describe the basic icons of windows operating system.

Ans: Basic icons of windows operating system

Icon Definition. An icon is a small picture or symbol on a graphical user interface (GUI) that represents a program (or command), file, directory (also called a folder) or device (such as a hard disk or floppy) Icon has a label at the bottom describing its name. Today virtually every major operating system employs icon-based GUIs. Some icons of windows operating system are given below

Recycle Bin: it is a temporary place for items that the user delete from computer it can hold any deleted item but its size is limited so if the size of deleted item is larger than the size of recycle bin then that item will be deleted permanently. We can restore deleted files from recycle bin easily. We can empty recycle bin to deleted file of folders permanently

Computer or This PC icon: That My Computer or this PC folder sitting at the top of your desktop and on your Start menu in Windows XP is a useful, multipurpose tool. The My Computer folder in Windows 10 is a gateway to all the data stored on the computer, attached devices, and the network as well as a shortcut to most of your system information.

Folder icon: folder icon is a directory where we store our data like documents images videos etc. we have folders inside folder which are called sub folder. We can copy move delete folders easily

File icon: File icon represent the type of file and file itself. File may be txt file image file document file etc.

Program icon: Program icon represent a type of computer program which is in machine readable form or executable file and can be distinguished from file by its .exe extension.

Shortcut icon: Shortcut of any program icon give us direct access to that program we create shortcut on desktop of different files from different directories or folders to access it directly without searching the program in specified location or directory.