Computer Programs are called as Computer software, or just software. A computer Software is set of programs that guides the hardware through its job. The computer program is the non-tangible component of a computer
system. A Computer software is different from computer hardware, that is the physical component of a computer system. Computer hardware and software work hand in hand cannot function without the other.
Types of Software
Computer softwares are mainly divided into two parts:
(a) System Software (b) Application Software
(A) System Software
System software is the software which manages and controls the hardware components and allows interaction between the hardware and the other different types of software. The computer’s operating system is a type of
system software. Device drivers are also a part of this category. System software can be separated into two different categories: Operating systems and Utility software.
A program that acts as an intermediary between a user of a computer and the computer hardware is called an operating system. The operating system is an essential component of the system software in a computer system. Application programs usually require an operating system to function.
Operating systems can be found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers. For example: UNIX, MS-DOS,WINDOWS, 98/2000/xp/7.
Functions of an operating system –
The basic functions of an operating system are:
I. Booting the computer
II. Performs basic computer tasks eg managing the various peripheral devices eg mouse, keyboard
III. Provides a user interface, e.g. command line, graphical user interface (GUI)
IV. Handles system resources such as computer’s memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices
V. Provides file management which refers to the way that the operating system manipulates, stores, retrieves and saves data.
I. Booting the computer : The process of starting or restarting the computer is known as booting. A cold boot is when you turn on a computer that has been turned off completely. A warm boot is the process of using the operating system to restart the computer.
II. Performs basic computer tasks : The operating system performs basic computer tasks, such as managing the various peripheral devices such as the mouse, keyboard and printers. For example, most operating systems now are plug and play which means a device such as a printer will automatically be detected and configured without any user intervention.
III. Provides a user interface : A user interacts with software through the user interface. The two main types of user interfaces are: command line and a graphical user interface (GUI). With a command line interface, the user interacts with the operating system by typing commands to perform specific tasks. An example of a command line interface is DOS (disk operating system). With a graphical user interface, the user interacts with the operating system by using a mouse to access windows, icons, and menus. An example of a graphical user interface is Windows Vista or Windows 7.
IV. Handles system resources : The operating system also handles system resources such as the computer’s memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices. Programs and input methods are constantly competing for the attention of the CPU and demand memory, storage and input/output bandwidth. The operating system ensures that each application gets the necessary resources it needs in order to maximise the functionality of the overall system.
V. Provides file management : The operating system also handles the organisation and tracking of files and directories (folders) saved or retrieved from a computer disk. The file management system allows the user to perform such tasks as creating files and directories, renaming files, coping and moving files, and deleting files. The operating system keeps track of where files are located on the hard drive through the type of file system. The type two main types of file system are File Allocation table (FAT) or New Technology File system (NTFS).
File Allocation table (FAT) : It uses the file allocation table which records, which clusters are used and unused and where files are located within the clusters.
NTFS : It is a file system introduced by Microsoft and it has a number of advantages over the previous file system, named FAT32 (File Allocation Table).NTFS also allows permissions (such as read, write, and execute)
to be set for individual directories and files.
The three most common operating systems for personal computers are Microsoft Windows, Mac OS X, and Linux
Types of Operating System
There are different types of operating system to support the computer system. Each type of operating system offers distinct facilities that are appropriate to the computer system in which it is used.
The operating systems are of mainly following types:
• Single-user, single task Operating System – This operating system is designed to manage the computer so that one user can effectively do one thing at a time. The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system.
• Single-user, multi-tasking Operating System- This operating system mostly used by people which are using desktop and laptop computers today. Microsoft’s Windows and Apple’s MacOS platforms are both examples of operating systems that will let a single user have several programs in operation at the same time. For example, it’s entirely possible for a Windows user to be writing a note in a word processor while
downloading a file from the Internet while printing the text of an e-mail message.
• Multi-user Operating System : A multi-user operating system allows many different users to take advantage of the computer’s resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn’t affect the entire community of users. Unix,
VMS and mainframe operating systems, such as MVS, are examples of multi-user operating systems.
• Real Time operating System : Real time operating system controls the environment as they have a data processing system in which the time interval required to process and respond to inputs is very small. The
time taken by the system to respond to an input and display the result of the required inputted information is termed as response time.A key characteristic of an RTOS is the level of its consistency concerning
the amount of time it takes to accept and complete an application’s task; the variability is jitter.A hard real-time operating system has less jitter than a soft real-time operating system. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. An RTOS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS.
• Time-sharing operating system : Time sharing is a type of operating system that enables many people, located at various terminals, to use a particular computer system at the same time. Because of the above
feature timesharing operating system is called multitasking operating system. In other words it is a logical extension of multiprogramming. Processor’s time which is shared among multiple users simultaneously is
termed as time-sharing.The main purpose of Multiprogrammed batch systems, is to maximize processor use, whereas in Time-Sharing Systems the primary objective is to minimize response time.
• Distributed operating System : Distributed systems use a number of central processors to serve multiple real time application and different users. Data processing jobs are distributed among the processors
accordingly to which one can perform each job most efficiently.
• Network operating System : This operating system runs on a server.This server is responsible for managing data, users, groups, security, applications, and other networking functions. The network operating
system allows shared file and printer access among multiple computers in a network. This can also be referred as a local area network (LAN), or a private network. Examples of network operating systems include Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, and BSD.
• Stand -Alone Operating System : A stand-alone operating system is a complete operating system that works on a desktop computer, notebook computer, or mobile computing device. Some standalone operating systems are called client operating systems because they also work in conjunction with a server operating system. Client operating systems can operate with or without a network. Examples of currently used stand-alone operating systems are Microsoft Windows, Mac OS, and Linux.
(i) Microsoft Windows : Microsoft developed Windows operating system that has a graphical user interface. Some of the popular Windows Operating System are Windows 3.1, Windows 95, Windows 98, Windows 2000, Windows NT, Windows ME, Windows XP, Windows Vista and Windows 7.
Windows 8 is the latest Windows operating systems from Microsoft. It is a graphical user interface (GUI) operating system which is very easy to learn and operate. Windows 7 provides many ways to manage the files stored on your computer. You can open, rename, print, delete, move and search
(ii) Mac OS : It is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface.
(iii) Linux : It is a UNIX-based operating system that is available for free on the World Wide Web. Many companies, such as Red Hat, Corel and Mandrake, create easy-to-use versions of Linux that you can purchase. Red Hat Linux is a popular version that comes with the GNOME desktop environment. GNOME displays pictures on the screen to help you perform tasks. Linux is an open source code operating system. It can be copied, modified and redistributed with few restrictions. This flexibility is one of the reasons why Linux is so popular among users.
• Embedded Operating System : An embedded system is a computer that is part of a different kind of machine. Examples include computers in cars, traffic lights, digital televisions, ATMs, airplane controls, point of sale (POS) terminals, digital cameras, GPS navigation systems, elevators, digital media
receivers and smart meters, among many other possibilities. In contrast to an operating system for a general-purpose computer, an embedded operating system is typically quite limited in terms of function – depending on the device in question, the system may only run a single application. However, that single application is crucial to the device’s operation, so an embedded OS must be reliable and able to run with constraints on memory, size and processing power. Thousands of connected embedded devices have been built on Windows Embedded platforms, from portable ultrasound machines to GPS devices and from ATMs to devices that power large construction machinery. With comprehensive features, easy-to-use and familiar Microsoft development tools, free evaluation kits and access to a large network of community support, working with Windows Embedded
Products helps yield faster time to market for your devices and decreased development costs.
• Mobile Operating System : A mobile operating system, also called a mobile OS, is an operating system that is specifically designed to run on mobile devices such as mobile phones, smartphones, PDAs,
tablet computers and other handheld devices. The mobile operating system is the software platform on top of which other programs, called application programs, can run on mobile device. Examples of mobile operating systems include Apple iOS, Windows Phone, and Google Android. Operating systems for mobile devices generally aren’t as fully featured as those made for desktop or laptop computers, and they aren’t able to run all of the same software. However, you can still do a lot of things with them, like watch movies, browse the Web, manage your calendar, and play games.
GUI (Graphical User Interface)
GUI is a program interface that takes advantage of the computer’s graphics capabilities to make the program easier to use.
Basic Components of a GUI
Graphical user interfaces, such as Microsoft Windows and the one used by the Apple Macintosh, feature the following basic components:
• Pointer : A symbol that appears on the display screen and that you move to select objects and commands. Usually, the pointer appears as a small angled arrow. Text -processing applications, however, use an I-beam pointer that is shaped like a capital I.
• Pointing device : A device, such as a mouse or trackball, that enables you to select objects on the display screen.
• Iicons : Small pictures that represent commands, files, or windows. By moving the pointer to the icon and pressing a mouse button, you can execute a command or convert the icon into a window. You can also
move the icons around the display screen as if they were real objects on your desk.
• Desktop : The area on the display screen where icons are grouped is often referred to as the desktop because the icons are intended to represent real objects on a real desktop.
• Windows : You can divide the screen into different areas. In each window, you can run a different program or display a different file. You can move windows around the display screen, and change their shape and size at will.
• Menus : Most graphical user interfaces let you execute commands by selecting a choice from a menu. MS DOS (Microsoft Disk Operating System)
Short for Microsoft Disk operating system, MS-DOS is a non-graphical command line operating system derived from 86-DOS that was created for IBM compatible computers. MS-DOS originally written by Tim Paterson and introduced by Microsoft in August 1981 and was last updated in 1994 when MS-DOS 6.22 was released. MS-DOS allows the user to navigate, open, and otherwise manipulate files on their computer from a command line instead of a GUI like Window. DOS has a character user interface (CUI) i.e : Communication between a computer and the user can be done by using characters. In Dos, one has to key in the commands on the prompt. Prompt is a place where commands are issued. It may look like C:> or C:\windows>
Utility software is software that helps to maintain and protect the computer system. It does not directly interface with the hardware. Examples include anti-virus software, firewalls, disk defragmenters and so on . System utilities are the core software functions that allow you to manage your computer in ways that you would find it inconceivable to be without
Functions of System Utility:
I. Disk Cleanup
Disk Cleanup is a function that comes with all versions of Windows Operating Systems. Disk Cleanup allows for you to scan your entire hard drive to search for extra room by deleting any unneccessary files
such as temporary files from the Internet and cookies that are downloaded when you visit webpages. You can find Disk Cleanup in Windows XP by going to the Start menu → All Programs → Accessories → System Tools → Disk Cleanup.
II. Disk Defragmentation
Defragmentation is the process of locating the noncontiguous fragments of data into which a computer file may be divided as it is stored on a hard disk, and rearranging the fragments and restoring them into fewer fragments or into the whole file.
III. System Restore
System Restore is a Windows utility that allows a user to restore their computer data to a specific former state (known as a restore point), undoing changes made since that time. System Restore can be found by going to Start → All Programs → Accessories → System Tools → System Restore
IV. Disk Compression
Disk compression is a type of function that allows for a program to search your hard drive and compress files, particularly old or unused files. It also serves to free up space, which is the main function of disk compression software.
It is used to scan computer for viruses and prevent the computer system files from being corrupt.
(b) Application software
(Also known as ‘apps’) are designed to achieve a complete task or a set of tasks. Application software consists of the programs for performing varied tasks particular to the machine’s utilization. There are various examples of application software that include MS Word, MS Excel, a console game, database systems, desktop publishing systems, program development software, a library management system etc.
There are various types of application software :
I. Word Processing : The most important computer application is that they are most commonly used to create, edit, and print documents. Word processing software allows users to create and manipulate documents
that contain text and graphics. With word processing software, you can insert clip art into a document; change margins; find and replace text; use a spelling checker to check spelling; place a header and footer at the top and the bottom of a page; and vary font (character design), font size (character scale), and font style (character appearance).
E.g. Microsoft Word, Google Docs, AppleWorks, Openoffice.org etc.
II. Spreadsheet : A spreadsheet is a type of document that stores the entire data in a grid form consisting of horizontal rows and vertical columns. This row/column structure allows the analysis of data using formulas and calculations. With spreadsheet software, data is organized in rows and columns, which collectively are called a worksheet. The intersection of a row and column, called a cell, can contain a label (name of cells), a value (number), or aformula or function that performs calculations on the data and displays the result.
E.g. Microsoft Excel, Correl Quattro Pro etc
III. Presentation Graphics : Presentation Graphics also called as the presentation software is a type of application program that helps you to create different timing and organized sequence of information and pictures that present a story or help in giving a public presentation of information through a slide show.
E.g.Microsoft PowerPoint, Apple Keynote, OpenOffice Impress, Corel Presentations, Adobe Persuasion etc.
IV. Multimedia authoring : Multimedia authoring software helps you to create a a presentation that has a variety of feature such as the audio and video sequences. Business presentation software usually enables you to include images and sometimes audio and video developed with other tools.
V. Database software : Database software allows you to create and manage a database. A database is a collection of data organized to allow access, retrieval, and use of that data. A query is used to retrieve data according to specifiedcriteria, which are restrictions the data must meet.
E.g.Microsoft Access, Corel Paradox, Lotus Approach etc.
VI. Desktop publishing(DTP) : Desktop publishing(DTP) software is used to design and produce sophisticated documents. DTP is developed specifically to support page layout, which is the process of arranging text
and graphics in a document. Complete DTP involves combination of type setting, graphic design, page layout and printing the document.
E.g.Adobe InDesign,Adobe PageMaker,Corel Ventura,Coreldraw,Microsoft Office Publisher etc.