Computer software and operating system : Class 11 NEB Notes

<h1>Unit: 3 Computer software and operating system</h1>

<h2># Software:</h2>
<p>A set of programme written for a computer to perform a particular task is called software. The programme is a sequence of instruction and instruction is a command given to the computer to perform certain tasks on given data.</p>
<p>It has no use without software. The computer will be metallic box if there were no software. Software is the interface between computer &amp; user. It is group of command that tells the computer what to do &amp; how to do it.</p>

<h2>## Categories of software</h2>
<ol>
<li><strong>System software:</strong><br>Software used to control and co-ordinate computer hardware and other software is called system software. It is responsible for resource management and task management; file, memory, trans &amp; language translation management. It is used to allow the user communicate with hardware. The system software is normally supplied by the computer manufacturer.</li>
</ol>

<h3>It can be classified as:</h3>
<ol>
<li><strong>a. Operating system</strong></li>
<li><strong>b. Language translator</strong></li>
<li><strong>c. Device drivers</strong></li>
</ol>

<h3>a. OS:</h3>
<p>It is the set of system software that acts as interface between the user of the computer &amp; computer hardware. It is running all time during the operation of the computer. The operating concerned with the allocation of the resources &amp; management of computer hardware. Its services are I/O, memory, security, file, command interpreter, processor &amp; virtual storage management.</p>
<p>Eg: Windows OS, Mac Linux, MSDOS etc.</p>

<h3>b. Language translator:</h3>
<p>It is a system software that converts statement set written in one language into another such as high level to assembly, high level to machine level language. There are three types of translation:</p>
<ol>
<li>i. Assembler</li>
<li>ii. Compiler</li>
<li>iii. Interpreter</li>
</ol>

<h3>Device driver:</h3>
<p>This type of software controls particular hardware which is essentially attached to the computer system. Different types of hardware devices which require a driver to connect a system are display printer, keyboard, mice etc. Some example of device driver: display drivers, printer drivers, USB drivers etc.</p>

<h3>2. Utility software:</h3>
<p>It is a software design to help manage and modify the computer hardware &amp; software. It is a set of programme that provide addition to the capabilities provided by the operating system. Eg. Antivirus software, backup utility, disk checker, file manager, disk cleaner.</p>

<h3>3. Application software:</h3>
<p>It is user oriented software i.e. used to solve a particular problem of user and make the users task easier. It is used by user to perform a specific task. The user may choose appropriate application software for performing a specific task, which provide the desired fit result. It can be classified into two types:</p>
<ol>
<li>a. Package software</li>
<li>b. Tailored software</li>
</ol>
<p>Eg: Word processing, presentation, image processing, accounting spread sheets.</p>

<h3>a. Package software:</h3>
<p>It is generalized set of program designed and developed for general purpose. It is generally sold in a large in size, error or bug free, advanced for standard setting are for specific work. All word kept processing data based management, graphics, DBMS, animation, web designing etc are its example.</p>

<h3>b. Tailored software:</h3>
<p>It is a software developed according to the needs of particular user or organization. This type of software is developed for some specific purpose for solving a specific problem for the specific user or the organization.</p>
<p>Eg: HRM, school management system, inventory management system etc.</p>

<h3>4. Web based software:</h3>
<p>It is a software that is accessed over a network connection use in HTTP rather than within a memory device. It often run inside a web browser however, web based application also may be client based where a small part of the program downloaded to a users desktop but processing done over the internet on and external server.</p>
<p>Eg: Online game, online shopping, google docs etc.</p>

<h3>5. Mobile Application software:</h3>
<p>It is a software developed specially for use on small wireless devices such as smart phone, tablets etc.</p>

<h2>## Operating system:</h2>
<p>OS is a set of program that manages computer hardware resources and provides common services for application program and controls the overall actions too. It also acts as a mediator between the user and computer hardware. It is a backbone of a computer system.</p>

<figure>
<p>Fig: diagram of OS</p>
<p>[User → Application Program → Operating System → Hardware]</p>
</figure>

<h3>## The role of OS is listed below:</h3>
<ul>
<li>Accept input from users through input devices</li>
<li>Send output to output devices</li>
<li>Help users to develop programs</li>
<li>Deals with faults &amp; inform the operator etc.</li>
<li>Platform for other application program.</li>
<li>Store and manage the files and application on the memory</li>
</ul>

<h3>Function of OS</h3>
<ol>
<li>Memory management</li>
<li>Input/Output</li>
<li>Processor management</li>
<li>Device management</li>
<li>File management</li>
<li>Security management</li>
<li>Interrupt handling</li>
<li>Error handling</li>
<li>Virtual storage</li>
<li>User interface</li>
<li>Time sharing</li>
</ol>

<h3>Processor management</h3>
<p>It is the process by which OS manage processes, threads, enable processes to share information, protect process resources &amp; allocate system resources to chooses process in the job processes the request then in a safe manner. It finds the status of process, args and processes, chooses a job, allocates the processors to the process and free the processor when the process is executed.</p>

<h3>2. Memory management</h3>
<p>It is the function responsible for managing the computer’s primary memory. When the user requests to the CPU for read/write operation. OS determines the amount of memory required for the program instructions and data. An OS does the following activities for the memory management:</p>
<ul>
<li>Keep tracks a primary memory that os what point of it are in. Used by whom, what point are not used.</li>
<li>Allocate the memory when a process or request it to do.</li>
<li>Deallocates the memory when the processor no longer needs or has been terminated.</li>
</ul>

<h3>3. Input/output management</h3>
<p>Input/output is an essential element for the essential operation of any computer. It allows the computer to interact with peripheral devices such as a keyboard, mouse, determined like modem (TV card, P-NTC card) disks or tapes CD, DVD &amp; floppy disk, printer etc. It coordinates, controls and assigns the input and output devices to different programmes being executed.</p>

<h3>4. File management</h3>
<p>Disk and file management is another important function of an OS. The OS helps in creating folders, sub-folders &amp; files, moving files, organizing files within the hierarchy of directory or folders. An OS keeps track of all the folders, sub-folders and files. The OS also helps in de-fragmenting the memory, efficiently managing files &amp; freeing the memory.</p>

<h3>5. Security management</h3>
<p>Security of computer system, data, and on it and the network security are emerging as critical issues. The OS can allow and disallow the access from other system, provide user accounts, password and encryption facility to protect the system.</p>

<h3>6. Controlling resource:</h3>
<p>The resources are controlled by OS. For eg: the printer is shared among members of computers. Similarly, hard disk is shared such that maximum resources are utilized by OS.</p>

<h3>7. Time-sharing:</h3>
<p>It is also a function of operating systems. It provides time slice to each terminal, but on the same computer system, at same time.</p>

<h3>8. User interface:</h3>
<p>It is the part of the OS that allows you to communicate with it so you can load programs, access files, and accomplish other tasks. Three main types of user interfaces are the command-driven, menu-driven and graphical user interfaces.</p>

<h3>9. Error handling:</h3>
<p>It is one of the main function of OS. OS detects the error like HD, memory overflow &amp; error related to I/O devices. After detecting the error OS takes appropriate action for consistency computing.</p>

<h2>## Types of OS based on processing method</h2>
<ol>
<li><strong>i. Multi-programming:</strong><br>The process of maximum utilization of CPU keeping it busy is called multi-programming. In this environment, processor processes several programs simultaneously. We know that CPU is much more faster than I/O units i.e., so after processing one program, it becomes idle. To utilize CPU to the maximum extend, multi-programming concept is applied.</li>
<li><strong>ii. Multi-tasking:</strong><br>A system able to handle process a number of tasks at a time is called Multi-tasking within a well-defined, fixed time constrain is called Real-Time system. In this system, more than one task is performed. On the priority basis, a high priority tasks interrupt low priority task. It can execute more than one program at a time. This enables computers to use more user-friendly interfaces based on graphical representations of I/O.</li>
<li><strong>iii. Multi processing:</strong><br>Multiprocessing is the co-ordinated processing of programs by more than one computer processor. It performs the same functions as single-processor OSs. They schedule and monitor operations and calculations in order to complete user-initiated tasks. It divides the work up into various sub tasks and then assign these subtasks to different (CPUs). It is really run on parallel processing. Each processor involved in a task must be able to inform the others about how its task is progressing. It allows the work of the processors to be integrated when the calculations are done. Such that delays &amp; other inefficiencies are minimized.</li>
<li><strong>iv. Distributed:</strong><br>Distributed Operating System is a model where distributed applications are running on multiple computers linked by communications. It manages the system shared resources used by multiple processors. The processor in it may be varying in size and function. It may include small microprocessors, workstations, minicomputers, and large general-purpose computer system.</li>
<li><strong>v. Real time:</strong><br>Real time os are the system that reacts gradually to the input without any delay. They are useful in the situation where immediate respond is required. They are designed specially control and monitor external activities with timing constraints or fixed deadline. The sensitive and time critical activities such as automation process, control system in factories and missile guidance use real time os. Eg: automobile engine, industrial robots etc.</li>
</ol>

<h2>## Types of Os based on user interface</h2>
<ol>
<li><strong>i. GUI (Graphical user interface):</strong><br>It allows to enter command by clicking &amp; pointing at the object that appear on the screen is called GUI. It takes advantage of computer graphical capabilities to make programme easier to use for user eg: windows, Mac OS, IOS etc.</li>
</ol>
<h3>Features</h3>
<ul>
<li>It is easy to operate &amp; user friendly.</li>
<li>User don’t have to remember the command &amp; syntax.</li>
<li>It required larger space and faster processor to operate.</li>
<li>GUI based os are usually 32 or 64 bits.</li>
<li>It is capable for operating, multi tasking, multi programming, multi users system.</li>
</ul>

<li><strong>ii. CUI (Character user interface or command line user interface.)</strong><br>The text based system in which in the user’s need to type in order to give the instruction to the computer is called CUI operating system. The OS provide the command prompt to enter the command manually. The user needs to memories all the command and their syntax. This was therefore, these these are comparatively difficult and tedious. The user’s type the command in command prompt &amp; go to the miles and syntax (code) of command.</li>
</ol>
<h3>Features</h3>
<ul>
<li>It is less user friendly and difficult to operate than GUI.</li>
<li>Commands are used to instruct the computer.</li>
<li>The user needs to remember the command for these OS.</li>
<li>It can’t display graphics, icons, pictures etc.</li>
<li>CUI based OS are usually 8 or 16 bits.</li>
<li>It is single tasking and single user OS.</li>
<li>It can be used in low memory &amp; low speed computer.</li>
</ul>

<h3>## Difference betʷ GUI and CUI.</h3>
<table border="1" cellpadding="5" cellspacing="0">
<tr><th>GUI</th><th>CUI</th></tr>
<tr><td>i) It is easy to operate.</td><td>i) It is difficult to operate.</td></tr>
<tr><td>ii) It is capable of multi-operating.</td><td>ii) It is single tasking.</td></tr>
<tr><td>iii) It is based on 32 or 64 bits.</td><td>iii) It is based on 8 or 16 bits.</td></tr>
<tr><td>iv) It required larger space to operate.</td><td>iv) It can be used in low memory.</td></tr>
</table>

<h2>## Types of OS based on mode of user</h2>
<ol>
<li><strong>1. Single user OS:</strong> In this, only one user can access and operate computer at a time. This type of OS are relatively simple and useful for personal computer, work station and micro computer. For eg: Window XP, Window 7, Windows 8, Ms dos.</li>
<li><strong>2. Multi user OS:</strong> Some it allows two or more users to access and operate computer simultaneously. This type of OS are generally found in network environment server and large computer environment. Where 100’s of computer users can access or permitted. Eg: Linux, Unix, windows server 2000, windows server 2003 etc.</li>
</ol>

<h2>## Type of OS based on number of task</h2>
<ol>
<li><strong>1. Single tasking OS:</strong> If an OS execute only one task or programme at a time. Then, it is called single tasking as the next task can only be started after completing the execution of first task. Eg: PC dos, Window dos etc.</li>
<li><strong>2. Multi tasking OS:</strong> When an OS allows the CPU to execute more than one task at a time then, it is called multi-tasking OS. Generally, window based OS are of this type. Context switching, multi threading are the example of multi-tasking OS.</li>
</ol>

<h2>## Windows keyboard shortcuts</h2>
<ul>
<li>Ctrl + C → Copy</li>
<li>Ctrl + V → Paste</li>
<li>Ctrl + X → Cut</li>
<li>Ctrl + Z → Undo</li>
<li>Ctrl + A → Select All</li>
<li>Ctrl + Y → Redo</li>
<li>Shift + delete → Permanently delete</li>
<li>Ctrl + S → Save as</li>
<li>F2 → Rename</li>
<li>F3 → Search</li>
<li>Alt + F4 → Close the window</li>
</ul>

<h2>## Open source OS</h2>
<p>It is a methodology or approach towards the design and development of software with intention of giving the user access to the source code. If we use open source software not only will you be able to use it, you will also be able to see how it works, debug it, modify it, re-distribute it. Some OS: Linux, Unix, Open solaris, etc.</p>

<h3>→ Linux and Unix distribution</h3>
<ol>
<li><strong>i. Unix:</strong> It is multi-user, multi-tasking, multi-processing, and time sharing OS. Originally developed in 1969 AD by a group of employees at AT and T (American Telephone and Technology). It was first programme in assembly level language, but was re-programmed in C in 1973 AD.<br>The development of UNIX has given birth to many operating system that can work on different types and size of computer. Eg: Linux and Solaris are developed from Unix. It is flexible as and can be used for any type of process or Unix os are widely used in server but nowadays it is also used in PCs and mobile devices.</li>
<li><strong>ii. LINUX:</strong> It is an open source, powerful, Unix based os. It runs on a variety of platform including PC, laptop, notebook, mobile and tablet devices. Super computer &amp; many more. It was developed by LINUX Torvalds at the University of Helsinki in Finland, as a college project. He released the Linux including all the source code. It was developed in mid 1990s. It use 95% of ‘C’ programming language &amp; 5% other language.</li>
</ol>
<h3>- Linux distribution:</h3>
<p>Linux isn’t a complete os. It is just a kernel. It takes the Linux kernel and combines it with other free software to create complete package.<br>Almost, 600 Linux distribution exist with close to 500 out of these one in active development because of that distribution have taken wide variety of forms, including those suitable to be used on desktops, laptops, notebook, notepad, mobile and tablet devices as well as use for embedded system (for specific task).<br>It is distributed through different distribution such as Red Hat, Ubuntu, Fedora, Mx Linux, Gentoo etc.</p>

<h2>## Mobile operating system:</h2>
<p>A mobile os is an operating system that are specially designed to run on mobile devices such as mobile phone, smart phone, palmpad (Personal Digital Assistance), tablet wearable and other handheld devices.<br>The mobile os manage hardware and it is possible for smartphones, tablets and wearable to run apps and other programmes in a user friendly way. It also manage mobile multimedia function. Internet connectivity, touch screen control, bluetooth connectivity, GPS navigation, speech cameras, speech recognition and many more. Some of the mobile os are Android os, Black berry os, Windows phone os etc.</p>

<h3>→ Types of mobile os</h3>
<ol>
<li><strong>i) Android os:</strong> It is google’s open and free software stack that includes an os, middleware and key application for use on mobile devices including smart phones.<br>Release date: 2008, September 23<br>Developer: Google, Huawei, Baidu<br>Programming language: Java, C, XML, Assembly language etc.<br>It uses linux to 2.6 to provide code core service such as security.</li>
<li><strong>ii) iOS (Iphone os):</strong> It was originally developed for its iphone devices. It is refer to as iOS. And is supported on number of Apple device including iphone, i-pad, i-pod etc.<br>Release date: 2007, June 27<br>Developer: Apple Inc.<br>Programming language: Swift, C++, C, Objective C etc.</li>
<li><strong>iii) Black Berry:</strong> It is proprietary mobile OS developed by Research in Motion (RIM) for use on the companies popular black berry handheld devices. Its platform is popular corporate user as it offers superb synchronization with Microsoft Exchange.<br>Release date: November 2003 (Black Berry 9700/9900)<br>Developer: BlackBerry Ltd.<br>Programming language: C++, micro ed V++ with Java.</li>
<li><strong>iv) Windows Phone OS:</strong> It is Microsoft’s mobile OS used in smartphones &amp; mobile devices with or without touch screen.<br>It is based on the Windows CE 6.2 kernel. In 2010, Microsoft announced a new smartphone platform called Windows Phone 7.<br>Release date: October 21, 2010<br>Developer: Microsoft Corporation<br>Programming language: C++, C</li>
<li><strong>v) Symbian OS:</strong> It is an mobile OS targeted at mobile phones that offers high level of integration with communication, personal information management (PIM) functionality, it combines middleware with wireless communication through an integrated e-mail box &amp; integrated PIM functionality (Agenda &amp; contacts)<br>Release date: 1977<br>Developer: Nokia, Symbian Ltd.<br>Programming language: C++</li>
</ol>