Operating Systems for your Desktop PC.

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Purpose: Define the subject of ICT and its objectives. Discribe the role of ICTs in key sectors of society and in mean of ICT standarts.

Plan:

1.Definition of ICT. Subject ICT and its purposes. An ICT role in key sectors of development of society

2.Standards in the field of ICT.

3.Communication between ICT and achievement of the objectives of the a sustainable development in the Millennium Declaration.

1. Under the information and communication technologies is offered to understand the complex objects, actions, and rules relating to the preparation, processing and delivery of information at the personal, mass communication and production, as well as all technologies and sectors, providing integrated these processes.

Information and communication technologies (ICT) - a set of methods, workflows and software and hardware tools that are integrated with the aim of collecting, processing, storage, distribution, display and use of information for the benefit of its members

To date, the concept of IT includes microelectronics, development and production of computers and software, connection and telephony, mobile services, providing Internet access, providing information resources of the Internet, as well as a variety of cultural phenomena associated with these areas of activity and rules (both formal and informal) that govern these areas of activity.

ICT Tools

By means of modern information and communication technologies to understand the software, firmware and hardware, as well as devices that operate on the basis of a microprocessor, computer technology, as well as modern facilities and broadcast of information systems, information exchange, ensuring operation for the collection, the production, accumulation, storage, processing, communication and access to information resources of computer networks (including global).

By means of modern information and communication technologies include computers, PC, terminal equipment kits for computers of all classes, local area networks, the input-output device information input means and manipulation of text and graphic information, means of archiving large volumes of information, and other peripheral equipment modern COMPUTER; means for converting data from the graphics or audio data to digital representation and vice versa; tools and devices to manipulate audiovisual information (on the basis of technology and Multimedia "Virtual Reality"); artificial intelligence system; computer graphics system, programming systems (programming languages, compilers, compilers, operating systems, software packages, etc..), modern means of communication, providing information user interaction both at the local level (for example, within a single organization or multiple organizations) and global (as part of the global information environment).

The concept of information technology

Under the information technology to understand the totality of methods, production, software and technological tools combined in the processing chain, ensuring the collection, storage, processing, output and dissemination of information. Information technologies are designed to reduce the complexity of the processes of information resources.

Computer information technologies involve the use of computer and network technologies for implementing a wide range of tasks:

Information - a collection of information about the properties of an object or process to digest the subject in the form of knowledge.

All the information which is used by people, can be divided into the following types:

§ mathematical - is any information related to numbers and formulas, it can be not only a mathematical, but physical and statistical information. Mathematical information can be processed by a variety of computing machines and devices and stored on paper in the form of books and records.

§ text - that information can be recorded on paper by hand or using a typewriter and printing equipment and stored on paper (manuscripts, documents, books, newspapers, etc.).

§ graphics - this information can be processed by a variety of means and methods of Fine (fine arts, photography) and stored in the form of paintings, drawings, sculptures, photo cards, etc .;

§ Sound - this information can be processed by means of a tape recording and stored on magnetic tapes, records and audio CDs .;

§ video information - this information can be processed by means of film and video and stored on film and videotape .

All these types of information have existed before the advent of the computer. Modern personal computer allowed to handle these types of information and greatly facilitated their joint use.

Information - a set of physical processes signals perceived by the subject through his sense organs.

Data - data obtained by measuring, monitoring, logical or arithmetic operations presented in a form suitable for storage, transmission and processing.

Information processes. The concept of information is inseparable from the concept of information processes. For information processes include:

• transmission of information;

• receiving the information;

• data storage;

• processing of information and its presentation for use;

• use of information.

Technical means - it is a personal computer, office equipment, communication lines, network equipment.

The software is directly dependent on the technical and information support and realizes the functions of storage, processing, analysis, storage, interface with the computer.

Information support - a set of data presented in some form for computer processing.

Organizational and methodological support is a complex of measures aimed at the functioning of the computer and software to obtain the desired result.

There is another approach to dealing with automated IT structure, according to which any IT can be divided into three interdependent and equally important components that make up its core:

- Hardware (Hardware);

- software (Software);

- algorithmic (intelligent) software (Brainware).

Data processing

All information supplied to the computer, or encoded digitized, i.e. all characteristics data assigned to the number. Thus, the computer operates with no sound, or video image, and a series of numbers. And it does not process sound or video, and the number. After the treatment, the number again converted into sound or video and we hear the music and see the cartoon on the computer screen.

To simplify the technical recording and processing information using the binary system. If you are using ten digits in the usual decimal notation to record all the numbers - 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, only two digits used in the binary system - 0 and 1, and all numbers are written with a combination of zeros and ones:

decimal system	binary system
0	00
1	01
2	10
3	11
4	100
5	101
6	110
7	111
8	1000
9	1001
10	1010
11	1011
12	1100

Table1-Data processing

Any sort of information is called the volume of information.

The unit of information is called a bit. The computer memory cell of 1 bit can be stored for 1 or 0.

8 bits make up one byte.

There are multiple byte units:

Kilobyte (KB ). 1 KB = 1024 bytes.

Megabyte (MB). 1 MB = 1024 KB.

Gigabyte (GB). 1 GB = 1024 MB.

Terabyte (TB). 1 TB = 1024 GB.

For example, we can say that if you make the computer the text of one typewritten page, it will have a capacity of about 2500 bytes.

2.Standards in the field of ICT. Communication between ICT and achievement of the objectives of a sustainable development in the Millennium Declaration.

ICT-standards system - a set of normative and technical and regulatory guidance documents, including a set of interrelated standards and other documents in the field of standardization related to ICT, documents defining the methodology of development, coordination, approval, modification, deployment, use and replacement, including a methodology to assess facilities for compliance with these standards and other documents in the field of standardization.

ICT industry - as a specific field of activity, which includes research, creation, development, evaluation, procurement, acquisition, implementation, operation and utilization of ICTs. It covers thus work as a developer and ICT suppliers and customers and users of ICT, including the activities for the implementation, operation and utilization of ICTs.

Industry Standard (IS) - standard related to processes, products and other aspects of a particular field of activity (whether commercial or not aimed at profit). In this document, under the industry standard it refers to a standard or other document in the field of standardization, designed for the use of ICT. The procedure for the development and application of established IS specialized body of public administration.

Standard - a document in the field of standardization, standardization of relevant principles, covering categories such documents as the standard of organization, the standard non-profit association, the industry standard or set of rules (the industry), the national standard, international standard.

International standard - a standard adopted by an international organization.

National standard - a standard adopted by a national authority of the Republic of Kazakhstan for Standardization.

Non-profit association Standard - a standard non-profit professional organization (union, association, etc.), designed for wide application by different stakeholders. The order of development of the standard and non-profit association established this association and is harmonized with the state and industry standards development orders.

Organization Standard - a standard developed and approved by the organization itself, based on the necessity of its use to improve production and quality assurance of products, works and services, as well as for the dissemination and use of knowledge in different fields of research results (the test), measurement and development.

Questions:

1. What is the definition of ICTand its purposes?

2. What is the ICT role in key sectors of development of society?

3.What kind of standards do you know in the field of ICT?

4. What kind of communications do you know between ICT and achievement of the objectives of a sustainable development in the Millennium Declaration?

References

2. Lorenzo Cantoni (University of Lugano, Switzerland) James A. Danowski (University of Illinois at Chicago, IL, USA) Communication and Technology, 576 pages.

3. Craig Van Slyke Information Communication Technologies: Concepts, Methodologies, Tools, and Applications (6 Volumes). ISBN13: 9781599049496, 2008, Pages: 4288

4. Utelbaeva A.K.,Utelbaeva A.K. Study guide for lectures on discipline “Computer science”, Shimkent 2008, 84 pages.

Resources:

1.http://www.intuit.ru/studies/courses/3735/977/lecture/14671

Lecture №2. Introduction to computer systems. Architecture of computer systems.

Purpose: to discuss and give a brief idea on computer hardware.

Plan:

1.Review of computer systems.

2.Evolution of computer systems.

3.Architecture and components of computer systems. Use of computer systems. Data representation in computer systems.

2. Evolution of computer systems.

Different Types of Computers. Тhese computers come in many sizes and shapes that perform different functions which is useful in our daily lives. You are using a type of computer even when you withdraw cash from an ATM (Automatic Teller Machine) or scan groceries at the shop, or use a calculator.

The computers can be mainly classified into four categories as briefly described below. This classification is done based on the size and the data processing power.

• Microcomputers: most common type of computers in the society. Can be used at yourworkplace, at school or on your study desk at home. Used by single user at a time. Small in size. Also called Personal Computers (PCs).

• Minicomputers:used by multi-users. In the middle when the computers are ranged fromsmallest to largest. Used in laboratories.

• Mainframes:Largest in size. Capable of handling and processing very large amounts of dataquickly.

• Super computers:Used for performing complex scientific and numerical computations suchas weather forecasting, fluid dynamics, nuclear simulations, theoretical astrophysics.

Different Types of Personal Computers (PCs).Personal Computer (Mostly referred to as PC in the community) is designed as a more user-friendly device to be directly used by the end-user rather having an especially skilled separate computer operator. It is less expensive compared to other types of computers listed above. PCs come in different forms as listed below and we will have a description on each form of PC separately.

It is noticeable that only few famous forms of PCs used today are listed below and the list may be extended by adding many more in the future with the advancement of the technologies. Desktop, Laptop, Netbook, PDAs, Wearable Computers, Tablets,

Desktop PCs.Usually the Desktop computers are placed in a fixed location and the name has derived as it is intended to be sitting on a top of a desk. A monitor, mouse, and a key board can be seen as parts of a typical desktop computer. These computers consume low power and cost effective than the laptop computers that will be described next. The spare parts are readily available and less expensive.

Laptop Computers.Laptops are similar to desktop PCs in operation, but designed for mobile use. Capable of operating on the battery power and the battery can be charged with the external power adaptor. An in-built keyboard, Liquid Crystal Display unit (LCD screen), a touch pad (also known as track pad) to act as the mouse are the commonly seen components. However, a mouse can be also used instead of the touch pad. Laptops are obviously smaller in size and weight less than the desktop PCs. Therefore, it is difficult to access its internal hardware thus difficult to upgrade as much as a desktop. But adding more RAM or Hard Drive is possible (You will learn about RAM and Hard Drive in next session). Built-in web camera is a common feature of a modern laptop computer and these laptops come in different weights, sizes, performances, speeds, and a layman may differentiate them specified by the diagonal distance of its display unit.

Netbook.Netbooks belong to the laptop family, but are inexpensive and relatively smaller in size. Though the set of features and the capacity of netbooks were lesser compared to regular laptops at the time of introducing them to the market, nowadays the netbooks come in advanced features and in high capacities as similar to modern laptops.

PDAs.Personal Digital Assistants (PDAs) are handheld computers which are also called palmtop computers due to its size which is smaller enough to keep it on your palm. Most of the PDAs are pen-based and come with a stylus (a writing pen) to be used as the input device which is sensitive to its touch screen. Most of them can access the Internet by means of Bluetooth or Wi-Fi facilities. PDAs allow you to organize your personal or business work and to manage your tasks through its facilities. It may be used as a Cellular phone to send and receive calls, to search in the web, to download and play audio/video files, to send/receive e-mails, to type in a text editor to jot down notes or write a document, take pictures or record videos, etc.

Wearable Computers.The computers that can be worn on the body are known as Wearable computers. There is a constant interaction between the computer and user. These computers are mostly used to track human actions when the hands and other sensory organs are engaged in other activities. And used with applications such as behavioral modeling systems and healthcare monitoring systems.

Tablets.Tablets are mobile computers larger than PDAs and smaller than Laptops described above. Usually operated by its touch screen and no formal key board are used. The people using them spent most of their time outside and would not have access to a keyboard or mouse.

The Central Processing Unit (CPU)

The Central Processing Unit is an electronic device which runs computer programs: a set of sequential instructions. It is also called as the Computer Processor or the brain of the computer. Тhere are two major componentsnamely the Control Unit (CU) and the Arithmetic and Logic Unit (ALU). The CU is the circuitry that controls the flow of data through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC. The ALU is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one, for purposes such as maintaining timers. The processors found inside modern CPUs have very powerful and very complex ALUs; a single component may contain a number of ALUs.

We consider the CPU as the processing device of the computer. You are aware that the CPU contains Control Unit (CU) and an Arithmetic and Logic Unit(ALU). These two components work together to perform the processing operations. On a PC, the CPU usually is contained on a single chip and sometimes is called Microprocessor. In addition to the CU and ALU, a microprocessor usually contains the registers and system clock.

The Control Unit (CU).As you know, a computer program or set of instructions must be stored in memory for a computer to process data. The CPU uses its CU to execute these instructions. Further, the CU directs and coordinates most of the operations of the computer. The speed at which the processor carries out its operations is measured in megahertz (MHz). The higher the number of MHz the faster the computer can process information. The Intel i7, Athlon, Celron, and Duron, Ultra Sparkare some examples for the brands of processors available in the market.

The Arithmetic and Logic Unit (ALU).ALU performs the arithmetic, comparison, and logical operations. Arithmetic operations include addition (+), subtraction (-), multiplication (*) and division (/). Comparison operations include comparing one data item to another to determine if the first item is greater than (>), equal (=), or less than (<) to the second item. Logical operations work with conditions such as AND, OR, NOT.

Memory Devices

Computer Memory.A character is stored in the computer as a group of 0s and 1s, called a Byte. The size of the memory is measured by the number of bites available. The following equalities give the measuring units of the memory.

8 Bits	= 1	Byte
	Bytes	= 1	Kilobyte (1KB)
1024KB	= 1 Megabyte (1MB)
1024 MB	= 1 Gigabyte (1 GB)
	GB	= 1	Terabyte (1 TB)

While performing a processing operation, a processor needs a place to temporarily store instructions to be executed and the data to be used with those instructions. The data and the instructions needed by the CPU are temporarily stored in the Memory. Therefore the memory acts as the internal storage of a computer. The programs that are stored in external storages are loaded into the memory before they start running.

Random Access Memory (RAM).The Random Access Memory (RAM) is a volatile form of a computer memory. This small memory is capable of memorizing temporarily. It can be read and written. That is, you can both write data into RAM and read data from RAM. Together with the CPU, RAM determines the computer's speed. A computer with a large RAM and a CPU can actually run faster than a computer with a powerful CPU but with a low RAM.

Read Only Memory (ROM)

As RAM is volatile, the computers need a non-volatile memory to read larger programs. This is known as the Read Only Memory (ROM). The programs which are needed to start up your computer (Ex: to boot the computer) are stored in ROM.

Cache.Most of todays computers improve their processing times by using cache (pronounced cash).

Memory cache, also called a cache store or RAM cache, helps speed the processes of the computer by storing frequently used instructions and data thus reducing the access time of data. When the processor needs an instruction or data, it first searches in the cache.

Input Devices .A computer executes instructions and processes data into information and stores the information for future use. Input devices are used to enter instructions and data into the computer.

What is Input? Input is any data or instructions you enter to the memory of a computer. Once input is in memory, the CPU can access it and process the input into output. There are four types of input namely: data, programs, commands, and user responses.

Data. Data is a collection of unorganized facts that can include words, numbers, pictures, sounds, and videos. A computer manipulates and processes data into information, which is useful.

Program. A program is a series of instructions that tells a computer how to perform the tasks necessary to process data into information. Programs are kept on storage media such as a floppy disk (not used now), hard disk, CD-ROM, or DVD-ROM. Programs respond to commands issued by the user.

Command. A Command is an instruction given to a computer program. Commands can be issued by typing keywords or pressing special keys on the keyboard. A keyword is a specific word, phrase, or code that a program understands as an instruction. Some keyboards include keys that send a command to a program when you press them. Instead of requiring you to remember keywords or special keys, many programs allow you to issue commands by selecting menu choices or graphical objects. For examples, programs that are menu driven provide menus as a means of providing commands. Today, most programs have a graphical user interface (GUI) that uses icons, buttons, and other graphical objects to issue commands. However, GUI is the most user friendly way to issue commands

Input Devices

An Input Device is any hardware component that allows you to enter data, programs, commands, and user responses into a computer. Some of the commonly used input devices are listed below.

Keyboard

Pointing devices

• Mouse

• Trackball

• Joystick

• Touchpad

• Light Pen

Scanners

Voice input systems

Web Cam

Bar code readers

Output Devices.

An output device is any computer component capable of conveying information to a user. Some commonly used output devices are listed below.

Display devices

Cathode Ray Tube (CRT) monitors

Liquid Crystal Display (LCD) monitors / Flat-panel displays

LED Monitors

Gas plasma monitors

Printers

- Impact printers

- Daisy Wheel and Dot Matrix printers

Non-Impact Printers

- Ink Jet printers

- Thermal Dye Transfer printers

- Laser printers

Plotters

Audio Devices

Speakers

Headphones

Monitor.The monitor displays the output to the user visually. Therefore it is also called the Visual Display Unit (VDU) or simply the screen. Similar to televisions, the sizes of monitors are varying and often expressed in diagonally measured distance in inches. The technology used with monitors is expanding rapidly and there are two major types of monitors that differ in the technology of visualizing the output to the user. They are Cathode Ray Tube (CRT) monitors, Liquid Crystal Display (LCD) and Light Emitting Displays (LED).

The CRT monitor has more lines of dots per inch, higher the lines more amount of the resolution. It creates the picture by number of rows or lines of the small tiny dots. For an instance the resolution of 1024 x 768 will be sharper than 800 x 600 resolutions.

The LCD consists of two sheets of polarizing material with a liquid crystal solution between them. When an electric current passed through the liquid crystal solution, crystals align so that light cannot pass through them. It is like a shutter either allows light to pass through or blocking the light.

The LED is the latest marketing innovation of display units. It looks similar to LCD and it is also a flat panel display. LED means Light Emitting Diode and relates to the way the display is illuminated. LED monitors still use the same Liquid Crystals as the previous LCD displays. The way the backlight works however with the LED's will lead to a number of improvements in the display.

Though CRT monitors are much cheaper than LCDs and LEDs, the CRTs consume more power than others

Printer.A computer printer produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical/tangible print media such as paper or transparencies. Many printers are primarily used as local computer peripherals, and are connected by a printer cable to a computer which serves as a document source. Some printers, commonly known as network printers can serve as a hardcopy device to be shared and used by any user among a group of users connected to the network. Individual printers are often designed to support both local and network connected users at the same time. There are several types of printers categorized based on the applied technology of printing text/graphics on the paper.

Impact Printers.Any impact printer forms characters and graphics on a piece of paper by striking a mechanism against in an ink ribbon that physically contacts the papers. Because of the striking activity, impact printers generally are noisy.

Many impact printers do not provide letter-quality print. Letter-Quality (LQ) output is a quality of print acceptable for business letters. Many impact printers produce near letter-quality (NLQ)

print, which is slightly less clear than LQ. NLQ impact printers are used for jobs that require only NLQ, such as printing of mailing labels, envelopes, or invoices.

Impact printers are also ideal for printing multipart forms because they easily can print through many layers of paper. Finally, impact printers are used in many factories and retail counters as they can survive in dusty environments, vibrations, and extreme temperatures.

Plotter.Plotters are special type of printers used to print graphicaloutput on paper. It interprets computer commands and makes line drawings on paper using ulticolored automated pens.

Storage Devices.Storage refers to the media on which data, instructions, and information are kept, as well as the devices that record and retrieve these items. In this section we will discuss about the storage media and storage devices.

Memory versus Storage.It is important to understand the difference between the memory. Memory holds data and instructions temporarily while they are being processed by the CPU. Storage, also called Secondary, Auxiliary storage, or Mass storage, holds items such as data, instruction, and information for future use.

Storage.Storage is non-volatile which means that items in storage remains even when power is removed from the computer. A storage medium is the physical material on which the items are kept. One commonly used storage medium is a disk, which is round, flat piece of plastic or metal with a magnetic coating on which items can be written. A storage device is the mechanism used to record and retrieve items to and from a storage medium.

Storage devices can function as source of input and output. For example, each time a storage device transfers data, instructions, and information from a storage medium into memory (a process called Reading); it functions as an input source. When a storage device transfers these items from memory to a storage medium (a process called Writing), it functions as an output source.

The speed of a storage device is defined by its access time, which is the minimum time it takes the device to locate a single item on the disk. Compared to memory, storage devices are slow. The access time of memory devices are measured in milliseconds.

Hard Disk.Hard Disk drive which is often referred to as Hard Disk or Hard Drive is a device to store and retrieve data in a computer. The hard drive can store important system files like the operating system, program files and other data. Though HDDs were originally designed to be used with computers nowadays the applications for HDDs have expanded beyond computers to include digital video recorders, digital audio players, personal digital assistants, digital cameras and video game consoles. HDD is a non-volatile storage device that stores digitally encoded data. It is an electromagnetically charged surface or set of disks that record data in concentric circles known as tracks. HDDs record data by magnetizing ferromagnetic material directionally, to represent either a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the material. A typical HDD design consists of a spindle which holds one or more flat circular disks called platters, onto which the data is recorded. The platters are made from a non-magnetic material, usually aluminum alloy or glass, and are coated with a thin layer of magnetic material.

Portable Hard Disks.Portable hard disk is an interesting and useful device because you can carry data about all over the place and transfer information, programs, pictures, etc. between computers. Modern portable hard disks have a massive capacity like 500GB.

The System Unit . Тhe System Unit of the computer is the box-like casing which contains the major electronic components that are responsible for the main functions of the computer. It should be mentioned here that many people use to refer to this as the CPU incorrectly. This erroneous reference may be due to CPU: The brain of the commuter being that significant. However, the electronic devices such as CPU, memory, hard disk drive are located inside the System Unit. In addition to the above parts, Motherboard, Floppy Disk Drive,Power Supply unit, andCD-ROM Driveare the other major components that youcan find within the system unit. A brief description of each above component is given next.

Motherboard.The motherboard is sometimes called the system board, planner board or main board. It is the main circuit boardof a computer. The motherboard contains severalconnectorsfor attachingadditional boards. Usually, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial/parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive.All of the basic circuitry and components required for a computer to function are onboard the motherboard or are connected with a cable. The most important component on a motherboard is the chipset. It often consists of two components or chips known as the Northbridge and Southbridge, though they may also be integrated into a single component. These chips determine, to an extent, the features and capabilities of the motherboard.

Power Supply Unit .Power Supply Unit (PSU) is another very important unit found in the system unit. Usually we connect the power code of the computer to the domestic mains supply. Therefore, PSU converts Alternating Current (AC) from mains supply to Direct Current (DC) with the required different voltages needed to power different components of the computer. Power supplies have a certain power output specified in Watts, a standard power supply would typically be able to deliver around 350 Watts. The more components like HDD, CD/DVD drives, and cooling fans, are connected to your computer the greater the power required fro m the power supply

CD-ROM Drive.The CD-ROM drive is a high capacity optical data storage device with a removable disk, it writes data onto or reads data from a storage medium.

A CD-ROM drive may be connected to the computer via an IDE (ATA), SCSI, S-ATA, Firewire, or USB interface or a proprietary interface

Questions:

1. Why does a computer need memory?

2. What is the best type of storage for my data?

3. What factors affect a computer’s screen display?

4. Are ink jet printers better than laser printers?

5. What’s the best way to add devices to a computer system?

6. How can I protect my computer system from theft and

damage?

References

2. Lorenzo Cantoni (University of Lugano, Switzerland) James A. Danowski (University of Illinois at Chicago, IL, USA) Communication and Technology, 576 pages.

3. Craig Van Slyke Information Communication Technologies: Concepts, Methodologies, Tools, and Applications (6 Volumes). ISBN13: 9781599049496, 2008, Pages: 4288

4. Utelbaeva A.K.,Utelbaeva A.K. Study guide for lectures on discipline “Computer science”, Shimkent 2008, 84 pages.

Lecture №3. Software. Operating systems.

Purpose: to provide the basic ideas of Software to the Students, to introduce the learner to the Windows 7 operating system and get the learner familiar to operate the computer through the Operating system Windows 7.

Plan:

1. Software. Types of the software, purpose and characteristic. Basic concepts of OS.

2. Evolution of operating systems. Classification of operating systems, including for mobile devices. Classification of desktop applications.

1. What is Software? Software, also called a computer program or simply a program, is a series of instructions that tells the hardware of a computer what to do. For example, some instructions direct the computer to allow you to input data from the keyboard and store it in memory. Other instructions cause data stored in memory to be used in calculations such as adding a series of numbers to obtain a total.

Before a computer can perform or execute a program, the instructions in the program must be loaded into the memory of the computer. Usually, they are loaded into memory from storage like hard disk.

When you purchase a program, you will receive one or more CD-ROMs or a single DVD-ROM on which the software is stored. To use the software, you often need to install the software on the computer‟s hard disk. Sometimes, a program can be loaded in memory directly from a CD-ROM or a DVD-ROM so that you do not have to install it on the hard disk to use it.

When you buy a computer, it usually has some software already installed in its hard disk. Thus you can use the computer as soon as you receive it. Software is the key to productive use of computers. With the correct software, a computer can become a valuable tool.

System Software. System software consists of the programs that control the operations of the computer and its devices. Functions that system software performs include starting up the computer; opening, executing, running, applications; storing, retrieving, and copying files; formatting disks; reducing file sizes; and backing up the contents of a hard disk. Accordingly you can see that the System Software will handle the smooth running of all the components of the computer as well as providing general functionality for other programs to use, tools to speed up the computer, tools to develop new software and programs to keep you safe from attacks.

Operating Systems (OS).The Operating System contains instructions that co-ordinate all of the activities of hardware devices of your computer. It also contains instructions that allow you to run any applications software. One may define the Operating system as an interface between a user and all computer resources.

There are two main types of Operating Systems:

Single-user OS: A type of OS which allows only one user at a time. There can be single-user OSeither as single-user single-task or single-user multi-task. The Single-user single-task OS has to deal with only one person at a time running only one application at a time. MS DOS is an example for a single user single task OS.

Multi-user OS: In some situations, we need to share the single computer among few users. Sothe OS should be a multi-user where more than one user is logged on to the computer and uses it at the same time. These multi users may work with remote desktop connections. Further, these different users may need to run different applications at the same time. So the OS must support multi-task facility as well. Obviously the computer should be a powerful one. Each user draws on a big power of the computer in a shared way. This type of Multi –user multi-task OSs have to manage some tasks as listed below:

Desktop OS vs. Server OS:

The OS can also be categorized as Desktop OS and Server OS depending on whether the OS is to be installed in a desktop computer or a server. For example, the latest versions of the Windows OS family can be categorized as follows:

Desktop OS: windows XP, windows 7, Windows 8

Server OS:

Operating Systems for your Desktop PC.

Utility Software. Utility software or utility programs are some small programs which performs specific task, usually related to managing a computer, its devices, or its programs. Most operating systems include several utility programs. Also, you can buy them as stand-alone software that offer improvements over the ones supplied with the OS. Following are some of the specific tasks done by commonly used utility programs:

Viewing files

Compressing files

Diagnosing problems

Scanning disks

Defragmenting disks

Uninstalling software

Backing up files and disks

Checking for viruses

Displaying screen savers

Application Software

Accordingly, the second major class of Software is the Application Software. Application software consists of programs designed to perform specific tasks of users. Application Software, also called a software application or an application, can be used for the following purposes, among others:

As a productivity/business tool

To assist with graphics and multimedia projects

To support household activities, for personal business, or for education

To facilitate communications

Software Package. Based on the purposes as listed above, the application software is three-fold namely General Purpose, Special purpose, and Bespoke. Let us look at each type of applications software briefly.

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