Computer Science 8

Computer Science 8

Unit - 1 Content Unit – 2 Unit – 3 Computer Network and Internet Unit – 4 Use of Computer and Multimedia Unit – 5 Computer Programming Unit – 6 Word Processing Spreadsheet Analysis Database

Unit - 1 Computer Network and Internet After studying this unit the students will be able to understand; features of a computer, classification of computers, functions and devices of a computer system, basic components of a computer, computer ports and, computer network. 1.1 What is a computer? First chapter described how computer systems can make day-to-day work effcient. A computer can be described as an electronic device, which accepts or collects data, processes them according to the given instructions and produces the desired output. Computer has become an essential device in our lives. Some of these features of a computer can be described as follows; A computer takes only a few seconds to perform Speed calculations. It executes more than one million instructions per second. Accuracy A computer provides correct output when correct instructions and data are given. Effciency A computer never gets tired. It can work round the clock with the same level of accuracy. A computer can be used to perform many tasks Versatility simultaneously. This is one of the special features of a computer. A computer is used to store large number of data and Storing and information Retrieving in a relatively small unit and we can retrieve them easily and quickly when needed. 1.2 Classification of computers As described in the early classes, a computer can be used to perform various tasks such as prepare documents, control machineries or to check illnesses. Hence, computers can be classified as follows; Figure 1.1 - Computer types 1.2.1 Classification according to size (i) Super Computers Figure 1.2 - Super Computers

These computers have higher computing power. They are large in size, expensive and rare.(Figure 1.2) These are used for scientific and engineering functions and to solve complex mathematical problems. For example, these computers are used in institutes like NASA, large scale businesses and for military purposes. (ii) Mainframe Computers These a have relatively less computing power and less expensive than the super computers. In mainframe computers, a number of users get connected to one computer using a number of terminals sharing, saving and retrieving data. (Figure 1.3 and 1.4) These are used in large scale businesses and in e-business. These types of computers are used even today in some large commercial institutions. (iii) Mini Computers These are slower, less powerful and less expensive than Mainframe computers and are also called common purpose computers. These are easy to use. A few users get connected to the central computer here through a few terminals to share data and information. Some banking systems use mini computers. (Figure 1.5 and 1.6)

(iv) Personal Computers/ Micro Computers This is a small computer meant for personal use. This consists of a small memory capacity, is smaller in size, is less speedy and is less expensive. Further, this consumes little electricity (Figure 1.7). Laptop computers and personal computers are some examples for this category 1.2.2 Classification according to technology Computers can be classified according to the technology used. These are, (I) Analog Computers These computers use analog signals such as environmental parameters (speed, pressure, and temperature). Speedometers, road lamps with sensors, meteorological machines can be given as examples. (Figure 1.8) (II) Digital Computers The computers used in day-to-day life are called digital computers. These computers use digital signals, using electricity. (Figure 1.9) (III) Hybrid Computers This is a combination of analog and digital computers. The ECG machine used in hospitals to check the function of the heart is an example for hybrid computers. This machine identifies the function of the heart beat which is an analog signal. Then it is converted to a digital signal and these converted signals are printed by this machine. 1.3 Function of a Computer System The main functions of a computer system is to input data, process and store data, and to produce information when needed. Several components are used for such functions. The following is the

function of a computer system; Data and instructions fed to the computer via an input device are stored in the primary memory. The data and instructions are used by the CPU for processing. The processed data are stored in the Primary Memory as information and send to the output device. The data and information which is to be stored are send to Secondary Storage device. The stored information can be sent an output device through Primary Memory. Control Unit sends the control signals to all the devices attached to the computer system. The flow of the data and instruction is indicated by a dotted line and the control signals are indicated by a solid line in the diagram above. 1.4 Basic Components of a computer system Certain devices are essential for the function of the computer system. 1.4.1 Input Devices Data and instructions are fed to the computer system using input devices. There are many input devices. The following are some of the input devices. (») Keyboard This is the most common input device. Though it is designed with the format of a conventional type writer, it provides keys for additional functions. Normally keyboards come in two sizes. That is from 101/102 keys to

104/108 keys. The functions of the keys in the keyboard are given below in Figure 1.11. Pointing Devices Example 1 - Mouse This is the most popular pointing device used. Mouse provides input via buttons. The mouse contains a left button and a right button. Mouse has a wheel to roll up and down in the screen. Laptop computers use, a touch pad or a mouse is as the pointing device. (Figure 1.12) Example 2 - Touch screen This is the input and output device in the modern computers and mobile phones. Data is fed by touching the screen. It also acts as a pointing device. (Figure 1.14) Example 3 - Joy Stick This is also a pointing device used in computer games which can move the cursor. (Figure 1.15)

Example 4 - Light pen Light pen is used to select menu items on the screen or to draw/write on the screen. (Figure 1.16) The appearance is similar to a normal pen. This is used in Computer Aided Designs (CAD). Imaging and Video Input Devices Example 1 - Digital Camera This is the input device used to input photographs and videos to the computer. Display screen serves as the output device of the camera. (Figure 1.17) Example 2 - Webcam The webcam is used to view a user connected to the computer through internet or to capture videos. (Figure 1.18) It is positioned on top of the laptop monitor, and for desktop computers, can be connected externally.

Example 3 - Closed Circuit TV (CCTV) The images or videos captured by cameras are fed as input to the computers. (Figure 1.19) CCTVs are commonly used to maintain road safety and the security of premises. Example 1 - Flatbed Scanners This is an input device which functions like a photocopying machine. The scanned image or document is captured by the laser beams and converted to digital data. The scanned picture / document can be saved in the computer. (Figure 1.20) Example 2 - Bar Code Reader This device is used to read the bar codes. (Figure 1.21) The bar code is converted to an alphanumeric value by the bar code reader and is fed to the computer connected to it. Example 3 - Magnetic Ink Character Reader - MICR This is available in banks. It is used to check the accuracy of a cheque. This device reads numbers printed at the bottom of the cheque, its data such as bank code, bank account number and feed them to the computer. (Figure 1.22)

Example 4 - Optical Character Recognition - OCR This is used to capture text in a document and to edit that captured text in the document. (Figure 1.23) This is commonly used in libraries and in government institutes. Example 5 - Optical Mark Recognition - OMR This is an input device which recognizes marks made using a pencil or a pen. It is commonly used to check forms filled in pen or pencil, correct MCQs of exam papers. It can read the marks and feed that data to the computer. (Figure 1.24) Example 6 - Automated Teller Machine - ATM ATMs have made bank transactions convenient for customers. (Figure 1.25) ATM machine reads the numbers in the debit or credit cards inserted into the machine and connect to the computer. Once the bank account number is read through the ATM, one system connects with the bank's computer for processing the transaction. (v) Microphone Microphone is used to feed sound to a computer. (Figure 1.26) 1.4.2 Output Devices There are several methods of producing the processed information by a computer system. Some of them are, (i) Soft copy (ii) Hard copy (iii) Sound

(i) Soft Copy The output on the screen is called a soft copy. The soft copy output can be provided on the following devices. Monitor/ Screen This is also called Visual Display Unit (VDU). There are several types of monitors available today. A - Cathode Ray Tube (CRT) Monitor This type of monitor, is large in size and consumes more electricity. (Figure 1.27) B - Liquid Crystal Display - LCD This is a flat screen type technology. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. (Figure 1.28) LED consumes less electricity. C - Light Emitting Diode - LED LED screens are designed using light emitting diodes. (Figure 1.29) LED displays have better brightness and they are used for symbols, billboards and name boards in common places and roads. This has become a popular medium today due to its low electricity consumption. Multimedia Projector This is the device used to get information output to a wide screen so that several people can view

it at the same time. This can be used as a visual aid by a teacher to display\\ presentations, to conduct business meetings or to watch videos for entertainment. (Figure 1.30) (ii) Hard Copy Hard copies are tangible computer outputs. The following are devices which provide hard copy output. Printers There are two main types of printers. These are, 1. Impact Printers Impact printers are a primary level device in the printing technology. Impact printer refers to a class of printers that have a head or needle which strike against an ink ribbon to make a mark on the paper. Its function it is noisy. However, since the ink ribbon used is not expensive, this is used in banks and shops for printing receipts etc. The following are some of the impact printers. Example 1 - Dot Matrix Printer Letters are printed on the paper as small dots here when the printer’s head strikes on the inked ribbon with needle like tips. (Figure 1.31) Example 2 - Line Printer This is a fast printer which prints one row at a time. This can print about 3000 lines per minute. (Figure 1.32)

2. Non Impact Printers Non impact printers does not operate by striking a head against a ribbon. Hence, it is not noisy. The printouts are better quickly. Running cost of these printers are more expensive than impact printers. The following are some of the non impact printers. Example 1 - Laser Printers Laser printer utilizes a laser beam to produce an image (through a mirror) on a drum. The light of the laser alters the electrical charge on the drum and apply toner (dried ink) in the cartridge. (Figure 1.33 and 1.34) There are laser printers which print about four A4 size papers per minute. Both black and white, as well as colour laser printers are available. The laser printer produces clear and quality printouts. Example 2 - Bubble/Ink Jet Printer Liquid ink stored in tanks is kept in the cartridge and ink is deposited on paper through small

nozzles and produce the print. (Figure 1.35) Example 3 - Thermal printers Heat is used to print the document. It is commonly used in businesses to print receipts in devices such as like ATM, and in printing labels (Figure 1.36). Example 4 - Plotter This is commonly used in computer based planning (architectural designs, town planning, designing sailing boats etc). A plan is drawn by moving a pen on the paper. (iii) Sounds The device which gives a sound output is called speaker. Speaker devices are designed for personal and common purpose.

1.4.3 Central Processing Unit - CPU This is the main component of a computer system. It is also called the brain of the computer as well as it functions according to the given commands. CPU manages the operating system and application software. CPU consists of three main components. The functions of those are as follows; 1. Arithmetic and Logical Unit Perform all mathematical and logical (ALU) functions. 2. Control Unit (CU) Controls all devices of a computer system. Positioned in the Central Processing 3. Memory Registers Unit. Temporarily stores data needed for the function of ALU. Main Components of Central Processing Unit Computer Speed The unit used to measure clock speed of a computer is Hertz (Hz) and the units used to measure computer speed are Megahertz (MHz) and Gigahertz (GHz). 1.4.4 Computer Memory Several computer memory or storage devices are used to store data and information and the functions of each are different. Computer memory can be classified as follows. Figure 1.39 – Computer Memory Primary Memory The memory that can be directly accessed by the Central Processing Unit is called primary memory/storage. There are three types of Primary Memory. ∗ Random Access Memory (RAM)

This memory temporarily stores data. (Figure 1.40) The data stored in RAM will be deleted when the computer is switched off. Therefore this is also called volatile memory. Data coming from input devices as well as data sent to output devices are held in RAM. ∗ Read Only Memory (ROM) The data in Read Only Memory is not erased when the computer is switched off. Therefore it is a Non-volatile Memory. The commands required for booting up a computer are stored in ROM. These commands are called BIOS (Basic Input Output System). Computer Manufacturing companies store these commands in a ROM with a smaller capasity and is connected to the mother boards (Figure 2.41). ∗ Cache Memory Though this is smaller in capasity than other memory, it is faster. This is also called CPU Memory. This acts as the mediator between CPU (Central Processing Unit) and Primary Memory. The data frequently used by are stored here. (Figure 1.42) The Central Processing Unit checks cache memory first to see whether the required data is available for processing. However, if the required data is not available then the data is fetched to cache memory from RAM for processing.

Secondary Memory Secondary Memory or the Secondary Storage is the device which stores data and information permanently. This is also called External Storage. There are internal storage devices as well as external portable secondary storage devices. Secondary memory is called non-volatile memory since it does not erase when electricity is not available. (Figure 1.43) These can be classified as follows. Figure 1.43 - Secondary Memory 1. Magnetic Media Devices Data is stored here by using magnetic field. Example 1 - Hard disk Drive The Hard Disk Drive (HDD), which is commonly used to store data and information, is located inside the computer. However, there are external hard disks as well. Today there are hard disks with large capacity due to the development of the technology. The user can read and write the data stored in HDD. Therefore, this medium is called Read / Write Memory. The capacity of a hard disk ranges from 250 GB to 4 TB. The maximum capacity will increase with technological development. Hard Disk is made of several components.

1. Platter – This is a metallic, aluminum or ceramic disk and data can stored on both sides using magnetic media. There can be several platters in a hard disk. 2. Spindle – Holds the platter and rotates it. 3. Head – Reads the magnetic data in the platter and writes on the platter. There are two heads for a platter; one on top and one on bottom. 4. Actuator arm – Moves the head. Enables reading and writing data anywhere in the platter. 5. Power connector – Connects the Hard Disk to power which is needed for its function. 6. IDE connector – Transmits data to the platter 7. Actuator – An electronic device which moves the arm connected to it. This is operated by a motor. External hard disk Example 2 - Magnetic Tape Used mostly in sever computers for back up due to its larger storage capacity. But tape is not used in day today life as it is slow in reading and writing (Figure 1.45). Example 3 - Optical media Since data stored digitally on a disk is read and written by laser beam, it is called optical media. Optical media is commonly used to carry data and information and there are several types. The followings are some of them;

Device Type Size Image CD-ROM Compact Disc Used only to read data 650 - 900 Read Only Memory and information MB 4.7 - 9.4 DVD-ROM Digital Used only to read data GB Versatile Disc - Read and information. Only Memory 25 - 128 Can be used to write GB Blue ray (BD) R data and information (Recordable) once until the capacity CD-R is filled. Compact Disc Can be used to write -Write once& data and information once until the capacity CD-RW is filled. (Compact Disc Data which is written Re-Writable) on the disk can be DVD-R erased and re-written. (Digital Versatile Can be used to write Disc - Write data and information Once) once until the capacity DVD – RW is filled. (Digital Versatile Data which is written Disc - on the disk can be Rewritable) erased and re-written. Blue-ray RE More data can be re- (Recordable written many times Erasable) until the capacity is filled. Blue - ray 3D Used to record video. 3. Solid State Devices Since these devices contain solid parts and does not contain moving parts they are called Solid State Devices. They are used to read and write data and information. Example 1 - USB Flash Drive This has become a very popular secondary storage device due to its easy portability and the ability to read and write data fast.

Example 2 - Memory Card This has the same function of USB flash drive. However, the method of connecting to the computer is different and it is smaller in physical size. This is used in digital cameras, mobile phones and computer gaming devices. E.g. - SD Card (Secure Digital Card) Activity Write advantages and disadvantages of Magnetic media, Optical media and Solid state media. 1.5 Computer Ports The interfaces which connect computer with its devices or with other computers are called ports. (Figure 1.48) Ports are positioned in the front or back of the computer. There are symbols to identify posts. All the ports are connected to the motherboard.

1. PS/2 Port Used to connect the keyboard and the mouse to the computer system. The purple port is for the keyboard and the green port is for the mouse. (Figure 1.50) However, USB port is mostly used today to connect the keyboard and the mouse to the computer system. 2. Parallel Port Used to connect the printer to the computer system. This consists of 25 holes. (Figure 1.51) However, USB port is mostly used today to connect printers to computer systems.

3. HDMI (High - Definition Multimedia Interface) port This port can be seen especially in laptops. (Figure 1.52) It connects the monitor, multimedia projector, digital TVs, and digital speakers to the computer. 4. RJ 45 Port This port connects computer of a computer network to the network router, network switch. (Figure 1.53) 5. Audio Ports/ Jacks This port connects audio media like microphones, speakers and head phones to the computer system. (Figure 1.54) Blue – Line In Green – Line Out, Head Phone Pink – Microphone 6. USB (Universal Serial Bus Port) This port is used to connect many types of input and output devices to the computer. (Figure 1.55)

7. Video port - VGA (Video Graphics Adaptor) This is also called the Graphic Port. This connects the monitor, or multimedia projector to the computer system. (Figure 2.56) The port consists of 15 holes. 8. Serial port This port connects devices such as modem to the computer. Today, USB port is used instead of the serial port. (Figure 2.57) Activity Observe and identify the ports in the computer in the laboratory. 1.5 Data Communication Transmitting data and information is called data communication. Data transmission can be carried out between two or more computers or devices such as printers. Data transmission needs a connection between a sender and a receiver. Creating such a connection is called networking. 1.5.1 Basic components required for data communication The following are the basic components that are needed for data communication. Figure 1.58

• Sender / Source – the person or the object which sends data • Medium – medium used to transmit data (telephone wires / wireless) • Receiver/ destination – the person or the object which receives data 1.5.2 Data Transmission Modes There are several modes of data transmission between sender and receiver. 1. Simplex Mode Data is transmitted from the sender to the receiver only. Getting print outs, watching television, and listening to radio can be given as examples Figure 1.59 - Simple mode communication 2. Half- duplex Mode Here, data is transmitted to one direction at a time. This means after data is transmitted from sender / source to the receiver, the receiver can transmit data back to the sender / source. Browsing internet to get information and walkie-talkie used by security forces can be given as

examples. Figure 1.60 – Willkie – Talkies Half duplex modes 3. Full Duplex Mode Data is transmitted to both sides at the same time is called Full duplex. Telephone conversation is an example for full duplex mode communication. Figure 1.61 - Full Duplex Mode communication 1.5.3 Data Transmission Medium This is another important feature when creating connections among systems. There are two types of data transmission medium. Those are called Guided/Wired and Unguided/Wireless. The following are some examples. (Figure 1.62)

Figure 1.62 - Data Transmission Mediums Guided / Wired If the medium used for data transmission is a physical medium, it is called guided or wired. Example 1 - Twisted Pair Pairs of twisted copper wire are used for data transmission. There are two types. 1. Unshielded Twisted Pair (UTP) The twisted copper wire pairs used for telephone connections. These are very flexible and low- priced. However, it is diffcult to transmit data for a long distance through UTP wires. It is suitable for maximum of 100 meters. 2. Shielded Twisted Pair (STP) STP is a better quality and secure data transmission medium. However it is expensive. (Figure 1.64)

Example 2 - Coaxial Cable This consists of an electronic cable pair. The outer cable which is like a braided copper net produces electromagnetic feld around the central cable. These two cables are separated by a plastic shield. These cables are expensive and used for TV antenna and CCTV.\\ Example 3 - Fiber Optics cable Fiber Optics cable consists of a pair of cables. There is a plastic jacket to separate the two cables. Core is a glass tube and there is glass cladding around it. (Figure 1.66). The data transmission is carried out by while reflecting light. These are used in modern telephone networks. The cable is relatively more expensive. Activity Write down advantages and disadvantages of copper wire and optical fiber (ii) Unguided/Wireless Media Data is transmitted as signal through the air without using physical medium is called

unguided/wireless media. Example 1 - Radio waves Data transmission is performed using radio waves. Wi-fi and Bluetooth are examples for radio waves based communication. Example 2 - Microwaves Microwaves travel in a linear mode. Figure 2.68) Transmission center is positioned facing each other. The distance between centers are decided based on geographical factor of the area. Microwaves are used in Satellite communication to transmit data as transponders. (Figure 2.69) Satellite centers, which are positioned in the sky above 36000 km, capture data transmitted as microwaves through satellite towers positioned in the Earth and then transmit the data back to the required tower. Using this method, data can be transmitted to any distance. This is also used in internet communication. Example 3 - Infrared Infrared data transmission is used in TV remote controllers, wireless keyboards and mouse etc.

1.5.4 Computer network devices There should be two or more computers to build a computer network. Connection devices used to connect computers with each other. (i) Network Interface Card (NIC) NIC has an RJ45 port and is built into the mother board in modern computers. In the port NIC was a separate code to be plugged to the mother board. Figure 1.71 (ii) Switch/Hub Switch/Hub acts as the mediator to build a connection between two or more computers. (Figure 1.74) A guided/wired transmission media is used. One end is connected to port in the computer and the other end is connected to the port in the Switch / Hub.

Differences between the switch and hub • The main difference is the data transmission speed. Hub sends the transmitted data to all computers but switch sends data to the relevant computer only. Here hub may create an unnecessary network data congestion. • In data transmission, hub uses half duplex mode and the switch uses full duplex mode. (iii) Wireless Fidelity - Wi-Fi Wi-Fi adapter has become the most popular media in computer networking. This allows the users to build a computer network easily and internet connections for mobile phones and laptop computers using radio waves. (iv) Router Router is the device used to build a connection between two or more computer networks. It is also called a Gateway. This finds out the most suitable ports for data transmission in network communication. (v) Modem The modem is used to connect the computers of a computer network or a personal computer at

home to the internet. The modem acts as a data translator. Digital signals sent from the computer is translated to analog signals and the analog signals send to the computer from the internet is translated to digital signals. This is called MOdulation and DEModulation. Hence, ‘MODEM’ is a combination of these two words. There are different types of MODEMs. Those are internal, external and wireless modems. Today routers have a modem inbuilt in the device. (vi) Firewall Firewall is a network security. Instructions to control the data and instruction transmission between internet and computer network are built into the system. A firewall operates as a secured barrier between internet and network. Firewalls exist in both forms as software and hardware. Modern concept of personal computer means doing personal work with computer. The name itself means that personal computer or PC is a computer for individual use. Personal computer is a computer of a single user. The use of computer perhaps begins at home by a single pc. The work of a small office may starts by a computer. Many schools and colleges or business institutions in our country had started their work by a single computer. However, the condition keeps on developing gradually. The use of computer is increasing, though the work in a house, office or institution had started with a single computer. The number of computers increased rapidly in these areas. When a computer is used individually, all the related devices or instruments can be used personally. For example, a user can use a printer. But a printer can be used by many other people at the same time. Whatever may be the use of a computer, a

printer is used less than a computer. Most of the time, the printer remains idle. On the other hand, it is very costly to buy a printer with a computer. However, by networking a printer with several computers can save considerable amount of money. Not only printer, inter-connectivity can be established through computers and related technologies. Communication of information with each other is very important. Now a days, use of internet is a great achievement in the field of communication. Internet is a kind of network. When the communication of information is done by sharing through computers it is called network. Nowadays Network system is essential in computer system. Classification of network Computer Networks can be of two kinds on the basis of physical locations of the computers planned for establishing network among them. a. Local Area Network b. Wide Area Network The network connections of computers or instruments within limited area or different floor of a multistoried building is called Local Area Network. Again, the networking which is done with the computers of distant places is called Wide Area Network (WAN). Network among the computers of different cities, such as, Dhaka, Chittagong and New York is wide Area Network. Network connection may be established with cable or without cable, i.e, wireless connection. Local Area Network is generally built up by cables. One machine may be directly connected with another. On the other hand, the Wide Area Network is established using wireless technology. The cables of telecommunication system may also be used for establishing computer Network. Now a days the network of WiFi, WiMax , mobile phones have gained enormous popularity. Consequently, the Wireless Network system or the network system without wires is expanding rapidly. The Topology of Local Area Network Topology is different types of arrangement of connecting the computers with each other in a network architecture. Some main organization of Local Area Network are: a) Bus Network b) Ring Network c) Star Network d) Tree Network e) Mesh Network and f) Hybrid Network Bus Network In Bus Network all computers are connected with each other through a common line or bus. In Bus Network any computer can send or receive any signal from any other computer. In this network computers are connected with data bus separately. So, the work of network is not disrupted if any computer is disconnected on goes out of order. Any new computer can be brought under network by connecting it with data bus. There is no central computer in bus topology. Ring Network The Ring Network architecture is circular. Any sent data or signal from a computer keeps on moving on the way to another computer. In this way the data keeps on moving until received by other user. There is no controlling or central computer or host computer in ring topology. As a result, everyone is self-sufficient either to send or receive data. Network becomes inactive when a computer fails in sending or receiving data. In order to set new computer, the total ring has to be dismantled. Another problem is that the speed of communication of information becomes weak if the network expands.

Star Network In star network one central controlling computer or host computer is connected with other computers. In this topology connected computers cannot communicate directly with each other. One computer communicates with other computers through central controlling computer or host computer. Host computer centrally establishes connection for communication of data or signal and controls their work. In star Network the total network becomes useless when problem occurs in host computer. However, when problem occurs in one or more computers only those computers become non-functional. But, other computers do not face any problem. Tree Network Tree Topology is actually the extended form of star network. In this organization computers are connected with host computer in different levels. Second level of computers is connected with third level of computer. Second level computers work as host of third level computer. In this system, third level computer cannot directly connected with central computer or hast. Mesh Network In mesh network computers are connected with each other. In this network there is no central controlling computer or host computer. Each computer in this network can establish connection with each other. In this network, the connection between the computers is termed as point to point link. Hybrid Network There are some advantages and disadvantages of hybrid network organization. Moreover, in any case only one network organization may not independent for some necessary work. For this reason, some network organizations together form hybrid network. Ring, star and mesh network together can create hybrid network. Generally co-axial cable or wire is used to build up connection between local area network host computer and other computers, printer, storage device and other machineries. PC can also be used as server and workstation in the network. Co-axial cable is used for data transmission. For cable connection of network-connected computer and machinery, one kind of controller consisting of especial chip of coordinated circuit is used. With every network connected machine, a small box is used named Tran silver. By Tran silver cable, data is received and sent. In internet, computers and machines of various companies can be used. Like intemet there is another widely used local area network system named Omni net of corves system. In this network system, IBM pc compatible computer, Macintosh computer and personal computer can be used together. Local talk is the effective and easy network system in Macintosh. It is very popular network system in Macintosh computer. Necessary Hardware and Software of Local Area Network First of all computers with proper configuration should be selected carefully to use in network system. Secondly, the cables and other connections should be selected with proper specification. A Network card is set inside the system of computer. Then the connection of the card is given with the expansion slot of mother board. Generally, what is done is that one network is used to give connection with computer or other machine 8/12/32 port or more than 8/12/32 port may remain in these hubs. This hub sets the connection of wires with every computer or other machine. Moreover, the computer network connection may be set without wires or cables. A modem is set to transform the computer signal into telephone signal and telephone signal into computer signal. Once one particular software and network operating system were needed for introducing computer network process. Now in windows 98/2000 operating system or Mac OS no separate

software is used when operating system is set up with different parameter of network. However, for building up a strong client server network system, server software and client software is used WiFi WiFi is such a network system by which network system is set up in a particular small area. BLUE TOOTH Blue tooth can be used to set up wireless network in a smaller area. In this system mobile and internet may work together. The machineries of Wide Area Network For Wide Area Network system, some steps, such as, direct wire connection V-Sat, WiMax, 3G etc are taken. The fastest speedlink is the Fiber Optics connection. In WiMax and 3G system broadband information communication system can be set up. The History and concept of Internet The word \"Internet\" stands for International Network. Internet is the network of all networks. For a long time LAN, MAN, WAN, ISDN and some other network systems have served the communication of information to a little or great extent. Different corporation, multinational company, educational and research institutions have been using network system for their own need. When telephone and satellite communication systems become united with computer, the computer users began to feel the necessity of expansion of network circle. In this circumstances, in the beginning of 90's, the main servers of the towns began to remain connected with each other by satellite and consequently, a revolution of information communication took place throughout the nations of the world. Communication in this process is very cheap; as a result, gained wide popularity. This system of information communication and media connection was termed as Internet in 1994. Whatever name may it be, it was accepted as world network or network of all networks. Now a days, people of different professions can know the latest and in detail about their own profession. Businessmen can communicate through internet in a very cheap cost and easy way. People who are doing research can know much information from the world store house of knowledge whenever they want in a very easy manner. This huge revolution is happening silently. Though the year 1990 is marked as its wide use, actually it began in 1969. Different sectors of America opened Advance Research Projects Agency Network (ARPA net) in this year. This is the man's first attempt to Computer Network. Though the theme were connected with defence. Gradually it becomes the media of communication in many Research Institutions and Universities in America. Even they were able to open their stored software programs. It is said earlier that internet is a spontaneously built system. It is free from bindings of copy right and this is why it extended silently. Though it was spontaneous, it is not undisciplined or uncontrolled. In the meantime the systems of its use have been built up. For example, whoever wants to be connected with internet, he needs a proper identity or personal account. This address is to collect from some particular institutions of America paying fixed fees. Moreover, for information communication internet has introduced internal rules and procedure which are communication protocol. Two protocols of these kinds are (1) UUCP (2) PCP/IP (UNIX to UNIX copy program). Internet first starts work by PCP/IP. Data, voice and graphics etc can be sent through them. However, it has some drawbacks. For example, the distance of the target place of the sent message must be mentioned while commanding. The second system is very much easier than the previous one. In PCP/IP (Transmission Control Protocol Internet Protocol) system, only the address of the target place of the sent information is to be mentioned. Though, the information are transformed in the same way in these two protocols.

However, for the users the second system is easier than the first one. The users do not have any direct PCP/IP or gateway communication, the communication software's which the users use does everything when it is necessary by itself. Though the use of internet started in 1990, it was not called internet before 1994. In 1990 the word \"Internet\" was first used and got much popularity. At that time, internet did not cross the boundary of Europe and America. However, within a year internet crosses this area and establish world-wide telephone, Fax, data conferencing, marketing, education, research, office management, telecasting, defense and medical work together. Beside, Information super highway, for wide communication media is going to establish. As a result, all big libraries, universities, research institutions, commercial and non-commercial institution, defence sectors, stock exchange and other numerous personal institutions got connected with each other. So, wherever a man is, he can get all the necessary information very quickly, and cheaply by the Internet based computer information system. All kinds of world information systems are involved in GII (Global Information Infrastructure). Actually, it emerged as Information Super Highway. Already, developed countries are involved in it. To tell the truth, GII has introduced a new world. GII has come for word to help student-researcher and other professional people who have inability to access the opportunity for their necessary information for knowledge due to their economic crisis or other problems. Due to the good service of GII, people can get any kind of book from any part of the world in the shortest possible time. Internet Document Webpage, Gopher, FTP file etc are called the document of internet. All these documents have separate addresses. Seeing the address it can be said what kind of document is it . By using these addresses, users can reach them. These addresses are called Uniform Resource Locator (URL). The first part of these addresses is used to mean format. The path of browser Resource can be described by this address. There are ten or more than ten kinds of formats, of them, the most used three formats are http: for world with web, gopher, for gopher menu or documents and ftp for FTP etc. After colon sign (:) there have two forward press. And the part after this internet address and it is divided into three by comma sign (,). The first part indicates the section of the computer that contains internet documents for example, www.goher or http:etc. The second part is host server and the third part indicates service by which the institute is run. For example, com stands for commercial institution and org stands for non-commercial organization. Another part of the address which is seen as last join that is the identity of country represented by two English letters for example, sg stands for Singapore. Natizen All educated people are familiar with the word Natizen. Citizen is a legal inhabitant who possesses the right to get passport and enjoy other facilities. Just uses of internet are now a day called Natizen. The number of Natizen is increasing day by day. The Natizen means achieving international citizenship. Requisites for internet connection The following devices and components are required for internet connection. Computer Internet can be used by a single computer. Internet with computers of higher speed is more advantageous. Modem Modem is a machine that transforms the symbol from digital to analogue and analogue to digital. The word \"Modem\" stands for Modulator and Demodulator. Therefore, modem is a very necessary device for internet connection. It can be external or internal. The speed of a modem is

generally 14.4, 28.8, 33.6 and 56 kbps. Though external modem is widely used, sometimes internal modem can be used. The price of internal modem is very cheap and no extra adapter is used for it. Moreover, it neither occupies more places nor it takes any electric connection or serial cable, for it is connected with extension slot of motherboard. External modem is better if someone wants to use a modem with more computers. For few general email and fax 14.4 kbps modem is enough. However, if any one wants to send many data, it is better to use 28.8 kbps or more powerful modem. Telephone Line Generally digital telephone is used for internet. Now all new telephone connection system is digital. Software is used for web browsing and email in internet. For example, Netscape communicator, Internet Explorer, Eudora Pro, Outlook Express etc. ISP ISP means Internet Service Provider. Their duty is to give the users internet connection and relevant service. Generally there is VSAT and server with ISP. Some ISP in Pakistan provides network service is ISN, Qubee , Brain Net , Excel Net, Gerrys Net, Fascom, Netsol, World Online etc. They provide an address to a person or institution. Mobile Internet At present huge number of mobile internet is used in jazz. Some GPRS mobile or CDMA mobile set can use internet. Mobile phone can be used as modem. At present the bandwidth is less than 3G. But they ensure quick network service. Network address If any person or institution is interested in getting internet connection, he must have an internet account or address and this account is the identity of World Wide Web or other document. All network accounts are stored in central Database Directory in USA. The internet service providers by using this directory provide opportunity for people to get connected with internet server all over the world. At the beginning, some educational and research institutions control internet directory and main servers. In the late 1990 when internet got quick popularity, National Science Foundation in the USA divided the responsibility of internet among three institutions. Of them, Network solution controls the registration of addresses and directory control, AT&T directors connects wide area Network and Genera Atomic hoods the responsibilities of managing computer. Later, these three intuitions together established interne Network information centre INTERNIC. The INTERNIC starts it function on January in 1993. One can get registered for two years with network accounts by paying 100 US$ to Network solution. Net time to keep the network active $ 50 is to pay every year. Network solution thus builds up main directory. It also ensures that any person or institution must have address or accounts of their own. It means that more than one institution cannot use the same account. The information from these main directory are sent to 9 (nine) fundamental servers and the users of ISP and other internet get their necessary information from these servers. The postal and telecommunication ministry of Brain net sanctions these accounts. WWW (World Wide Web) Through network established an inventive system of information sending and receiving. Their innovation system later gets much popularity through internet as World Wide Web. In short it is also called web. The users of interne can explore any information of the world through internet. It does not matter how the stored information general text, graphics, audio or video, the users can get them on their computer. It is called internet multimedia. Some softwares are needed for working in the web-site. They are called web-software or browser. By this softwares mention a

particular account, the books from Library of Congress in America can be read within seconds. In the next moment one can enter into web-site of computer. This system has brought a revolutionary development in communication of information. For working in the mentioned web- site a particular software or browser is needed. Mark first made a browser named Andris Mokaik in 1993. The National Centre for supper computer Application of Illion University in the USA does marketing for it. Generally speaking, when it comes to market, it reached to a stage of popularity when people saw that the use of web is increasing first, they found the easiest way for sending message and institution sending information through homepage. Not only present developed part or organization but also the organization or people of the past of the world, have chosen web as their media of information communication. Thus everyday users attachment with website is increasing. While discussing web, hypertext can be discussed. Hypertext is such information presenting system that it can set connection with other information. Suppose someone is watching discussion on computer. At a certain stage he can find the word printer is displayed with another colour and it is underlined. In this circumstance if he clicks on it with mouse he will have information about printer. Again while discussing printer he can get the information of new connection. The program by which such hyper documents can be read is browser. And the exploration with this software in the web is known hall browsing and he made virtual computer in on-line by himself. After that seeing the price and doing calculation, he made a configuration and sent the price to the web-page of the shop. If he had credit card he can complete formalities for paying the prices on web-page. This one can buy computer or other things for home. What the customer did in this case is called on line application. The process of Web Browsing The meaning of 'Browse' is \"to look through the pages of a book for employment\". However, the meaning of the word 'Browse' in computer is little different. A computer user goes through the lists of different types of internet topics. The meaning of internet Browsing is to roaming from one web-page to another. By internet web-Browsing information web-page stored in server can be collected or seen. Different kinds of software are used for this purpose. Of them Netscape communicator, Internet Explorer etc are widely used. How to work through Netscape communicator is discussed below: For opening a web page internet connection is to be set at the beginning. On double clicking on Network icon, a dialogue box appears for typing address. After typing address of web page in the location box and pressing enter, it can be seen that on status Bar, web side found, waiting for reply, connect to last etc are coming one after another. When data starts coming on computer, the percentage of opening of page can be seen on status Bar. It is better to read web page on off line when it comes fully on computer. This is because the bill of on line will continue as long as you spend on it or saving the web-page on one's computer it can be read off line. While working on web page one can go from one page to another. By clicking \"Forward button\" one can go to next page and by clicking Back Button\" one can go to previous page. Home Button can be clicked in order to go to the beginning point. When cursor goes on the link it looks like fist with raised finger. And clicking on that link, details about that page/subject is opened. How to create Bookmark To stop the repetitions of typing web address each time, users can make book mark to store them. The easiest way of creating bookmark is to click Add Bookmark command of bookmark menu after web-side is loaded fully. Then the bookmark of the web-side is made independently. The second way is to select bookmark go to window menu. Then bookmark dialog box is found. After

clicking \"insert\" in the \"item\" of the dialog box, dialogue box comes \"Book mark properties\". Bookmark is then made while typing address on the web page \"OK\" is clicked. Thus attached accounts are displayed on the Bookmark Menu. The process of web search There is a huge storage of web pages in different places of the world. There are different kinds of information and data on those web pages. No one knows exactly, where the information of a subject is stored in the world. In this case the users can look for them on web page. The searching can be done in two ways, firstly, clicking search as Toolbar, secondly, typing the address of search Engine in the location Box. The search Engine is a kind of page which finds the necessary subject on behalf of the users. Some search Engine of these kinds are- yahoo.com, Altavista.com, webcrawler.com, google.com etc. However, yahoo.com and google.com popular search Engines. For searching anything by it, write http: //www.yahoo.com in the location box and press Enter button. After a while the web-page of yahoo appears on the computer. There is a blank box on the page and search beside it .Write the necessary subject in this box and press Enter button, then see \"yahoo\" category Matches (1-20of ) titled page appears. There may have the names of many web pages on the typed subject Necessary information can be collected by clicking on them. E-Mail E-mail is the short form of Electronic Mail. Its duty is to send the information of one computer to another. The invention of telephone in 1786 has added an extra dimension for distance communication. Then Telex, Fax and many other communication systems have already been invented. However Email has brought about a revolutionary change than anything else. It is faster and reliable. International communication from Worldcall through telephone takes Rs. 50 per minute while email takes Rs. 3 per minute. Through interne connection email can be sent in different addresses in home and abroad. The sent email is stored in ISP server Mail Box of the receiver. When the receivers cheek Mail it appears on computer. E-Mail Address E-Mail address is the identity of communication through interne. For sending and receiving e- mail an e-mail address is important as an address is needed to send a letter. A number is needed to call somebody. This address is formed with user name @ Domain. For example [email protected] is an e-mail address. It is important to notice that E-Mail address is divided into two parts. In the first part meaning before @ the identity or name of the user is written. There is no limitation about the letter needed to write user's name. Writing name in short is advantageous. English letters, number and sign can be used. However, no number can be written before name and no space between letters. The part after @ is Domain name, and domain name is divided by comma (,). The first word after @ is called host machine name. In this address PK link is the host machine name. The word after host machine name indicates which kind of work the organization maintains. For example, com stands for commercial institution and org stands for non-commercial organization. Moreover, net means Network organization and Gov stands for government organization Military, corn stands for companies; edu stands Educational, ac mean Academic institution. The last part of Domain name is called TLD or level Domain which means the word of two letters of a country which bears the identity of that country. For example, for Brain net the particular TLD is pk and more examples of these TLD are given below. Africa .za, Australia, .au, Singapur .sg, India in, Japan .ja, Canada .ca, Argentina .ar Austria .at, Belgium .be, France .fr, Hong-Kong .hk, Malaysia .my, etc. In case of domain name there is another important subject is IP address. This IP address is the sum of such numbers that is divided

by three (.) sign. This address is provided by an institution named International Assign Numbers Authority (IANA). Generally number-based address is provided. However, there is a dedicated computer server which establishes the combination between domain name and numbers. The process of using E-mail Specific software is necessary to use e-mail. Netscape communicator is one of the most popular current software for e-mail. Here the use of e-mail can be described. If one can know the system of using software, he will be able use other software without any problem. This is because there are some common subjects in all software which are very friendly to the users. The procedure for sending e-mail The primary steps for sending e-mail by Netscape communication are given below:- 1. When Netscape communication is opened the first internet browsing screen appears. 2. Communicatory Messenger Mailbox is to be selected or Ctrl+2 commanded should be given. Then Inbox Netscape Folder will appear. From the window messenger New Massage has to be selected or Ctrl+M command should be given or new Msg button on the toolbar have to be clicked. As a result composition appears window. That is the place for e-mail. The following steps are followed to e-mail. In the beginning of the composition window there are To: Cc: Bcc: Group: Reply etc popup menu. If anyone them is selected a text box is displayed at the right side. It is necessary to put all the necessary information in that text box. For example- To: In this box the e-mail address of the receiver is typed. Cc: Only those addresses are typed in box to whom the sender wants to send the e-mail. In this case e- mail addresses are typed putting comma (,) after every address, except the last one. Cc stands for carbon copy. In this box only those addresses are typed whom the sender wants to send copy of the same e-mail but do not let them know. The function of Cc and Bcc are almost the same. However, in cc the receiver of the copy can see the names of other recipients of the same copy at the end of the documents. So, the receiver can understand who has sent the e-mail copy. However, in Bcc the typed addresses do not move with documents. As a result, the receiver does not know the means of other recipients. Bcc stands for Blind Carbon Copy. Group: In the group box, only the name of the groups prepared earlier are typed. Reply to: In this box the address of the sender is typed. Follow up: In this box those e-mail addresses are written who needs to follow up in the next subject. There is a tool bar below the text box where all the tools are arranged for editing. Here font and different formats etc format menu for formatting text. Then there is a blank space which looks like a page of paper where the main part or the message or text is typed. Attached: In this box, the name of the file and path are typed that the sender wants to send with the e-mail. This is the system of sending attached file. The attached document can be opened with the relevant program. If any excel file is attached the receiver can open that with Excel. After completing the function of e-mail typing and formatting, File>Attach>File is selected while attaching a file. Alternately one can click on attach button in Toolbar or Attach File Document. Tab is to select and click the right side of it. Then Enter File to Attach appears at the window. The file which is necessary to attach, is to be searched and then click on open button. The file is attached with the Document ready for sending. Setting up Internet Connection

After completing e-mail text composition the second main work is to set up Internet connection click the icon of Dial -Up-Network on the Desktop. Connect to dial box appears type password there and click on connect button. Computer is connected with Internet. Sending E-mail After setting up the internet connection select Send from File Menu or click Send icon from Toolbar. By this command, e-mail is sent to its destination. When any mail is sent, it stays in sent Folder. For deleting the sent file select Edit>Delete Message or select the delete button from key board. E-mail Printing For printing e-mail: Open it and select File> print or click Print icon form toolbar. Checking the E-mail Any received e-mail is stored in ISP server of the receiver who takes it to his computer in his leisure time. To do this, the user has to set up internet connection and select File>Get Message >New from Inbox Netscape window or execute ctrl +T command or click get Msg from toolbar. Getting new message dialogue box appears on the screen. If there is any e-mail comes to the computer through dialogue box and is stored in inbox then the internet is disconnected if there is no work. This is because the much time you will spend on on-line, the more bills will come to. Therefore it is better to do off line work, disconnecting the internet. For example, reading the received e-mail and preparing the answer can be done on off line. For instant reply, select the message and execute the command Reply from Message Menu or click Ctrl+R from key board and click Ctrl+R from key board and click Reply, button from toolbar. After that type message in mail body and send it as usual. If any e-mail is sent to the same address in the Address Book. As a result not need to write the same address again for sending e-mail. The Process of saving e-mail address in address book Select Address Book from communicator menu or execute Ctrl+shift+2 then address book appears on the windows. Then select File>New card or click on new card from toolbar and the new card dialogue box appears. Writing all information there click OK button and save in the address book. Exercise Multiple choice questions 1. To get the internet connection, the most required accessories are- a. Computer, Scanner, Telephone line, Software b. Computer, Modem, Disk driver, Software c. Computer, Modem, Telephone line, Software d. Computer, Modem, Printer, Software [The following paragraph is applicable for questions 2-5] A plan has been set that all computers lying in different floors of a 10-storeyed building of a bank in Lahore will be brought under a network. 2. Their network may be established by- i. using cables ii. using satellites iii. using radio link Which one of the following is correct? a. i and ii b. ii and iii c. i and iii d. i, ii and iii

3. What will be the type of their network? a. LAN b. WAN c. MAN d. ISDN 4. After starting the network, they- i. all can use the software combined ii. can coordinate with all the computers work. iii. can exchange the device of one computer to another computer Which one of the following is correct? a. i b. i and ii c. ii and iii d. i, ii and iii Long Questions Look at the diagrams All over the world personal computers are gradually communicating data under the LAN system presented above or under any of the networks. There are 10 computers in Rani's school. Recently their school has decided to attach internet connection and LAN for the use of Rani and her classmates. a. What is internet? b. Explain one of the main characteristics of LAN-3 organization that presented in the diagram. c. Which one of the network stated in the diagram is appropriate for Rani's school and why? d. State the logic in favour of the internet connection for Rani's school.

Unit 2 Use of Computer and Multimedia After studying this unit the students will be able to understand; 2.1 Uses of Computer: Computer works with data. Character, number, picture, word, moving picture etc are taken into computer as input. Computer takes them as data & processes them. When a computer works as a calculator, numbers become its data. Again when it works with graphics or moving pictures, animation etc. those items also become its data. Computer hardware converts these data into machine language. Operating system & application programs of a computer display those character, number, symbols or words. Any type of data can be processed in modern computer. Computer can accomplish small to large types of calculation now. Same thing is applicable for picture and word. Uses of computer are not limited within one or two works at present. Various types of works can be done by computer. Necessity of computer has become compulsory almost in every works in social life. In a word, computer can be used almost in every work. Though, use of computer has not been started in all sectors in our country yet, but its possibility & importance is increasing day by day. Let us discuss the recent uses of computer & its prospects in some sectors: Computer in the Business Sector Modern business has not been spread remarkably in our country. Most of our people are still involved in the small markets in our country. But the cities and towns have been influenced by modernism. Grocery shops have now been transforming into shopping plaza, departmental shops etc. We all know that business means lots of calculations. Calculation gets bigger as the business gets bigger. Relevantly computer has contributed in the business sectors. Besides foreign affairs, computer has vast access in market analysis, future planning, export-import, selling, bill-making, salary-allowance, presence-absence of the employees, stock of materials etc. The modern concept is called e-commerce that computer has bought in the business sector. Electronic commerce or e-commerce is the identity of 21st century business. It is guessed that business will be led by internet in future. Business industries of the modern world & some industries in our country has already developed their own web-site & started marketing. The largest book-store of the world is now on the internet. From man's wearing to house hold goods & industrial machineries are sold by e-commerce.

Many industries in our country have already started such business. Business of our country has not become that much dependent on computer as its implementation is yet to spread. So influence of e-commerce has not spread yet. But it has no doubt that e-commerce will be the main resort in business sectors in near future. Computer has replaced the type writers, calculators, fax, PABX, TV, VCP, audio players etc in the business sectors gradually. Works such as business-seminar, marketing, share-management, data-entry, description, leaflet, brochure, research-paper, project-profile, advertisement, drawing- design & presentation can be done by using computer. It will be difficult for any business industries if it fails to adjust with this revolution. If we take bank-management as the most important center point of business sectors, we will find wide spread application of computer there. Now we have 24 hours banking advantage in our country. Some banks have advantage of banking (deposit, withdrawal, bill-pay, account report etc) without any help of man. These can be done at any time. There are some banks where an account holder can transact money at any branch of that bank. Computer is used in data processing, communication, data management, accounts & insurance companies. Computer in Management: Management is an important part of any administration. Administrators used to accomplish their duties by physical labour in the past. The work of administration is so complex and difficult that everyone realizes it importance. The labour has decreased as well as the work efficiency & speed has increased in the management of accounts, labour, administration after computer was introduced. Any administrative work, such as data analysis, working, submitting necessary data, publishing result immediately, condition of buying & selling, pointing out the demand etc can be done very fast and efficiently. Many things can be done and controlled automatically by computer. Computer is an indispensable machine in the education administration for student-teacher- employee management, book management for a library, project management for development works, communication & data management. Computer in Publication: Computer has brought revolution in the fields of publication. Developed countries have computerized press machines. We cannot use them here as they are very expensive. These computerized machines only need to set up the page for them, rest of the work is done by the computer. For printing text are typed and formatted according to the need of user. This phase is called compose. In the past this work was done by letters produced with lead in our country. This type of press was called letter press. We were depended on the letter press until the middle of 80s. Wooden frames of letters were used to publish large fonts in the poster by the letter press. Letter pattern made from lead would become unusable after several impressions. Some of them were broken from the top side, some were broken from the bottom side & some were totally broken. As a result, some letters were not printed correctly. Computer composing was started in our country in the late 80s. Now all the newspapers, magazines & books are composed using computer in our country. Letter press is now used to publish a few types of printing. Output of computer compose is much more attractive than the letter press. Advantages of Computer Composing: Compose can be done swiftly. Urdu, English & other languages can be composed in the same computer. Letters don't break & the lines remain straight.

Font size can be increased and decreased according to need at any time. Composed text can be saved in the computer and used later when necessary. No need to compose again. Book containing thousands of pages can be saved in the computer. Composed subjects can be used in electronic or digital media. Page decoration, use of graphics, colour variation etc have become easy in publishing for computer. Computer is now used in publishing newspapers, books, leaflet, advertisements etc. Computer has begun a modern age in designing web-page, digital-books etc. Computer in Education: Computer has introduced a new method of education against the traditional style of education. Computer has introduced multimedia software & internet in the education sector in place of traditional chalk, duster, black-board, pencil, pen & exercise khatas. Students are getting information in a developed & attractive way through multimedia software & internet than a book. Information in a paper has transformed into a digital form. We would find various application of computer in the academies. Such as- Teaching: Computer has no competitor in attracting students' attention. Not only that, computer is the most active media to make the students remember their lesson. Students can learn faster & memorize the lesson for a long time when most of their sensory orgams are involved. For example, when a teacher gives any lecture, students only use their ears. When any important word is written on the board, students will use their eyes. But when any picture is drawn, students be able to memorize the picture & lesson for a long time. It is proved. If the picture is a moving-picture then it will have the best impact. A moving-picture has much impact than a story. Computer can provide us all these advantages in teaching. The students of preparatory level get very attentive when various stories, histories etc are presented with cartoon characters. History, Geography, other branches of Science etc can be taught with colourful pictures in the upper classes. For science Celestial globe, Solar system, planetary system, Animal world etc can be presented using multimedia projector. Many such things have already been made. We can also make them according to our need. How many countries are there in the world, names of the capital cities, currency names, population, percentage of education etc can be known from a computer very easily. We can listen to national anthems as well as information of the countries. These advantages are available in the common computers now. So there is no doubt that the computer education system is much better than the traditional education system. Administration and Storage Data: The headmaster, accountant or the responsible officer can easily store the teachers' and employees' names, address, salary and employment as well as the students' names, address, roll no, class test result and information about school fees. If parents want to know the update information of their children then the computer can display all the information instantly. There is no need to find papers and documents from the shelf. So, time and labour both are saved. Parents don't have to wait for a long time. The officer can satisfy the parents also. The headmaster can observe students progress if the computer has a network connection with headmaster's computer. Moreover, he can keep teachers' evaluation in his computer. Communication: Various letters are needed to make communication for administration. Thana education office, district education office and ministry of education have to communicate with each other through letters. Often these letters have same text. Sometimes, there are slight changes to make. The same letter has to be written every time. Letter need to be written again if there is any typing mistake.

Use of white marker or eraser hampers its cleanliness. On the other hand, every letter can be stored in a computer. Letters can bc copied and overwritten when needed. Mistakes can be corrected while typing a new letter. Letter written in a computer is much standard than a typed letter. It also looks very attractive. Besides this, school and college can communicate directly through computer networking. Preparing and Storing Exam Results: Say, 100 students sit for the SSC exam from a school every year. Result of 100 years can be stored in a computer. So, the result sheet cannot be damaged by storm or insects. Any result can be seen whenever needed. On the other hand, result of the students can be prepared and stored in a computer. Testimonial: Testimonials are provided from school to each student every year after the exam. Testimonial is printed keeping blank-spaces for name, father name, date and year etc. Those blanks are filled in by hand when they are provided. Such testimonial can be made using computer. Student name, father name, date and year can be typed and a new printed testimonial can be provided to the student. In this way the whole testimonial becomes a printed one. Printed testimonial does not have any problem. Computer in the Industries: Standard of production can be maintained by the computer. Computerized machine produces goods exactly to the specification. Computer also takes care of other machines. Computer can identify if there is any problem in any part of the machine. Another advantage of computer is that it can work 24 hour ceaselessly. Advantages of producing goods by computerized machine are: It needs comparatively less workers and maintain proper standard, less wastage of raw materials and there is almost no possibility of any accident. As a result, total production cost decreases. Standard of the product & its demand increases, which increases the benefit. Making industries computerized require buying special materials, set them and salary of specialized manpower which may require a lot of investment at the primary stage. But this expenditure decreases gradually as these machines run for a long period. At one stage industrial expenditure becomes comparatively lower than the traditional one. In a word, we can say that we are living in the age of computer. Besides the above sectors, computer is also used in agriculture, sports, entertainment etc. Multimedia: The most important sector of computer technology in the world is now multimedia. Most people don't have a clear concept of multimedia because it is a current use of computer. Many people think that computer containing CD drive; standard card etc is called multimedia. Multimedia does not mean some parts of a computer. It is such an idea that can make man's thought coordinated and interactive. IBM PC in the 80s had text-based system. As computer appeared as a calculator machine, its first target was to display 10 numbers, then 26 letter & then other symbols. Gradually the demand of the users increased. Where a user gets text in the PC he demands variation of fonts. Not only that, users begun to show interest in graphics also. Now there is PC with audio-video facilities. Operating system \"Liza\" gives the opportunity of image with graphics or non-text in the operating system level. These facilities were widened when Macintosh or MAC OS came. Actually fonts displayed in Liza and Macintosh are also graphics. This idea from MAC OS has been applied in the modem PC with Windows Operating System.

It is to mention that graphics was not over-looked when PC started its journey in 70s. Graphics, audio-video were kept in mind especially for home and school computer. But a programmer had to use programming language to use graphics in that time. Home PC or school PC had graphics and multimedia before Macintosh computer came. During this time some educational sectors used multimedia by adding audio-video with text and graphics. But multimedia has wider range in this new century. The word \"multimedia\" means \"more than one medium\". Multimedia is a combination of medium or media that is used to express ideas of man. In a word, multimedia is a combination of text, graphics & sound. We should keep it in mind that multimedia was introduced from very beginning of cinema, television and video. Multimedia is a different idea in computer. Besides all other facilities, there is another extra advantage while using multimedia in computer. It is called interactivity. Interactivity is not possible for TV or Cinema as programming is not available for them. Programming makes a huge difference with a computer and other technologies. So, multimedia in computer means using the capability of programming. Interactivity is the result of this programming. Introduction of Different Media in Multimedia: It is mentioned earlier that multimedia has mainly 3 medium. They are 1. Text, 2. Graphics and 3. Sound. 1. Text: Text means written form of language of man. These texts are displayed with some image in a computer, but the difference with other media is that texts are displayed as symbols in computer. They are not displayed in a form of graphics or sound. According to traditional concept text is a still media. Texts multimedia can be both moving and three dimensional. This media can be created by hand or machine. Text created by hand is taken as image by the computer. 2. Graphics: Drawing, photograph, sculpture, sketches etc are used as graphics. Graphics can be still and moving. Moving graphics is called animation. Image can be two dimensional or three dimensional like the texts. Except that image taken by photographic machine or camera is also graphics. Moving photography is called cinema or video. 3. 4. Sound: Sound is an important media for man. Sound has been used before written language. Multimedia is using all the sounds surrounding us whether it is man's language, songs, birds' charming or sound from the environment. Generally we identify sound as natural and mechanical. Sound can be mono and stereo. Single wave of sound is mono and several waves of sounds are called stereo sound.

Classification of Multimedia: Primarily, multimedia can be classified in to two types. They are: Linear and Non-linear. Cinema, video, television etc are Linear Multimedia. On the other hand, computer based multimedia is Non-linier Multimedia. Actually, Linier multimedia keeps going alternately with the time. On the other hand, Non-linier multimedia can be interactive and can be changed instantly. Classification of multimedia can be displayed with such diagram: It may be mention, that the Linier multimedia will be gone soon. On the other hand, hyper multimedia is based on interne. Hyper link is source of this multimedia. Hyper multimedia is interactive though the time based multimedia is not interactive. Interactivity: Using various medium is not called multimedia. Actually in a computer multimedia means interactivity. It may also be called multimedia programming. Once computer programming meant only language or data based programming. Now programming can be done with various applications. There are various multimedia authoring tools. Such as (authorware, apple media tool kit), internet development tools (such as page mail, front page), software development tools (such as Microsoft SDK, mackintosh programmers workshop), games development tools (apple sprite development tools), multimedia development tools (such as director, hyper studio, hyper card, super card, author ware) etc. Recently the idea of object oriented programming is expanding. Many programming have been done by scripting language and Macro. Even application program can be made by scripting language. Such as Macro and programming of Excel, hyper talk the scripting language of hyper card, Lingo the scripting language of director. As a result computer programming is not limited only within language. So, professionally when we talk about computer programming it will include both the person who knows & the person who knows directors lingo. A Multimedia programmer who works with text, graphics, audio, animation etc. is the creator of that multimedia. Though now those are called multimedia programmer who use media to make interactive program. Actually, there is a huge difference between making a topic and adding interactivity in it. Director can be called programming software. It will help to make interactive software by adding media created in the Premier or Photoshop. There is another thing about interactivity. If we add a style in the Microsoft word or if we add an effect or animation in a video file; it is not interactivity. Demand of the people who knows working and programming with multimedia is increasing & it will increase more in the future.

Assembling multimedia with PC: In the past different types of parts were added to make a multimedia P C. Sound card and CD drives were added with a common PC to make a multimedia PC. Often 3D accelerator card was also added with multimedia PC. It may contain extra video RAM or memory to a PC. TV card and modem may also be added with it. There may be speaker, microphone. DVD drive and video capture card also added in a multimedia PC instead of CD drive. In modem PC these equipments have already been added. So, a modem PC means a multimedia PC. It is to mention that a common PC has enough to do with multimedia, but more powerful PC can be used to create a multimedia presentation. Different standard of capture card, fire ware/ USB card, RAM, VGA card Hi-speed hard disk are required for video editing. Hi-speed microprocessor, ram & v-ram is required for animation. Professions on multimedia and its application: The recent working sectors for multimedia in Brain net are based on different media. Brain net has large industries in audio sectors. Digital system is available in these audio studios. Video sectors had started earlier. These sectors are getting bigger with the help of some private TV channels. Like other countries the Home Video has extended in our country. Yet they are not able to present any professional or mid-level presentation. This sector can be a large part of the video sector. Beside this, making industrial and training video has vast prospect. One can easily get a job in advertising, home video industry, software farm, academy, web page design farm etc by taking a professional training on video. Multimedia is becoming a large sector in 21\" century. Though multimedia had small sector once; it is now seen all around our lives. There are some large sectors where we can use multimedia. Such as: 1. Business: Multimedia can be used in audit report, simulation, statistics, modeling, marketing simulation, investment analysis, digital brochure, e-commerce etc. Multimedia can be used in marketing and promoting goods on TV, multimedia based advertisement for internet, video-based advertisement and promotion and selling advertisement based on multimedia. 2. Entertainment: Multimedia has changed the way of entertainment. Multimedia is used in TV, video and cinema. Multimedia can be used in making cinema, adding special effect, making video, animation, TV program, making interactive TV program, computer games etc. 3. Science & Research: Multimedia can be widely used in science and research sectors. It is used in medical science, genetic research, chemistry, modeling, mathematical research, physics, space research etc. 4. Digital Publishing: Publishing means paper based presentation. But in near future publishing will be digital. 5. Real-estate: Real-estate business is spreading very fast. Multimedia can be used in this sector. Model of a flat, house and building can be demonstrated by multimedia. 6. Law and Administration Management: Multimedia can be used in law and administrative management. Multimedia can be used to draw pictures of criminals, to identify crime area, to create database etc. 7. Education: Education sector is a vast area where multimedia can be used. Software based interactive education can change our experience of learning. May be one day all books will be written

and used in digital multimedia. Multimedia can also be used to make educative research, internet and intranet. Summary: Today we cannot think of our lives without computer. In the past, computer was used for various types of works. Computer is an essential media for storing information. Computer is inevitable in the industries and management. Use of computer is increasing in engineering, medical, banking, business, communication, research, publication and press. Computer can be used for various works in the education sector. Exercise Multiple choice questions 1. Rahim is a student of a secondary school situated in a district headquarter (sadar). He wants to take the help of computer in his learning for achieving good results in the examination. In this respect he will be benefited i. by using CD based multimedia software ii. by receiving the necessary subject-matters getting from the download of internet. iii. by communicating with his friends on the studied chapters through e-mail. Which one of the following is correct? a. i and ii b. i and iii c. ii and iii d. i, ii and iii [Read the following paragraph and answer questions 2 and 3] Kabir is using internet attaching VGA card and floppy drive. Recently he has decided to convert his PC as a multimedia computer. 2. What are the hardware to be added with Kabir's computer? a. Sound card, Speaker and Modem b. Sound Card, Speaker and DVD drive c. Sound Card, Hyper card and DVD drive d. Sound Card, Hyper card and Modem 3. After getting attachment, Kabir can use the computer for- i. education, music and movie. ii. research, communication and watching TV. iii. e-mail, web browsing and paper reading. Which one of the following is correct? a. i and ii b. ii and iii c. i and iii d. i, ii and iii 4. What is the modern idea of computer related to trade and commerce? a. Interactivity b. Electronic Commerce c. Electronic Bank d. Electronic Sharing Long questions Amina reads in class nine. She went to visit her friend's house and saw that her friend was learning English language with the help of computer. Learning English by computer using sound and picture amazed her. She returned home and requested her father to buy a computer enriched with multimedia. a. What is multimedia? b. Describe one of the main characteristics of multimedia. c. Describe how the use of computer makes Amina's learning enjoyable.

d. Analyse that the use of computer will make Amina's learning more fruitful.