Types of Network
The following are the general types of networks used today.
· Local Area Network (LAN)
· Metropolitan Area Network (MAN)
· Wide Area Network (WAN)
A network connecting systems and devices inside a single building or buildings close to each other is called Local Area Network
(LAN) (Fig.6.1). Generally LANs do not use the telephone network. They are connected either by wire or wireless. Wired connection may be using twisted pairs, coaxial cables or Fiber Optic cables. In a wireless LAN, connections may be using infrared or radio waves.
Wireless networks are useful when computers are portable. However, wireless network communicates slowly than a wired network.
The number of Computers in the network is between two to several hundreds. LAN is generally used to share hardware, software and data. A computer sharing software package and hard disk is called a file server or network server. A Network that spans a geographical area covering a Metropolitan city is called Metropolitan Area Network (MAN)
A WAN is typically two or more LANs connected together across a wide geographical area. The individual LANs separated by large distances may be connected by dedicated links, fiberoptic cables or satellite links.
Network Topology
The network topology is the structure or layout of the communication channels that connects the various computers on the network. Each computer in the network is called a node.
There are a number of factors that determine the topology suitable for a given situation. Some of the important consideration is the type of nodes, the expected performance, type of wiring (physical link) used and the cost.
Networ can be laid out in different ways. The five common topologies are star, ring, bus, hybrid and FDDI.
Star Network : In a star network all computers and other communication devices are connected to a central hub. Such as a file server or host computer usually by a Unshielded Twisted Pair (UTP) cables.
Ring Network: In a ring network computers and other communication devices are connected in a continuous loop Electronic data are passed around the ring in one direction, with each node serving as a repeater until it reaches the right destination. There is no central host computer or server.
Bus Network: In a bus network all communication devices are connected to a common cable called bus There is no central computer or server. The data transmission is bidirectional.
Hybrid Network: A hybrid network is a combination of the above three networks suited to the need.
FDDI Network: A FDDI network (pronounced as fiddy short for Fiber Distributed Data Interface) is a high-speed network using fiber optic cable. It is used for high tech purposes such as electronic images, high-resolution graphics and digital video. The main disadvantage is its high cost.
Basic Elements in Networking
All networks require the following three elements
1. Network services
Network services are provided by numerous combinations of computer hardware and software. Depending upon the task, network services require data, input/output resources and processing power to accomplish their goal.
2. Transmission media
Transmission media is the pathway for contacting each computer with other. Transmission media include cables and wireless Technologies that allows networked devices to contact each other.
This provides a message delivery path.
3. Protocols
A protocol can be one rule or a set of rules and standards that allow different devices to hold conversations.
Modem
Computers at different parts of the world are connected by telephone lines. The telephone converts the voice at one end into an electric signal that can flow through a telephone cable. The telephone at the receiving end converts this electric signal into voice. Hence the receiver could hear the voice. The process of converting sound or data into a signal that can flow through the telephone wire is called modulation.
The reverse process is called demodulation. The telephone instrument contains the necessary circuit to perform these activities.
The device that accomplishes modulation – demodulation process is called a modem. It is known that the electrical and sound signals are analog - which continuously vary with time.
Data Transmission Rate
The speed at which data travel over a communication channel is called the communication rate. The rate at which the data are transferred is expressed in terms of bits per second (bps)
Transmission Mode
Internet
Several networks, small and big all over the world, are connected together to form a Global network called the Internet.
Today’s Internet is a network of about 50 million or more computers spread across 200 countries. Anyone connected to the Internet can reach, communicate and access information from any other computer connected to it.
Communication Protocol
Internet is a packet-switching network. Here is how packetswitching works: A sending computer breaks an electronic message into packets. The various packets are sent through a communication network-often by different routes, at different speeds and sandwiched in between packets from other messages. Once the packets arrive at the destination, the receiving computer reassembles the packets in proper sequence. The packet switching is suitable for data transmission. The software that is responsible for making the Internet function efficiently is TCP/IP. TCP/IP is made up of two components.
TCP stands for transmission control protocol and IP stands for Internet Protocol.
TCP breaks up the data to be sent into little packets. It guarantees that any data sent to the destination computer reaches intact. It makes the process appear as if one computer is directly
connected to the other providing what appears to be a dedicated connection.
IP is a set of conventions
Who Governs The Internet ?
The Internet as a whole does not have a single controller. But the Internet society, which is a voluntary membership organization, takes the responsibility to promote global information exchange through the Internet technology. Internet Corporation for Assigned Names and
185 Numbers (ICANN) administers the domain name registration. It helps to avoid a name which is already registered.
ICANN is an acronym for the Internet Corporation for Assigned Names and Numbers, a global multi-stakeholder organization that was created an 1998 and empowered through actions by the U.S. government and its Department Of Commerce ICANN is the main Internet governance institution. Its primary responsibility is to manage the Internet's core infrastructure, which consists of IP addresses, domain names, and root servers. It coordinates the Internet's DNS, IP addresses and autonomous system numbers, which involves a continued management of these evolving systems and the protocols that underly them.
World Wide Web
Web is a multimedia portion of the Internet. It consists of an interconnection system of sites or servers all over the world that can store information in the multimedia form. The Multimedia sites include text, animated graph, voice and images.
The World Wide Web is the most graphically inviting and easily navigable section of the Internet. It contains several millions of pages of information. Each page is called a web page. A group of related web pages linked together forms a web site. The first page of the website is called a Home page. The Home page usually contains information about the site and links to other pages on that site.
E-mail - The World Wide Web is getting a lot of attention due to its main attraction of Electronic mail. Electronic mail is usually used to exchange messages and data files.
FTP: File Transfer Protocol, abbreviated as FTP is used for the net user for transferring files around the world. The transfer includes software, games, photos, maps, music and such other relevant materials.
Telnet: Telnet is a protocol that allows the user to connect to a remote computer. This feature is used to communicate a microcomputer with mainframe.
Getting connected to Internet
To use an Internet in the simplest way, we need
· A Computer
· A Telephone lineA Modem
· Internet Service Provided or ISP
The ISPs are the companies which allow the user to use the Internet for a price. One has to register with the ISP for an Internet account. ISP provides the following:
Exercises
I. Fill in the blanks
1) _________ is considered to be the father of today’s computer.
2) __________ invented the Slide Rule.
3) The first generation of computers used _____________for circuitry and ________ for memory.
4) Integrated circuits were used in ____________ generation of computers.
5) ___________ refers to the physical items associated with a computer system.
6) The hardware devices attached to the computer are called
__________.
7) __________ refers to programs that make the computer to do some thing.
8) Software can be classified into ___________ and __________software.
9) An ____________is an integrated set of specialized programs that is used to manage the overall operations of a computer.
10) The ________ translates the whole source program into an object program.
11) A ________ allows users to quickly and efficiently store, organize, retrieve, communicate and manage large amounts of information.
12) ________ computers are useful in solving differential equation and integration.
13) The digital computers are classified into __________,________, __________ and __________.
14) ________ is the planned step-by-step instruction required to turn data into information.
15) _______ is the raw material that is given to a computer for processing.
16) A ________ computer accepts handwritten input on a screen.
17) Raw data is processed by the computer into _________.
18) PC refers to ___________.
19) _________ software allows to create, edit, format, store and print text and graphics.
20) The word computing means ___________.
21) A computer system is the interpretation of physical entities called _________ and non physical entities called_________
22) The computer uses_________ devices to accept data and program.
23) CPU stands for _________
24) ALU stands for _________
25) RAM stands for _________
26) ROM stands for _________
27) The stored program concept is conceived by _________
28) Main memory is also known as _________ memory.
29) The performance of the memory system is defined by _________ time and _________ time.
30)_________ supplements the main memory.
31) _________ is popular input device for GUI application.
32)_________ is a input device mainly used to capture images.
33) Monitor is a commonly used output unit, sometimes called as_________
34) The smallest dot that can be displayed on the monitor is called a_________
35) Printers can be classified into _________ and _________ printers.
36) The ________,________ can access the hardware directly.
37) Operating System is the ________ between the user and computer hardware.
38) Operating System comes under ________ software.
39) The ________ ,________ is only means by which a user interacts with the computer.
40) ____________is a typically two or more LANs connected together across a wide geographical area.
41) ____________network computers and other communication devices are connected in a continuous loop.
42) In a high speed network ____________cables are used.
43) The device that coordinates the data transfer is called____________, ____________
44) The OSI provided a network architecture with ____________layers.
45) All computers understand and work only in
____________form.
46) ____________signals continuously vary with time.
47) Communication in ____________mode is faster.
48) ____________protocol is used to assist communication between a microcomputer and a mainframe.
49) ____________tools, that allow the Internet user to find specific document through keywords or menu choices.
II. State whether the following are true or false
1) The concept of using ‘electronic brains’ gave birth to computers.
2) The most powerful personal computers are known as super computers.
3) Blaise Pascal developed the tabulating machine using punched cards.
4) Herman Hollerith designed the difference engine.
5) Compilers translate higher level language into machine language.
6) Word processing is a type of task-oriented software.
7) Fifth generation computing devices is based on artificial intelligence.
8) The input devices accept data and send them to the processor.
9) A hybrid computing system is a combination of desirable features of analog and digital computers.
10) The personal computers are sometime called the home computers.
11) The operating system is a software.
12) Keyboard is an output device.
13) Touch sensitive screen is an input device.
14) Main memory is a non-volatile memory.
15) ALU performs arithmetic and logical operations.
16) Registers are a part of secondary storage.
17) Bar code reader is an output device.
18) Light pen is an input device.
19) Inkjet printers are impact printers.
20) CD – ROM stands for Compact Disk – Read Only Memory.
21. Logic gate has two or more outputs.
22. Logic circuits have two or more outputs.
23. AND is an universal gate.
24. XOR is a fundamental gate.
25. NAND gate can be used to realize OR gate.
26. NOR gate can be used to realize OR gate.
27. Full adder can be realized using two half adders and an OR gate.
28. XOR gate is used to build half adder.
29. XOR gate circuit is an OR gate following by an inventor
30.Flip-flop is used as a storage.
III. Answer the following.
1) What is a computer?
2) What is the name of the machine developed by Charles Babbage?
3) What are peripheral devices?
4) Define ‘Data’.
5) Define ‘Information’.
6) What do you mean by an algorithm?
7) What is a word processor software?
8) What is an operating System?
9) What is an analog computing system?
10) What is a lap-top computer?
11) How are the human being and the computers are related?
12) What are the components of the digital computer?
13) What are the functional units of a computer system?
14) Write the essentials of the stored program concept.
15) Write the main functions of the central processing unit.
16) What are the different types of main memory?
17) Define memory read and memory write operations.
18) What do you mean by memory access time?
19) What is the advantage of EEPROM over EPROM?
20) When do we use ROM?
21) What is an input device?
22) List few commonly used input devices.
23) What is an output device?
24) List few commonly used output devices.
25) What is a storage device?
26) List few commonly used storage devices.
27) What is the role of ALU?
28) What is a control unit?
29)What are registers?
30)What is a bus?
31. What are the reasons for networking?
32. Mention a few areas, where computer networks are employed
33. What are the elements that a computer communication should ensure?
34. List the general types of networks used today.
35. Explain WAN.
36. How data is transmitted in different forms?
37. What are the transmission modes?
38. What is TCP?
39. What is the role of ICANN?
40.Explain URL.
1. UNIVAC is
A) Universal Automatic Computer
B) Universal Array Computer
C) Unique Automatic Computer
D) Unvalued Automatic Computer
2. The basic operations performed by a computer are
A) Arithmetic operation
B) Logical operation
C) Storage and relative
D) All the above
3. The two major types of computer chips are
A) External memory chip
B) Primary memory chip
C) Microprocessor chip
D) Both b and c
4. Microprocessors as switching devices are for which generation computers
A) First Generation
B) Second Generation
C) Third Generation
D) Fourth Generation
5. What is the main difference between a mainframe and a super computer?
A) Super computer is much larger than mainframe computers
B) Super computers are much smaller than mainframe computers
C) Supercomputers are focused to execute few programs as fast as possible while mainframe uses its power to execute as many programs concurrently
D) Supercomputers are focused to execute as many programs as possible while mainframe uses its power to execute few programs as fast as possible.
6. ASCII and EBCDIC are the popular character coding systems. What does EBCDIC stand for?
A) Extended Binary Coded Decimal Interchange Code
B) Extended Bit Code Decimal Interchange Code
C) Extended Bit Case Decimal Interchange Code
D) Extended Binary Case Decimal Interchange Code
7. The brain of any computer system is
A) ALU
B) Memory
C) CPU
D) Control unit
8. Storage capacity of magnetic disk depends on
A) tracks per inch of surface
B) bits per inch of tracks
C) disk pack in disk surface
D) All of above
9. The two kinds of main memory are:
A) Primary and secondary
B) Random and sequential
C) ROM and RAM
D) All of above
10. A storage area used to store data to a compensate for the difference in speed at which the different units can handle data is
A) Memory
B) Buffer
C) Accumulator
D) Address
11. Computer is free from tiresome and boardroom. We call it
A) Accuracy
B) Reliability
C) Diligence
D) Versatility
12. Integrated Circuits (ICs) are related to which generation of computers?
A) First generation
B) Second generation
C) Third generation
D) Fourth generation
13. CD-ROM is a
A) Semiconductor memory
B) Memory register
C) Magnetic memory
D) None of above
14. A hybrid computer
A) Resembles digital computer
B) Resembles analogue computer
C) Resembles both a digital and analogue computer
D) None of the above
15. Which type of computers uses the 8-bit code called EBCDIC?
A) Minicomputers
B) Microcomputers
C) Mainframe computers
D) Super computer
16. The ALU of a computer responds to the commands coming from
A) Primary memory
B) Control section
C) External memory
D) Cache memory
17. Chief component of first generation computer was
A) Transistors
B) Vacuum Tubes and Valves
C) Integrated Circuits
D) None of above
18. To produce high quality graphics (hardcopy) in color, you would want to use a/n
A) RGB monitor
B) Plotter
C) Ink-jet printer
D) Laser printer
19. What are the stages in the compilation process?
A) Feasibility study, system design and testing
B) Implementation and documentation
C) Lexical Analysis, syntax analysis, and code generation
D) None of the above
20. Which of the following IC was used in third generation of computers?
A) SSI
B) MSI
C) LSI
D) Both a and b
21. The main electronic component used in first generation computers was
A) Transistors
B) Vacuum Tubes and Valves
C) Integrated Circuits
D) None of above
22. A dumb terminal has
A) an embedded microprocessor
B) extensive memory
C) independent processing capability
D) a keyboard and screen
23. One millisecond is
A) 1 second
B) 10th of a seconds
C) 1000th of a seconds
D) 10000th of a seconds
24. The output quality of a printer is measured by
A) Dot per sq. inch
B) Dot per inch
C) Dots printed per unit time
D) All of the above
25. Which of the following was a special purpose computer?
A) ABC
B) ENIAC
C) EDVAC
D) All of the above
26. What was the computer invented by Attanasoff and Clifford?
A) Mark I
B) ABC
C) Z3
D) None of above
27. Which of the following storage devices can store maximum amount of data?
A) Floppy Disk
B) Hard Disk
C) Compact Disk
D) Magneto Optic Disk
28. Which computer was considered the first electronic computer until 1973 when court invalidated the patent?
A) ENIAC
B) MARK I
C) Z3
D) ABC
29. A physical connection between the microprocessor memory and other parts of the microcomputer is known as
A) Path
B) Address bus
C) Route
D) All of the above
30. High density double sided floppy disks could store _____ of data
A) 1.40 MB
B) 1.44 GB
C) 1.40 GB
D) 1.44 MB
31. A high quality CAD system uses the following for printing drawing and graphs
A) Dot matrix printer
B) Digital plotter
C) Line printer
D) All of the above
32. Which of the following is not an input device?
A) OCR
B) Optical scanners
C) Voice recognition device
D) COM (Computer Output to Microfilm)
33. The accuracy of the floating-point numbers representable in two 16-bit words of a computer is approximately
A) 16 digits
B) 6 digits
C) 9 digits
D) All of above
34. In most of the IBM PCs, the CPU, the device drivers, memory, expansion slots and active components are mounted on a single board. What is the name of the board?
A) Motherboard
B) Daughterboard
C) Bredboard
D) Fatherboard
35. In most IBM PCs, the CPU, the device drives, memory expansion slots and active components are mounted on a single board. What is the name of this board?
A) Motherboard
B) Breadboard
C) Daughter board
D) Grandmother board
36. Magnetic disks are the most popular medium for
A) Direct access
B) Sequential access
C) Both of above
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