INFORMATION TECHNOLOGY, Lecture notes of Computer Science

Download INFORMATION TECHNOLOGY and more Lecture notes Computer Science in PDF only on Docsity!

Contents

• FUNDAMENTALS OF INFORMATION TECHNOLOGY
• INTRODUCTION.............................................................................................................................................
  • What is Data?............................................................................................................................................
  • What is Information?
  • Characteristics of Information
• Types of data.................................................................................................................................................
• What is a computer?.....................................................................................................................................
  • What are the advantages of using a computer?.......................................................................................
  • Characteristics of Computer
• CLASSIFICATION OF COMPUTERS
  • Classification by Process
  • Classification by Purpose
  • Classification by Processor Power
  • Classification by Size
• Computer System Evolution/ Generations
  • First Generation: Vacuum Tube (1940-1956)
  • Second Generation: Transistors, (1956-1963)
  • Third Generation: Integrated Circuits, (1964-71)
  • Fourth Generation; Microprocessors (1980-to present)
  • Fifth Generation; Artificial Intelligence (Present and beyond)
• Data Processing Cycle
• Data Processing...........................................................................................................................................
  • Methods of Data Processing
    • Single User Programming....................................................................................................................
    • Multiple Programming........................................................................................................................
    • Real-time Processing...........................................................................................................................
    • On-line Processing
    • Time-sharing Processing
    • Distributed Processing
    • Disadvantages
• Uses of Data in Business Organizations:
• Modes of Data Processing
  • 1. Manual Data Processing..................................................................................................................
  • 2. Mechanical Method
  • 3. Electronic Method...........................................................................................................................
• Qualities of good Information.....................................................................................................................
• Computer System........................................................................................................................................
• Computer hardware....................................................................................................................................
  • Computer - Input Devices
    • Keyboard
    • Mouse
    • Advantages
    • Joystick
    • Light Pen..............................................................................................................................................
    • Scanner
    • Microphone.........................................................................................................................................
    • Magnetic Ink Card Reader (MICR).......................................................................................................
    • Bar Code Readers................................................................................................................................
  • Computer Output Devices
    • Monitors..............................................................................................................................................
    • Cathode-Ray Tube (CRT) Monitor
    • Flat-Panel Display Monitor
    • Printers................................................................................................................................................
    • Impact Printers
    • Non-impact Printers
  • System Unit
  • Power Supply
  • The Motherboard....................................................................................................................................
  • Central Processing Unit (CPU).................................................................................................................
  • 1. Memory Unit
  • 2. Control Unit
  • 3. ALU (Arithmetic Logic Unit)
    • Arithmetic Section
    • Logic Section
  • Computer Memory
    • Cache Memory....................................................................................................................................
    • Primary Memory (Main Memory).......................................................................................................
    • Characteristics of Main Memory
  • Types of ROMs
  • Advantages of ROM
    • Secondary Memory.............................................................................................................................
    • Characteristics of Secondary Memory
• Memory Unit of Measurement...................................................................................................................
  • Computer - Ports.....................................................................................................................................
  • Types of ports
  • Serial Port
  •  Used for external modems and older computer mouse
  • Parallel Port
  • PS/2 Port
  • Universal Serial Bus (or USB) Port
  • VGA Port
  • Power Connector
  • Ethernet Port
  • Digital Video Interface, DVI port
• Computer software.....................................................................................................................................
  • Types of computer software...................................................................................................................
  • System software
  • Examples of system software
  • Operating system:...................................................................................................................................
  • USER INTERFACES
    • 1. Graphical user Interfaces (GUI)...................................................................................................
    • 2. Command Line Interface.............................................................................................................
  • Objectives of Operating System..............................................................................................................
  • Functions of Operating System
• TYPES OF OPERATING SYSTEMS..................................................................................................................
  • Real-Time operating Systems:
  • Single-User/Single-Tasking Operating Systems:
  • Multi-User/Multitasking Operating Systems:
  • Utility Software
  • Application Software...............................................................................................................................
  • Examples of Application software are the following −
• Features of application software are as follows.........................................................................................
• OFF SHELF PACKAGES
  • Advantages of off shelf packages............................................................................................................
  • Disadvantages of off shelf packages
• CUSTOMIZED/TAILOR-MADE PROGRAMS
  • Merits of customized programs..............................................................................................................
  • Demerits of customized programs..........................................................................................................
• Factors to bear in mind when choosing a package.....................................................................................
• Programming Languages.............................................................................................................................
• Language processors...................................................................................................................................
• Generations/Classification of computer languages....................................................................................
• Low Level Languages...................................................................................................................................
  • 1. 1 st Generation languages (1GL) - Machine languages.....................................................................
  • 2. 2 nd Generation languages (2GL)......................................................................................................
• High Level Languages..................................................................................................................................
  • 3. 3 rd Generation Languages (3GL) / Procedural languages................................................................
  • 4. 4 th Generation Languages (4GL)/Problem oriented languages
  • 5. 5 th Generation Languages (5GL)......................................................................................................
• Computer Viruses
  • Types of Virus..........................................................................................................................................
• Ways in which Virus Spread........................................................................................................................
• Impact of virus on your computer system..................................................................................................
• Ways of protecting a computer against Viruses
• Most Effective Antivirus..............................................................................................................................
• Booting........................................................................................................................................................
• Types of Booting

Types of data

The main types of data that can be input into a computer and processed are:

 Numeric

 Text

 Images

 Audio

 Video

What is a computer?

A computer is an advanced electronic machine that takes raw data as input, performs arithmetic

and logical operations at a fast speed, and provides results as output.

Typically, a computer performs the following functions:

 It accepts information from the user through various input devices.

 It performs basic arithmetic and logic operations on the desired data.

 It provides the desired results.

What are the advantages of using a computer?

 Increase your productivity. ...

 Connects you to the Internet. ...

 Can store vast amounts of information and reduce waste. ...

 Helps sort, organize, and search through information. ...

 Get a better understanding of data. ...

 Keeps you connected. ...

 Help you learn and keep you informed. ...

 Can make you money.

Disadvantages of Computer

1) Unemployment

As we discussed above that computers can perform many tasks automatically, this reduces the

need for people and increases unemployment in the society.

2) Health Issues

Improper and prolonged use of computers can negatively affect your health. For example, if you

are constantly working on the computer, your eyes will become dry, which can result in eye

strain, headache, etc.

4) Virus and Hacking Attacks

Viruses are computer programs developed to damage or steal your personal or sensitive data. In

addition, hacking is the process of gaining unauthorized access to computers for certain illegal

purposes. Viruses are usually transferred via email, internet download, or removable devices.

6) Spread of False or Inappropriate Content

Not every information on the Internet is true. There are many resources for sharing incorrect

information or providing inappropriate content to users.

Characteristics of Computer

Speed

Computers have an incredible speed that helps a human to complete his tasks in some time. It

can handle trillions of instructions per second which is really incredible.

Accuracy

This means that computers allow users to handle complex numerical calculations or tasks not

only with speed but also with accuracy.

Multitasking

Multitasking is one of the major benefits of computers. A person can do many different tasks at

the same time while working on a computer.

Storage

Computers can store and access vast amounts of data or information. The storage capacity of

computers has increased these days compared to earlier days.

CLASSIFICATION OF COMPUTERS

There are the different categories of computers. Computers can be generally classified into four

classes. Basic Computer Classification includes.

1. Classification by process

2. Classification by purpose

3. Classification by processor power

4. Classification by size

Classification by Process

Under this classification computers are classified according to how the data processed is

presented. This classification is further divided in to 3 sub classes which include;

 Digital computers

 Analogue computers

 Hybrid computers

Digital Computers

These are computers designed to process data in numerical or discrete form. The numbers

operated on by a digital computer are expressed in the binary system; binary digits, or bits, are 0

and 1. Applications of digital computers are used for reservations systems, data-processing,

word-processing applications, desktop publishing, electronic games and many other purposes

Analogue Computers

These are computers that process data that’s in a continuous form or measurable quantities/units.

For example pressure, electrical voltage. The output from these computers is often in form of

smooth graphs from which information can be read. Examples of analogue computers include

those used in thermometers, voltmeters and speedometers etc.

Hybrid Computers

Hybrid computers are those that have the combined features of both the digital computers and

the analogue computers. This means they can present data in numerical form as well as

continuous form. Examples include the common microcomputers.

Classification by Purpose

The hybrid computers can be classified according to the work they are intended to perform this

gives us 2 categories;

 Special purpose

 General purpose

Special Purpose Computers

These are computers designed to handle only a particular task. Their form of operation is

restricted in nature, e.g. computers that are used in digital watches, Lifts in tall buildings, Petrol

pumps, Missiles. These computers cannot perform any other task other than what they have been

designed for. For example computers embedded in missiles cannot perform any other duty other

than weapon guidance.

General Purpose Computers

Unlike special purpose computers general-purpose computers can be adopted to perform any task

or solve specific problems by means of specially written programs. For example a typical

computer of this type can perform calculations, keep data, time, word process a document, Store

data bases etc. Previously, computers used to be classified according to the purpose they were

used. E.g. word processing computer

Classification by Processor Power

Computers can also be classified according to the power of the processor (CPU). Processor

power is the ability of the computer to process data at very high speeds.

Examples of processor types are

 Pentium I

 Pentium II

 Pentium III

 Pentium IV

 Intel Celeron

 Core

Computer System Evolution/ Generations

Computer system evolution looks at the different classification of computers as they evolved.

Each generation of computer is characterized by a major technological development that

fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper,

and more powerful and more efficient and reliable devices. The evolution is from the 1st

generation to the 5th generation.

First Generation: Vacuum Tube (1940-1956)

 The first computer was manufactured

 The 1st generation of computers relied on vacuum tubes to store and process information.

 These computers were colossal in size, consumed a great deal of power, were short-lived

 They generated a great deal of heat.

 First generation computers had extremely limited memory and processing capability

 They were used for very ltd scientific and engineering work.

 They were very expensive

 They were not widely used

Second Generation: Transistors, (1956-1963)

 Here, transistors replaced vacuum tubes as the devices for storing and processing

information.

 They were smaller and more reliable than vacuum tubes

 They generated less heat, and consumed less power.

 2nd generation computers had enough memory and processing power

 They were used more widely for scientific work and for business tasks such as automating

Third Generation: Integrated Circuits, (1964-71)

 The development of the integrated circuit was the hallmark of the third generation of

computers.

 Users interacted with third generation computers through keyboards and monitors.

 This Computers for the first time became accessible to a mass audience because they were

cheaper than their predecessors.

 The computer eventually reduced in size, became more portable and occupied less space

 During this generation many high level programming languages were introduced, including

BASIC, FORTRAN (FORmular TRANslator) and COBOL (Common Business Oriented

Language).

 The memory and processing speed of the computers increased to megabyte

Fourth Generation; Microprocessors (1980-to present)

 The microprocessor brought the fourth generation of computers, as thousands of integrated

circuits were built onto a single silicon chip.

 The first generation filled an entire room can now fit in the palm of the hand.

 Computers became smaller, faster, more reliable and lower in price.

 As these small computers became more powerful, they could be linked together to form

networks, which eventually led to the development of the Internet.

Fifth Generation; Artificial Intelligence (Present and beyond)

 Fifth generation computing devices, based on artificial intelligence, are still in

development.

 They have some applications, such as voice recognition.

 There is widespread use of computer networks and the increasing use of single-user

workstations.

 The goal of fifth-generation computing is to develop devices that respond to natural

language input and are capable of learning.

Methods of Data Processing Single User Programming

It is usually done by a single person for his personal use. This technique is suitable even for small

offices.

Multiple Programming

This technique provides facility to store and execute more than one program in the Central

Processing Unit (CPU) simultaneously. Further, the multiple programming technique increases

the overall working efficiency of the respective computer.

Real-time Processing

This technique facilitates the user to have direct contact with the computer system. This technique

eases data processing. This technique is also known as the direct mode or the interactive mode

technique and is developed exclusively to perform one task. It is a sort of online processing, which

always remains under execution.

Advantages

 Information is more up to date therefore providing better information for management.

 Information is readily available for instant decision making

 Provides better services to users or customers in terms of quick service.

 It’s a fast and reliable mode of data processing

Disadvantages

 Costly, as the system becomes more complex to run and to develop because in certain

circumstances they are run on a 24hr basis.

 Not easy to use, user has to be trained

On-line Processing

This technique facilitates the entry and execution of data directly; so, it does not store or

accumulate first and then process. The technique is developed in such a way that reduces the data

entry errors, as it validates data at various points and also ensures that only corrected data is

entered. This technique is widely used for online applications.

Advantages

 The files are maintained up-to-date.

 Information is readily available for current decisions. This information is fed back to the

work stations where they are needed.

Disadvantages

 These systems are complex to develop

 They are costly in terms of hardware, software, storage media, operating system

communication facilities etc.

Time-sharing Processing

This is another form of online data processing that facilitates several users to share the resources

of an online computer system. This technique is adopted when results are needed swiftly.

Advantages

 It delivers better services to users as the information output is normally faster.

 The problem of the processor idle time is solved because the processor does not need to

wait for the slower communication peripherals

 Files are held on-line hence inquiries are possible

 Helpful to small companies which cannot afford purchasing the computer and its related

facilities

Disadvantages

 The users have got no control over the central computer

 The response time is also slow whenever there are many tasks

Disadvantages

 Time lag between origination of the transactions and the information availability.

 Late information is not suitable in situations where instant decisions are required.

 Management information is often incomplete due to missing data.

 Often master files are kept off line therefore access may not always be available.

 Undesired commands may be executed without the users knowledge

 Batch files created are not easy for a novice user to edit, so changing settings requires the

user to repeat the batch each time.

 The master file is not always kept up-to-date.

Uses of Data in Business Organizations:

 Data can be used for decision making

 Used for planning and operating functions of the organization

 Provides insight about the industry, market and other elements of the environment in which

the firm competes.

 Used for controlling purposes

 Managing performance

 Trends analysis

Modes of Data Processing

 Manual data processing

 Mechanical data processing

 Electronic data processing

1. Manual Data Processing

This method is done by individuals using simple tools such as pens, markers, rulers, erasers and

people’s mental capacity for the data to be processed.

Advantages

 It’s cheap

 Flexible

 Easy to adopt

 Simple to use

Disadvantages

 Only low volumes suitable for each worker

 No automation of calculation or totaling potentially leading to more errors

 More personnel required for most tasks

 It takes longer time than an electronic document

 It’s tiresome as it involves a lot of mental thinking

 More prone to errors

 It is slow for a large volume of data to be processed as it cannot compute a thousand

instructions in a second as compared to a computer.

2. Mechanical Method

This method involves the use of machines like the traditional typewriter, duplicating machines

etc. it is semi manual and semi electronic.

Advantages

 It is faster than the manual method

 Quality of output is much better than the manual method

 More accurate compared to manual

Disadvantages

 The method has the weakness of machine breakdowns that may disrupt the process

 It is more expensive than the manual method

 It’s slower than electronic data processing

 Not suitable for processing large volumes of data