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Computer Fundamentals and Programming in C

Reema Thareja, Assistant Professor, Institute of Information Technology and Management

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CHAPTER 1

INTRODUCTION TO COMPUTERS

1^st gen-1940-56

2^nd gen 1956-63

3^rd-64-71

4^th—72-89

5^th-mordern day

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INTRODUCTION TO COMPUTER SOFTWARE

A computer is a machine that takes instructions and performs computations based on those instructions.

CHARACTERISTICS OF COMPUTERS

Speed
Accuracy
Automatic
Diligence
Memory
No I.Q.
Economical
Versatile

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GENERATION OF COMPUTERS

The word generation means the state of improvement in the product development process. Similarly, computer generation refers to the different advancements of new computer technology.

First Generation (1940-1956) Vacuum Tubes

The first generation computers used very large number of vacuum tubes for circuitry and magnetic drums for memory.

UNIVAC and ENIAC computers are prime examples of first-generation computing devices.

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Advantages: Fastest calculating device of their time

Disadvantages:

1. Dissipate a lot of heat

2. Consume a lot of electricity

3. Very bulky in size

4. These computers were frequently down due to hardware failures.

5. These computers needed constant maintenance because of low mean time between failures

6. Limited commercial use because these computers were difficult to program

7. Very expensive

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Second Generation (1956-1963) Transistors

The second generation computers were manufactured using transistors.
While first generation computers were programmed using machine language, second generation computers moved towards symbolic, or assembly languages, which allowed programmers to specify instructions in words.
At this time, high-level programming languages like COBOL, FORTRAN, ALGOL and SNOBOL were also being developed.
Second generation computers were first to store instructions in memory, which moved from a magnetic drum to magnetic core technology.
Second generation computers were first developed for the atomic energy industry.

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Advantages:

1. Consumed less electricity and thus dissipated less heat as compared to first generation computers

2. Faster, cheaper smaller and more reliable than first generation computers

3. Could be programmed using assembly language and high level languages

4. These computers had faster primary memory and a larger secondary memory

Disadvantages:

1. Second generation computers were manufactured using transistors that had to be assembled manually. This made commercial production of computers difficult and expensive.

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Third Generation (1964-1971) Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers.
These computers had few megabytes of main memory and magnetic disks which could store few tens of megabytes of data per disk drive.
High level programming languages like COBOL and FORTRAN were standardized by ANSI
Some more high level programming languages like PL/I PASCAL and BASIC were introduced at this time.
Third generation computers were the first to implement time sharing operating systems.
Input to these computers could now be provided using keyboards and mouse.

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Advantages:

Faster than second generation computers and could perform 1 million transactions per second.

2. Smaller, cheaper and more reliable than their predecessors

3. These computers had faster and larger primary memory and secondary storage

4. They were widely used for scientific as well as business applications

5. During this generation of computers, standardization of existing high level languages and invention of new high level languages was done

6. These computers had time sharing operating system which allowed interactive use of computer by one or more users simultaneously thereby improving the productivity of the users.

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Fourth Generation (1971-1989) Microprocessors

The microprocessor started the fourth generation of computers with thousands of integrated circuits built onto a single silicon chip.

Fourth Generation (1971-1989) Microprocessors

The microprocessor started the fourth generation of computers with thousands of integrated circuits built onto a single silicon chip.

Fourth Generation (1971-1989) Microprocessors

The microprocessor started the fourth generation of computers with thousands of integrated circuits built onto a single silicon chip.

Fourth Generation (1971-1989) Microprocessors

The microprocessor started the fourth generation of computers with thousands of integrated circuits built onto a single silicon chip.

Semi-conductor memories were used which were very fast, even the hard disks became cheaper, smaller in size and larger in capacity.
For input, floppy disks (in addition to magnetic tapes) were used to port data and programs from one computer to another.
During this period many new operating systems were developed like MS-DOS MS-Windows UNIX and Apple’s proprietary operating system.

Development of GUIs, the mouse and handheld devices.
In this period, several word processing packages, spreadsheet packages and graphics packages were introduced.

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Advantages:

1. Smaller, cheaper, faster and more reliable

2. Consumed less electricity and therefore dissipated less heat

3. They had faster and larger primary memory and secondary storage

4. They could be used as general purpose computers.

5. GUIs enabled people to learn to work with computers very easily. So the use of computers in both office and home became widespread.

6. Networks allowed sharing of resources thereby efficient utilization of computer hardware and software

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Fifth Generation (Present and Beyond) Artificial Intelligence

The fifth generation computers are completely based on a new concept of artificial intelligence.

Although such computers are still in development, there are certain applications like voice recognition which is widely being used today.

In the fifth generation of computers the aim is to develop devices that respond to natural language input and are capable of learning and self-organization.

The two most common are LISP and Prolog.

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CLASSIFICATION OF COMPUTERS

Computers can be broadly classified into four categories based on their speed, amount of data that they can hold and price.

CLASSIFICATION OF COMPUTERS

Computers can be broadly classified into four categories based on their speed, amount of data that they can hold and price.

CLASSIFICATION OF COMPUTERS

Computers can be broadly classified into four categories based on their speed, amount of data that they can hold, and price.

Classification of Computers

Super Computer

Mini Computers

Mainframe Computers

Micro Computers

Intelligent Terminal

Dumb Terminal

Laptop

Workstation

Network

Desktop

Handheld

Cellular Telephones

H/PC Pro Devices

Network

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APPLICATIONS OF COMPUTERS

Word Processing
Internet
Digital Audio or Video Composition
Desktop Publishing
Government
Traffic Control
Legal System
Retail Business
Sports
Travel and Tourism
Hospitals
Business and Industry

Geology
Astronomy
Weather Forecasting
Simulation
Education
Online Banking
Industry and Engineering
Robots
Decision Support Systems
Expert Systems

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BASIC ORGANIZATION OF A COMPUTER

A computer is an electronic device which basically performs five major operations which includes:

1) accepts data or instructions (input)

2) stores data

3) process data

4) displays results (output) and

5) controls and co-ordinates all operations inside a computer

INPUT

STORAGE

OUTPUT

CPU

CONTROL UNIT

ARITHMETIC LOGIC UNIT

Data and instructions

Results

Flow of data and instructions

Control exercised by control unit