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Computer System

Introduction to Computer System

Presentation 1

Objectives In this presentation, you will learn about • History of Computer • Characteristics of Computer  Computer System Components

• Generations of Computer

What is Computer System? • A complete, working computer. Computer systems will include the computer along with any software and peripheral devices that are necessary to make the computer function. Every computer system, for example, requires an operating system.

Data and Information • Data is the plural form for Datum, which means raw fact. • Data: Refers to the raw facts about people, places, things etc.

• Information: Refers to the processed data. Name














Data Information

Total mark obtained by these six students is 398.

Processing data

What is a Computer? The Computer is an electronic device. Receives Data and Instructions

Processes data according to instructions

Store data and results for future use

Displays data and results

Activity 1.1.1 1.Collect the names of the students in your class and marks obtained by them in Mathematics. Find the average mark of your class in Mathematics. Identify the data and information in this activity.


• In early times, the need for calculating devices led to the evolution of computers.

Abacus • Earliest of the calculating devices, originated around 3000 BC. • It is a rectangular frame with vertical rods and beads attached for calculation. • Each rod represents the decimal values, (i.e.) units, tens, hundreds etc starting from right.

Abacus • The upper portion of the rod contains 2 beads and the lower portion contains 5 beads. • The upper beads represent 5s and the lower beads represent 1s. • Arithmetic calculation can be done by changing the position of the beads.

Napier’s Bones • Invented in the year 1617. • Consists of long rectangular rods. • Each rod is divided into 10 squares.

Napier’s Bones • The first square contains a digit and the remaining squares shows the multiples of that digit. • Two-digit multiples are separated by a diagonal line in the square.

Pascaline • Invented by Blaise Pascal. • Consists of a rectangular box made of brass. (36 cm length x 13 cm width x 8 cm height)

• It has some 5 internal wheels later on 6 and 8 wheels, which are rotated by notched dials.

Pascaline • The dial was rotated using pins. A full rotation of the wheel at right rotates one-tenth the wheel to its left.

• The wheels moved only in clock-wise direction.

1.2 COMPUTER SYSTEM COMPONENTS • Hardware and Software • Programming Languages • IPO Cycle • Block diagram of Computer

Hardware • Hardware – refers to the physical components of a computer • Input devices • Keyboard, mouse

• Output devices • Printer, system unit , speakers

Software • Software is a set of programs that activate the hardware.

• A program is a set of instructions that tells the computer what to perform and how to perform the given task.

Types of Software • Software is broadly classified as • System Software and Application Software.

• System software • Acts as an interface between the user and the hardware. • Operating system is a system software that controls all the activities of the hardware.

Types of Software • Application software • Set of programs that is used to perform a specific task.

• Word processors such as MS-Word, StarWriter are some of the examples for the Application software.

Programming Languages • Computer can understand Machine language or Low-Level language • Machine language consists of 0s and 1s. • Instructions given to the computer in Englishlike languages are called High-Level languages.

Programming Languages • A translator is a software that translates High-Level language to Low-Level language or vice-versa. • Compiler, interpreter and assembler are some of the programs that act as a translator. Machine Language

Compiler (Or) Interpreter

High-Level Language

Processing Stages: IPO • IPO stands for Input-Process-Output. • To get any output, there should be an Input and it has to be processed.

Processing Stages: IPO For example, • To prepare ice cubes the water has to be cooled below the freezing temperature. • Here, water is the input, cooling is the process and ice is the output. Input



Block Diagram of a Computer Basic Units of a computer: • Input Unit • Memory unit • Central Processing Unit that contains Control Unit, ALU (Arithmetic and Logic Unit) and Registers • Output Unit

1.2.1 INPUT UNIT • This unit is used for entering data and programs into the computer system by the user for processing. • The Input Unit consists of one or more input devices. • Commonly used input devices are keyboard and mouse.

1.2.2 Central Processing Unit • Also called as Processor. • Responsible for executing the given instructions. • Comprises of the following units: • Control Unit • Arithmetic and Logic Unit (ALU) • Registers

1.2.2 Central Processing Unit (Contd..) • Control unit • Controls the flow of instructions between the various units of a computer.

• ALU • Used to perform all the arithmetic operations and logical comparisons.

• Register • Is a small temporary storage location present inside the CPU.

1.2.3 Output Unit • The input from the user is processed by the processor to get the results. • The results are conveyed to the user using the output unit.

1.2.3 Output Unit (Contd..) • The output unit consists of one or more output devices. • The most commonly used output devices are Monitor and Printer.

1.2.4 STORAGE/ MEMORY UNIT • The storage unit is used for storing data and instructions before and after processing • Memory can be classified into two types; 1. Primary memory 2. Secondary memory


i) Generation Computers • The first generation computers used a component called “Vacuum Tube”. • The first electronic computer is called ENIAC (Electronic Numerical Integrator and Calculator)

i) Generation Computers • It was developed by J. Presper Eckert and John W. Mauchly in the 1940s. • ENIAC used 18000 vacuum tubes and it occupied 1800 sq.ft. of space.

ii) Generation Computers Transistors: • Invented to overcome most of the problems faced with vacuum tubes. • Used to relay and switch the electronic signals.

ii) Generation Computers Transistors: • Found to be more powerful, reliable, cheaper and smaller in size than vacuum tubes. • Time for making calculations reduced from milliseconds to microseconds.

iii) Generation Computers • Integrated circuits (IC) is the invention of III generation computers • These circuits are integration of electronic components, such as • Transistors, Conductors, Diodes and Resistors

iii) Generation Computers • IC chips reduced the cost and size of computers • High technology is required to manufacture the Integrated Circuits.

iv) Generation Computers • LSI and VLSI technology were implemented to integrate 1 million electronic components on a single chip. • Storage capacity was increased. • Microprocessors and PCs were developed. • Computers shrunk to a small size and it was used in schools, offices and even at homes. • These computers are easily portable as they are small in size.

v) Generation Computers • The electronic components were miniaturized

• Storage capacity of the memory and hard disc were increased. • The VLSI technology was replaced by ULSI (Ultra Large Scale Integration) technology. • There was a remarkable growth in the computer network and Internet. • Multimedia applications with superior quality were made easy to develop during this generation

Summary In this presentation, you learnt the following: • A computer is an electronic machine. • Data means raw fact. • The processed data is called as Information. • Abacus was the earliest of calculating devices. • I Generation computers used a component called “Vacuum Tube”.

Summary In this presentation, you learnt the following: • II Generation computers used Transistors. • III Generation computers used IC Chips. • IV Generation computers used LSI and VLSI technology. • The VLSI technology was replaced by ULSI technology in V generation.

Summary In this presentation, you learnt the following: • IPO stands for Input-Process-Output. • The basic units of a computer are • Input Unit, Central Processing Unit and Output Unit. • The most commonly used input devices are keyboard and mouse.

Summary In this presentation, you also learnt the following: • CPU comprises of Control Unit, Arithmetic and Logic Unit and Registers. • The most commonly used output devices are Monitor and Printer.

Assignment Answer the following: 1.

Define Data.


Define Information.


Define Computer.


Give short notes on Abacus, Napier’s bones and Pascaline.


Name the components used in the different generations of computer.

Assignment Answer the following: 6. Name the 3 basic units of a Computer. 7. Mention the functions of Input unit, CPU and Output unit.

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