Class 6^th

 

Created By: Shahid Mahmood Bajwa

                     SST (CS) GHS 102/12-L

         Chichawatni,Sahiwal

E.Mail: GHS102.12L_cci @yahoo.com 

Checked By: Mirza Imran Haider   

                      SST (CS) GHSS Okanwala

          Chichawatni,Sahiwal

Context

Chapter: 1                             Introduction to Computer

Chapter: 2                  Component Of The Computers

 Chapter: 3                              Input &Output Devices

Chapter: 4                                            Storage Devices

Chapter: 5                                    Presentation of Data

Chapter: 6                                      Computer Siftware

                                        

                                  

Chapter: 1

Introduction to Computers

Computer

A Computer is electronic devices which can process a given input in a prescribed manner to produce a desired output, at a very high speed with remarkable accuracy also perform all arithmetic and logical functions according to instructions given in a order to solve any problem and produce processed information.

Advantages of Computers:

Speed
Its speed enables the computer to perform millions of calculations per second.

Storage
A computer has too much storage capacity. Once recorded, a piece of information can never be forgotten.

High Accuracy
A computer can be considered as 100% accurate. Computer errors that undetected are extremely rare.

Versatility
Computer can perform any type of task, provided it can be reduced to a series of logical steps.

Diligence
Computer never gets tired. It performs most boring, repetitive and same task.

Automatic Operation
Computer works automatically without manual intervention. Once a program is fed into computer the individual instructions are processed on after the other. Computer works automatically without manual intervention.

Obedience
The ability to take in and store a sequence of instructions for the computer to obey. Such a sequence of instruction is called a PROGRAM and it must be written in the Computer Language.

Decision Making Capability
Computer can take simple decisions, such as less than, greater than or equal to. It also determines whether a statement is true or false.


Hardware

The physical components and other attached input and output devices of computers are called Hardware.

How Hardware Connected

All Hardware components may be connected mechanically, electrically or electronically with each other. Hardware includes input/output devices, CPU, backing storage devices and electronic circuit.


Software

Computer required a number of instructions to do any job. The set of instructions forms programs. Numbers of programs are combined for some purposes are called software.

They are designed by manufactures and programmers.

Types of Software

1. System Software: for computer machine only

2. Application Software: for computer user only


Ages of Computer

The history of computing is divided into three ages during which man invented and improved different types of calculating machines. These ages are,

• Dark age - 300 BC to 1890

• Middle age - 1890 AD to 1944

• Modern age - since 1944 AD

Dark Age (3000 BC to 1890 AD

ABACUS
About 5000 years BC, Chinese developed the first calculating machine named Abacus.

Structure of Abacus

Abacus consists of a rectangular wooden frame having rods which carry round beads. Counting is done by shifting the beads from one side to another.

OUGHTRED’S SLIDE RULES

Year:                            In 1632

Name:                          AD William Oughtred,

 Profession:                   English Mathematician

Development:               Developed a slide rule.

Structure:                      This device consists of two movable rules placed side by side on which number were marked.

PASCAL’S CALCULATOR

Years:                          1942

Name:                          Blasé Pascal, 1623-1662

Profession                    French developed

Development:               The first mechanical calculating machine in 1642.

Structure:                      This machine consists of gears, wheels and dials. It was capable of adding and subtracting operations.

GOTTEFRIED WILHOLM LEIBNITZ

Year:                            1671,

Name:                          German, Gottfried Von Leibniz (1646-1716)

Profession:                    Mathematician

Development:               Improved Pascal’s calculator to make it capable of performing all math’s operations.

JACQUARD’S LOOM

Year:                            1801,

Name:                          Joseph Marie Jacquard

Profession:                    A French Person

Development:               Developed the first punch card machine.

BABBAGE DIFFERENCE ENGINE

Year:                            1823

Name:                          Charles Babbage (1792-1871)

Profession:                    An English mathematician

Development:               He gave the true concept of computer at Cambridge University,

he developed Babbage Difference Engine in 1823 and Babbage Analytical Engine in 1833.

Middle Age (1890 AD TO 1944 AD)

DOCTOR HERMAN HOLLERITH

Year:                            1880s

Name:                          Herman Hollerith

Profession:                    An American

Development:               Developed a machine which used punch card system.

Structure:                      The machine could sense and punch holes, recognize

the number and make required calculations.

HOWARD AIKEN- MARK-1 COMPUTER

Year:                            1937,

Name:                          Professor Howard Aiken

Profession:                    Professor

Development:               Build the first electro-mechanical computer Mark-1,

He completed his project in 1944 with the help of IBM   Engineers.

Structure:                      Mark 1 could multiply two, twenty digit numbers in 5 seconds and made a lot of noise

ABC (ATANASOFF BERRY COMPUTER)

Year:                            1938

Name:                          Dr. John Vincent

Development;               ABC a special purpose computer at  USA.

Modern Ages (Since 1944 AD)

JOHN VON NEUMAN

Year:                            1945

Name:                          Dr. John Von Neuman

Development:               ENIAC

Structure:                      The concept of Automatic Data Processing (ADP) according to the stored program and data.   

FIRST ELECTRONIC COMPUTER

Year:                            1946

Name:                          John Presper Eckert and John Williams Mauchly

Development:               Electronic Numerical Integrator And Calculator (ENIAC)

Structure:                      The first electronic computer made at USA.

This was based on decimal number system and it has no memory. It weighed 27 tons.

EDSAC (FIRST STORED PROGRAM COMPUTER)

Year:                            1949

Name:                          Mourice Wilkes

Development:               EDSAC (Electronic Delay Storage Automatic Computer)

Structure:                      It was first computer based on stored program concept. It was completed by at Cambridge University in 1949.

EDVAC

Year:                            1951

Name:                          by John Williams Mauchly

Development:               EDVAC  (Electronic Discrete Variable Automatic Computer)

Structure:                      Not Special.

UNIVAC (FIRST COMMERCIAL COMPUTER)

Year:                            1951

Name:                          John Presper Eckert and John Williams Mauchly

Development:               UNIVAC ( UNIVersal Automatic Computer

Structure:                      Itwas the first commercially used computer made by in June 14, 1951.

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Classification of Computers

According to Purpose

1. General Purpose Computers

General purpose computers are designed to solve a large variety of problems. Most digital computers are general purpose computers and used in business and commercial data processing.

2. Special Purpose Computers

The special purpose computers are designed to solve specific problems. The computer program for solving a specific problem is built right into the computer.

Most analog computers are special purpose computers. These special purpose computers are widely used in industrial robotics.

Types of Computers

1. Analog Computers

Analog computers are used to process continuous data.

Analog computers represent variables by physical quantities.

Any computer which solve problem by translating physical conditions such as flow, temperature, pressure, angular position or voltage

 It is a computer which uses an analog quantity and produces analog values as output.

Thus an analog computer measures continuously. Analog computers are very much speedy. They produce their results very fast. But their results are approximately correct.

All the analog computers are special purpose computers.

2. Digital Computers

Digital computer represents physical quantities with the help of digits or numbers.

These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.

3. Hybrid Computers

Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system.

Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world.

Features:    The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form.

Classification of Computers According to Size

1. Super Computers

Here very large computers used are called Super Computers. These computers are extremely expensive and the speed is measured in billions of instructions per seconds.

2. Main Frame Computers

The most expensive, largest and the most quickest or speedy computer are called mainframe computers.

These computers are used in large companies, factories, organizations etc. the mainframe computers are the most expensive computers, they cost more than 20 million rupees. In this computers 150 users are able to work on one C.P.U.

The mainframes are able to process 1 to 8 bits at a time. They have several hundreds of megabytes of primary storage and operate at a speed measured in nano second.

3. Mini Computers

Mini computers are smaller than mainframes, both in size and other facilities such as speed, storage capacity and other services.

They are versatile that they can be fitted where ever they are needed.

Their speeds are rated between one and fifty million instructions per second (MIPS).

They have primary storage in hundred to three hundred megabytes range with direct access storage device.

4. Micro Computers

These are the smallest range of computers.

Micro computers of today’s are equivalent to the mini computers of yesterday in terms of performing and processing. They are also called “computer of a chip” because its entire circuitry is contained in one tiny chip.

The micro computers have a wide range of applications including uses as portable computer that can be plugged into any wall.

5. Laptop Computers

The smallest computer in size has been developed. This type of small computers look like an office brief case and called "LAPTOP" computer.

The laptops are also termed as "PORTABLE COMPUTERS."

A typical laptop computer has all the facilities available in microcomputer. The smallest laptops are called "PALMTOP".

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Generations of Computer

First Generation of Computer (1946-1959)


Main Features

• Major Innovation - Vacuum Tubes

• Main Memory - Punched Cards

• Input Output Devices - Punched cards and papers

• Languages - Low level machine language

• Operating System - No operating system, human operators to set

             switches

• Size - Main frame for example ENIAC, EDVAC, UNIVAC

Advantages of First Generation
1. Vacuum tubes were used as electronic component.
2. Electronic digital computers were developed for the first time.
3. These computers were the fastest calculating devices of their time.
4. Computations were performed in millisecond.

Disadvantages of First Generation
1. Too large in size.
2. They were unreliable.
3. Induce a large amount of heat due to the vacuum tubes.
5. Not portable.
6. Limited commercial use.

Second Generation of Computers (1959-1964)

Main Features

• Major Innovation - Transistors as main component.

• Main Memory - RAM and ROM.

• External Storage - Magnetic tapes and Magnetic Disk.

• Input Output Devices - Magnetic tapes and Magnetic Disk.

• Languages - Assembly language, some high level languages for Example BASIC, COBOL, FORTRAN.

• Operating System - Human handles punched card.

• Size - Main frame for example IBM-1401, NCR-300, IBM-600 etc.

Advantages of Second Generation
1. Smaller in size as compares to 1st generation.
2. Much more reliable.
3. Less heat generated.
4. Computation was performing in micro second.
5. Less hardware and maintenance problem.
6. Could be used for commercial use.

Disadvantages of Second Generation
1. Very costly for commercial use.
2. It still required frequent maintenance.
3. Frequent cooling also required.

Third Generation of Computers (1965-1970)

Main Features

• Major Innovation - Integrated circuit (ICs) as basic electronic component.

• Main Memory - PROM and DRAM.

• External Storage - Improve disk (Floppy Disk)

• Input and Output Devices - Keyboard for input, monitor for output.

• Languages - More high level languages.

• Operating System - Complete operating systems were introduced.

• Size - Mini, for example: IBM SYSTEM / 360, ICH-360, HONEY WELL-316 etc.

Advantages of Third Generation
1. Smaller in size as compared to second generation.
2. More reliable.
3. Portable
4. Less electricity consumption.
5. Heat generation was rare.
6. General purpose computer.

Disadvantages of Third Generation
1. Air conditioning was required in many cases due to ICs.
2. Very advance technology was required to make the ICs.

Fourth Generation of Computers (1971-1981)

Main Features

• Major Innovation - LSIC and VLSIC (Micro Processor)

• Main Memory - EPROM and SRAM.

• External Storage - Floppy Disk and Hard Disk.

• Input and Output Devices - Monitor for output.

• Languages - Languages and application software.

• Operating System - MS-DOS and PC-DOS

• Size - Micro computer e.g. IBM-PC, Apple Macintosh etc.

Advantages of Fourth Generation
1. Smaller in size and much reliable.
2. No cooling system required in many cases.
3. Much faster computation.
4. Portable and cheap.
5. The heat generated was negligible.
6. Totally general purpose computer.

Disadvantages of Fourth Generation
1. Very advanced technology was required to fabricate to the ICs.


Fifth Generation (1981-Onward)


Main Features

• Major Innovations - ULSIC (Ultra large scale integrated circuit)

• Main Memory - EEPROM, SIMM and DIMM.

• External Storage - Modified magnetic and Optical disks.

• Input/output Devices - Keyboard, Pointing Device, Scanner as input and Monitor as main output.

• Languages - AI (Artificial Intelligence) Expert systems.

• Operating System - GUI based e.g. Windows 95, Windows NT.

• Size - Very small in size example: Laptop, Note book, Digital Diary, Palm top and Pocket PC.

Advantages of Fifth Generation
1. Very large storage capacity.
2. Long bit processor builds.
3. Artificial Intelligence Language developed.

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Programming Language

A programming language is a type of software.

Program:

A program is a set of step by step instruction that directs the computer to do the tasks you want it to do and produce the result you want.

Programming Languages:

A set of rules that provides a way of telling a computer when operations to perform is called a Programming Language.

Machine Language (Low Level Language)

Computer has a language that is called Machine Language (machine level language) for instructing computer to perform specific task.

It is also called binary language because it is the language of 0s and 1s,

Each computer has its own unique machine language.

Assembly Language

In assembly language, the statements are written in symbolic codes that are easier for human to read and write as compared to machine language.

Each assembly language statement corresponds to one machine language statement.

Advantages of Assembly Language

1. Operation codes of machine language are mnemonics, which are easy to remember.
2. An Assembly language program may be written easily as compared to machine language.
3. The memory addresses are used in machine language which is replaced by the variable names in this language.
4. Revision of complete program is quite easy.
5. The insertion and deletion of the instructions in the program are quite easy.

Disadvantages of Assembly Language

1. As compared to machine language assembly language is less efficient.
2. An assembly language program cannot be executed on small size computers.

High Level Language

High level languages are closer to human languages than low-level language and include statement like GOTO and PRINT which are regular words.

The program of high level languages do not have to be written for a particular computer, but it can be execute on any machine that has a compiler for that language.

Internet

Internet is the largest network of the world that connects computers located t different parts of the world.

The Internet has had a huge impact on society. The Internet provides information and service, as well as the ability to communicate to people all around the world in a variety of ways. These range from bulletin boards and chat rooms to voice conversations and video conferencing.

The Internet creates new ways for citizens to communicate, congregate and share information. It is obvious that the Internet has and will continue to change the way we live.

Advantages of Internet

1. It gives information about every field of life.
2. You may take advantages from encyclopedias and dictionaries with the help of Internet.
3. You my get information according to your need through Internet.
4. It gives a co-ordination with whole world and its interests.
5. It helps to exchange views with the person of same mental attitude.
6. Internet brings the world closer.
7. Current happening incident can be discovered by the use of Internet.
8. Any kind of topic related with politics, fashion, science etc can be discovered by use of Internet.

Disadvantages of Internet

1. The student waste their precious hours on sitting on Internet without taking any positive and constructive benefit.
2. Most of the people using Internet to satisfy their negative desires.
3. Adult material is easily available through Internet which destroys the moral values of young boys and girls.
4. Computer hacking is very common by the use of Internet some extreme minded people can digest the money through the use of credit cards of others.
5. The students waste their time in useless talking with each other.
6. Several hours on Internet without any purpose produce wrong effects on a person.

Compiler

A compiler is complex system software that automatically converts a program written in some high-level language into an equivalent low-level machine language.

The compiler or the language processor converts the entire program into machine code before execution.

Interpreter

An interpreter is  type of translator that converts each statement of a program written in a high level language into machine code and executes it before translating the next statement of the source program.

Compiler differs from a compiler that translates the entire source program into object program without undergoing its execution.


Advantages and Disadvantages of Computers:

Following are some advantages and disadvantages of computer in our life.

Advantages

1. Computers make us more productive in many of our jobs.
2. In education they can help us for better understanding faster learning and broaden our thinking.
3. In hospitals we have better diagnosis, proper treatment and better healthcare.
4. In business, they are used to record stocks of raw materials as well as finished products, making customer's bill, analyzing sales of various products etc.
5. In banks, they are used for day-to-day processing of customer's accounts and payments.
6. In manufacturing, they provide ways to develop a representation of the product and to test it in a variety of simulated environments.

Disadvantages

1. Unemployment due to automation.
2. Wastage of time and energy in useless computer activities.
3. Data security.
4. Privacy
5. Computer Crimes.

CHAPTER NO 2

Component Of The Computers

Main Components Of A Digital Computer?
There are three main components of a digital computer.

·        Input

·        Out put

·        C.P.U

INPUT:
The devices that are used to enter data and instruction into the computer system are called Input devices.
Example: - Key board, Mouse, Scanner, Camera, etc.


OUTPUT:
The devices that are used to receive processed data from the computer are called Output devices.
Example: - Monitor Printer, Speaker, Microphone, etc.


C.P.U (Central Processing Unit)
It stands for Central Processing Unit. It is the “Brain” of the computer. It is the main part of the computer system. All data passes through it and is processed in it.
C.P.U consists of two main parts:
1:- Control Unit.
2:- Arithmetic and Logic Unit.
C.P.U (Central Processing Unit)


It stands for Central Processing Unit. It is the “Brain” of the computer. It is the main part of the computer system. All data passes through it and is processed in it and the result is sent to the out put units.


C.P.U perform
Task of the C.P.U:- The C.P.U performs many tasks:-

(1) It can perform arithmetic calculations, such as (-, +, ×, %,÷) etc.
(2) It can perform logical decisions.
(3) It helps other devices in data transmission.
(4) It can perform manipulating tasks such as word processing.


Components of the CPU
C.P.U consists of two main parts:

·        C.U

·        A.L.U

C.U (Control Unit)

It stands for Control Unit. It controls all computer operation and the orders to all of its units.

A.L.U (Arithmetic and Logic Unit)

It stands for Arithmetic and Logic Unit. It performs all arithmetic and logical operations on the data. They consist of two parts.
Arithmetic section:- Arithmetic section of the ALU performs basic arithmetic operations such as (-, +, ×, %,÷).
Logic section:- Logic section of the ALU performs logical operations, such as greater than, less than, equal to, not equal, etc.

Memory

Cash Memory
It is part of the C.P.U. It is in the path between the main memory and the processor. It is in the form of a memory, but is faster than the main memory.


Secondary memory
The secondary memory is an external memory. It is also called the Auxiliary Storage Device. It can store system files, compilers, assemblers and other programs. It includes devices such as magnetic tape, floppy disk, CDs etc.
Types Of Computers

Computer can be divided into three types.
1. Analogue computer: -
 These are special purpose computers and are mostly used in engineering and medical fields etc. Their input and output is in form of wave’s i.e. they accept data and provide results in form of waves.



2. Digital computer: -
The computer, which accepts and provides data in digital form i.e. in the form of letters, numbers, symbols,  called Digital Computers.



3. Hybrid computer: -
These are also special purpose computers. But they have the capability for input in digital form and provide output in analogue form or input in analogue form while output in digital form.

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CHAPTER NO 3

Input & Output Devices

INPUT Devices
The devices that are used to enter data and instruction into the computer system are called Input devices.
Example: - Key board, Mouse, Scanner, Camera or web cam, Track ball, Light pen.


1.                          Key board:
A key board is an input device. Type writer like in appearance, it has from 84 to 108 buttons/keys. These are in groups: Alphabetic and numerical keys, (arranged as on a type writer), Numpad keys, Function keys, etc.


2.                          Mouse:
A small round hand held input device which is moved about on a desk or table top. It looks like a mouse and so is called a mouse. It is used to select options, to draw and helps in many other functions.


3.                          Joy stick:
It is and input device. It consists of a head of buttons and is used for computer games. It controls the movement of a certain object on the screen.


4.                          Track ball:
A track ball operates like a mouse. In the case of the track ball,the ball on the device is rotated.

5.                          Light pen:
It is a hand held pen like input device used to make structures which could not be done with a mouse.


6.                          Scanner:
This device is used to transfer the image of a photo, drawing or written text off a flat page into the computer.


7.                          Web camera:
This input device can be used to input moving images and still picture images into a computer. It can store still picture images and send them to the computer.
OUTPUT Devices
The devices that are used to receive processed data from the computer are called Output devices or the results of processed data or called output.

TYPE OF OUTPUT
There are two main types of output.
1. SOFTCOPY:-
This refers to data that is shown as a display on the screen or audio/voice. Such copy can not be held in the hand.


2. HARD COPY: -
This refers to printed output in the form of text or graphics.


LIST OUTPUT DEVICES

MONITER: -
This is a T.V like device that is used to display the result of a computer.
PRINTER:-
This is used to print the soft copy on to paper. Some print out only text and others both text and graphics. The size of the print is generally that of standard paper sizes.
There are two main types of printer.


1. Impact printer
2. Non-impact printer.

CD- WRITER: -
This is used to read data from and write data on CDs.


Write a detailed note on printers.
A printer is an output device. A printer receives information and prints it on paper. Printers may be categorized in tow ways.
Firstly into
1. Slow speed printers and
2. High speed printers:

1. Slow speed printers, e.g. Dot Matrix and Daisy wheel printers.

2. High speed printers, e.g. Laser printer and Drum printer with a speed up to 2000 lines per minute.


Secondly into
1. Non-impact printers and
2. Impact printers.

1. Non-impact printers:-
These printers use magnetic, electrostatic, chemical, thermal, optical, inkjet or laser principles to write on paper.


Advantage: -
They can not produce a fast single copy and make little noise.


Disadvantages: -
They can not produce multiple copies without having to print the same data repeatedly, which is time consuming. They are costly.
Examples: - Thermal printer, Inkjet printer, Drop on demand printer.


2. Impact printers:-
These printers print by striking a ribbon again the paper.
Disadvantages: - They are noisy. Have limited graphics. There are two types of impact printers.
1. Character printers
2. Line printers.

1. Character printer: -
Which print one character at a time and so is slower, e.g Dot
Matrix printer and Daisy wheel printer.


2. Line printers: -
Which print a line of characters essentially at the save time and so are faster, e.g. Drum printer and Chain printer.


Daisy wheel printer: -
These printers are also called letter quality printers. It is called Daisy wheel printer, because of a wheel on which characters are embossed all around. An electronic motor spins the Daisy wheel. This printer does not printer pictures, drawings or graphics.
Plotter: -
It is a printing device. It prints only drawings with the help of special pens fixed onto its arm. A plotter can make drawings on big sheets of paper. There are two types.
1. Drum plotters
2. Flat bed plotters.

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CHAPTER NO 4

Computer Storage

Main memory:
Main memory is a type of computer memory. It is located within the C.P.U. In size, it is much smaller than that of secondary storage devices. The main memory may or may not be permanent. There are two type of main memory.


RAM:
It stands for Random Access Memory. It can also called Temporary or Primary memory. In the RAM, stored data can be read, written, deleted and modified, so it is called Read/Write memory also. When the computer is shut down, all the data stored in the RAM is lost, so it is also called volatile memory. RAM is used to hold those programs and data that are being executed in the processor.


ROM:
It stands of Read Only Memory. It is a permanent storage of memory. It can not be deleted or modified as it only readable. The data still remains in the ROM even it we shut down the computer, so it is also called Non-volatile memory.
SECONDARY MEMORY:
Secondary storage devices are useful and add to the functionality of a computer as they can be used for both input and output, so they are also called dual purpose devices. The data of this device is stored in a magnetic form. Such data can be stored for a long time, even if the computer is off.



Secondary Memory Devices:
 Some of the most important devices which are commonly in use now-a –days are:


Floppy Disk:
It is a disk coated with magnetic material. They are commonly available in two sizes (1) 3 ½ inches. (2) 5 ½ inches.
The storage capacity such floppy disks is 1.44 MB and 1.2 MB respectively. With the help of a floppy disk, we can transfer up to 1.44 MB data from one computer to another.


Hard disk:
This is another secondary storage device. It is a metallic disk fixed in the computer which can store a large amount of data that can be accessed by the computer. The storage range is from 5 MB up to some Terabytes.


CD:
It stands for compact disk and is sometimes called optical disk. It is a plastic disk recorded on by means of laser beam rays. We can not store data on CDs, they contain read only data with a capacity of up to 650 MB storage, hence the storage memory is called CD.ROM, (Compact Disk Read Only Memory).


Magnetic Tape:
It is a reel of tape coated with a magnetic substance such as iron oxide. The reel of tape usually enclosed in a plastic box called a cassette, (similar to an audio cassette). As per an audio cassette, it is sequential with one thing recorded after another, hence to access data on it, other data must be passed over first. This takes time as compared to the direct retrieval possible from disks.
Write a short note on:-


SIMM:
It stands for Single Inline Memory Module. It is an arrangement of memory chips on the single side of a circuit board that forms a package of RAM. As SIMMs are removable,
the RAM can be increased or decreased by adding or removing SIMMs. SIMM memory chip capacity is usually 32 bits.


DIMM:
Is stands for Dual Inline Memory Module. Dual means double and in DIMMs the memory chips are doubled up on both sides of the circuit board.
The effect is to double the capacity of memory chips from 32 to 64 bits.
Units of Storage
We know that memory or storage occurs in the main memory and also in the secondary memory. In both cases the memory is stored in the form of the digits of either ‘0’ or ‘1’. Some units for the measurement of this type of memory are as follows:-


BIT:
A bit is the smallest unit of memory. It is a binary digit with the values of ‘0’ representing ‘off ‘and ‘1’ representing ‘on’




Nible:
A nible contains 4 bits.


Byte:
A byte contains 8 bits or 2 nibles. It is a higher unit of memory than bit and nible and can represent one alphanumeric character.


Kilobyte:
This unit of memory contains approximately 1000 bytes. Actually 210 bytes = 1024 bytes is one kilobytes, 1KB.


Megabyte:
It contains around one million bytes. Actually 220 bytes = 1048576 bytes is one megabyte, 1MB.


Gigabytes:
It is 240 bytes = 220 × 220 = 1048576 × 1048576 = 1.0995116 × 1012 = 1099511600000 bytes.


Terabytes:
It is the largest unit of memory/ storage. It is equal to the square of the GB. 1TB = 280 bytes.


Memory Unit Square of  ( No. of KBs)


Kilobyte 25 bytes=32 byte 1KB


Megabyte Kilobyte (KB) 1024 KB

Gigabyte Megabyte 1073741824 KB


Terabytes Gigabyte 1.1805816×10
The difference between:-


RAM and ROM:
RAM stands for (Random Access Memory) and the ROM stands for (Read Only Memory).
We can directly access the RAM, but we can not access the ROM.
We can easily save, delete and modify the saved data in RAM, but in the ROM we can not.
RAM is washed when the computer is shut down, but ROM is a permanent memory.


SIMM and DIMM:
SIMM is a single sided memory chip, while the DIMM is a double sided memory chip. The capacity of SIMM is usually 32 bits, but the capacity of DIMM is double that of SIMM usually 64 bits.


GIGABYTES and TERABYTES:
Gigabytes, is a smaller unit of memory than Terabytes.1 GB = 240 bytes, while 1 TB = 280 bytes. The TB is the square of the GB.


Hard disk and floppy disk:
Both are secondary memory devices. The floppy disk is a removable unit. While the Hard disk is fixed inside the computer. The Floppy disk storage capacity is up to 1.44 MB. While Hard disk are available in various types with storage ranging form 5 MB. Up to some terra bytes. Data can be easily be transfer from one computer to another by means of a Floppy disk, But this can not be easily done using the Hard disk.
Volatile and Non Volatile Memory

The erasable memory called volatile memory and non erasable memory called non volatile memory.

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CHAPTER NO 5

Data Types

Data:
Anything which can be fed to the computer is called data.


Types of data: -


There are three types of data.


1. Alphabetic data:
This type of data consists on only alphabet type characters.


2. Numeric data:
This type of data consists upon Number such as (0…9).


3. Alphanumeric data:
This type of data is combination of alphabets and numeric data.

Numbering system:
Generally a number system is a term used for a set of different symbols or digits, of something.


Digital computers are the machines which responds numbers (1, 2, 3, 4) rather than letters (A, B, C, D).


TYPES OF NUMBER SYSTEM:
Following are the number systems which are used in computers and in our daily life for counting and arithmetic purposes.
1. Decimal Number System ( 10 digits; 0 to 9).
2. Binary Number System (2 digits; 0 to 1)
3. Octal Number System ( 8 digits; 0 to 7 )
4. Hexa-Decimal System ( 16 digits; 0 to 9 and then A ,B , C, D, E, F) that is  (10, 11, 12, 13, 14, 15).

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CHAPTER 6

File System

Executable files:
A file which is written in machine language is called an executable file.
Types of executable files:-
There are three main types of executable files.


1. File with .EXE Extension:
Theses files which are having .EXE as their extension means that they are the executable version of a program, The file is executed whenever the name of such file is entered.


2. File with .COM Extension:
The file with extension .COM has contents which the computer runs when we enter the name of these files. An example of such files is the MS-DOS program which is called COMMAND.COM.
This file is us to interpret the user commands internally i.e internal commands of DOS. In other words these external commands must have separately stored in order to be executed by the COMMAND.CON interpreter.

3. File with .BATExtension:
 The file with .BAT extensions are also containing programs. If the names of these files are typed at the command prompt, MS-DOS runs the program that is contained in the file. These file are called batch files.
The word ‘batch’ means a collection.
In the AUTOEXE.BAT file, there is a batch or collection of commands which will be interpreted or executed by the “COMMAD.CON” before any other activity is started up.

Command:
The instruction given to the computer to do the work is called command, or command is the name of action or instruction like.
 
The general syntax of a command is Command Arguments Switches.

Command:-
Are the name of action.

Arguments:-
Are the requirements, which are required by that command.




Switches:-
Are the special characters that amend the working of that command.


Types of Dos commands
There are following two types of DOS command.


1. Internal command:
These commands are in a file COMMAND.COM. DOS loads this file in the RAM, when the computer starts. As these commands are internal part of the COMMAD.COM, so these are called internal commands.
2. External commands:
Extenal commads are stored on separate files. When we use any external command, then the computer loads its file from the disk to the RAM for use. CHKDSK, FORMAT, DISKCOPY, etc are few external commands.


Directory:
It is used to protect the files. The directory is like draw in which the files are kept.
There are two types of directory.
Root directory:
The starting directory of a drive is called iroot directory. It is normally shown by back slash (\). For example the root directory of drive A is A:\, similarly or C is C:\.


Subdirectories:-
Those directories, which are created under the root directoried, are called subdirectories. Each subdirectory can also have files as well as subdirectories.


INTERNAL COMMANDS:
The following are internal commands:
DIR CLS TYPE DATE RD VER.


EXTERNAL COMMANDS:
The following are external commands:
PRINT XCOPY CHKDSK EDIT.
Q NO 8:- Fill in the blanks:-
1) There are two types of software, namely system software and --------------------- Software.
2) The syntax of print command is -----------------------------------------------
3) Diskcopy A:B: command is used to -------------------------------------------
4) Executable file have extension ----------------------------------------------.
5) The extension bat stand for ------------------------------------------------.
6) To check the version of the dos we use ---------------------------------.
7) Erase command performed similar function as ----------------command.
8) To display the contents of the text file we use -------------------command.
9) Subdirectories in dos are called ------------------------ windows.
10) Dos stand for -------------------------------------------.
Q NO 9:- Mark True or False for each of the following.
1) Device drivers are a kind of application software..................
2) Renaming a file named landfill to new file can be done by the command COPYODFILE NEWFILE...................
3) Deleting a file named EXTRAFILE.EXE can be done by the command DELEXTRAFILE.EXE.....................
4) The scandisk command checks your computer for viruses..................
5) MSWORD is an application software ............................
6) A computer command is an instruction to the user to do specific job------------
7) In dos ? and* are called wild card -------------.
8) Diskcopy command is an internal dos command----------------.
9) Msdos.sys is a dos kernel file--------------------.
10) Print command is used to take soft copy of a text file on a line printer---------.

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CHAPTER 7

Operating System

An operating system is the software, which makes your computer functional. Without an operating system it is not possible for a computer to work. It makes the hardware of the computer and other’s software functional.

In other words for the hardware and software of the computer to work, there must be an operating system for the computer.

Tasks Are Performed By An Operating System
It makes the computer functional.
It manages the hardware and software of the computer.
It manages the hard disk, floppy drive, and other drives attached to the computer.
It gives you a backup and restores facility.
THE COMPLETE ENVIRONMENT OF WINDOWS.

If window server 2003 is installed on your computer, and you turn on your computer, you will see the following start up screen on your computer.


START BUTTON:
At the bottom of the screen, there is a start button. It is called the start button, because it is the starting point of windows. When you click on it the following menu will appear, called the start menu.


START MENU:
It shows all the commands/tolls available in window server 2003 this is the only menu from where you can selects the command you want to run.


TASK BAR:
It is the bar usually at the bottom on the screen having the start button on it.


DESKTOP:
It is all the area, which you see on the screen. It is the area where you can move icons, open your programs, create icons for the programs, and delete icons.


ICON:
These are small figures having the name under them. These represent the programs, folders, and Windows icons.


WINDOWS:
This is frame used by Windows operating system to open a program. A typical Windows has the following parts:-


BORDER:
These are the borders, which shows the area taken by the program.
TITLE BAR:- This is the bar at the top of a Window, which shows the name of the program running in it.


STATUS BAR:
It shows items like data, number of objects in the windows, etc.


VERTICAL SCROLL BAR:
Appears when the program or text exceeds the vertical area provided by the window.


HORIZONTAL SCROLL BAR:
Appears where the program or text exceeds the horizontal area provided by the window.

Clip control:
These maximize, restore and close buttons at the top of the window.


Maximize Button:
When you click on this button, the respective window will take its largest possible size and will take up the whole desktop area.


Minimize Button:
When you click on this button, the respective window will take its smallest possible size and appers on the taskbar.


Close button:
When you click on it, the respective window will be closed.


Restore button:
When you click on it, it brings the window to its previous position.


Control Menu:
It is used to manage the size and postion of a window. It appears when you click on the right icon at the title bar.It has the following options:-
 Restore
 Maximize
 Minimize
 Move
 Size


Move:
Used to move the windows from one position to another on the desktop


Size:
Used to set the size of the window


My computer:
This icon comes with window 9x operating system. It shows all the devices that a computer has, like floppy drive A, hard disk C, and D, CD- drive F or E, printers, Deal Up networking, Control panel, Scheduled tasks like anti virus program, and web folders.


Recycle bin:
When you delete some object from your computer, it comes in the recycle bin.
It has two options:-
Restore:
When you click on it, the selected item will be undeleted or restored back to its original location in the computer.

Empty Recycle Bin:
It is used to delete all the items from the recycle bin. Once the items are deleted from the recycle bin, there is no way to restore them back.


Control Panel:
As its name indicates, it is the panel consisting of a program used to control the computer and peripherals.


Display:
It is used to set the following properties:-


Background:
It sets the background of the windows environment like wallpaper, pattern that appears on the desktop.


Appearance:
It is used to sets the colour and size of different parts of a windows.


Screen saver:
It is used to sets the screen saver of the computer.



Mouse:
It is used to sets the different function of the pointer:-
Double click speed:- It is used to increase or decrease the double click speed used to run the programs.
Right handed and left handed mouse:- It is used toset the mouse for right hand or left hand use.
Motions:- It is used to set the mouse movement
speed.


Keyboard:-
It is used to set the function of the keyboard eg. Repeat rate, delay after first repeat, etc.


Modem:
It is used to set the modem used in the computer.


Network:
It is used to set the network option.


Printer:
It is used to add / install the printer.


Add /Remove programs:
It is used to add or remove the program from the hard disk of the computer.



Fonts:
It is used to add / remove fonts.


Shuting down window server 2003
If you want to close or shut down the windows 9x.
 Start___shut down___selects shut down___ok.


Operating system:
Operating system is the first software that first loads into the system memory (RAM) when the computer starts. Operating system is an interface between the user and the computer hardware.


Concept of booting:
The system BIOS (Basic Input Output System) plays a key roll in searching the operating system. The Bios is a burnt in program stored on a chip during the manufacturing process of the computer motherboard.
VIRUS:
Virus is a parasitic program that is found in the programs or in the boot sector of the disk.
Boot sector of the disk
It is the logical part of the disk, which contains the operating systems commands necessary to boot up the computer.
The boot sector is the first area read by the computer when it is turned on.

Effect of Viruses
Viruses are very dagerous and destroy the programs, data files, information on the screen, and even wash the computer hard disk. Viruses are spread when floppy disks or CDs are used to transfer the data from one computer to another.


ANTIVIRUS:
Antivirus is a program, which detects the virus in the boot sector and memory of the computer. It also detects the virus in the data files and other files in the disk.
It is used to detect the virus and try to remove it.


TYPES OF VIRUS:
 The different types of viruses are:-
• Macro Virus
• Devolving Virus
• Boot Sector Virus
• TSR File Virus
• Non TSR Virus
• Companion Virus
• Overwriting Virus
• Multipartite Virus


Devolving virus:
Some viruses are badly written and ‘lose’ there own macros. The original virus may consist of the set {Auto, File Save, and File Save As}.However, if the user invokes file{Save As, the virus will fail to copy the File Save macro}. The resulting virus set { Auto, File Save, and File Save As}is known as a Devolved Macro and the original virus is devolving.

·        Use standalone PCS:

·        Avoid the use of Modem:
Ensure that you are the only user of your computer and software

·        Never use Pirated software

·        Only use public domain or shareware software from recognized source:-

·        Avoid using non-certified anti-virus software:-

·        Write protect critical or sensitive files

·        Use of anti-virus software:

Anti-virus software is the solution to many problems created by viruses.

·        Uses of Scanners:- A scanners is a program that knows how to find a particular collection o viruses.

·        Uses of checksummers:- A checksummers is a change detector. Executable files should not change, except for a good reason like updating of the software. A checksummers aims to detect changes.

FILL IN THE BLANKS:-


1. GUI stands for Graphical user interface.
2. The software, which is loaded first in to the memory when a computer is started, is called Operating system.
3. BIOS stands for Basic input output system.
4. FDISK command is used to Partitions of hard disk.
5. During installation portable option is chosen for Lop top machines.
6. Anti-virus is used to Remove the virus.
7. Scanners are used to Find a particullor colleution of virus.
8. Chechsummers are used To change the detecter.
9. Boot sector viruses infect Floppy disk.
10. TSR stands for Terminate-and-stay-resident.
MARK TRUE OR FALSE FOR EACH OF THE FOLLOWING.

1. window server 2003 is a complete operating system. (True).

2. window server 2003 is multitasking operating system.(True)
3 window server 2003 is multi user operating system. (True).
4. window server 2003 can support 8 monintors at a time (True).
5. window server 2003 is a command based operating system (True).
6. Start button is used to open My computer folder (False).
7. The three basic parts of windows 9x are my computer, control panel, and recycle bine (False).


8. Close button is used to shut down windows (False).


9. Control menu is used to control the size, the position of windows (True).


10. Recycle bin contains all the deleted items until they are restored or permanently deleted (True).