Basic Computer lesson 1

INTRODUCTION TO COMPUTER

Computer is the electronic device which is the man made machine. The word of computer derived from Latin word ‘Computare’ which means to calculate. Since computer is defined as one which calculate or Computare. A computer is an electronic device, which can perform certain mathematical calculation and logical operation at a very high speed.

Full Form

C= Common                           U= Use for

O= Operate                             T= Technology

M= Machine                           E= Education and

P= Purpose                             R= Research

Simply, a computer is defined as an electronic device with ability to:

·         Accept user supplied data and instructions.

·         Store them; perform mathematical calculations and logical operations. (Execute the instructions)

·         Output the results according to user specifications.

·         Transfer data, images and sound through the telephones lines or cables at a very fast rate.

In other words computer are data processing machines, which processes data and provides meaningful information. And Data may be defined as a collection of facts, observations or occurrences in the form of text, image or sound.

The concept of modern digital computing was forwarded by Charles Babbage, so he is also termed as The Father of the computer.

CHARACTERISTICS OF COMPUTER

1.      Speed

Computer operates at a very high speed with the speed of light due to its operations caused by electrical. The computer’s speed at performing single operation can be measured in terms of fraction of second. Speed: Computer can calculate complex calculation at a very high speed. Computer takes a few micro/nano second to execute as operation.

1 Millisecond =          1/1000^th of a second.

1 Microsecond = 1/1000000^th of a second

1 Nanosecond = 1/1000000000^th of a second

1 Picoseconds = 1/1000000000000^th of a second

2.      Accuracy

If the program and data have no error, the result given by the computer will be 100% accurate. Mistake will be occurred in calculation by wrong data or mistakes in instruction.

3.      Consistency.

Unlike human beings, computers are highly consistence. They never get bored too. Hence they are ideal machine for carrying out repetitive and voluminous work. It is a capacity of performing repeated operation without any tiredness and any mistakes. A computer is capable of performing the required task continuously with the same speed, accuracy and efficiently without any error. Computer never gets tired, bored and laziness to do the task.

4.      Storage Capacity

The computer is special device by its storage capacity. Large amount of data can be stored in a computer’s memory.

0 or1=1Bit	1character=1 Byte	1024MB=1GigaBytes
4Bits=1Nibble	1024Bytes=1KiloBytes	1024GB=1TeraBytes
8Bits=1Byte	1024KB=1MegaBytes

5.      Communication Media

It is one of the main characteristic of computer. Using Internet phone, E-Mail, PC to PC Phone etc can be use for worldwide communication.

6.      Easy To Use

The computer is very easy to use by using the different parts and systems. We can use the computer inside the room in a comfortable way.

7.      Tending Job Handlers

The computers are widely used for jobs. They are versatile so can be used for various jobs.

8.      Economic (Less Expenses)

The computer works in various fields so it reduces cost .We can use it for communication, study, research, and for other fields too. 

COMPUTER SYSTEM

Input must be provided as data, instruction, and information. Then such information must be stored so that it can be used later. Such information may be manipulated arithmetically, and the processing of data is done to meet the requirement and obtain output, it must be controlled by some process.

These operations are carried out together to get the result. Such combination including input unit, central processing unit [primary storage, arithmetic and logical unit, control unit] and output unit together is known as computer system. It is also referred as the computer Architecture.

1.       Input Device

Information is entered to the computer through input device. It converts input information into a suitable form acceptable to a computer.

a.         Mouse

Mouse is a small handful input device with one or more buttons used as for pointing or drawing. As you move the mouse on the plain surface an arrow moves on the screen which is known as mouse pointer. You can press one of the mouse buttons to initiate an action or operation. Different software and programs accepts different mouse clicking but generally, single left click is used to select and double left click is used to open the selected item. With most of the popular software you can use mouse clicking with modifier keys like shift, Alt and Control also. Mouse is used only with graphical user interface not with command line user interface

b.         Keyboard

As you see simple typewriter, the keyboard is same as appearance but by the help of keyboard you can initiate or apply different commands to the computer so it is called the most popular input device. Generally you will get keyboards with more than 100 keys. Now, you will get Enhanced or Multimedia keyboard with which you can easily play music and movies. The Apple keyboard and IBM keyboard has same key appearance on the main keys but some of the modifier and function keys have different functions. As appearance you will get two types of keyboards, first one is QWERTY keyboard on which the top left row starts with QWERTY and second one is DVORAK keyboard on which the top left row starts with DVORAK but it is not so popular.

Types of keys:

Modifier Keys:

The modifier keys have different functions as defined as the program or operating systems. Shift, Control, Alt, Command (Macintosh), Option (Macintosh) etc are the popular modifier keys.

Numeric Keypad:
The numeric keys at the right of the keyboard with numbers and arithmetic operators.

Main keys:
The main keypad with characters numbers and symbols.

Cursor movement keys:

Arrow keys, home, End, page up and page down keys are used to move cursor in most of the operating systems and programs.

Special purpose keys:

Insert, Delete, ESC, Print Screen, Scroll Lock, Pause, Start (windows), Shortcut (windows) keys are the special purpose keys used on computer keyboards.

c.         Light Pen

Light pen is used as pointing device, which is very sensitive to light. When the light pen tip is placed against the screen, it is capable of sensing its position on the Cathode Ray Tube (CRT). As the tip of he pen is moved over the surface of the screen, its light sensitive elements detects the light emitted from the screen. We can select the desired option of the menu by touching light pen against desired option. Now days, light pens are used in many big hotels room for the customer for selecting their choice of menu and other items

d.         Joy-Stick

A joystick is a pointing device, one of the input devices that are used to move the cursor on the screen. It has a stick with balls at its upper and lower ends. As the handle moves to the different direction the pointer moves on the screen. Joystick is mostly used while playing computer games.

e.         Scanner

A scanner is a device that has eh capability of capturing images and converting it into a unique set of electrical signals. In other words, a scanner copies an image, creates and stores it on a computer disk in a form that can be used by the computer. Any image on paper, whether text or graphics, printed or drawn can be scan to the computer by the help of scanner. Scanner works same as photocopier but the copier copies date to the paper and the scanner copies data to the computer disk.

f.          Optical Character Recognizer

An Optical Character Reader is a direct entry input device. This can detect alphanumeric characters printed on any paper. A light source converts the alphabets, numbers and similar such characters into electrical signal which are then sent to the computer for processing. The text to be scanned should be illuminated by low frequency light source. The reflected light from the text is received by the light sensitive cells and generates the signal depending on the type of text.

g.         Barcode Reader

Bar Code Reader is an input device, which reads the bar codes and converts them to electrical pulses, which are sent to the compute for processing. Usually bar codes are universal code and uses standard code, which has vertical bars of varying width representing ten digits. The first five represents the manufacturer and the second five digits identify the products.

2.       Central Processing Unit

The central processing unit is the brain of the computer. Its main function is to store primary data and execute programs. It also control input output device and memory. Its major sections are

a)      Arithmetic and logic unit

b)      Memory

                               I.      Primary Memory

1)      Random Access Memory

2)      Read Only Memory

                            II.      Secondary Memory

c)   Control unit

a)        Arithmetic and logic unit

The arithmetic and logic unit performs all the arithmetic computations and logical operations. The arithmetic computations include addition, subtractions, multiplications and division operation while logic operation is comparisons.

b)        Memory

The function of memory is to store information. There are two general categories of memory.

1.         Primary Memory

i.          Random Access Memory [RAM]

The read and write memory of a computer is called RAM. The user can read information from RAM and can write in the RAM. Its advantage is its volatility.

a. Static RAM         b. Dynamic RAM

ii.         Read Only Memory [ROM]

ROM allows reading only the contents of the memory many times as desire. User cannot write in the ROM. The content if ROM is written by the company. It can’t be written again.

2.         The Secondary memory contains Hard Disk Drive Floppy Disk, Optical Disk, Magnetic Tape, Removable Disks (Pen-Drives).

c. Control Unit

The control unit controls and co-ordinates all the activities inside the computer. It generates the control signals necessary for the execution of instruction. In fact, it generates control signals which are necessary for the operation of CPU, memory and input / output devices. It controls the entire operation of the computer. Hence, the Controls Unit of CPU is the actual brain of the computer.

The Total Roles of CPU in Computer

§  Performance

§  Software Support

§  Reliability and Stability

§  Energy Consumption and Cooling

§  Motherboard support

3.         Output Device

The output devices receive results and other information from the computer and provide them to the users. This device receives instructions from CPU in control signals and converts them to the user’s specified terms and conditions. Those devices helps user to get information from computer. There are two main types of output first one is paper output which is also known as hardcopy output and second one is onscreen output which is also known as softcopy output. Some popular output devices are as follows.

a.         Printer:

Printer is a popular hardcopy output device, which gives the paper output for the user. Generally, printers are categorized in two main category first one is Impact and second one is Non impact.

Impact Printer:

An impact printer is like a typewriter and the characters are formed by physically striking the type device against the ribbon. The printer head directly touches the paper against the ribbon in impact printer to print a character.

Some common Impact printers are:

·         Dot Matrix                          

·         Line Printer

·         Band Printer

·         Daisy wheel printer

ii.   Non-Impact Printer

The non impact printer creates images in the paper without striking in any way. The popular types of non impact printers are Bubble jet or ink jet printer and Laser printer

Some common non-impact printers are:

·         Inkjet

·         Laser Printer

b.         Monitors

i.    Cathode Ray Tube [CRT]

ii.   Liquid Crystal Display [LCD]

c.         Display Adapters

d.         Plotters

e.         Speakers

GENERATIONS OF COMPUTER

There is no technological development in history, to data. That has progressed as fast as computer technology. The evolution of modern digital computing is often divided into generations .

1.   First Generations [1951-1958]

2.   Second Generations [1959-1964]

3.   Third Generations [1965-1971]

4.   Fourth Generations [1971-present]

5.   Fifth Generations

First Generations [1951-1958]

First generations of computer used Vacuum tubes as the electronic device for their hardware implementation. So these computers were very large. For Example ENIAC. These computers were very slow occupy large space and has less storage capacity

Second Generations [1959-1964]

Three scientists invent semiconductor transistors and it brings revolutions in computer. These transistors marked the arrival of second generations of computer and replace Vacuum Tubes. These tubes were smaller, faster and more reliable.

Third Generations [1965-1971]

The Integrated Circuit [IC] is responsible for the emergence of the third generations of computer. An IC is an electronic circuit with large number of components built on small silicon chips. This generation of Computer is made distinct from previous ones by semiconductor memories also.

Fourth Generations [1971-present]

The development of VHSI [Very High Scale Integration] circuit and microprocessor was developed by American Intel Corporation in 1971. A microprocessor is a processor built on a single chip.

Fifth Generations are under development.

We can conclude the generations of computer in the following way.

In 1960’s decade a convention was organized to clarify the generation of the computer by the compute scientists. At that time Two main components of the computer Memory (Storage) and Processing devices were taken to divide the generation. Now, computers are defined in five generations.

Sn.	Generation	Time Period	Processing Devices	Machine	Advantages/ Disadvantages
1.	First	1942-1954	Vacuum tube (Valve)	ENIAC, EDVAC, EDSAC	Large in size. Slower in performance. More heat generating.
2.	Second	1955-1964	Transistors	LEO mark III, ATLAS, UNIVAC II, ICT 13000, IBM P4000	Smaller in size Good performance and low heat generation comparing previous generation.
3.	Third	1965-1974	IC(Integrated Circuit)	VAX 11/780, ICT 1900 series, IBM 360 series, UNIVAC 1108/9000 series	Good performance. Smaller size.
4.	Fourth	1975- Till now.	LSIC, VLSIC, ULSIC	IBM PC, Apple Macintosh etc.	Very good performance. Very reliable.
5.	Fifth	1990- Yet to come	Bio chips		Artificial Intelligence (AI)

TYPES OF COMPUTER

There are different types of computers. Exiting due to the advance technology of science different computers has different size, functions and model.

1.      On the basis of work

a.       Analog Computers

The computer which can process continuous variables only is the analog computer. The speedometer of motorbike, analog thermometer etc. are the examples of the analog computers.

b.       Digital Computers

The Digital computer can process discrete variables only. Most of the digital calculators are the example of the digital computer. It directs numbers or digits that represent numbers letters and other special symbols.

c.       Hybrid Computers

The Hybrid computer can process continuous as well as discrete variables. The computer which is used in jet planes and fighter planes is the hybrid computer. It performs the task of analog as well as digital computer.

2.      On The Basis Of Size

a. Super Computer:
Super computers are the most powerful and faster of all computer system. Supercomputers are even faster then the mainframes. The supercomputers are being used in the complex scientific calculations and research project. The supercomputers are important innovation in history of computer. They may be employed in massive data processing, solving very complex problems. Supercomputers are used in weather forecasting, rock launching, seismology, nuclear physics, weapon research and so on. The costs of these computers are very high (more than 15 million dollars). CRAY I, CRAY X-MP, HITAC S-300 etc. are the popular super computers.
b.  Main frame computer:
Mainframe computer is larger than mini computer and smaller than supercomputer. It is very popular in database field. It is also applied as web server. It can support more than 1000 processors at the same time.
c. Mini computer :
The mini computer is larger in size comparing microcomputer but it has a big storage capacity and processing capabilities. The compute is mostly used in connection more terminal or workstations. Workstations are points where the workers work sharing a single computer as the file server. A minicomputer may have as many as 100 or more terminals connected to it.
d. Micro computer
A computer which is based on the microprocessor is called a microcomputer. It is small, low cost digital computer. Microcomputer has a microprocessor on a single chip, which is its Central Processing Unit (CPU). It also has other units like input devices memory unit. It is also called personal computer. IBM PC, Apple Macintosh etc. are the microcomputers. Microcomputer can be classified as follows.
Desktop                    Laptop                          Notebook                     Palmtop

3.      On the basis of Brand / Compatibility

a.       I.B.M. –PC

International Business Machine is one of the computers developed by American Company. The computer made by this company is called I.B.M.-PC. It is very

expensive.

b.       I.B.M.- Compatible

The computer not made by I.B.M but made as like I.B.M-PC is called I.B.M-Compatible. It is very cheap and may up to $500.

c.       Apple Or Macintosh

It is also another American company. Their computers are very easy to use and different from I.B.M. computers.

4.      On The Basis Of Model

a.       XT-Model

XT-Model computer is old architecture model. This type of work very slow, less facility and cheap.

b.       AT-Model

AT means Advance Technology. This type of computers are fast working, providing various facilities and some expensive.

c.       Ps/2-Model

The IBM Company launched Personal System-2[PS/2] model of computers in around 1990. These computers are some expensive an work better then AT-Model. Most of the companies followed this model now-a-days.

1. Hardware

The physical components of computer are called hardware, which can be touched and felt..  All the peripheral parts attached with the computer are known as the hardware parts of the computer like Monitor, Mouse, Keyboard, CPU, Speaker etc. Such component may be electronic, electrical, mechanical etc.

a.       External Parts

1.         Primary Parts          

i. Casing or CPU      ii. Monitor       iii. Keyboard                iv. Mouse pad         v. Mouse

2.         Secondary Parts

i. Printer         ii. Scanner     iii. Sound Box          iv. Digital Camera

b.      Internal Parts

1.         Primary Parts

i.    Mother Board  ii. CPU  iii. Hard Disk  iv. VGA

2.         Secondary Parts

i.    Sound Card ii. Internal Modem Card iii. Net Card iv. Floppy Drive v. CD ROM

2.      Software

Consists of set Programs of instructions which causes computer operated. Software performs the desired data processing functions. It is classified into the following types,

a.         System Software

i.          Operating System Software

The operating system is the master controller of the computer system. The operating system creates link between hardware and the application software of the computer. It controls entire system and creates environment for different application software. Operating system can be divided in two main parts.

1.         Command line User Interface (CUI):

In command line user interface the command must be typed for each and every action. MS DOS is the popular CUI operating system. In CUI The user must close the running file to open next new file, user could not work with multiple application at the same time. In CUI Operating system user could not use any pointing device like mouse, touch pad, track ball etc.

2.         Graphical User Interface:

In Graphical User interface the user can apply any command or action by the help of pointing devices. Windows, Mac OS are the popular graphical operating systems. In graphical operating system the user can work with multiple applications at the same time, which is known as multi tasking

ii.         Language Software [COBOL, PASCAL, C]

b.         Application Software

That software which has particular task is the application software like documentation, presentation, publication etc. Microsoft word, Excel, PowerPoint, Adobe PageMaker, Photoshop etc are the application software.

i.    Tailored Software

ii.   Packaged Software

c.         Utility Software

The software which checks the system and manages file to make the system up to date is the utility software. It works as the doctor of the computer. It any error occurs on the computer it automatically fixes it. All the antivirus programs, System tools etc. are the utility software

i. Normal Utility        ii. PC Tools              iii. Proxy