Introduction to Computer

 

Computers are now affecting every of human activity are bringing about many changes in Government, Education, Industry, etc. The computers we see today is quite different from the one made in the beginning. The number of applications of a computer has increased the speed and accuracy of calculation has increased. computers are presently used

Applications of Computers:
There are 2 types of applications of Computers for Business Purpose and Office Purpose:
• One of handing large volumes of data.
• Second one preparation reports, letters and documents etc.,

Office Use:-
Computer helps to store the information of employees in an office.

Railways / Airlines:-
Computers are used at the reservation counters to keep the details of the seats available in trains and airlines.

Hospitals:-
Computer are used to detect diseases of patients.

Science:-
Also used and linking, universities and research laboratories..

Schools:-
• Improving the standard of education and performance.
• Doing the scientific experiments with the latest advancements.

The most Common uses for the computer within the home

    * Computer Games
    * Working from Home
    * Banking from Home
    * Connecting to the internet

Importance of Computers in (Our) Daily Life:

    * Reservation of tickets in Airlines & Railways
    * Payment of Telephone & Electricity bills
    * Deposited and withdrawals of money from Banks (Internet Banking)
    * Medical Diagnosis and Weather forecasting
    * Managing Accounts
    * Playing Computer Games
    * Educational use
    * Supermarkets
    * Working from home (Tele-working)
    * Internet


What is a Computer
I guess the easiest way I can explain it is as a computer is electronic device that is designed to automatically accept input (data), stores and process them producing output (results). It can process both numerical and non-numerical (arithmetic and logical) calculations.
The word computer comes from the word “compute” which means calculate.

How computers work
Computers process information using the instructions from the user to produce the desired result. The instruction that you feed in the computer, through a software, is the basic input. This input could be fed through a key board. These instructions are then sent to the processor known as the Central Processing Unit (CPU) for processing. After proceeding has been performed, sends the result, known as the output to the screen or printer as desired by you

Advantages of Computers:
The number of ways to that computers effect human lives is uncountable. Computers can perform all the functions that a human being can do, to a certain extent, but at a much faster speed and with greater accuracy.
A computer makes the job much simpler and most of all, the least time consuming.

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History of Computers

HISTORY & CLASSIFICATION OF COMPUTERS:
The computers evolved as a result man search for fast and accurate calculating devises.  The work of the computers depend upon many others factor such as acceleration of technology growth in the early 1900’s. Charles Babbage begin too is work on the analytical machine, which provide to be proto type of the modern computer. This concept is opened up avenues for the future development of computers.

History of Computers:

ABACUS: (Calculating Machine)

The History of computers dates back to a long ago, the first calculating device to old computational work was ‘Abacus'. The abacus could perform addition, subtraction, multiplication and division. The abacus is an instrument used to perform arithmetic calculations. It was developed in 1200 A.D  

  

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LOGARITHMS: 

The John Napier invented logarithms in 1617. 'Napier' designed a set of rods that helped to make multiplication easier. The rods were arranged in a manner that made it possible to fit them together into a multiplication table.  The rods were called Napier bones.

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SLIDE RULES:

Napier's rods later became the bases for a well known invention by "William Oughtred", an english mathematic which is known as the "Slide rule". It was an improvement over the logarithm tables as the final value could be straight away read on the scale.

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PUNCHED CARDS:

ln year 1880, Dr.Herman Hollerith developed punched cards. Even today these cards are extensively used in modified form as input devise.

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LEIBNIZ:

Leibniz a famous German mathematician improved Pascal's machine in 1671. The machine was able perform all the four basic mathematical operations like addition, subtraction, multiplication and division. The draw back of this machine was that it was very slow.

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PASCAL'S CALCULATOR :

In the year 1642, Pascal developed the first real calculating machine, which could add numbers by using gears, wheels and dials. All the mechanical calculators developed later were based these ideas.

 

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DIFFERENCE ENGINE (Charles Babbage):

(Born in London, England)Charles Babbage is the father of modern computer Science, first designed a engine called "Difference Engine", which would compute and check the tables but the engine was of limited use. Later he designed a general purpose computing device called "ANALYTICAL ENGINE".
This could do arithmetic calculations very fastly. If completed this analytical engine could perform following functions :

(a) All Arithmetic Operations
(b) Instructions & data fed to computer in advance.
(c) Store intermediate results
(d) Capable of taking logical decisions.

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Generations of Computers

History of Computer Generations:

The evolution of computer started from 16th century and resulted in the form that we see today. The present day computer, however, has also undergone rapid change during the last 50 years. Generations in computers means a change or improvement in the technology over a period of time.
 

There are 5 Generations of computers they are:
First Generation -> 1940-1956
Second Generation -> 1956-1963
Third Generation -> 1964-1971
Fourth Generation -> 1971-Present
Fifth Generation -> (Present and Beyond) 

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First Generation ( 1940-1956 ):
These computers are designed based on the vacuum tube technology. The computers were large, slow and accurate with high power requirement and large amount of heat generated.
Ex:  ENIAC - (Electronic Numerical Integrator And Calculator)

       EDVAC – (Electronic Discrete Variable Automatic Computer)
       EDSAC - (Electronic Delay Storage Automatic Calculator)
       UNIVAC - (Universal Automatic Computer)

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Second Generation  ( 1956-1963 ):
These computers used transistors which were a smaller and more reliable devices then vacuum tubes.second generation computers used high level languages, such as COBOL, FORTRAN etc.Operating systems also developed in this period.
Ex: IBM 1401

      IBM 1620

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Third Generation  (1964-1971):
These computers used integrated circuit ( I.C's) These were much efficient than the earlier ones.These computers were highly reliable, cheaper and faster than the second generation computers. 3rd generation computers used Small Scale Integrated circuits(SCIC) and Medium Scale Inegrated Circuits (MSIC).
Ex: IBM 360 

      ICL 1900

      VAX 750    

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Fourth Generation (1971-Present):
These computer used Large Scale Integrated Chips (LSIC). These are very fast, reliable compact and accurate. 4th generation computers replaced SSI and MSI circuits by LSIC (Large Scale Integrated Chips) and VLSI ( Very Large Scale Integration)circuits.
Ex: IBM - PC 
 

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Fifth Generation (Present and Beyond):
Fifth generation computers as aimed specifically at A.I.M (Artificial Intelligence Technology). The speed is externally high in 5th generation computer. The concept of Artificial intelligence has been introduce to allow the computer to take own decision. Fifth generation computers are still in development stage.

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Memory Types

MEMORY UNIT AND IT'S TYPES:

There are two types of computer memory (1) Primary (2) Secondary. Primary memory is accessible directly by the processing unit. RAM is an example of primary memory. RAM stores data temporarily. RAM will loose its contents when the power is switched off or if there is power failure. Secondary memory is located outside the computer. Primary  memory is more expensive than secondary memory. Secondary storage devices to store large quantity of data for future use.

 

Memory Unit :

It is a device that can accept data or instruction, hold them and deliver then on demand at a later time. The  memory unit is also referred as primary storage.

Memory is of two types.

I. Primary Memory

II. Secondary Memory

(I). Primary Memory:

Primary Memory  is mainly of two types

(a) Random Access Memory (RAM)

(b) Read only memory (ROM)

(a) Random Access Memory (RAM)

During the executing of a program that data required by the program is stored in Ram. It provides a volatile storage, i.e. the data are lost in the even to a power failure. So Ram used to store data temporarily.

RAM is 3 types:

1. Dynamic Ram (DRAM)

2. Static Ram (SRAM)

3. Cache Memory

Dynamic Ram:

This is computer memory, that losses its memory capability once the power source is removed.

Static Ram:

This is Ram of Ram provides a static storage of data.

Cache Memory:

It is very speed memory which used to store portion of a programme from the main memory temporarily. This cache memory is more faster but more expensive. Data is transferred automatically between the buffer and primary storage.

(b) Read only memory (ROM):

In this memory, basic start up routines and BIOS (Basic Input Output Systems) are permanently loaded during the manufacturing time. It provides a non-volatile storage. i.e., the data does not get erased when the power is switched off.

ROM is 4 Types :

(a) ROM (Read Only Memory) :

This is stored at the time of manufacture of the chips

(b) Programmable Read Only Memory (PROM):

Once the chip has been programme, the recorded information can't be changed. i.e. the PROM becomes rom and the storaged information can only be read.

(c) Erasable & Programmable Read Only Memory (EPROM):

It is similar to PROM except that erasing is possible by exposing to ultraviolet Radiation.

(d) Electrically Erasable & Programmable Read Only Memory (EEPROM):

A recently developed type of memory that can be programmed and erased by electrically signals. EEPROM used in many electronic devices.

(II).Secondary Memory:

Secondary memory storage is used to store the data and program permanently.Secondary memory is located outside the computer. Secondary storage devices to store large quantity of data for future use.

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Types of Computers

 Computers can be classified into two types:

(i) Digital Computers
(ii) Analog ComputersDigital Computers:
The digital computer is a digital system that performs various computational tasks. The word digital implies that the information in the computer is represented by variables that take a limited number of discrete values.Digital Computers work on the principle of counting of numbers. The internal architectural design of computers differs from one system model to another. The basic organization remains the same for all computer systems.

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Analog Computers:
Analog computers used relational method of comparison for processing the data. But today’s problems of computing require processing involving numerical calculations and logical Analysis. The people tried to develop the computers having both the features of digital as well as Analog that has give rise to special branch of computers called Hybrid computers.- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - -

And Hybrid computers are again divided into two types.

(a) General purpose computers and
(b) Special purpose computers.General purpose computers:
General purpose computers are used for commercial Applications and different varieties of works.Special purpose computers:
Special purpose computers are of different types basis on the features of operations and areas of uses. They are classified as follows:

(a) Super Computers
(b) Mainframe Computers
(c) Mini Computers
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Super Computers:
These are used for research laboratories and design of super sonic jet engines etc., Ex: CRAY -1, CRAY -2, ETA -10, CYBER 205, CDC, STAR 100, etc.,
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Mainframe Computers:
This are used for very large data handling where multi user environment is needed (parallel data processing)
Ex : IBM 4300, IBM -370, IBM- 360 etc.,
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Mini Computers:
These are used for process control, cad, scientific research and on line reservation systems etc.,
Ex: PDP-11, HCL Magnm, HCL Oaysi, HCL Horizon II E, IBM 9375 etc.,

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Micro Computers:
Micro Computers are also called personal computers. These are the mostly used computers in small business and companies and basically single user computers.
There are very low cost systems
Ex. Commodore, uptrans 800, DCM Tandy, IBM PC etc. 

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And There are different types of computers in use-> Desktops

-> Laptops (or) Note Book Computers

-> Palmtop

-> Personal Digital Assistants (PDAs) (or) Handheld PC

-> Tablet PC

These were some of the different types of computers available today. Looking at the rate of the advancement in technology in the near future we can definitely look forward to many more types of computers.

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Computer Parts

I think that the Personal Computer is really a collection of separate items working more pleasant and efficient.

Let's take a look at each of these parts.

 

(1) Motherboard

(2) CPU (Processor)

(3) RAM (Memory)

(4) Hard Drive

(5) CD - Rom

(6) Floppy Drive

(7) Key Board

(8) Mouse

(9) Speakers

(10) Monitor

Basic Components :

(1) System Unit (CPU)

(2) Monitor

(3) Key Board

(4) Floppy Drive / Hard Drive

Optional Components :

(1) Mouse

(2) Printer

(3) Scanner

(4) Modem

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Look at Input and Output Devices:

Input Devices:

·         Digital camera

·         Keyboard

·         Microphone

·         Mouse

·         Scanner

·         Web Cam

·         Light pen

·         Joy stick etc.,

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Output Devices:

·         Monitor

·         Printer

·         Plotter

·         Speaker

·         Projector etc.,

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Storage Devices

Secondary storage is also known as auxiliary memory or external memory or back up storage. The secondary storage devices are used in most computer systems to supplement the limited storage capacity of the primary memory section. This is similar to our keeping a diary or a note book when our memory is incapable of storing many facts and figures. We refer to our diary whenever we need the data.

Secondary Storage Devices are

1. Magnetic tape

2. Magnetic disks

3. Compact Disk Read Only Memory (CD-ROM)

The data is either stored or erased by laser beam to CD-ROM.

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Magnetic Tape:

Magnetic tap is one of the most popular storage medium for larger data that are sequentially accessed and processed. The tape is plastic ribbon usually 1/2 inch wide that is coated as one side with magnetic material. It is similar to the tape used on a tape recorder except that is higher quality and more durable.

Advantages

(a) Unlimited Storage Capacity

(b) Low Cost

(c) Portability

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Magnetic Disks :

A magnetic disk is a, circular plate coated on both sides with a magnetic material. It is very similar to a gramophone record. Each disk consists of a number of invisible concentric circles called tracks. Each track is further sub-divided into sectors. Information is recorded on the tracks of a disk surface in the form of invisible tiny magnetic spots. The presence of a magnetized spot is represents as '1 ' bit and its absence represented a '0' bit.

Magnetic disks are two types:

1. Floppy Disk

2. Hard Disk

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Floppy Disk:

The floppy disk is a flexible, circular shaped medium with a magnetic coating on it. It is sensitive to touch and dust. A floppy disk enclosed in a leather jacket to protect it from external damage and dust.

There are three types of floppy’s available.

1) 3.5" Floppy Disk ( Capacity 1.44 Mb ) introduced : Sony

2) 5.25" Floppy Disk ( Capacity 1.2 Mb ) introduced : Shugart

3) 8.0" Floppy Disk ( Capacity 100 Kb ) introduced : IBM

The 3.5" disks are the most popular and commonly used.

On the Basis of Capacity they are of two types:

(a) High density

(b) Low density

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Hard Disk:

Hard Disk is also a secondary storage device. The hard disk storage system was developed to reduce the problem of diskettes frequently getting damaged.

Hard disks come in different capacities. The minimum capacity is generally twenty times that of a high density floppy disk in terms of storage capacity. The hard disk is generally fixed inside the computers.

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Compact Disk Read Only Memory (CD-ROM):

CD-ROM disks are made of reflective metals. CD-ROM is written during the process of manufacturing by high power laser beam. The storage density is very high, cost is very low and access time is relatively fast.

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Input/Output:

The term Input/Output is used to describe any program, operation or device that transfers data to or from a computer and to or from a peripheral device. Every transfer is an output from one device and an input into another. Devices such as keyboards and mouse are input-only devices while devices such as printers are output-only. A writable CD-ROM is both an input and an output device.

Input Devices:
Input device is a hardware device which is use to input data, image, and video to the computer.

Input Devices:

Digital camera
Keyboard
Microphone
Mouse
Scanner
Web Cam
Light pen
Joy stick
Etc.

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Out put Devices:
Output device is a hardware device which is use to receives or displays output from a computer

Output Devices:Monitor
Printer
Plotter
Speaker
Projector
Etc.

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System Unit

 

SYSTEM UNIT:

The brain behind everything that takes place in pc is contained within the system unit.

(a) Central Processing Unit (CPU):

The Microprocessor or CPU is the computer's most important component. It does all the thinking for the p.c. and runs the programs.

(b) Ram (Random Access Memory) :

When a computer is switched on and is running a program, RAM is used for purpose of holding the program and

its data, but when the p.c. switched off, anything held in ram is lost.

(c) ROM (Read only memory):

In this memory basic start up routines and BIOS (Basic Input Output System programs) are permanently loaded during the manufacturing time. It provides a nonvolatile storage. i.e., the data does not get erased when the power is switched off. It can't be altered and fresh information can't be written into a Rom. It information can be read only

THERE ARE 2 SIDES OF SYSTEM UNITS:
(i)  Front view of system unit
(ii) Back view of the system unit

FRONT VIEW OF SYSTEM UNIT:

(a) Power on/off:
Generally Computers have a main power switch on the front of the system unit.(b) Reset Button :­
This Button can be used to restart computer
(c) Turbo Button :­
Some computers offer a choice of speeds at which they can run.
(d) Key lock :­
This lock prevents the keyboard from working and hence works as a safety lock.(e) Lights :­
System unit may display a verity of colored lights on the front panel.(f) Floppy Disk Drive :­
Computer can have either the 5 1/4" or 3 1/2" floppy drive or both.

Parts of front view:

(1) 5 1/4" floppy drive

(2) 3 1/2" floppy drive

(3) Power on off switch

(4) Push Button for floppy eject

(5) Reset Button

(6) Turbo Button

(7) CPU speed display

(8) Key lock or system lock.

(9) Power indicator light.

(10) Fixed disk drive in use indicator light.

BACK VIEW OF THE SYSTEM UNIT:

(a) Power in and out sockets:
Cables plugged into these sockets carry power from the electrical outlet.(b) Serial Ports :
Serial ports connect computer to a mouse or modem. Most computers are
fitted with two serial ports.(c) Monitor Port :
A cable from monitor plugs into this port and carries the information to
be displayed on the monitor.(d) Parallel Port :
This port is usually used for connecting the computer to printer.(e) Key Board Port :
The cable from keyboard plugs into the key board port.(f) Fan Housing:
The electronic components in pc generate a lot of heat.
To prevent overheating, a fan placed at the back of the unit helps in removing the hot air from system.(g) Compartments for expansion cards:
PCs are easily expandable to provide a modern sound or faster graphics.

INSIDE A SYSTEM UNIT:

The brain behind everything that takes place in pc in contained within the system unit. Inside the unit are components constituting of pc that run programs that handle typed instructions, and determine the results.

(A) Mother Board :­

All the electronic components in a pc are mounted on a piece of fiber glass, called the mother board. A printed circuit board that has slots to connect cards into. they also include a CPU and memory.

(B) Central Processing Unit (CPU) :

The Central Processing Unit is the computer's most important component. It does all the thinking for the pc and runs the programs that you request. Without the CPU, the computer is nothing.

(C) Ram Chips:­

When a computer is switched on and is running a program, Random Access Memory (Ram) is used for purpose holding the program and its data. But when switched off, anything held in Ram is lost.

(D) Floppy Disk Drive :­

Floppy disk drive consists of a slot to accept a floppy a motor that spins the disk, a recording & reading device that moves across the disk in order to read (or) write data.

(E) Hard Disk Drive :­

It is computer's main storage unit, holding large amounts of data and programs. It uses a hard material (typically aluminum).

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Hardware & Software

The term hardware refers to the physical components forming the computer which are nothing but input, output, storage and processing units and additional accessories.

The term of software refers to programs which are invisible to the eye and which are essential to be made use by the user to run on the computers either to run the system or to run his job. Software is a set of programs and the program is a set of the instructions. An instruction is any character or word or group of words which instruct the computer in a way that the computer can understand.

Software is broadly classified into two types.

(a) System Software

(b) Applications Software

System Software:

System Software is used to run the system and control the system. System software mainly consists of operating system and maintenance tools.

Operating system acts as the interface between the applications software and the hardware. it consists of  3 basic modules. Namely (a) I-O Control (b) File Control (c) Process Control

The operating  system is a set of programs that are used to make the resources of the computers to be available  to the user of the application software. The maintenance tools include antivirus tool kit and some utilitie software to make the system run in good condition. Anti Virus tool kit is software to fight the virus and protect the stem from bugs and troubles. These bugs and troubles are created by the virus, the software to disturb the maintenance and running of the computer and software in good condition.

Application Software:

Application software is that which is used by the user for writing his own applications. It is sub-divide into 3 categories

a) Application Programs

b) Programming Languages

c) Utilities

a) Application Programs

An Application program is a software designed for a specific type of applications like documentation, graphics etc.,

b) Programming Languages

programming language is a language which is used to write some programs to do a specific job. It  is universal in nature.

c) Utilities

Utilities are one type of software which give support for the user in using other type of Application Software.

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