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 = 1/1000th of a second.
1 Microsecond = 1/1000000th of a second
1 Nanosecond = 1/1000000000th of a second
1 Picoseconds = 1/1000000000000th 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
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
