ICT

UNIT-1

Q1) Define Computer. Explain about Characteristics and Limitations of Computers

A) Computer is an Electronic Device which performs calculation. Here the computer can perform two types of
calculations. They are arithmetic and Logical Calculations.
(or)
Computer is an advanced electronic device that takes raw data as input from the user and processes these
data under the control of set of instructions and gives the result and saves output for the future use.

The basic components of a modern digital computer are: Input Device, Output Device, Central Processor
Unit (CPU), mass storage device and memory.

accepts data Input

processes data Processing
produces output Output
stores results Storage

Characteristics of Computer System:

A computer system is better than human beings in a way that it possesses the following capabilities:
(i) Speed:
Speed is the amount of time taken by the computer in accomplishing a task of an operation. The time taken by
a computer to perform a particular task is far less than that taken by than a human being. Different computers are
classified on the basis of their speed by comparing their MIPS (Million Instructions Per Second).

(ii) Accuracy:
Accuracy refers to the degree of correctness and exactness of operations performed by a computer. In the
absence of bad programming, computers do not commit errors and are capable of handling complex instructions
accurately. If the data fed into a computer is not error free, it is likely to produce inaccurate results.

(iii) Diligence:
Computer systems are non-respondent to human factors like fatigue, tiredness or boredom. Therefore, they
are more likely to work repeatedly and efficiently. In case of any failure in a computer system, there are provisions for
immediate backup of information and programs.

(iv) Versatility:
Computers are capable of performing all levels of tasks- simple or complex. Therefore, they can be used in
any area-science, technology, business, finance, accounts, and communications and so on.

(v) Storage:
It refers to the capacity of a computer to store data and programs. Storage is done in storage media such as
CDs, Floppies, DVDs, RAM (Random Access Memory), ROM (Read Only Memory).

(vi) Networking:

It refers to concept of data sharing. The computers can support client-server Technology. By using this
characteristic the end user can access data from various locations. There are 3 types of networks majorly available in
Computers. They are 1) LAN 2) MAN 3) WAN. Here “LAN” means “Local Area Networking”, “MAN” means
“Metropolitan Area Networking” whereas “WAN” means “Wide Area Networking"
Limitations of a Computer System:
Although a computer is far better in performance than a human being, it fails in certain ways as follows:
(1) Computers can’t think:
Computers cannot think and they can’t do any job unless they are first programmed with specific instructions
for same. They work as per stored instructions. Algorithms are designed by humans to make a computer perform a
special task. This is also called artificial intelligence.

(2) Computers can’t decide:

Computers are incapable of decision making as they do not possess the essential elements necessary to take
a decision i.e. knowledge, information, wisdom, intelligence and the ability to judge.

(3) Computers can’t express their Ideas:

In any type of research ideas plays a vital role. In this context, computers can’t express their ideas.

(4) Computers can’t implement:

Though computers are helpful in storage of data and can contain the contents of encyclopedias even, but only
humans can decide and implement the policies.

Q2. Explain about the Applications of Computers.

A)
Computers are used in so many fields in our daily life. From Engineers to Doctors, Students, Teachers, and
Government Organization they all use computers to perform specific tasks, for entertainment or just to finish office
work. Computers have made our life easier.

Business:

A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which made
it an integrated part in all business organizations. Computer is used in business organizations for:
Budgeting
Sales analysis
Managing employees database
Banking:
Today banking is almost totally dependent on computer. Banks provide following facilities:
Banks provide online accounting facility, which includes current balances, deposits,
overdrafts, interest charges, shares, and trustee records.
ATM machines are making it even easier for customers to deal with banks

Insurance:
Insurance companies are keeping all records up-to-date with the help of computers. The insurance
companies, finance houses and stock broking firms are widely using computers for their concerns. Insurance
companies are maintaining a database of all clients with information showing
procedure to continue with policies
next due installment of a policy
maturity date

Education:
The computer has provided a lot of facilities in the education system.
The computer provides a tool in the education system known as CBE (Computer Based
Education) which involves control, delivery, and evaluation of learning.
The computer education is rapidly increasing the graph of number of computer students.

Marketing: In marketing, uses of computer are following:

Advertising - With computers, advertising professionals create art and graphics, write and
 revise copy, and print and disseminate ads with the goal of selling more products.
At Home Shopping - Home shopping has been made possible through use of computerised
catalogues that provide access to product information and permit direct entry of orders to be
filled by the customers.

Health Care:

Computers have become important part in hospitals, labs, and

dispensaries. The computers are being used in hospitals to keep the record of
patients and medicines. It is also used in scanning and diagnosing different diseases.
ECG, EEG, Ultrasounds and CT Scans etc., are also done by computerised
machines. Some major fields of health care in which computers are used are:
Diagnostic System - Computers are used to collect data and
identify cause of illness.
Patient Monitoring System - These are used to check patient's
signs for abnormality such as in Cardiac Arrest, ECG etc.

Military: Computers are largely used in defence. Modern tanks, missiles, weapons etc. Military also employs
computerised control systems. Some military areas where a computer has been used are:
Missile Control
Military Communication

Communication: Communication means to convey a message, an idea, a picture or speech that is received and
understood clearly and correctly by the person for whom it is meant for. Some main areas in this category are:
E-mail
Chatting
Video-conferencing

Government: Computers play an important role in government. Some major fields in this category are:
Budgets
Male/Female ratio
Computerization of voters lists

Q3. Explain about the Block Diagram of Computer

A)
A computer is a fast and accurate device, which can accept data, store data, process them and give, desired
results as output. The computer is organized into four units as shown in the following diagram.

Input Unit

Any device designed to assist in the entry of data into a computer is known as input device. Input devices
convert data from any convenient external format into binary codes that a computer can store and manipulate
internally. Some of the most common, most popularly used devices are following.
a) Mouse b) Light Pen c) Touch Screen d) Keyboard e) Scanner f) OCR and MICR g) Bar Code Reader
h) Joy Stick etc.
Output Unit:

Any peripheral device that converts the stored binary coded data into convenient external forms as test and
pictures are known as Output device. Some of the most popularly used Output devices are following:
a) Visual Display Unit (Monitor)
b) Printer : Dot Matrix and Impact/Non Impact, Printer, Daisy wheel Printer, Line Printers, Ink-jet, Laser
Printer etc

Central Processing Unit:

The Central Processing Unit (CPU) is the heart of the computer.. The CPU accepts the data from the Input
unit processes it and gives the result/output to the output device. The data/result can be stored for the use by storing it
in the secondary memory. The total operations of the computer is synchronized and controlled by the CPU. The
processing capacity of a computer is measured in terms the amount of data processed by the CPU in one operation.
The CPU has three important sub units.
1)Arithmetic-Logic unit
2)Control Unit
3)Memory Unit
Arithmetic-Logic Unit (ALU): The ALU is an electronic circuit used to carry out the arithmetic operations like
addition, subtraction, multiplication and division. This unit carries out logical operations like greater than, less than, be
equal to etc. It performs the operation on the data provided by the input devices. A comparison operation allows a
program to make decisions based he on its data input and results of the previous calculations.
Logical operations can be used to determine whether particular statement is re TRUE or FALSE.
The ALU operates on the data available in the main memory and sends them back after processing again to main
memory.
Control Unit: The control unit coordinates the activities of all the other units in the system. Its main functions are to
control the transfer of data and information between various units and to initiate appropriate actions by the arithmetic-
logic unit.

Memory Unit: Memory Unit is used to store data either temporarily or permanently.
There are 2 types of Units are available in Computer.
They are 1) Main Memory Unit
2)Secondary Memory Unit.
Main Memory Unit
The main memory is also called primary memory, is used to store data temporarily. They are RAM and ROM

Secondary Memory:

This is the permanent memory. The data stored in it is permanent. But you can delete the data if you want.
There are different kinds of secondary storage devices available. Few of them are Floppy disks, Fixed (hard)
disks and Optical disks etc.
a) Floppy Disk
b) Fixed or Hard Disk
c) Optical Disk like: CD (Compact Disk) DVD (Digital Versatile Disk)
d) Magnetic Tape Drive
Q4. Explain the types of computers?

Computers are classified according to their functionality and size.

 Based on Functionality: According to functionality computer can be divided in to three types:
Analog, Digital, Hybrid
Analog Computer: ―An analog computer is a form of computer that uses the continuously-
changeable aspects of physical fact such as electrical, mechanical to model the problem being
solved. The examples of Analog computers are Thermometer, analog clock, speedometer, etc.

Digital Computer: A computer that performs calculations and logical operations with quantities
represented as digits, usually in the binary number system of ―0‖ and ―1‖. Examples are: IBM
PC, Apple Macintosh, Calculators, Digital watches, etc.

Hybrid Computers: A computer that processes both analog and digital data. Examples are: Hybrid
computer is the computer used in hospitals to measure the heartbeat of the patient, Devices used
in petrol pump.

 Based on Size:
Super Computer: Supercomputers are one of the fastest computers currently available.
Supercomputers are very expensive and are employed for specialized applications that require
extremely large amount of mathematical calculations. For example, weather forecasting, scientific
simulations, graphics, nuclear energy research, electronic design, and analysis of geological data.

Main frame Computer: Mainframe is very large in size and is an expensive computer capable of
supporting hundreds or even thousands of users simultaneously. Mainframe executes many
programs concurrently and supports much simultaneous execution of programs.

Mini Computer: A midsized computer, in size and power, In general, a minicomputer is a

multiprocessing system capable of supporting from 4 to about 200 users simultaneously. Mini
computers have operating systems with multitasking and network capabilities enabling them to
serve more than one user.
 Micro Computer: Micro computers is a digital computer whose processing unit consists of one or
more microprocessors, one or more input / output units and sufficient memory to execute
instructions. They are used in schools, homes, office etc. Some popular micro computer is IBM
system, etc.

Q4) Explain about various types of input devices

a)
A computer is only useful when it is able to communicate with the external environment. When you work with
the computer you feed your data and instructions through some devices to the computer. These devices are called
Input devices. Similarly, computer after processing gives output through other devices called output devices.
I. Input Devices
Input devices are necessary to convert our information or data into a form which can be understood by the
computer. A good input device should provide timely, accurate and useful data to the main memory of the computer
for processing followings are the most useful input devices.

1.Keyboard:

This is the standard input device attached to all computers. The layout of the keyboard is just like the traditional
typewriter of the type QWERTY. It also contains some extra command keys and function keys. It contains a total of
101 to 104 keys. It internally contains ASCII chart and encoder. Here ASCII means American Standard Code for
Information and Interchange.
Encoder converts the digital information into binary(0,1) information. There are various types of keys are there Like
Alphabetical keys(A-Z),Numerical Keys(0-9),Functional keys(F1 to F12) and other special keys. They are
manufactured by various companies like Microsoft, TVS, and IBM etc.

2.Mouse:
The mouse is an input device which is used with your personal computer. It rolls on a small ball and has two or three
buttons on the top. The Left mouse button is used for 90% works on the desktop, the right mouse button is used on
rare occasions(refresh,wallpaper change),middle mouse button is used scroll the screen. The cursor moves very fast
with mouse giving you more freedom to work in any direction
3. Scanner:
The keyboard can input only text through keys provided in it. If we want to input a picture the keyboard cannot do that.
The Scanner is an optical device that can input any graphical matter and display it back.
4. Magnetic Ink Character Recognition (or) Reader (MICR):
This is widely used by banks to process large volumes of cheques and drafts. Cheques are put inside the MICR. As
they enter the reading unit the cheques pass through the magnetic field which causes the read head to recognize the
character of the cheques.
5. Optical Mark Reader (OMR):
This technique is used when students have appeared in objective type tests and they had to mark their answer by
darkening a square or circular space by pencil. These answer sheets are directly fed to a computer for grading where
OMR is used.
6. Optical Character Recognition (OCR):
1. This technique unites the direct reading of any printed character. Suppose a set of handwritten characters
on a piece of paper, put it, inside the scanner of the computer. This pattern is compared with a site of patterns stored
inside the computer. Whichever pattern is matched is called a character read. Patterns that cannot be identified are
rejected. OCRs are expensive though better the MICR.
7. Joy Stick:
This is one of the popular input devices, which is used for playing video games. It moves the cursor at any
direction to play the video game.
8. Touch Screen:
The Touch screen takes input as when a finger or object comes in contact with the screen, the light beam is
broken, and the location of the breaking of a light beam is recorded, which acts as inputs.
9. Light Pen:
Light is a type of pointing device that is used to choose a displayed menu option on screen for a program.
This pen contains a photocell placed in a small tube.

Q5) Explain about Various types of Output Devices

Output Devices
Output devices are those peripheral devices that allow a user to retrieve information from a computer. Any
Output devices can be divided into two basic categories.
1. Hard Copy:
It is that form of output which can be read directly and immediately, stored to be read later. This output is on
paper and which is permanent.

2. Soft Copy:
It is the magnetic or audio form of output which is usually unreadable directly and which is not long-lasting.

Monitor
 Monitor is the most important output device of a computer system.
 The monitor is the display screen of a computer.
 Cathode Rays Tube (CRT) and Liquid Crystal Display (LCD) are the two types of Monitors.
 In the market of Computers 15’,17’,19’ and various size of monitors are available.
 The CRT monitor looks like a television.
 At one end of CRT Monitor there is a device that produce electrons and bombard it towards the other end
where the screen is located, resulting in the screen glowing because of a substance on the screen. The
CRT Monitors are expensive and occupies more space as compared to LCD Monitors.
 LCD stands for Liquid Crystal Display. It has a sharp and better picture quality than CRT Monitors. LCD
monitors are relatively expensive then CRT monitors. Basically, the LCD monitors were designed for
laptops. Nowadays they are getting popular because of its slim size and flat screen.
Printers
 A Printer takes print commands from a computer and print out text / images on a paper.
 Different types of printers are available for various purposes. A printer for office use must be heavy duty
and fast while for photographs it must produce high quality prints.
 Dot-Matrix, Ink-Jet, Laser-Jet are the different types of printers.
 Print quality of Laser-Jet printer is excellent as compared to Ink-Jet or other types of printers, but they are
relatively more expensive than the others.
 Most laser printers produce black & whiter prints while some can produce color prints as well. The color
laser printers are way too expensive then black & white laser printers.
Speakers
Speaker is an important part of a computer system. Some systems have a built-in speaker, though they are
small in size. Speaker is an essential part of a computer because they can notify about various system notifications
through various sounds. Big speakers, woofers & sub-woofers are used for enhance sound quality or creating a mini
home theater.