Introduction of Computer

Concept and characteristics of computer
 The word “Computer” is derived from the Latin word “Computare” which means to calculate.
 Definition of Computer: - An electronic device which accepts raw data from users and
processes it to give meaningful result and store the important data for future use is called
 Data: - The raw facts about anything are called data. Examples: Students data are name,
address, class, roll no. etc.
 Instruction: - Instruction is specifying what must be done to the data.
For examples:
SP = 1000 and CP = 700 are data.
To find profit (SP>CP) = SP-CP =1000-700= 300
 Information: - The processed data which gives meaningful result is called information.
Example: 300 is profit.
 Hardware: - All the physical parts of the computer which we can touch and feel are called
Example: Mouse, Monitor, Keyboard etc
 Software: - A set of program written in a programming language for a computer to perform a
particular task is called Software.
 Firmware: - The information written in ROM permanently by the manufactures is called
firmware. Many computer manufacturing company make essential software, required for start
up of the computer and available in ROM chips. The best example of firmware is BIOS
(Basic input output system).
 Program: - A sequence of instructions that perform certain task is called Program.
 User: - The person who uses computer is called user.
 Peripheral: - The input, output and storage devices which can be connected to the system
cabinet are called Computer Peripherals or peripheral devices. Examples: Printer, Scanner,
Card reader etc.

# Characteristics of a computer:
a) Speed b) Accuracy c) Diligence d) Reliability
e) Versatility f) Automatic g) Storage Capacity
a) Speed: - Computers can perform billions of calculations within fractions of a second. Actually
most modern computers perform a task in a Pico seconds. The processing speed of computer is
measured in the unit of Hertz (Hz).
b) Accuracy: - Accuracy means correctness. Computer works on GIGO (Garbage input and garbage
output) principal. It means the computer provides the correct result if the inputs are correct.
c) Diligence: - The computers never feel tired and bored to do a same task repeatedly. The computer
can perform the same task with same speed and accuracy for a long time if it is provided the
suitable environment and correct instruction.
d) Reliability: Computers are designed in such a way that their every individual part has a very high
life span.
e) Versatile: - Modern computer perform various types of job efficiently. Same computer can be
used in bank, office, school, cyber etc for doing different types of tasks. Some computer plays
movies and music in it, other uses it as a server computer etc.
f) Automatic: Computer is an automatic machine because a task has started; a computer can
proceed its own till its completion. A computer can be programmed to perform a number of tasks
with the help of program.
g) Storage Capacity: - A computer has high storage capacity. It has data storage area called
memory. Any data stored in the memory can be retried at any time and at very speed.

# Limitation/ Disadvantages of computer
a) Computer is an automatic device, even it requires operator to operate the computer.
b) Computer is very expensive in comparison to other electronic devices, so every people cannot
afford it.
c) Computer cannot think itself to give decisions.
d) Computer requires technical person for maintenance if it does not work properly.

Application areas(Uses) of Computer
Although, the early computers were mainly used for mathematical calculations to predict impacts of
bomb, path of artillery shells, calculate some other numerical values etc. By the development in
technology, modern computers have played an important role in society. In modern days, computer
are used in different fields, some of them are as follows:
a) Education
Computer has been used in education to help the students in their study and the teachers to organize
and prepare their teaching materials and collect required information from the internet. Due to the
availability of eBooks in CD, DVD and in internet, Computer has been very helpful and essential
device for students and teacher for their better education.
b) Offices
Modern computers are very necessary and useful resources in office. In offices, computers are used in
preparing the reports, letters, notice, salary sheet, income and expenditure reports etc. So that
efficiency and work speed of the employees will be improved. Generally Microsoft Office and
accounting package are used in an office to handle the daily works.
c) Health and Medical field
Computers have played a vital role in medical field as it has been used in hospital to help doctors,
nurse and technicians to diagnose disease, getting information about patient, disease and drugs.
Similarly, many computerized equipment such as CT scan machine, eye testing machine and many
computerized machines are used for experiment and disease diagnosis. Surgeon also uses the
computerized device to get the information about the condition of patient.
d) Home
Nowadays computer are used in home to storing personal records, photos, videos, playing games,
listening music, watching, watching movies etc. It can be used even to connect the internet and use
services like email, chatting, online TV streaming, downloading songs and movies etc
e) Bank
Computerized technology has brought revolution in bank. Unlike in manual system, deposit and
withdraw became quickly in computerized bank. A computer is also used to maintain ledger, to
provide the online service to the customers who need services from their home, to transfer amount etc.
For these purposes, there is a central computer called server. In bank, mostly in head offices, this
stores all the necessary information centrally so that it can be accessed from any branch office of the
bank. Because of this, a customer can get services from any branches of the bank.
Due to the computer with network facility, nowadays banks also provide ATM service to customers
so that a customers with ATM card can perform a cash transaction immediately with the ATM
machine at any time and from any place.

f) Industries
Computers have been used in industries for various purpose such as keeping the employees record,
income and expenditure record, salary sheet, measurement and display of physical quality, quality
control of production etc. The different tasks which are risky for human beings are being done by
computerized robots in industries so that human life will not be at risk.
g) Science and technology
Since the invention of early computer, it has been a great aid for the mathematician and scientist for
doing fast and correct calculation. Scientific and technological research work involves complex and
massive calculations.
In many case, simulation is also required. Such massive calculation and simulation are not possible in
paper or by hand calculations. Modern computers are most for scientific research for the analysis of
h) Recording and film studio
The modern computer can also be used for recording songs, movies and dialog. It is also used in film
studies to do animation and movie production. It is used to make the movie more interesting, more
popular and more attractive.
Nowadays, the music and songs can be recorded at different tracks, time and place. Similarly, movie
editing also has been very easy due to the computerized system.
i) Weather forecasting
Weather forecasting is not an easy task as it is done after the analysis of the images, temperature,
wind speed, humidity etc. of different places, which is sent by the satellite. The analysis of these large
data is not possible without the use of computer. Computer analyzes the direction of the wind, cloud
structure, past data and many other factors to forecast the weather. Due to the use of specific
computers, we can see that BBC, CNN and other news channels predict the weather forecasting.
j) Reservation
By using the computer with internet facilities, the reservation for the air ticket, train ticket, bus ticket
etc. becomes possible. It also stores information regarding passenger such as name, address, age,
destination, data etc. Due to the credit card and debit card facility the passengers can reserve and
purchase the tickets even from their own home computer.
k) Military
Since the past, computers have been used by armed force for testing and development of military
devices like missiles, tanks and bullets etc. The pilot-less fighter planes can carry missile and drop at
the pin-point area by the use of the computerized system. It also plays important role in military
l) Communication
Due to the invention of the internet, modern computers are massively used for fast, reliable and cheap
communication all around the world. Text, photo, animation, email, voice etc can be uncharged
between two computers through the internet.
m) Library
We can use computer in library also to keep the records of books, magazines, reports, newspaper and
other documents. We can keep also records of the library members with which books they have
borrowed with detailed information.
Nowadays, many books are available in the digital format in the form of CD and DVD too. Similarly,
many e-books are kept in the internet as e-library to read such e-books also, we need computers.
n) Desktop publishing house
Desktop publishing house is the place where the design and publication of different materials like
book, magazine, journal etc take place. Before publishing these materials, if should be designed
properly. Nowadays, there are many computerized software for desktop designing and publishing
which makes it very easy and efficient. Some of the desktop publishing software as MS-Word, Adobe
PageMaker and others, which is used to manipulated by computer system.

History of Computer

The development of personal computer has taken a long period of time to extend the use of computer
at present days. There were not the advanced technologies in the ancient days. So it passed through a
several phases to become this phase at present days.
The development of commuter from ancient days to present days can be classified into 3 Era which
are as follows.

1.1) Abacus
Abacus is the first calculating device.
 An abacus consists of rectangular frame containing a number of rods or beads which is divided
into two unequal parts called heaven and earth.
 The lower part called, an earth consist 5 beads and the upper part called, a heaven consists of 2
 By moving the beads, it is used for counting as well as to find addition and subtraction.
 A skilled abacus operator can work on addition and subtraction problems at the speed of a person
equipped with a hand calculator.

1.2) Napier‟s Bone
John Napier, a great Scottish mathematician invented” Principle of logarithm” i.e. log in 1614
 Then, based on his own principle, he invented a simple device containing 10 rods made by ivory
sticks marked with numbers in 1617 AD, called Napier‟s Bone.
 People could use it for faster multiplication and division.

1.3) Slide Rule
 Based on the principle of John Napier, William Oughtred, an English mathematician, made a
simple device called slide rule in 1624 AD.
 I had multiple rulers marked with numbers in one pack.
 People could use it for faster multiplication and division also.
 It was still in use in the 1960‟s by the NASA engineers of the Mercury, Gemini and Apollo
programs which landed men on moon.

 Pascaline was invented by Blaise Pascal in 1642 AD, when he was just 19 years old.
 He invented that device to help his father who was a tax collector.
 It had some cogs and gears rotating in complement to each other and it could do addition
and subtraction up to 8 digits only.
 Multiplication and division were done by repeated addition and subtraction respectively.
 Later a computer programming language was called „Pascal‟ to honor him for his
contribution in the development of computer.
5. Stepped Reckoner
 Gottfried Wilhelm Von Leibniz was a great mathematician managed to build a four
function (addition, subtraction, multiplication and division) calculator in 1671 AD on the
basis of Pascaline.
 It could find square root too.
 Although the Stepped Reckoner employed the decimal number system, Leibniz was the
first to advocate use of the binary number system which is fundamental to the operation
of modern computers.
6. Jacquard‟s Loom
 Joseph Marie Jacquard invented Jacquard‟s Loom in 1801 AD.
 This Loom was the first to use Punch Card.
 Later the same Punch Card technology was used for Computer Programming.
7. Difference and Analytical Engine
 Difference Engine was developed by Charles Babbage in 1822 AD, which was equal to
the size of a room.
 Difference Engine was his first invention and it was powered by stem.
 Difference Engine was fully automatic for mathematical calculation.
 He obtained government funding for the development of Difference Engine due to the
importance of numeric tables in ocean navigation.
 By promoting their commercial and military navies, the British Government had
managed to become the earth‟s greatest empire.

Analytical Engine

 Charles Babbage also designed another engine in 1833 AD, but unfortunately he was unable to
complete it.
 The analytical Engine contained all components as follows.
 The store equivalent to memory.
 The mill equivalent to CPU.
 The input section using punched card.
 The output section using punched card.
And modern computers are based on it. That‟s why, for all his contribution, he is known as “father of
8. Lady Augusta Ada
 Lady Augusta Ada was the admirer and follower of Charles Babbage.
 She was fascinated by Babbage idea.
 She suggested Babbage to use binary number system for computer program and data to be fed
into Analytical Engine on Punch Card.
 She gave the concept of computer programming for the first time, so she is considered as “First
Computer Programmer”.
 She invented subroutine and important of looping.
 She found that the same set of Punch Card could be reused to repeat certain instructions.
 One programming language “ADA” was named to honor her for her great contribution in
computer programming.

9. Tabulating Machine
 The very first census of 1790 had only required 9 months, by 1880 the U.S. population had
grown so much that the count for the 1880 census took 7.5 years. Automation was clearly needed
for the next census. The census bureau offered a prize for an inventor to help with the 1890
census and this prize was won by Dr. Herman Hollerith for the development of Tabulating
 By using the similar ideas of Jacquard‟s Loom he made Tabulating Machine in 1886.
 It could process on the Punch Cards and perform the census calculation faster and accurately.
 Hollerith‟s technique was successful and the 1890 census was completed in only 3 years at a
savings of 5 million dollars.
 He established his own company called Tabulating Machine Company (TMC).
 Later, TMC was joined with other company and established IBM company in 1923 AD.
 IBM is the largest computer manufacturing company in the world even today.

B) Electro- Mechanical Era
10. Mark-I
 It was designed by Howard Aiken.
 This was the first programmable digital computer.
 This machine works on decimal not in binary format.
 Its dimension was 51 feet long, 8 feet tall and 3 feet wide.
 It had a 50 feet rotating shaft running its length, turned by a 5 horse power electric motor.
 It consumed a lot of electricity and emitted a lot of heat.
 It was also called IBMASCC (International Business Machine Automatic Sequence
Control Calculator).
 This project was a joint partnership between IBM and Harvard University.
 It can automatically perform sequence of arithmetic operations: addition, subtraction,
multiplications, division and table reference.
 It could add or subtract two of numbers in three – tenth of a second, multiply them in
four seconds.

11. ABC (Atanasoff Berry Computer)
 J. V. Atanasoff was a Professor of Physics and mathematics, with the help of his graduate
student Clifford Berry; he built a machine that could solve different types of
mathematical problems successfully tested in 1942.
 This machine was the first to store as a change on a capacitor, which is how today
computers store information is in their main memory (RAM).
 It used 45 vacuum tubes for internal logic and capacitors for storage.

C) Electronic Computer Era:
12. ENIAC (Electronic Numerical Integrator and Calculator) [1943-1946)
 Dr. John W. Mauchly and John Presper Eckert developed ENIAC at the Moore School of
Electrical Engineering of the University of Pennsylvania in 1946, USA.
 It was the first electronic computer.
 This had no moving parts except the input and output.
 ENIAC was developed for military need and was used for many years to solve ballistics (fire
weapons) achieved problems.
 The addition of two numbers was achieved in 200 microseconds and multiplication in 2000
 It occupied a room measuring 9m*15 m and contained 18,000 vacuum tubes, more than 70,000
resistors, 10,000 capacitors, 60,000 switches and weighed 30 tons.
13. EDVAC (Electronic Discrete Variable Automatic Computer) [1944-1951]
 It was invented by John W. Mauchly and J. Presper Eckert.
 He was the first to introduce the stored program concept in a computer.
 It used binary number system rather than decimal numbers for its operation.
 It had almost 6,000 vacuum tubes and 12, 000 diodes and consumed 56 KW of power.
 It covered 490 square foot of floor space and weight nearly 7 tons.
 The machine requires 30 personal to operate.
 This machine ran till 1961 at research laboratory.
14. EDSAC (Electronic Delay Storage Automatic Computer) [1947-1949]
 It was invented by Maurice Wilkes at Cambridge University, England. In 1949AD.
 It also used vacuum tubes.
 Although, started after EDVAC, it was completed before EDVAC.
 It used binary number system.
 Both input and output used paper type.
 This machine was used to calculate a table of squares and a list of prime numbers.
15. UNIVAC (Universal Automatic Computer) [1951]
 It was invented by John W. Mauchly and J. Presper Eckert.
 This computer was the first commercial computer and general purpose computer produced in
large quantity.
 Before this, all the computers were either used for defense or census.
 The UNIVAC was also the first computer to come equipped with s magnetic tape unit and was the
first computer to use buffer memory.

Generation of Computer:
Generation of Computer terminology is a change in technology a computer is/was being used. Initially
generation of computer was used to distinguish between varying hardware technology.
There are 5 generation of computers which are as follows:

1) First Generation Computer
 The computers which were made approximately between 1941 and 1955 AD are classified as the
first generation computer.
 These computers had used vacuum tube as their memory and processing devices.
 Vacuum tube was developed by Lee De Forest in 1908 AD.

Characteristics of a First Generation Computer

a) Technology: Vacuum tube was used as its main components.
b) Processing Speed: Processing speed was measured in Milli-second.
c) Input/output Device: Punch Card was used as input / Output devices.
d) Computer Type: Computers were electro-mechanical.
e) Memory: Vacuum tube was used as memory device.
f) Storage Device: First Punch cards used and later magnetic drum were used as storage device.
g) Operation Mode: Computers should be set up manually as there was no operating system
h) Reliability and Accuracy: The computers were not fully reliable and accurate.
i) Programming Language: Machine Level Language was used for computer programming.
j) Size and Cost: The size of computer was very large and its cost was also very expensive.
k) Availability: The Computers were only available to the military purpose and university research.
l) Power Consumption and Heat Emission: Computers consumed a lot of electricity power and
emitted a lot of heat.
m) Portability: Computers were not portable because of its huge size.
n) Examples: ENIAC, EDVAC, UNIVAC etc.

Vacuum Tube:

A vacuum tube is a hollow glass cylinder containing a positive electrode and a negative electrode
between which is conducted in a full or partial vacuum tube. A grid between these electrodes
controls the flow of electricity.
The major disadvantages of tubes include the fact that they require bulky power supplies and the
high voltages can resent an electric shock hazard.

2) Second Generation Computer
 The computers which were made approximately between 1955 and 1964 AD are classified as the
Second generation computer.
 These computers had used transistor and diodes as their memory devices.
 Transistor was invented by three scientists John Bardeen, William Shockley and Walter Brattain
in 1947 AD and won the Nobel Prize in 1956 D for it.

Characteristics of a Second Generation Computer

a) Technology: Transistor was used as its main components.
b) Processing Speed: Faster processing speed as it was measured in Micro-second.
c) Input/output Device: Punch Card was used as input / Output devices.
d) Computer Type: Computers were electro-mechanical.
e) Memory: Magnetic Core (Ferrite) was used as internal memory.
f) Storage Device: Magnetic Tape was used as secondary storage device.
g) Operation Mode: Computers should be set up manually as there was no operating system
h) Reliability and Accuracy: These were more reliable and accurate than first generation
i) Programming Language: Assembly and High Level Language such as FORTRAN (Formula
Translation), COBOL (Common Business Oriented Language) etc. were used for computer
j) Size and Cost: The Computers were smaller in size and less expensive than 1st generation computer.
k) Availability: The Computers were available for general purpose.
l) Power Consumption and Heat Emission: Power consumption and Heat emission was less than
st generation computer.
m) Portability: Computers were not portable.
n) Examples: IMB 1401, ICL 2950 / 10, IBM 1620 etc.


Transistor is derived from the two words “transfer” and “register” and it is the device which is
made of three terminal semi-conductor materials that amplifies the electric signal or opens or
closes the electronic circuit.
They were much smaller than vacuum tubes and consumed much less power. Electronic circuits
could make more complex, with more transistors switching faster than vacuum tubes.
3) Third Generation Computer
 The computers which were made approximately between 1964 and 1975 AD are
classified as the third generation computer.
 These computers had used IC (Integrated Circuit) as memory and processing device.
 The first IC was developed by Jack Kilby and Robert Noyce in 1958. Later Robert Noyce
established Intel Company.

Characteristics of a Third Generation Computer
a) Technology: IC was used for the electronic circuit in computer.
b) Processing Speed: Faster than previous generation computer as processing speed was
increased into Nano-Second.
c) Input/output Device: Keyboard and Monitor were introduced as input and output
devices for the first time respectively.
d) Computer Type: Computers were electronic.
e) Memory: Semiconductor memory was used as primary memory.
f) Storage Device: Magnetic disk was used as secondary storage device.
g) Operation Mode: Operating system was introduced for the automatic and
multi programming.
h) Reliability and Accuracy: Computers became fully reliable and accurate.
i) Programming Language: Further development of High Level Language for Computer
j) Size and Cost: The computers were smaller and less expensive than previous generation

k) Availability: The Computers were available for general purpose as well as personal
l) Power Consumption and Heat Emission: Power consumption and Heat emission was
less than previous generation computer.
m) Portability: Computers became portable for the first time because of the personal or
Desktop Computer.
n) Examples: IBM 360 Series, UNIVAC 9000, ICL 900 Series.
Integrated Circuits:

ICs range from simple logic modules and amplifiers to complete microcomputers
containing millions of elements. The impact of ICs on our lives has been enormous. ICs
have become the principal components of almost all electronic devices. These circuits
have demonstrated low cost, high reliability, low power requirements and high processing
speeds compared to the vacuum tubes and transistors which preceded them.

4) Fourth Generation Computer
 The computers which were made approximately between 1975 to till now having
microprocessor as CPU and VLSI (Very Large Scale Integration) are classified as fourth
generation computer.
 First commercial microprocessor was Intel 4004 which was made by Intel Corporation in
1971 AD.
 It was 4 bit processor because it could process only 4 bits of data at a time.
 It is one of the most important generations because many achievements in the hardware
and software technology took place during this generation.

Characteristics of a Fourth Generation Computer

a) Technology: ICs and microprocessor are used as main components with VLSI and ULSI
o) Processing Speed: Faster than previous generation computer as processing speed was
increased into Pico -Second.
b) Input/output Device: Input / Output devices have been further refined and invented
various devices such as scanner, touch screen, printer etc.
c) Computer Type: Computers were electronic.
d) Memory: Semiconductor memory with huge capacity has been used as primary memory.
e) Storage Device: Use of magnetic and optical disk with large storage capacity for
secondary storage device.
f) Operation Mode: Multiprogramming, Multiprocessing, multimedia and distributed
operating system become possible.
g) Reliability and Accuracy: The computers have become fully reliable and accurate.
h) Programming Language: Advanced HLL and 4 GL for application and database
programming have been used.
i) Size and Cost: The computers were smaller in size and less expensive than previous
generation computers.
j) Availability: The Computers were available for general purpose as well as special
k) Power Consumption and Heat Emission: Power consumption and Heat emission was
less than previous generation computer.
l) Portability: Computers have become portable because of the development of personal or
Desktop Computer, Laptop, Notebook and PDA.
m) Examples: IBM PC, Apple Mac Book, HP 300, Acer, Dell etc.

A microprocessor is a computer processor on a microchip. It is sometimes called a logic
chip. It is the “engine” that goes into motion when you turn your computer on. A
microprocessor is designed to perform arithmetic and logic operations that make use of
small number – holding areas called registers. When the computer is turned on, the
microprocessor is designed to get the first instruction from the BIOS that comes with the
computer as part of its memory. After that, either the BIOS, or the operating system that
BIOS loads into computer memory, or an application program is “driving” the
microprocessor, giving it instructions to perform.

5) Fifth Generation Computer
 Although the computer of this generation have not come yet in reality, but computer
scientists are trying since 1990 AD.

 It is said that the computer of this generation will use AI (Artificial Intelligence) and bio-
chips as memory device so that they can think and decide like a human being.

 Bio-chips will be made of biological organism and protein fibers obtained from the living
 So, this computer will have power of sense, logic and decision making capacity.

Advantages of AI

i. Game playing: AI in computer has been used in playing different intellectual games like
chess. Computer can play master level chess. Other various games also can play due to AI.
ii. Speech recognition: Speech recognition is a way of commanding computers to perform
work through speech rather than inputting through input devices. From 1990s, speech
recognition has reached a practical level for limited purpose.
iii. Understanding natural language: Due to the use of AI, computer can easily understand
the meaning of the text written in natural language.
iv. Automated planning and scheduling: NASA‟s remote agent program became the first on
– board autonomous planning to control the scheduling of operations for a spacecraft which
lies 100 million miles from earth.

Characteristics of a Fifth Generation Computer
 They will be capable of fully parallel processing.
 Computers will use super conductor memory like bio-chips so that the speed will be very
 The computers will be intelligent and knowledge base because of AI.
 Instead of HLL, natural language like English, Nepali, and Hindi etc will be used for
giving instruction and making computer program.
 They will be large scale data processing on the basis of knowledge processing.
 The computers are not available in market. These are still in development phase or in
testing phase or exists somewhere in the world as failed project.

1.5 Computer Speed and measurement Unit
The different measurement units and their relationship for microcomputer speed are as follows:
1,000 Hz = 1 Kilo Hertz (103 Hz)
1,000 KHz = 1 Mega Hertz (106 Hz)
1,000 MHz= 1 Giga Hertz (109 Hz)
1,000 GHz= 1 Tera Hertz (1012 Hz)

Speed of computer

Unit Symbols Fraction of second
Milli-second ms 1/1,000
Micro-second μs 1/1,000,000
Nano-second ns 1/1,000,000,000
Pico-second ps 1/1,000,000,000,000

Measuring units of computer storage are: Memory is measured in bytes. A byte is combination of
8 bits and represents one character, a letter or symbol.

0 or 1 1 bit(Binary Digit)
4 bits 1 Nibble
8 bits 1 byte
1024 bytes 1 kilo bytes(KB)
1024 KB 1 Mega Bytes(MB)
1024 MB 1 Giga Bytes(GB)
1024 GB 1 Tera Bytes(TB)
1024 TB 1 Peta Bytes(PB)
1024 PB 1 Exa Bytes(EB)
1024 EB 1 Zeta Bytes(ZB)

History of Computer in Nepal
 It was in 2028 B.S. when HMG brought IBM 1401 (a 2nd generation computer) on rent for Rs. 1
Lakhs and 25 thousand per month to process census data. It took
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