Chapter 1

INTRODUCTION
▪ Er. Ashish K.C (Khatri)
M.Sc. Information System Engineering, Gandaki College of Engineering and Science
- Teaching Assistant at Pokhara Engineering College
- Computer Science Teacher at Vidya Niketan Sec. School ( +2 and School )
- Former Computer Science Teacher at Ex-Army Public Sec. School ( +2 and School )
7/20/2019ref. Sunrise Computer Science Grade XI © Er. Ashish K.C(Khatri) 1

CLASS 11 VS CLASS 4-10
▪ Full marks : 75 Practical : 25 [External Examiner]
▪ Pass marks : 24
▪ Time : 3 hrs
▪ Group A ( Long answer question)
Any 3 out of 4 question [ 10 marks each] i.e 3*10 = 30
▪ Group B (Short answer question)
Any 9 out of 11 question [5 marks each] i.e 9*5 = 45

CHAPTER 1.
INTRODUCTION
TO COMPUTER
7/20/2019ref. Sunrise Computer Science Grade XI © Er. Ashish K.C(Khatri)
6

DEFINITION
▪ The word ‘Computer’ is derived from latin word ‘Computare’ which means to compute or
to calculate.
▪ Computer is an electronic machine which generates information by processing raw data
according to the prescribed sequence of instructions.

WORKING PRINCIPLE:
Input Process
Storage
Output

WHAT IS IPO CYCLE?
▪ The information processing cycle is a set of steps the computer follows to receive data,
processes the data according to instructions, display the result to the user and stores the
result.

FEW EXAMPLES OF IPO:
▪ Atm . We insert our atm card (input) and it checks our pin mumber(proccessing) . If it matches
with some it further continues . We write the amount (input) , it automatically counts the money
(proccessing) and gives us the amount we require (output)
▪ micro oven - we select the power (input) and it process and we get the food which is now hot
(output)
▪ washing machine - we select the mode (input) it processes and our clothes are washed and we
get it automatically washed by the machine (output)
▪ Air conditioner - we select the mode (input) , it checks what temperature the mode matches with
(proccess) and we get the result as our room cools (output)
▪ Fan - we we select the mode (input) , it speeds up (process) and finally it gives us cool air
(output)
▪ Lock and key - we first insert the key (input) , then turn the key (process) and finnally the lock is
opened(output)
▪ Calculator - we type a number (input) and then add operation signs (process) and we get the
result after adding = sign (output)

CHARACTERISTICS OF
COMPUTER:

▪ High Speed :
- the processing speed of a computer is measured in terms of Mega Hertz(MHz) or
Giga Hertz(GHz).
Unit Meaning Part of second Power
Millisecond One thousandth of a second 1/1,000 10^-3 sec
Microsecond One millionth of a second 1/1,000,000 10^-6 sec
Nano One billionth of second 1/1,000,000,000 10^-9
Pico One trillionth of second 1/1,000,000,000,000 10^-12

▪ Accuracy:
-GIGO(Garbage-In-Garbage-Out):

▪ Diligence:
- hardworking
- never gets tired while working
- can work for long time without losing its speed and accuracy

▪ Consistency:
- repeating
- computer can repeat the same task consistently (again and again) without feeling
boring.
▪ Versatility:
- flexible, multitalented, all-rounder
- computers are able to run different programs efficiently and without slowing down.
- can perform different task one by one simultaneously.

▪ High Storage:
1 Bit 1 or 0
4 Bits 1 Nibble
8 Bits 1 Byte
1024 Bytes 1 Kilobytes (KB)
1024 KB 1 Megabyte (MB)
1024 MB 1 Gigabyte (GB)
1024 GB 1 Terabyte (TB)
1024 TB 1 Petabyte (PB)
1024 PB 1 Exabyte (EB)
1024 EB 1 Zettabyte (ZB)
1024 ZB 1 Yottabyte (YB)

▪ Automation:
- during processing no interference with user.
- can automatically perform operations.
- executes the instruction automatically one by one
▪ Communications :
- exchange message from one place to another

LIMITATIONS OF COMPUTER:
▪ No self intelligence
▪ No thinking and decision-making power
▪ No feeling
▪ No learning power

Applications of Computer:
▪ Offices
▪ Education
▪ Banking
▪ Communication
▪ Project Management
▪ Entertainment
▪ Health and medical
▪ Desktop Publishing
▪ Military
20

History of Computer:
▪ Mechanical Era
▪ Electro-Mechanical Era
▪ Electronics Era
21

# Mechanical Era:
- only mechanical devices were used for the purpose of counting and computing
manually.
- machines were based on the moving parts, operated completely by machines and
they did not have any logical control in operation.
22

Few inventions in mechanical
era:
1. ABACUS :
- developed by chinese before 3000 B.C
- consists of rectangular frame carrying
no. of rods and coils along with beads.
- two parts : heaven and earth
- heaven : upper part with 2 beads
- earth : lower parts with 5 beads
23

2. Napier’s Bone :
- developed by John Napier, Scottish Mathematician, in 1617 A.D
- Set of rods for purpose of multiplication.
25

3. Slide Rule :
- In 1620 A.D, developed by English Mathematician William Oughtred.
- two movable scales sliding upon one another.
- uses principles of logarithm.
- easy to find product, quotient or any other functions simply viewing on the scale.
- can calculate square, squareroots.
27

4. Pascaline
- 1642 A.D, developed by French mathematician Blaise Pascal.
- consists toothed wheels or gears having digits 0 to 9.
- can add and subtract 8- bit numbers.
- no direct multiplication or division.
- to help his father, tax superintendent.
30

5. Leibnitz Calculating Machine:
- In 1671 A.D, developed by German mathematician Gottfried Wilhelm Von Leibniz.
- In 1694, a modification was made using stepped dials, so called stepped reckoner.
- could perform addition, subtraction, multiplication and division.
32

6. Jacquard’s Loom:
- in 1801 A.D, developed by French Silk Weaver Joseph Marie Jacquard.
- used punched card for intricate design of patterns.
- function of loom was based on presence or absence of holes.
- this gave the concept of binary system.
- first programmable device.
34

7. Difference Engine:
- In 1822 A.D, invented by Charles Babbage.
- would be able to compute table of numbers, such as logarithm tables.
- funded by British government.
- could eliminate errors.
- became most expensive due to complexity in design and computing.
36

8. Analytical engine:
- In 1833 A.D,
- was very large and powered by 6 steam engines
- used punched cards to represent data
- patterns of punched holes were used to represent the raw data
- first machine to use binary system
37

9. Lady Augusta Ada Lovelace:
- First computer programmer
- student of Charles babbage
- operated and programmed Analytical Engine
38

10. Boolean Algebra:
- in 1854 A.D, Gorge Boole an English mathematician introduced concept of Boolean
algebra.
- is a method of reducing statements in logic to algebraic statements by using simple set of
statements.
- Boolean logic is the principle of arithmetic operations on modern digital computers.
39

11. Tabulating Machine:
- In 1887 A.D, developed by Dr. Herman Hollerith, an American census statiscian.
- automatically read census information that had been punched onto cards.
40

# Electro-Mechanical Era:
- electricity was used to operate the computers but computers still had many
mechanical components.
41

Few inventions in Electro-
mechanical era:
1. Mark-I :
- In 1937 A.D, developed by Howard Aiken of Harvard University
- also known as Automatic Sequence Controlled Calculator (ASCC)
- handled 23-decimal places and could perform all four arithmetic operations
- handle logarithms and trigonometric functions
- used 18000 vacuum tubes
42

2. Atnasoff Berry Computer (ABC):
- In 1939, developed by Dr. John Vincent Atanasoff (prof. of Mathematics and Physics)
and Clifford Berry.
- first electronic special purpose computer.
- used 19000 vaccum tubes.
- mainly designed for special purpose of solving systems of simultaneous equations.
- used by military to computer firing and blasting missiles.
43

# Electronic Era
- is modern era of computer in which mechanical devices were replaced by fully
electronic circuits.
- calculations were based on digital mechanism,
- computers in this era also had the stored program concept.
- major significance is the classification of computers in generation based on electronic
component.
4

Few Inventions of Electronic
era:
1. ENIAC:
- Electronic Numerical and Integrated Calculator.
- first general purpose computer
- built in 1946 by John Mauchly and J. Presper Eckert.
- capable of reprogrammed to solve a full range of computing problems.
- used around 17000 vacuum tubes, 7200 crystal diodes, 70000 resistors, 10000
capacitors and around 5 million hand soldered joints.
- took input from IBM card reader and IBM card punch as output.
45

2. John Von Neumann:
- contributed a new understanding of how practical fast computers, should be organized
and built.
- these ideas are often referred to as stored program technique.
- In 1945 he proposed:
a. stored program technique inside the computer
b. Binary number to be used in computer
46

3. EDSAC:
- Electronic Delay Storage automatic computer
- was early British computer developed by Maurice V. Wilkes and his team at Cambridge
University in 1949
- first computer used to store a program.
- used 3000 vacuum tubes to process data.
- programs were input using paper tape and output result were passed to tele-printer.
47

4. EDVAC :
- Electronic Discrete Variable Automatic Computer.
- First stored program computer in U.S.
- was completed in 1952 by J. Presper Eckert and John William Mauchly.
- was bult for U.S Army’s Ballistics research Laboratory
- used magnetic tape for storing data and instructions.
- used 600 vacuum tubes and 12000 diodes.
48

5. UNIVAC :
- Universal Automatic Computer
- first commercial computer produced in U.S developed by J. Presper Eckert and John
William Mauchly in 1951
- first general purpose electronic digital computer.
- used magnetic tape for data input and output.
- used 5200 vacuum tubes to process data.
49

# History of Computer in Nepal
- in 2018 B.S, an electronic calculator called “ Facit ” was used to prepare census that
took more than 6 years.
- In 2028 B.S, IBM 1401( a second generation computer) was brought in rent to
compute census. It took 1year and 7 months.
- In 2031 B.S, National Computer Center ( NCC ) was established.
- In 2038 B.S ICL 2950/10 ( Fourth generation computer) was brought to compute
census data. It took 1 year and 3 months.
- After 2039 B.S, other computers were allowed to import.
50

Generations of Computer:
- generation in computer terminology is a change in hardware and software that a
computer used.
- The development of computer that took place in five distinct phases is known as
generation of computer.
51

# First generation:
- 1942 to 1955 A.D
- based on Vacuum tube technology.
- operating speed was upto millisecond.
- very expensive to operate and used large amount of electricity
- used magnetic drums for memory
- input was in the form of punched card and output in the form of printout
- used machine level language
- Examples: ENIAC, UNIVAC, EDSAC, etc
52

# Second Generation:
- 1956 to 1964
- used transistors as main component.
- transistor made it smaller, faster and cheaper than first generation
- required less power and emitted less heat
- used magnetic disk and magnetic tapes for storage
- used assembly language and high level language
- Example: IBM 1401, IBM 1620, UNIVAC-II, etc
56

# Third Generation:
- 1965 to 1972
- used Integrated Circuit as main component.
- more reliable, smaller, cheaper than previous generation
- used semiconductor device as memory.
- consumed less power and generated less heat
- used high level programming language
- Operating System were used
- Keyboard was used as input device and monitor as output
- Example: IBM-360, ICL-1900, VAX-750, etc
58

Classification of IC:
60
Integrated Circuit No. of components
SSI ( Small Scale Integration) 1 to 20
MSI (Medium Scale Integration) 20 to 100
LSI (Large Scale Integration) 100 to 1000
VLSI (Very Large Scale Integration) 1000 to 10,000
ULSI (Ultra Large Scale Integration) more than 10,000

# Fourth Generation:
- 1973 to present
- based on microprocessor technology
- used VLSI for electronic circuits
- smallest and cheapest among all other generation
- are portable and more reliable
- consume less power and generate small amount of heat
- used Graphical User interface operating system
- Mouse were used
- Example: IBM-PC, Apple/Macintosh, etc
61

# Fifth Generation:
- are future generation computers.
- will have parallel processing.
- will possess Artificial Intelligence.
- will implement knowledge based problems solving technique.
- will use bio-chips as main component.
62

# Artificial Intelligence:
- is the technique and software that enables computer to mimic human behavior.
- is a science of making machines that imitates human thinking and behavior.
63

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