HISTRORY, BASICS AND INTRODUCTION OF COMPUTERS, MEDIUM - ENGLISH, BOARD - CBSE

1. COMPUTER SCIENCE
CLASS XI
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2. INDEX
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3. UNIT - 1
COMPUTER FUNDAMENTALS
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4. EVOLUTION OF COMPUTERS
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5. EVOLUTION OF COMPUTER
• STARTED WITH NEED OF PERFORMING FAST
CALCULATIONS.
• ERROR FREE CALCULATIONS.
• THIS FIRST EVER JOURNEY STARTED WITH ABACUS.
• LET US NOW SEE THE DEVICES EVOLVED IN THIS
PHASE WAY BEFORE INVENT OF COMPUTERS.
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6. ABACUS
• Discovery of Mesopotamians in 3000 B.C.
• Performs Addition and Multiplications with two movable
Beads.
• Each Row Represents 10’s Place,
• Right to Left
• First Row (r1) = 1’s Place
• Second Row (r2) = 10’s Place
• Third Row (r3) = 100’s Place …
• The starting position of the top beads (representing the
value of five) is always towards the top wall of the abacus.
• The lower beads (representing the value of one) will always
be pushed towards the lower wall as a starting position.
• Even today, apt tool for young children to do calculations
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7. NAPIER’S LOGS AND BONES
• This is Logarithms
• Developed by John Napier – 1617
• The set of numbering rods (Napier’s Bones) are used
to perform multiplication and division.
• Any two no.s can be multiplied falling in range of 2-9.
• There are 10 bones corresponding to the digits 0-9
• 11th bone – representing Multiplier.
• By placing bones corresponding to the multiplier on
the left side and the bones corresponding to the digits
of the multiplicand on the right , the product of two
numbers can be easily obtained.
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8. NAPIER’S LOGS AND BONES
11th bone placed in between, which can
multiply L.H.S. * R.H.S.
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9. PASCALINE
• Blaise Pascal, a French mathematician - 1642
• made up of gears
• used for adding numbers.
• This machine was also called Pascaline and was capable
of addition and subtraction along with carry-transfer
capability.
• It worked on clock work mechanism principle.
• It consisted of various numbered toothed wheels having
unique position values.
• The addition and subtraction operations was performed
by controlled rotation of these wheels.
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10. LEIBNITZ’S CALCULATOR
• Gottfried Leibnitz, a German
mathematician – 1673
• extended the capabilities of Pascaline
to perform multiplication and division
as well.
• The multiplication was done through
repeated addition of numbers using a
stepped cylinder each with nine teeth
of varying lengths.
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11. JACQUARD’S LOOM
• Joseph Jaquard devised punch cards and
used them to control looms in 1801
• For automation of cotton weaving process.
• The entire operation was under program’s
control.
• Through this historic invention, the
concept of storing and retrieving
information started.
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12. DIFFERENCE ENGINE AND ANALYTICAL
ENGINE
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13. DIFFERENCE ENGINE AND ANALYTICAL ENGINE
• Charles Babbage, an English
mathematician
• Difference Engine -
• 1822
• calculate various mathematical
functions.
• do polynomial evaluation by finite
difference
• theoretically could also solve differential
equations.
• Analytical Engine -
• 1833
• basis of modern computer.
• perform all the four arithmetic
operations as well as comparison.
• It included the concept of central
processor, memory storage and
input-output devices.
• Even the stored information could be
modified.
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14. CHARLES BABBAGE
Both these great
inventions earned him the
title of ‘Father of Modern
Computers’.
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15. MARK 1
• 1944
• Prof. Howard Aiken
• in collaboration with IBM constructed an
electromechanical computer named Mark 1.
• multiply two 10 digit numbers in 5 seconds.
• based on the concept of Babbage’s Analytical engine.
• first operational general purpose computer which could
execute
• Pre-programmed instructions automatically without
any human intervention
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16. VON NEUMANN COMPUTER
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17. VON NEUMANN COMPUTER
• 1945
• Dr. John Von Neumann
• proposed the concept of a stored program computer.
• As per this concept
• the program and data could be stored in the same memory unit.
• According to Von Neumann architecture
• the processor executes instructions stored in the memory of the computer with only one communication channel.
• Hence, the processor at a time can either fetch data or an instruction. That means at one point of time either the
data or an instruction can be picked (fetched) from the storage unit for execution by the processor.
• Therefore, execution takes place in sequential manner.
• This limitation of Von Neumann Computer is known as Von Neumann bottleneck.
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18. ENIAC
Electronic Numerical Integrator and
Calculator
1946
weighed about 27 tons
was of the size 8 feet * 100 feet * 3 feet
consumed around 150 watts of power.
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19. EDVAC
Electronic Discrete Variable
Automatic Computer
first stored program computer
1952
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20. 20
Quiz

21. SUMMARY – EVOLUTION OF
COMPUTER
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22. • Evolution of Computer:
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3000 B.C. ABACUS
1617 NAPIER’S LOG AND BONES
1642 PASCALINE
1673 Leibnitz’s Calculator
1801 Jacquard’s Loom
1822 DIFFERENCE ENGINE
1833 ANALYTICAL ENGINE
1944 MARK 1
1945 Von Neumann Computer
1946 ENIAC
1952 EDVAC

23. GENERATION OF COMPUTERS
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24. CONCEPTS
• What are Vacuum Tubes?
• Vacuum Tubes are delicate glass device that
can control and amplify electronic signals.
• This were widely used in first generation of
computers.
• What is an Integrated Chip or IC ?
• An IC is a small silicon chip or wafer made up
of extremely purified silicon crystals.
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25. Concept:
• What is transistor?
• A transistor is a solid state semiconductor device which are
smaller than vacuum tubes, highly reliable, consumed less
electricity and generated less heat.
• What is magnetic core ?
• Developed in beginning of second generation of computer.
• These are tiny ferrite rings that can be magnetized in either
clockwise or anticlockwise direction so as to represent binary 1
or binary 0.
• Were used as primary memories.
• In later generations used as secondary storage device in form
of magnetic disks.
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26. FIRST GENERATION (1942-1955)
• Concept of stored programs.
• Used thousands of vacuum tubes to control and
amplify electronic signals.
• Huge computers that occupied lot of space
• High electricity consumption and high heat generation
• were prone to frequent hardware failures
• Difficult to have Commercial production
• High Cost
• Required continuous maintenance
• Continuous air conditioning was required
• Programming was done in machine language
• Example : ENIAC , EDVAC , UNIVAC 1
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27. SECOND GENERATION (1955-1964)
• They bring innovation with the use of transistors and
magnetic cores.
• This led to existence of operating system.
• Programming Languages: FORTRAN, COBOL, ALGOL
• Commercial applications of the computer increased
• now the computers were used in business and
industries for applications like
• payroll,
• employee management,
• inventory control etc.
• Eg: :IBM 1401, IBM 1620, UNIVAC 1108
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28. THIRD GENERATION (1964-1975)
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• Used ICs, with numerous transistors, capacitors, resistors and
other electronic devices.
• A small scale integration (SSI) chip used to have -10 transistors
on a single chip.
• A medium scale integration (MSI) chip had - 100 transistors per
chip.
• Memory Size increased.
• Various mainframe computers and minicomputers were
developed during this generation.
• Operating Systems with multitasking and multiprogramming
features were developed.
• ICs made the computers highly reliable, relatively inexpensive
and faster, computers these days were found in areas of
• education,
• small businesses
• offices along with industrial and business applications.
• IBM 360 was a very popular third generation computer.

29. FOURTH GENERATION (1975 ONWARDS)
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30. FOURTH GENERATION (1975 ONWARDS)
• Large Scale Integration (LSI) and Very Large scale integration (VLSI) technology was used by which up
to 300,000 transistors were used on a single chip.
• Thus integration of complete CPU on a single chip was achieved in 1971 and was named
microprocessor which marked the fourth generation of computers.
• computers based on microprocessor technology had faster accessing and processing speeds
• increased memory capacity
• more efficient operating systems were developed
• New concepts of microprogramming, application software, databases, virtual memory etc. were
developed and used.
• Compact and Portable
• Good Accuracy
• Easier Commercial Production
• Beginning of Computer Networks.
• Less Expensive.
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31. First Generation Second
Generation
Third Generation Fourth Generation Fifth Generation
1942 - 1955 1954 - 1964 1964-1975 1975 onwards Still under
development.
Vacuum Tubes Transistors Integrated Chips (IC)s -
transistors, capacitors,
resistors and others.-
with SSI, MSI technology
(IC)s with LSI, MSI
technology -
Microprocessors
ARTIFICIAL
INTELLIGENCE
Size: Huge and
Bulky
Size: Smaller
than 1st gen.
Smaller, Faster, Reliable
Computers with Large
Memory
Compact, Portable, Can
go from one place to
another, small in size
MINI SIZE, BEHAVE
LIKE HUMANS
Consumed Lot of
Electricity
Consumed Less
Electricity
Low power
consumption
Negligible power
consumption
SUPERCOMPUTERS
High Heat
Dissipation
Less Heat
Dissipation.
less emission of heat
as compared to prev.
gen.
Negligible heat
dissipation
PARALLEL
PROCESSING
Costlier Less Expensive Inexpensive Cheap, Very less
production cost
VARIABLE
- - - Networking and data
communication became
popular
Eg: UNIVAC 1 –
used for business
application.
Eg: IBM 1401 &
IBM 1620
Eg: IBM 360 series,
Honeywell 6000
series
Mainframe
computers
DIGITAL
COMPUTERS, NANO
COMPUTERS
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32. DATA AND INFORMATION
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33. • Data can be any character, text, word, number or raw facts.
• Information is data formatted in a manner that allows it to be utilized by human beings in
some significant way.
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34. FUNCTIONAL COMPONENTS OF A
COMPUTER
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35. 35
Figure - A Figure - B

36. FUNCTIONAL UNITS OF COMPUTER
• Input Unit
1. The input unit consists of input devices that are attached to the computer.
2. These devices take input and convert it into binary language that the computer understands.
3. Eg: keyboard, mouse, joystick, scanner etc.
• Output Unit
1. The output unit consists of output devices that are attached with the computer.
2. It converts the binary data coming from CPU to human understandable from.
3. Eg: monitor, printer, plotter etc.
• Arithmetic and Logic Unit (ALU)
1. The ALU, as its name suggests performs mathematical calculations and takes logical decisions.
2. Arithmetic calculations include addition, subtraction, multiplication and division.
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37. • Control Unit
1. The Control unit coordinates and controls the data flow in and out of CPU and also
2. controls all the operations of ALU, memory registers and also input/output units.
3. It is also responsible for carrying out all the instructions stored in the program.
4. It decodes the fetched instruction, interprets (understands) it and sends control signals to input/output devices until the
required operation is done properly by ALU and memory.
• Memory Registers
1. A register is a temporary unit of memory in the CPU.
2. Registers can be of different sizes(16 bit , 32 bit , 64 bit and so on)
3. Accumulator (ACC) is the main register in the ALU and contains one of the operands of an operation to be performed in
the ALU.
• Central Processing Unit (CPU)
1. Once the information is entered into the computer by the input device, the processor processes it.
2. The CPU is called the brain of the computer because it is the control center of the computer.
3. As the CPU is located on a small chip, it is also called the microprocessor.
4. It first fetches instructions from memory and then interprets them so as to know what is to be done.
5. Thereafter CPU executes or performs the required computation and then either stores the output or displays on the
output device.
6. The CPU has three main components which are responsible for different functions – (ALU) , (CU) and Memory registers.37

38. IPO CYCLE
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39. MEMORY UNIT
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Memory Unit
PRIMARY MEMORY (Main Mem)
[INTERNAL MEMORY]
ROM (Read Only
Mem)
RAM (Random Access Mem)
SECONDARY MEMORY (Aux. Mem)
[EXTERNAL MEMORY]
Pen-Drive, FD, CD, DVD, HDD,
SDD, USB, FLASH MEMORY

40. • Memory attached to the CPU is used for storage of data and instructions and is
called internal memory or Primary Memory or Main Memory.
• During processing, it is the internal memory that holds the data.
• The internal memory is divided into many storage locations of the same size and has an
address, each of which can store data or instructions.
• Address helps the computer can find any data easily without having to search the entire
memory.
• When the task is performed, the CU makes the space available for storing data and
instructions, thereafter the memory is cleared and the memory space is then available
for the next task.
• Primary memory is volatile in nature. That means when the power is switched off, the
data stored in this memory is permanently erased.
• That is why secondary memory is needed to store data and information permanently for
later use. Some of the examples of secondary storage devices are hard disk, compact
disks, pen drives etc.
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41. INTERCONNECTIONS BETWEEN
FUNCTIONAL COMPONENTS
BUS ARCHITECHTURE
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42. SYSTEMBUS
CONTROL BUS
DATA BUS
ADDRESS BUS
Bus Architecture
• A bus is a transmission path (set of conducting wires) over
which data or information in the form of electric signals, is
passed from one component to another in a computer.
• The bus can be of three types – Address bus, Data bus
and Control Bus.
• The address bus carries the address location of the
data or instruction.
• The data bus carries data from one component to
another and the control bus carries the control signals.
• the system bus is the common communication path that
carries signals to/from CPU, main memory and
input/output devices.
• The input/output devices communicate with the system
bus through the controller circuit.
• This controller circuit helps to manage various
input/output devices attached to the computer.
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43. 43

44. BOOTING
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45. • CPU runs JUMP
instruction.
• to BIOS
BIOS
• Self-
Diagnostic
• Tests
POST
• Located by
BIOS
• Loads boot
sectorBootable Drive
• On boot sector
• Loads and
executes O.S.
Boot Strap Loader
•Boot Sector checks master
boot rec (MBR)
•Partition Table
•Executes & Load O.S.
MBR
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46. 46

47. 47

48. 48

49. • When the computer is switched on, a copy of boot program is loaded from ROM into the
main memory. This process is called booting.
• The CPU first runs a jump instruction that transfers to BIOS (Basic Input output System)
and it starts executing.
• The BIOS conducts a series of self diagnostic tests called POST (Power On Self Test).
• These tests include memory tests, configuring and starting video circuitry, configuring
the system’s hardware and checking other devices that help to function the computer
properly.
• Thereafter the BIOS locates a bootable drive to load the boot sector.
• The execution is then transferred to the Boot Strap Loader program on the boot sector
which loads and executes the operating system.
• If the boot sector is on the hard drive then it will have a Master Boot record (MBR) which
checks the partition table for active partition.
• If found, the MBR loads that partition’s boot sector and executes it.
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50. Booting
Cold Booting/
Hard Booting
Warm Booting/
Soft Booting
Cold Booting:
• When the system starts from initial state i.e. it is
switched on, we call it cold booting or Hard
Booting.
• When the user presses the Power button, the
instructions are read from the ROM to initiate
the booting process.
Warm Booting:
• When the system restarts or when Reset button
is pressed, we call it Warm Booting or Soft
Booting.
• The system does not start from initial state and so
all diagnostic tests need not be carried out in this
case.
• There are chances of data loss and system
damage as the data might not have been stored
properly.
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51. CLASSIFICATION OF COMPUTER
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52. Classification of
Computer
Digital
Computers
Analog
Computers
Hybrid
Computers
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53. DIGITAL COMPUTER
• These computers, uses digital technology.
• Data of any form of letters, symbols or
numbers is represented in binary form i.e.
0s and 1s.
• Binary digits (1) and (0) means presence or
absence of current or voltage.
• It computes by counting and adding
operations.
• The digital computers are used in industrial,
business and scientific applications.
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54. ANALOG COMPUTER
• An analog computer works on continuously
changeable aspects of physical phenomenon such
as fluid pressure, mechanical motion and electrical
quantities. These computers measure changes in
continuous physical quantities say current and
voltage. These computers are used to process data
generated by ongoing physical processes. A
thermometer is an example of an analog computer
since it measures the change in mercury level
continuously. Although the accuracy of an analog
computer is less as compared to digital computers,
yet it is used to process data generated by
changing physical quantities especially when the
response to change is fast. Most present day analog
computers are well suited to simulating systems. A
simulator helps to conduct experiments repeatedly
in real time environment. Some of the common
examples are simulations in aircrafts, nuclear power
plants, hydraulic and electronic networks.
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