Updated Latest Computer Science All in One Notes Comprehensive Study Guide With Programming Concepts Algorithms Data Structures Networking Database Management Systems Web Development Operating Systems Cyber Security and Software Engineering Revision Resou

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ACT – ASSOCIATION OF COMPUTER TEACHERS
MALAPPURAM



ComprehensiveStudy Notes on

COMPUTER SCIENCE
CLASS XI
Contents

1 The discipline of Computing 2

2 Data Representation and Boolean Algebra 6

3 Components of Computer System 15

4 Principles of programming and problem solving 24


5 Introduction to programming 28

6 Data types and operators 30

7 Contro Statements
F 35

8 Arrays 40

9 String handling using I/O functions 45

10 Functions 47

11 Computer networks 52

12 Internet and mobile computing 60

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2

CHAPTER 1
The discipline of Computing


Computing milestones and machine evolution
1. Development of number systems:

Origin Base Features
Egyptians (3000 BC) 10 • Right to left
Sumerian/ 60 • Sexagesima system F



• Left to Right
Babylonian
• Used blank space for 0
Chinese (2500 BC) 10 • Used bamboo rods to represent digits
India (1500 years • Invented a symbo for zero F



ago) • Positiona decima system
F F



• Hindu-Arabic Numera system F




Greek (500 BC) 10 • Ionian number system
Roman Numeral • 7 letters[ I, V, X, (50 ),C (100),
F



D(500), M (1000 ) ]
Mayans 20 • Great accuracy


Evolution of the computing machine:
1.Abacus:
• means calculating!!board.

• Discovered!!by!!the!!Mesopotamians.
• Used!!for!!arithmetical!!calculations.
2. Napier's!!bones.
• John! ! Napier! ! invented! ! a! ! set! ! of! ! numbered! ! rods! ! to! ! simplify! ! multiplication! ! process! ! (
Napier's!!bones).
• He also!!invented!!logarithm.
3. Pascaline:
• Blaise! ! Pascal!!developed!!in!!1642
• can! ! perform! ! arithmetic operations.
al


• Operated!!by!!dialling! ! a!!series!!of!!wheels,!! gears!!and!!cylinders.
4. Leibniz's calculator! ! ! ! :
• Leibniz! ! designed! ! a! ! calculating! ! machine!!called!!step!!reckoner.
• Expanded!!on!!Pascal’s!!idea!!to!!perform!!multiplication!!and!!division!!too.




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5. Jacquard's!!loom:
• Joseph! ! Jacquard!!invented!!a!!mechanical!!loom!!to!!simplify !! a!!textile !! manufacturi
ng ! ! process.
• The! ! loom! ! controlled! ! by!!punched!!cards!!had!!the!!ability!!to!!store!!information.
6. Difference!!Engine
• Developed!!by!!Charles!!Babbage
• compile!!mathematical!!tables,!!do!!arithmetical!!operations!!and!!print!!results!!automatically.
• Developed! ! by! ! Charles! ! Babbage! ! in! ! 1833
• Had!!many!!essential!!features!!found!!in!!modern!!digital!!computer.
• Programmable!!using!!punched!!cards
• It!!had!!a!!store!!(memory)!! and!!a!!separate!!‘Mill’!!(Processor)
8. Hollarith’s!!Machine
• Herman!!Hollarith!!made!!first!!electromechanical!!punched!!card!!tabulator!!with!!input,!!output!!a
nd!!instructions.
• Used!!electricity!!to!!read,!!count!!and!!sort!!punched!!cards.
9. Mark-I Computer:
• Developed!!by!!Howard!!Aiken
• Could! ! do! ! all!! 4! ! arithmetic!!operations,logarithmic!! and!!trigonometric!!functions.
Generations!!of!!Computer
1) First!!generation!!computers:
• Used!!Vacuum!!tubes
• The! ! ENIAC!! (Electronic! ! Numerical! ! Integrator! ! and! ! Calculator! ! ),! ! the
first!!general! ! purpose! ! programmable! ! electronic!!computer(built! ! by!!J.! ! P.! ! Eckert!!and! ! John!!
Mauchly.)
• UNIVAC(! ! UNIVersal! ! Automatic! ! Computer! ! ).! ! -! ! first! ! commercially! ! successful!! computer
• Von!!Neumann!!designed! ! EDVAC(! ! Electronic!!Discrete!!Variable!!Automatic! ! Computer!!)
with! ! a!!memory!!to!!store!!program!!and!!data.(!!stored!!program!!concept)
2) Second! ! Generation! ! Computers! ! :
• Vacuum! ! tubes! ! were! ! replaced! ! by!! transistors ! ! reducing ! ! size.
• less! ! electricity,! ! less! ! expensive.
• Concept!!of!!programming!!language!!was!!developed.!! High!!Level!!Languages!!like!!FORTAN
(FORmula! ! ! ! TRANslation),! ! COBOL!!(COmmon Business! ! Oriented! ! Language)! ! ! ! developed.
• Magnetic! ! core! ! memory! ! (Primary!!memory! ! )! ! and! ! magnetic! ! disk! ! memory! ! (Sec
ondary!!memory!!).
• The! ! popular!! computers! ! are! ! IBM! ! 1401! ! and!!IBM!!1620




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3) Third! ! Generation!! Computers:
• Silicon! ! chips! ! or! ! IC(Integrated Circuits)!!that!!contain!! very!! small!!transistors!!were
developed by Jack Kilby F F F




• Transistors were replaced by IC's. F F F F




• It reduced size, increased speed and efficiency, and became cheaper.
F F F F F F F F




• High Level Language BASIC (Beginner’s All Purpose Symbolic Instruction Code )
F F F F F F F F F F F




was developed F




• Moore's Law states that the number of transistors on IC's doubles approximately every two
F F F F F F F F F F F F F




years.
• The popular computers are IBM 360 and IBM 370.
F F F F F F F F




4) Fourth Generation Computers:
F F




• Microprocessors are used (a single chip with Large Scale of Integration (LSI) of electronic F F F F F F F F F F F F F F




components)
• Later LSI circuits were replaced by VLSI ( Very Large Scale Integration ).
F F F F F F F F F F F F




• IBM PC and Apple II are popular computers. Programming Languages like. C, C++, Java etc.were
F F F F F F F F F F F F F F F




developed.
e). Fifth Generation Computers:
F F




• They are based on Artificial Intelligence (AI).
F F F F F F




• AI is the ability of machines to simulate human intelligence
F F F F F F F F F




• Presently in the development stage. F F F F




• Common AI programming Languages- LISP and Prolog. F F F F F F




Program:
The set of detailed instructions given to a computer for executing specific tasks.
F F F F F F F F F F F F




Programming languages are artificial languages designed to give instructions to the computers.
F F F F F F F F F F F




• Machine language (Low Level Language -LLL).consists of 0's and 1's. This is the only language
F F F F F F F F F F F F F F F




understood by the computer. F F F




• Assembly language, with English like words instead of 0's and 1's EDSAC (Electronic Delay
F F F F F F F F F F F F F F




Storage Automatic Calculator ) built in 1949 was the first computer to use assembly language.
F F F F F F F F F F F F F F




• Later, High Level Languages (HLL) like, BASIC, C, C++, Java etc were developed.
F F F F F F F F F F F F




Algorithm and Computer programs: F F F




An algorithm is a step by step procedure to solve a problem.
F F F F F F F F F F F




Theory of computing:
F F




• This branch deals with how efficiently problems can be solved based on computation models
F F F F F F F F F F F F F F




and related algorithms. The study is based on a mathematical abstraction of computers called
F F F F F F F F F F F F F F




model of computation. F F




• The most commonly used model is Turing machine named after the computer scientist Alan
F F F F F F F F F F F F F




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Turing. He is considered as the Father of modern computer science and Artificial intelligence.
F F F F F F F F F F F F F




Turing machine:
F




• Introduced by Alan Turing F F F




• Theoretical device that uses symbols on a long tape (acting like memory)
F F F F F F F F F F F




• The tape contains cells with a blank, 0 or 1
F F F F F F F F F




• The action decided by the current state, symbol currently being read and table of transition
F F F F F F F F F F F F F F F




rules.
• Considered as the first theoretical development towards the idea of Artificial Intelligence.
F F F F F F F F F F F




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CHAPTER 2 F




Data Representation and Boolean Algebra
F F F F




Number system
F




• The number of symbols used in a number system is called base or radix.
F F F F F F F F F F F F F




Number System Base Symbols used F F Example

Binary 2 0, 1 F (1101)2
Octal 8 0, 1, 2, 3, 4, 5, 6, 7
F F F F F F F (236)8
Decimal 10 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
F F F F F F F F F (5876)10
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
F F F F F F F F F F F F F F F




Hexadecimal 16 (A, B, C, D, E, F represents 10, 11, 12, 13, 14, 15
F F F F F F F F F F F F (12AF)16
respectively)

• MSD: The leftmost digit of a number is called Most Significant Digit (MSD).
F F F F F F F F F F F F




• LSD: The right most digit of a number is called Least Significant Digit (LSD).
F F F F F F F F F F F F F




Number Conversions
F




Decimal to binary conversion
F F F




Repeated division by 2 and grouping the remainders( 0 or 1)
F F F F F F F F F F




Example: Convert (30)10 to binary.
F F F F




2 Remainders F




2 0

2 1

2 1

2 1
0 1



(30)10 = (11110)2
F F




Decimal fraction to binary
F F F




1. Multiply the decimal fraction by 2.
F F F F F




2. Integer part of the answer will be first digit of binary fraction.
F F F F F F F F F F F




3. Repeat step 1 and step 2 to obtain the next significant bit of binary fraction.
F F F F F F F F F F F F F F




Example: Convert (0.625)10 to binary.
F F F F




0.625 x 2 = 1.25 F F F F




1 0.25 x 2 = 0.50
F F F F




0 0.50 x 2 = 1.00
F F F F




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F F F F F F

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(0.625)10 = (0.101)2 F F




Decimal to Octal conversion
F F F




Repeated division by 8 and grouping the remainders.(0,1,2,3,4,5,6 or 7)
F F F F F F F F F




Example: Convert (120)10 to octal. F F F F




8 120 Remainders
8 15 0
8 1 7 (120)10 = (170)8 F F




8 0 1

Decimal to Hexadecimal conversion
F F F




Repeated division by 16 and grouping the remainders( 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E or F)
F F F F F F F F F F




Example: Convert (165)10 to hexadecimal. F F F F




16 165 Remainders F




16 10 5

16 0 10 (A) F
(165)10 = (A5)16 F F




Binary to decimal conversion
F F F




Multiply binary digit by place value (power of 2) and find their sum.
F F F F F F F F F F F F




Example: Convert (110010)2 to decimal. F F F F




(110010)2 = 1×25 + 1×24 + 0×23 + 0×22 + 1×21 + 0×20
F
F
F
F
F
F
F
F
F
F
F Weight 25 24 23 22 21 20
= 32 + 16 + 0 + 0 + 2 + 0 = (50)10
F F F F F F F F F F F F F Bit 1 1 0 0 1 0

Binary fraction to decimal
F F F




Multiply binary digit by place value (negative power of 2) and find their sum.
F F F F F F F F F F F F F F




Example: Convert (0.101)2 to decimal. F F F F
Weight 2-1 2-2 2-3
(0.101)2 = 1×2-1 + 0×2-2 + 1×2-3
F F
F
F
F
F Bit 1 0 1

= 0.5 + 0 + 0.125 = (0.625)10
F F F F F F F




Octal to decimal conversion
F F F




Multiply octal digit by place value (power of 8) and find their sum.
F F F F F F F F F F F F




Example: Convert (167) 8 to decimal. F F F F F




(167) 8 = 1×82 + 6×81 + 7×80
F F
F
F
F
F

Weight 82 81 80
= 64 + 48 + 7 = (119)10
F F F F F F F

Octa digit F 1 6 7
Hexadecimal to decimal conversion F F F




Multiply hexadecimal digit by place value (power of 16) and find their sum.
F F F F F F F F F F F F




Example: Convert (2B5) 16 to decimal. F F F F F




(2B5) 16 = 2×162 + 11×161 + 5×160
F F
F
F
F
F

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= 512 + 176 + 5
F F F F F




= (693)10
F




Octal to binary conversion
F F F




Converting each octal digit to its 3 bit binary equivalent. F F F F F F F F F




Octal digit F 0 1 2 3 4 5 6 7
Binary equivalent F 000 001 010 011 100 101 110 111


Example: Convert (437)8 to binary. F F F F




3- bit binary equivalent of each octal digits are
F F F F F F F




4 3 7

(437)8 = (100011111)2 F F
100 011 111

Hexadecimal to binary conversion F F F




Converting each hexadecimal digit to its 4 bit binary equivalent.
F F F F F F F F F




Example: Convert (AB)16 to binary. F F F F




Octal digit F 0 1 2 3 4 5 6 7 8 9 A B C D E F

Binary equivalent F 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111

4- bit binary equivalent of each hexadecimal digits are
F F F F F F F




(AB)16 = (10101011)2 F F




Binary to octal conversion
F F F




Form groups of 3 bits each from right to left and then convert each to its octal form
F F F F F F F F F F F F F F F F F




Example: Convert (10111000011) 2 to octal. F F F F




Group the given binary number from right as shown below:
F F F F F F F F F




010 111 000 011
if the left most group
F F F F F


does not have 3 bits, F F F F F (10111000011)2 = (2703)8 F F



then add leading zeros
F F F F
2 7 0 3
to form 3 bit binary.
F F F F




Binary to Hexadecimal conversion
F F F




Form groups of 4 bits each from right to left and then convert each to its hexadecimal form
F F F F F F F F F F F F F F F F F




Example: Convert (100111100111100)2 to hexadecimal.
F F F F




0100 1111 0011 1100 (100111100111100)2 = (4F3C)16 F F

if the left most group
does not have 4 bits,
then add leading zeros 4
to form 4 bit binary. 15(F) 3 12(C)




Octal to hexadecimal conversion
F F F




Convert octal to binary and then binary to hexadecimal.
F F F F F F F F




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Example: Convert (537)8 to hexadecimal equivalent.
F F F F F F




First convert (537)8 into binary.
F F F F




5 3 7

= (101011111)2
F

101 011 111



Then convert (101011111)2 into hexadecimal.
F F F F




0001 0101 1111


1 5 15(F) = (15F)16
F




(537)8 = (15F)16 F F




Hexadecimal to octal conversion
F F F




Convert hexadecimal to binary and then binary to octal.
F F F F F F F F




Example: Convert (A3B)16 into octal equivalent.
F F F F F F




First convert (A3B)16 into binary.
F F F F




= (101000111011)2
F




Then convert (101000111011) 2 into octal.
F F F F




101 000 111 011
= (5073)8
F (A3B)16 = (5073)8 F F



5 0 7 3



Representation of integers F F




3 methods : (i) Sign and magnitude representation, (ii) 1’s complement representation &
F F F F F F F F F F F F




(iii) 2’s complement representation
F F F




i) Sign and magnitude representation (8 bit form)
F F F F F F




• Find binary equivalent of integer
F F F F




• Make the first bit 1 for negative numbers and 0 for positive numbers.
F F F F F F F F F F F F




= 10111
= 00010111
Sign and magnitude of +23 = 00010111


= 10111
= 00010111
Sign
and magnitude of -23 = 10010111
ii) 1’s complement representation
F F




• If the number is negative, it is represented as 1’s complement of 8-bit form binary.
F F F F F F F F F F F F F F




• 1’s complement of a binary is obtained by changing 0 to 1 and 1 to 0.
F F F F F F F F F F F F F F F




• If the number is positive, the 8-bit form binary itself is the 1’s complement.
F F F F F F F F F F F F F




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Example: Represent +23 in 1’s complement form.
F F F F F F




Binary of 23 in 8-bit form = (00010111)2
F F F F F F F




+23 in 1’s complement form = (00010111)2(For +ve numbers, no need to find 1’s
F F F F F F F F F F F F F F




complement)
Example: Represent -23 in 1’s complement form.
F F F F F F




Binary of 23 in 8-bit form = (00010111)2
F F F F F F F




-23 in 1’s complement form = (11101000)2
F F F F F F F F (by replacing 0 with 1 and 1 with 0)
F F F F F F F F




iii) 2’s complement representation
F F




• 2’s complement of a binary number is calculated by adding 1 to its 1’s complement.
F F F F F F F F F F F F F F




• If the number is negative, it is represented as 2’s complement of 8-bit form binary.
F F F F F F F F F F F F F F




• If the number is positive, 8-bit form binary itself is the 2’s complement.
F F F F F F F F F F F F




Example: Represent +23 in 2’s complement form.
F F F F F F




Binary of 23 in 8-bit form = (00010111)2
F F F F F F F




+23 in 2’s complement form = (00010111)2(For +ve numbers, no need to find 2’s
F F F F F F F F F F F F F F




complement)
Example: Represent -23 in 2’s complement form.
F F F F F F




Binary of 23 in 8-bit form F F F F F = (00010111)2
F




-23 in 1’s complement form = (11101000)2
F F F F F F F (by replacing 0 with 1 and 1 with 0)
F F F F F F F F




-23 in 2’s complement form = 11101000 +
F F F F F F F




1
= (11101001)2
F




Representation of floating point numbers F F F F




• Any number in floating point notation contains two parts, mantissa and exponent.
F F F F F F F F F F F




• Eg: 25.45 can be written as 0.2545×102, where 0.2545 is the mantissa and the power 2 is the
F F F F F F F F F F F F F F F F F F




exponent.

Representation of characters F F




Different methods to represent characters in computer memory are: ASCII, Unicode, ISCII,
F F F F F F F F F F F F




EBCDIC

ASCII(American Standard Code for Information Interchange) F F F F F




• Uses 7 bits per character, can represent only 128 characters.
F F F F F F F F F




• ASCII-8, which uses 8 bits, can represent 256 characters.
F F F F F F F F




EBCDIC(Extended Binary Coded Decimal Interchange Code) F F F F F




• 8 bit code used in IBM Machines. It can represent 256 characters.
F F F F F F F F F F F




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