Computer Science All-in-One Notes by ACT Malappuram Latest Updated 2025–2026 Comprehensive Study Resource Covering Programming Data Structures Algorithms Databases Networking Operating Systems Software Engineering and Problem Solving for Students Masterin

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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 Control Statements 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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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 • Sexagesimal system
• Left to Right
Babylonian
• Used blank space for 0
Chinese (2500 BC) 10 • Used bamboo rods to represent digits
India (1500 years • Invented a symbol for zero
ago) • Positional decimal system
• Hindu-Arabic Numeral system
Greek (500 BC) 10 • Ionian number system
Roman Numeral • 7 letters[ I, V, X, L (50 ),C (100),
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! !tran sistors ! ! reducin g ! ! 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
developedL byL JackL Kilby
• TransistorsL wereL replaced L byL IC's.
• ItL reducedL size, L increasedL speedL andL andL becameL cheaper.
efficiency,


• HighL LevelL LanguageL BASICL (Beginner’sL AllL PurposeL SymbolicL InstructionL CodeL
)L wasL developed
• Moore'sL LawL statesL thatL the L number L ofL transistorsL on L IC'sL doublesL approximatelyL everyL two
years.
• The L popularL computersL areL IBML 360L andL IBML 370.
4) FourthL GenerationL Computers:

• MicroprocessorsL are L usedL (aL single L chipL withL LargeL ScaleL ofL IntegrationL (LSI) L ofL
electronicL components)
• LaterL LSI L circuitsL wereL replacedL byL VLSIL ( L VeryL LargeL Scale L Integration L ).
• IBML PCL andL Apple L IIL areL popular L computers. L ProgrammingL LanguagesL like. L C, L C++, L JavaL
etc.were L developed.
e). FifthL GenerationL Computers:
• TheyL areL basedL onL ArtificialL IntelligenceL (AI).
• AIL isL theL abilityL ofL machinesL toL simulateL humanL intelligence
• PresentlyL in L theL developmentL stage.
• CommonL AIL programmingL Languages-L LISPL andL Prolog.
Program:
TheL setLofL detailedL instructionsL givenL toL aL computerL forL executingL specificL tasks.
Programming L languagesL areL artificial L languagesL designedL to L giveL instructionsL toL the L computers.
• MachineL languageL (LowL LevelL LanguageL -LLL).consistsL ofL 0'sL andL 1's.L ThisL isL the L onlyL
languageL understood L byL the L computer.
• AssemblyL language, L withL EnglishL likeL wordsL insteadL ofL 0'sL andL 1'sL EDSACL (Electronic L
DelayL StorageL AutomaticL CalculatorL ) L builtL in L 1949 L wasL theL firstL computerL toL useL
assemblyL language.
• Later, L High L LevelL LanguagesL (HLL)L like, L BASIC, L C, L C++,L JavaL etcL wereL developed.
AlgorithmL andL ComputerL programs:
An L algorithmL isL aL stepL byL stepL procedureL to L solveL aL problem.
TheoryL ofL computing:
• ThisL branchL dealsL with L howL efficientlyL problemsL canL beL solvedL basedL on L computation L
modelsL andL relatedL algorithms. L TheL studyL isL basedL on L aL mathematical L abstraction L ofL
computersL calledL modelL ofL computation.
• TheL mostL commonlyL usedL modelL isL TuringL machineL namedL afterL the L computerL scientistL Alan
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