Programming in C

Introduction to Computing

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Introduction to Computing provides the essential foundation of computer science. This chapter covers fundamentals, computing history, computer components, problem solving, pseudo-code, flowcharts, memory, variables, instructions and programs.

Fundamentals of Computing

  • Computing is using algorithms and machines to transform raw data into useful information.
  • Main purpose: automate tasks, solve problems and perform calculations.
  • Example: Sorting marks to find the highest scorer.
Quick Example
Input: [72, 89, 34, 91]
Output: [91, 89, 72, 34]

Historical Perspective

  • Abacus used for basic calculations.
  • Mechanical calculators such as Pascaline and Leibniz machine.
  • Babbage's Analytical Engine introduced programmability.
  • Electronic development: vacuum tubes, transistors, ICs, microprocessors.
  • Modern computing includes personal computers, cloud, AI and IoT.
timeline-computing

Early Computers and Machines

  • Mechanical: Difference Engine.
  • Electromechanical: Zuse machines, punched card devices.
  • Electronic: ENIAC and EDVAC.
eniac-block

Components of a Computer

  • Input devices such as keyboard and mouse.
  • Output devices such as monitors and printers.
  • CPU contains ALU (arithmetic and logic) and CU (control unit).
  • Primary memory includes RAM and ROM.
  • Secondary memory includes HDD and SSD.
  • Software includes system software and application software.
computer-block-diagram

Problems and Algorithm Characteristics

  • Well-defined problem: has clear input, clear output and defined end state.
  • Ill-defined problem: unclear goals or conditions.
  • Algorithm characteristics: finiteness, definiteness, input, output, effectiveness.
Tip: In exam answers, clearly state if the problem is well-defined and list algorithm characteristics.

Pseudo-code and Flowcharts

  • Pseudo-code expresses the steps of a solution in simple English-like statements.
  • Flowcharts represent logic using shapes: oval (Start/End), rectangle (process), diamond (decision), parallelogram (I/O).
Pseudo-code Example: Sum of first n numbers
READ n
sum ← 0
FOR i FROM 1 TO n
  sum ← sum + i
END FOR
PRINT sum
Flowchart Structure

Start → Input n → Initialize sum → Loop (i ≤ n?) → Add → Update → Output sum → End

flowchart-sum-n

Memory, Variables and Values

  • Memory stores data and instructions in binary.
  • Variables represent named memory locations.
  • Values are actual stored data such as numbers and characters.
  • Data types determine size and operations allowed.
Memory Layout Example
Address   Content
0x1000    0x05     (integer 5)
0x1004    0x00     
0x1008    'A'      (character A)
memory-layout

Instructions

  • Machine instructions are binary codes executed by the CPU.
  • Assembly uses mnemonic symbols.
  • High-level languages require compiling or interpreting.
  • Instruction cycle: Fetch, Decode, Execute, Store.
Assembly-like Example
LOAD R1, 5
LOAD R2, 10
ADD R3, R1, R2
STORE R3, 0x200

Programs

  • A program is a sequence of instructions that performs a task.
  • Lifecycle includes writing, compiling, linking, running, testing and maintaining.
  • Example: Sorting program takes a list, processes it and outputs the sorted form.
program-lifecycle
Course OutlineOverview of C