PROGRAMMING

1. The Computing Model

Programming acts as the bridge between a human-defined task and the physical electronic devices that execute it. The layers of this model include:

• 
  

  Task & Algorithm: The conceptual problem and the step-by-step solution.

  
  

• 
  

  Program: The algorithm expressed in a specific programming language.

  
  

• 
  

  Instruction Set Architecture (ISA): The boundary between software and hardware.

  
  

• 
  

  Microarchitecture, Logic Gates, & Devices: The physical implementation that executes the instructions.

  
  

2. Low-Level Languages

Machine Language

• 
  

  Definition: A language consisting of binary-coded instructions built into a computer's hardware and used directly by the CPU.

  
  

• 
  

  Characteristics: Every processor type has its own specific Instruction Set, and instructions typically perform only one very basic task.

  
  

Assembly Language

• 
  

  Definition: A low-level language that replaces binary opcodes with mnemonics (e.g., ADD, MOV) and replaces binary addresses with names.

  
  

• 
  

  Assembler: A program that translates assembly language code into machine code.

  
  

3. High-Level Languages & Translation

High-level languages allow programmers to write code that is more "human-readable" and independent of specific hardware.

• 
  

  Compiler: A program that translates a high-level language (like C++ or Java) into machine code or an intermediate code all at once before execution.

  
  

• The Process:

  1. 
     

     Source Code: The high-level instructions written by the programmer.

     
     

  2. 
     

     Translation: The compiler checks for syntax errors and converts the code.

     
     

  3. 
     

     Object Code: The machine language version produced by the compiler.

     
     

4. Expressing Logic: Pseudocode

Pseudocode is a way to express algorithms using a mixture of English and programming logic without worrying about strict syntax.

Core Constructs:

• 
  

  Variables: Used to store data (e.g., Set count to 1).

  
  

• 
  

  Selection (Control Flow): Choosing between different paths of execution using IF, ELSE IF, and ELSE statements.

  
  

• 
  

  Repetition (Looping): Repeating a series of statements as long as a condition is met (e.g., WHILE loops).

  
  

5. Software Testing

To ensure a program works correctly, developers use a Test Plan, which specifies how many times and with what data the program must be run.

Testing Approaches:

• 
  

  Code Coverage (White Box/Clear Box): Designing test cases by looking at the internal logic and structure of the code itself.

  
  

• 
  

  Data Coverage (Black Box): Designing test cases based on the range of allowable input and output data values, without looking at the internal code.

  
  

• 
  

  Implementation: Using the test cases to verify that the program produces the expected results.