Paper 2

• Computational Thinking

  • The use of computers to solve problems
  • Development of algorithms to solve problems
  • Using abstraction, decomposition and algorithmic thinking
• Decomposition


  Breaking down the problem into smaller ones which we might solve individually
• Abstraction


  Thinking about what information/data is important in the problem, and what details we should ignore
• Algorithmic thinking


  The logical process of getting from the problem to the solution. The steps needed to build the required algorithms
• Computational thinking is a systematic approach to solving problems
• Decomposition


  • Breaking down the problem into smaller ones which we might solve individually
  • Smaller problems are easier to solve
  • They can be solved independently of the other problems
  • They can be tested independently
  • Then combined to produce the full problem
• Abstraction


  • The process of removing unnecessary information and focussing on the important details
  • Allows you to develop a general idea of what the problem is and how to solve it
• Abstraction


  • Saving a file on a computer
  • Using a map
• Pseudocode


  Fake code, between English and programming code, a language neutral way to represent an algorithm
• Pseudocode


  • Data items to be processed are given meaningful names like variables and constants in high-level programming languages
• Algorithm


  A sequence of steps to solve a problem
• Programming Constructs


  • Sequence - order in which things happen
  • Selection - choosing between possible actions (e.g. If, Elif)
  • Iteration - repeating actions, often referred to as LOOPS (e.g. Forever BLOCK in Scratch, While - Python)
• Developers should plan and design before programming
• Pseudocode is a clear and concise way to represent an algorithm
• Advantages of Pseudocode


  • Can be done easily on a word processor
  • Easily modified
  • Implements structured concepts well unlike flowcharts
• Disadvantages of Pseudocode


  • It's not visual
  • There is no accepted standard, so it varies widely from company to company
• There are many computer languages (e.g. C, Python), most are built from the same basic "building blocks" called programming constructs
• George Boole (1815 - 1864) was an English mathematician and the author of "Mathematical Analysis of Logic" written in 1847, in which he introduced the world to Boolean logic
• Inside a computer there are circuit boards and on these circuit boards are chips which use Boolean logic gates and are the foundation for how computers work
• Types of logic gates

  • AND
  • OR
  • NOT
• Logic gates


  Take some form of input on the left-hand side, process these inputs through the gate and deliver an output on the right-hand side

  
• Logic gate inputs and outputs

  Usually represented by a 1 or a 0 to represent true or false
• AND logic gate


  • Has two inputs and one output
  • If both inputs are true, the output is true
  • If either or both inputs are false, the output is false
• OR logic gate


  • Has two inputs and one output
  • If either or both inputs are true, the output is true
  • Only if both inputs are false, the output is false
• NOT logic gate


  • Has one input and one output
  • Produces the opposite output to the input (true becomes false, false becomes true)
• Solving logic circuits


  1. Start from the inputs on the left and work across the diagram

  2. Use binary counting to populate the input table

  3. Work out the output columns based on the logic gate rules
• Logic circuits can have more than two inputs and multiple logic gates combined
• Solving logic circuits without a full truth table


  1. Determine the output of each logic gate based on the given inputs

  2. Work through the circuit step-by-step to find the final output
• what gate is this?

  a AND gate

  
• What gate is this?

  a OR gate

  
• What gate is this?

  a NOT gate

  
• Learning the concepts behind your code and learning the terms and how they work and why it's advantageous to do certain things in programming is so important
• The difference between an average programmer and a very talented programmer is that the talented programmer understands what's going on in their code
• Data types are a means of classifying different types of data
• Data types


  Determine properties like what operations can be performed on the data and how it will be stored
• Basic primitive data types

  • Integer
  • Real/Float
  • Boolean
  • Character
  • String
• Integer


  A whole number
• Real/Float


  A number with a decimal part
• Boolean


  One of two values: true or false, 1 or 0
• Character


  A letter, number or symbol in a given character set