Topic 1: Hardware and communication

• Abstraction


  Simplifying a complex problem by paying attention to the important ones and ignoring the unnecessary
• Decomposition


  Breaking down of a complex program into simpler forms so that it can be easily solved
• Algorithm


  List of instructions that are required to be followed while solving a problem
• Sequence


  The order in which instructions occur and are processed
• Selection


  Determines which path a program takes when it's running, also known as 'IF statements' or branching
• Iteration/Repetition


  The repeated execution of a section of code when a program is running, also known as loops or looping
• Types of Iteration


  • Count Controlled - Repeatedly executes a section of a code a fixed number of predetermined times
  • Condition Controlled - Repeatedly executes a section of a code until a condition is met
• An Algorithm can either be represented in flow charts or pseudocode
• Data Types


  • Integer - Whole numbers, Positive and Negative numbers
  • Real - Numbers, including fractions and decimal points
  • Char(Character) - Letter, digit, space, punctuation mark, or various other symbols
  • String - A sequence of characters
  • Boolean - True or False
• Sequence


  The most common programming construct, the order in which a program runs or is executed
• Selection


  The process of determining the path that a program takes when it's running, by testing a condition
• Count-controlled iteration


  Repeatedly executes a section of code a fixed number of predetermined times, using for and next statements
• Condition-controlled iteration


  Repeatedly executes a section of code until a condition is met, using while repeat, repeat until, or do loop statements
• Key Terms


  • Cores - Individual processors within a CPU
  • Bus - Part of a computer architecture used to transfer data between components
  • MDR - A register that contains data either just in from or about to depart for the main memory
  • Registers - Low-capacity storage locations within the CPU
  • Address - Each memory location is identified by one
  • ALU - Performs arithmetic and logical functions in a CPU
  • Control Unit - Part of the CPU that coordinates the flow of data
  • Clock Speed - The frequency at which a CPU operates
• ROM


  Read-Only Memory, a small piece of non-volatile memory on the motherboard containing the first instructions for the computer
• RAM


  Random-access Memory, a volatile memory that holds information being executed by the processor
• Cache Memory


  • Integrated directly within the CPU
  • Stores frequently used program instructions and immediate results of calculations
  • Acts as a 'middleman' between the processor and the memory
  • Faster than RAM but smaller and more expensive
• Clock Speed


  The amount of instructions the CPU can carry out per second, measured in hertz
• Multicore Processor


  A single chip containing two or more independent processing units, allowing more than one instruction to be carried out at a time
• Parallel Processing


  Two or more processors working together to perform a single task, by splitting it into smaller sub-tasks executed simultaneously
• Network


  Two or more computers connected together for the purpose of communication
• Advantages of a Network


  • Ability to share hardware
  • Ability to share software
  • Ability to share data/Files
  • Central backup of data
• Disadvantages of a Network


  • It can be expensive
  • Hackers can gain access to data more easily
  • If the server is down, all workstations on the network can be affected
• LAN


  Local Area Network
• WAN


  Wide Area Network
• Network Topology


  The arrangement of the links and nodes in a network
• Bus Topology


  Nodes are connected via a single cable or backbone, messages are sent to all nodes across the backbone
• Advantages of Bus Topology


  • Cost-effective, less cabling, easy to set up, easy to expand
• Disadvantages of Bus Topology


  • Difficult to troubleshoot, Data collisions are more likely to occur
• Data Collisions


  When two sets of data are detected on the network simultaneously, causing the network to slow down
• Ring Topology


  Data travels around the ring in one direction, preventing data collisions
• Advantages of Ring Topology


  • Prevents data collisions, Data is quickly transferred without a bottleneck
• Disadvantages of Ring Topology


  • Difficult to troubleshoot, if there is a problem with the main cable, the whole network goes down
• Star Topology


  All nodes connect via a central node, the most common network topology
• Advantages of Star Topology


  • Easy to set up, Better security, Non-centralized failure has little impact
• Disadvantages of Star Topology


  • Very expensive to install, needs extra hardware
• Network Devices


  • Network interface card (NIC) - Enables wired network connection
  • Wireless network interface card (WNIC) - Enables wireless network connection
  • Router - Stores addresses of computers on the network
  • Switch - Looks at each packet of data and sends it to the one it was intended for
  • Hub - Broadcasts data to all devices on a network
  • Bridge - Used for linking a network between buildings