computer science

• General purpose computer


  Designed to be versatile and can be used for many different tasks
• Embedded system


  Designed to perform a specific task
• General purpose computers


  • Desktop computers
  • Smartphones
  • Tablets
• Embedded systems


  • Pacemakers
  • Microwave ovens
  • Digital watches
• Benefits of embedded systems

  • Cost - typically less expensive than general-purpose computer systems
  • Power consumption - typically consume less power because they are designed specifically for task
• CPU


  • The most important hardware component in a computer
  • Has two main functions: to process data and instructions, and to control the rest of the computer system

  
• Fetch-Decode-Execute (FDE) cycle


  1. Fetch the instruction

  2. Decode the instruction

  3. Execute the instruction

  
• Common CPU components


  • Arithmetic logic unit (ALU)
  • Control unit (CU)
  • Registers
  • Cache
  • Buses
  • Clock

  
• Registers


  • Temporarily store data from the CPU
  • Store results of calculations from ALU
• Cache


  Temporarily hold data and instructions that the CPU is likely to reuse
• Cache is used instead of RAM because it is faster and easier to access, as it is closer to the CPU
• Types of registers


  • Memory Address Register (MAR)
  • Program Counter (PC)
  • Current Instruction Register (CIR)
• Primary memory


  • RAM
  • ROM
  • Flash
  • Cache
  • Virtual Memory
• Primary memory characteristics


  • Permanent (non-volatile) or Volatile
  • Data can be changed or not
  • Speed (ranked 1-4, 1=fastest)
• RAM


  Volatile, data can be changed, speed rank 2
• ROM


  Non-volatile, data cannot be changed, speed rank 3
• Cache


  Volatile, data can be changed, speed rank 1
• Flash memory


  Non-volatile, data can be changed, speed rank 4
• Secondary storage


  • Magnetic storage
  • Optical storage
  • Solid state storage
• Secondary storage characteristics


  • Media
  • Suitability
  • Capacity
  • Durability (1-5)
  • Portability (1-5)
  • Speed (1-5)
• Secondary storage devices


  • Portable hard disk drives
  • CD/DVD/Blu-ray
  • Flash memory drives
• GPU


  Graphics Processing Unit
• RISC processor


  Processes a limited number of relatively simple instructions, breaking down complex commands into a longer list of simpler instructions, allowing for faster processing
• CISC processor


  Able to process complex instructions without having to break them down, but more power consumption and heat produced