Computing Topic 1

• What is the CPU and what does it control?

  Central Processing Unit, the circuitry that controls the manipulation of data.
• What does the CPU consist of?

  ALU, control unit, registers
• What is the ALU's function?

  Circuits that perform operations on data
• What is the control unit's function?

  circuits coordinating the activities of the CPU.
• What is the registers function?

  Quick, small stores of data within the CPU.
• What is the Von Neumann Architecture?

  architecture which stores a program in memory as instructions and executes them sequentially using the ALU, control unit and registers

  
• What is the fetch-execute cycle?

  • Fetch - next instruction is retrieved via the CPU from main memory.
  • Decode - instructions are broken down into components to determine what the instruction is and what data is being used.
  • Execute - The control unit (CU) activates necessary circuit/data transfers
• What is a register?

  Small storage space for temporary data in CPU
• What is a PC?

  Personal Computer or program counter. A register that tracks RAM address of the next instruction to be fetched.
• What is the Memory Address Register (MAR) ?

  A register that tracks the RAM address of the instruction that is needed to be fetched.
• What is the Memory Data Register (MDR) ?

  Stores instructions that have been transferred from RAM to CPU.
• What is the Current Instruction Register (CIR) ?

  Stores the instructions that has been fetched from RAM, and is about to be decoded or executed.
• What is the accumulator (ACC)?

  Register that stores results of mathematical or logical instructions.
• What is cache memory?

  Temporary storage for frequently accessed data.
• What are benefits of cache memory?

  • Closer to CPU than RAM meaning data and instructions can be provided to the CPU at a faster rate.
  • More cache memory means higher performance as frequently used instructions can be stored and accessed faster.
• What are limitations of cache memory?

  Costly, so most computers have a small amount.
• What is clock speed and what is it measured in?

  Clock speed is the speed at which the CPU can process instructions, measured in Gigahertz (GHz).
• How does quicker clock speed improve performance?

  The FDE cycle is performed faster by the computer and offers better performance as more instructions are processed each second.
• What is the default clock speed?

  3.5 GHz
• What is meant by overclocking?


  When speed is increased (3.9GHz). Computer performs faster but may overheat causing the machine to be damaged
• What is meant by underclocking?


  When speed is decreased (3.1GHz). Computer performs slower but increases lifespan.
• What is a core & and multi-core?


  Core - A complete set of CPU components

  Multi-core: More than one set of components within the same CPU
• How does number of cores affect performance?


  More cores means higher performance as computer can process more instructions at once
• What are limitations of having more cores?


  One core may be waiting for another core to finish processing, leading to performance not increasing at all.

  
  

  Some software is not written to make use multiple cores, so it will not run any quicker.
• What is an embedded system?


  A computer system built into a larger machine to provide a means of control. They perform specific tasks which is stored in ROM.
• What are examples of embedded systems?


  Smartphones, smartwatches, traffic lights, and home appliances such as refrigerators and washing machines.