Computer science - cpu test

• nano = 10 to the power of -9

  micro = 10 to the power of -6

  milli = 10 to the power of -3

  one = 10 to the power of 0

  kilo = 10 to the power of 3

  mega = 10 to the power of 6

  giga = 10 to the power of 9

  terra = 10 to the power of 12
• Purpose of the CPU:

  • receive and process data in the fetch-decode-execute cycle.
• Factors that affect the speed of the CPU:

  • cache size
  • clock speed
  • number of cores
• The cache:

  • temporary storage of data
  • stores copies of recent data and instructions
  • Much quicker getting data from the cache than from the RAM
  • the larger the cache, the more data it can fit - improving speed
• Number of cores:

  • a core is, in simple terms, a complete copy of a CPU
  • A quad core processor has four separate processing units, each with its own: registers, ALU, Accumulator, control unit, etc
  • they can improve the CPU speed because, the more cores, the more power the CPU has to run multiple programs at the same time.
• Clock speed:

  • measured in Hz
  • number of cycles per second
  • the more cycles per second, the faster the CPU
• instructions per second = clock speed x number of cores
• Registers:

  • tiny superfast pieces of onboard memory Inside the CPU
  • each has a specific purpose
• Memory address register:

  • Holds the address of the instructions about to be used by the CPU, so they can be located quickly
• Memory data register:

  • holds the actual data of the next instructions
• Control unit:

  • sends signals to control how data moves around the CPU
• Program counter:

  • holds the memory address of the next instruction to be fetched from memory
• Accumulator:

  • holds the result of the calculation
• Embedded system:

  • an embedded system is a system that has a specific task and operates within the main program
• The fetch-decode-execute cycle:

  Fetch:

  • instruction is fetched from memory using the address in the program counter
  • program counter changes to the next instructions address

  Decode:

  • instructions interpreted by the control unit

  Execute:

  • result stored in the accumulator
  • instruction Is carried out
  • the cycle repeats