1.1 - System Architecture

• What is a general purpose computer?


  A computer designed to be able to carry out a wide range of instructions e.g. PC, Phones
• What do general purpose computers consist of?


  Hardware - Physical components.

  Software - Programs that run on a computer.
• What are the two purposes of the Central Processing Unit?


  To process data and instructions.

  To control rest of computer system.
• What is an embedded system?


  A special purpose computer built into another device e.g. Calculators
• Advantage and Disadvantage of Embedded Systems?


  1. Tend to require less power.
  2. Limited number of functions.
  3. Cheaper to design and build.
• Name the Three Factors affecting CPU performance?


  1. Clock Speed
  2. Number of Core
  3. Cache Size
• How does each factor affect CPU performance?


  1.Clock Speed - Higher clock speed more instructions can be processed, 1 hertz = 1 billion fetch-decode-execute cycles.

  2.Number of Cores - More cores more instructions, each core in a CPU process data independently of the rest.

  3. Cache Size - Temporary memory of a small amount of highspeed RAM, bigger cache, less time processer has to wait for instruction.
• Describe the General Purpose Computer model?

  • CPU receives data and instructions from a input or memory.
  • Data and instructions processed by CPU and results to output or secondary storage.
• What is an input and output device and an example of each?


  Input - Device used to input data or information into computer. e.g. Keyboard or mouse.

  Output - Device used to output data or information from a computer. e.g. Monitor
• What is the 4 main parts of the CPU?

  1. Control Unit
  2. Arithmetic Logic Unit
  3. Cache
  4. Registers
• What is the function of the control unit?


  Fetches, decodes, executes instructions, issues control signals that control hardware and moves data around the system.
• What is the function of the arithmetic logic unit?


  Performs arithmetic and logical operations, performs calculations.
• What is the function of Cache?


  Small amounts of high-speed random access memory built directly within the processor and used to temporarily hold data and instructions and allows for faster processing.
• What is the function of registers?


  Small amounts of high-speed memory contained in the CPU?
• What is the function of the program counter?


  Hold the memory address of the next instruction to be fetched from primary memory.
• What is the function of the accumulator?


  Holds the data being processed and the results of processing.
• What is the function of Buses in the CPU?


  A channel of communication used to transport data and instructions in the CPU.
• What is the function of the Memory Address Register (MAR)?


  Holds the address of the current instruction that is to be fetched from memory or the address in memory to be which data is to be transferred.
• What is the function of Memory Data Register? (MDR)


  Holds the contents found at the address held in the MAR, or data which is to be transferred to primary memory.
• What are the main aspects on Von Neuman Architecture?

  • Data and instructions stored as binary digits
  • Data and instructions stored as primary memory
  • Decodes and executes instruction, before cycling around to fetch next instructions until no more instructions are available
• Explain the fetch-decode- execute?

  Fetch:

  1. Copy memory address from the program counter to the MAR.
  2. Copy the instruction stored in the MAR to the MDR.
  3. Increase Program Counter to point to the address ready for next cycle.

  Decode:

  4. Instruction in the MDR is decoded by the control unit.

  5. Control Unit prepare the next stop.

  
  

  Execute:

  6. Instruction is performed e.g. Calculation, halt program, load data from memory
• What is a input device?


  Device used to enter data into a computer.
• What is a output device?


  Device used to present information.