1.1

• What is the function of the CPU?

  The function of the CPU is to process and execute instructions using the FDE cycle.
• What does the FDE cycle stand for?

  The FDE cycle stands for fetch, decode and execute.
• What is the FDE cycle?

  The FDE cycle is a sequence of steps performed by the CPU to process a single instruction. It's the fundamental operation cycle of every digital computer.
• 1. The memory address that is held in the program counter is then copied into the MAR. 
  2. The program counter now holds the address of the next instruction, ready to be fetched.
  3. The processor sends a signal through the address bus to the memory address held in the MAR.
  4. The data held in the MAR is then sent through the data bus to the MDR.
  5. The data in the MDR is copied into the CIR.
  6. The data held in the CIR is decoded and then executed. The results are stored in the ACC.
  7. The cycle then repeats.
•   Von Neumann Architecture

  inside the CPU is the CU (Control Unit), the ACC (Accumulator) and register, such as CIR, PC, MAR, MDR, etc.

  
  

  An address bus is connected to the CPU and the main memory, with data flowing from the CPU to the main memory through the address bus.

  
  

  A data bus is connected to the CPU and the main memory, with data flowing both ways through the data bus.
• ALU (Arithmetic Logic Unit)


  The ALU is a digital circuit that calculates and solves arithmetic and logical operations through binary.
• CU (Control Unit)


  The CU coordinates the operations carried out by the computer.

  
  

  The hardware is monitored. The input and output of devices and response of instructions are sent to the CPU. The data flow is controlled within the CPU.

  
  

  The CU sends signals between the different internal components:

  • Memory Read
  • Memory Write
  • Hard Disk Drive Read
  • Input/Output Write