Von Neumann architecture

Von Neumann architecture

1. registers

   • program counter
     • Stores the address of the next instruction to be run.
   • Current Instruction Register
     • Stores the instruction currently being executed
   • Memory Address Register
     • Stores the memory address where the data or instruction will be fetched/written.
   • Memory Data Register
     • Stores the data or instruction which is being fetched/written from/to memory.
   • Accumulator
     • Stores the intermediate results of a calculation.

2. Control Unit

   • It controls the flow of data between the CPU and other parts of the computer system. For example, it sends control signals to the memory, ALU and input/output devices.

3. Cache

   • Stores frequently used instructions for the CPU. There are 3 different levels of cache. See page 3 of the revision guide for more information.

4. Arithmetic and logic unit

   • The arithmetic logic unit performs all the calculations for the CPU. For example it will perform simple addition and subtraction, binary shifts and logic operations (AND / OR / NOT)