Von Neumann Architecture

Notes made on this video: GCSE (J277) 1.1 Von Neumann architecture

Notes

• Von Neumann designed computers that stored programs.

• Key characteristics are: CPU, CU, ALU, and an Internal Cache and Clock.

• Each instruction is stored with an address in memory.

• The CPU fetches the instruction from memory, decodes it, and executes it.

• PC holds the memory address of the next instruction to be fetched. It is incremented by one after each instruction.

• MAR holds the address of the memory location to be accessed.

• MDR holds the data that has been fetched from memory.

• The Accumulator is a register that stores the results of calculations.

Fetch stage

• The program counter is checked as it holds the address of the next instruction to be executed.

• This address is sent to the MAR.

• The address in the PC is then incremented by one to point to the next instruction.

Decode stage

• The instruction is in the CU, which decodes it.

Execute stage

• The CU sends the instruction to the ALU, which executes it.