Difference between Von Neumann and Harvard Architecture

Von Neumann Architecture

It is a program that consists of code (instructions) and data. The below figure shows a block diagram of the von Neumann architecture. Von Neumann uses the data bus to transfer data and instructions from the memory to the CPU.

Harvard Architecture

Harvard architecture uses separate buses for instructions and data as shown below in Figure. The instruction address bus and instruction bus are used for reading instructions from memory. The address bus and data bus are used for writing and reading data to and from memory.

Von Neumann vs Harvard Architecture

Von Neumann Architecture	Harvard Architecture
1. It requires less hardware	1. It requires more hardware
2. Von-Neumann Architecture requires less space.	2. Harvard Architecture requires more space.
3. Von Neumann Architecture is based on the stored-program concept.	3. Harvard Architecture is based on relay-based computer models.
4. Controlling becomes simpler since either data or instructions are to be fetched at a time.	4. Controlling becomes complex since data and instructions are to be fetched simultaneously.
5. In Von Neumann Architecture, Common bus used for transferring instructions and data.	5. In Harvard Architecture, Separate buses are used to transfer instructions and data.
6. Speed of execution is slower since it cannot fetch the data and instructions at the same time.	6. Speed of execution is faster because the processor fetches data and instructions simultaneously .
7. Von Neumann Architecture is cheaper than Harvard architecture.	7. Harvard Architecture is more expensive than Von Neumann’s architecture.
8. It is mainly used in personal computers (PC)	8. It is mainly used in micro-controllers and signal processing.