Wednesday, 5 December 2012

Difference between Harvard and Von Neumann architecture

        This is one of the common question asked in VTU B.E. 7th sem C.S. 1st unit of Embedded Computing Systems and since this answer is not given in the prescribed text book, i thought of finding the answer and posting it in my blog, so that it will be helpful for many vtu students. I Hope it is helpful.

Von Neumann Architecture:

  • It is named after the mathematician and early computer scientist John Von Neumann.

  • The computer has single storage system(memory) for storing data as well as program to be executed.

  • Processor needs two clock cycles to complete an instruction.Pipe lining the instructions is not possible with this architecture.

  • In the first clock cycle the processor gets the instruction from memory and decodes it. In the next clock cycle the required data is taken from memory. For each instruction this cycle repeats and hence needs two cycles to complete an instruction.

  • This is a relatively older architecture and was replaced by Harvard architecture.

Harvard Architecture:

  •  The name is originated from "Harvard Mark I" a relay based old computer.

  • The computer has two separate memories for storing data and program.

  • Processor can complete an instruction in one cycle if appropriate pipelining strategies are implemented.

  • In the first stage of pipeline the instruction to be executed can be taken from program memory.In the second stage of pipeline data is taken from the data memory using the decoded instruction or address. 

  • Most of the modern computing architectures are based on Harvard architecture.But the number of stages in the pipeline varies from system to system.


you can also find the differences in the following links: