Von Neumann Architecture

Von Neumann Computer Model

Blocks:

• Contains three main blocks: CPU, Memory, IO devices
• These blocks are connected together using System Bus

Components:

• Memory – Storage of Information (program and data)
• Processing Unit – Computation/Processing of Information
• Input – Getting information in to computer
• Output – Getting information out of computer
• Control Unit – Monitor and control all the above

Key Points:

• A memory to store both program and data
• Address and Data bus are shared between program and data memory
• CPU is allowed to access either program or data memory at a time
• Limited data transfer between CPU and memory
• Program can be easily modified by itself since it is stored in read-write memory
• It offers flexibility like executing code in data memory. Programs are written as data then executed as instructions. And having a uniform address space means that main memory can be used as instructions or data as different situations demand.
• Also known as Princeton Architecture.

Limitations:

• Limited throughput because of single & shared bus design.
• CPU is continually forced to wait for needed data to be transferred to or from memory.

Mitigations:

• Providing cache between CPU and Memory
• Providing separate caches for program and data
• Providing CPU stack or other on-chip scratchpad memory to reduce memory access

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Related topics:
Harvard Architecture   |   Von Neumann Vs Harvard Architecture   |   Modified Harvard Architecture   |   Microprocessor Vs Microcontroller   |   Choosing a Microcontroller

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List of topics: Microcomputer

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