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Concept of Computer Architecture and Organization

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In computer fields, computer architecture is a set of rules and ways that explain the functionality, organization and implementation of computer systems. Some definitions of computer architecture and organization describes the capabilities and programming model of a computer but not a particular implementation.

The term computer is used to describe a device made up of a combination of electronic and electro-mechanical (electronic and mechanical) components.

By itself, a computer has no intelligence and is referred to as hardware, which means simply the physical equipment. A computer can`t be used until it is connected to other parts of a computer system and software is installed.



The design, arrangement , construction or organization of the different parts of a computer system is known as Computer Architecture. It is the conceptual design and fundamental operational structure of a computer system.

It is a framework and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the Central Processing Unit (CPU) performs internally and accesses addresses in memory.

It may also be defined as the science and art of selecting, interconnecting hardware components to create computers to meet functional performance and cost.


The first document of Computer Architecture was a correspondence between Charles Babbage and Ada Lovelace, that describes the analytical engine. Here is the example of other early important machines: John Von Neumann and Alan Turing.

Computer architecture is the art of determining the needs of the user of a structure and then designing to meet those needs as effectively as possible with economic status and as well as the technological constraints. In ancient period, computer architectures were designed and prepared on the paper and then, directly built into the final hardware form. Later, in today`s computer architecture, prototypes were physically built in the form of transistor logic (TTL) computer such as the prototypes of the 6800 and the PA-RISC tested, and tweaked before committing to the final hardware form. (Wikipedia and Quora)


Under the Computer architecture, it consists of 6 layers. They are as follows:

  • Electrical and electronic component level
  • Digital logic level
  • Micro programmed level
  • Machine level
  • System software level
  • Application program level

  • Electrical and Electronic component level

Almost all the modern computer devices are built from a simple electric component such as transistors, capacitors, a resistor which works on suitable power supplies.

  • Digital logical level

All the basic operations of the machine are provided at this level. The basic element at this level can store, manipulate and transmit data in the simple binary form. These digital logic elements are called gates which are normally constructed or made from a small number of transistors and other electronic components.

The standard digital logic devices are combined together to form computer processor or computer memories.

  • Micro program level

In this level, a sequence of microinstruction constitutes the microprogramming, which we called firmware, which is permanently stored in ROM. At the time, when the computer was made without microprogram level processor, it was built from a combination of a digital logic component.

The use of micro programmed level enables a manufacturer to produce a family of processors all of which process the same set of machine instruction at the machine level which differs in terms of construction and speed.

  • Machine level

Several hardware levels are presented in machine level. These are the basic elements of the computer. They are processor, input/output device, main memory, auxiliary storage, etc.

  • System software level

The program that directs the internal operation of a computer system is called system software.

  • Application software level

The program directs the computer to solve user-oriented problems are called application software.

According to the Computer architecture, it has three subcategories:

  • Instruction set Architecture
  • Micro-architecture
  • System Design


Computer Architecture is to design a computer that maximizes performance while keeping power consumption in check, costs low relatively to an amount of expected performance and it is also reliable.

There are many aspects to be considered like Set Design, Functional Organization, Logic Design and Implementation are the first prior.

Computer Organization

Computer organization refers to the operational units and their interconnection that realize the architecture specification. Computer organization deals with physical aspects of computer design, memory and their types and microprocessors design.

Whereas computer architecture deals with design aspects of computer that assembly programmer needs to know like instruction set (i.e. instruction supported), instruction format (i.e. how instruction will be specified), addressing modes, data types supported, etc.

The difference between Computer Architecture and Computer Organization are:

Computer Architecture

Computer Organization

Computer architecture is concerned with the structure and behavior of computer system as seen by the user.

Computer organization is concerned with the way the hardware components operate and the way they are connected together to form a computer system.

It includes information, formats, instruction set, and techniques for addressing memory.

It includes Hardware details transparent to the programmer such as control signal and peripheral.

It describes what the computer does.

It describes how the computer performs.Ex, circuit design, control signals, memory types and etc.

(Wikipedia and Quora)


Shrestha, Prachanda Ram, et al. Computer Essentials. Kathmandu: Asmita's Publication, 2014.

Wikipedia and Quora. 4 May 2016. 25 May 2016. <>.

Computer architecture it has three subcategories:

  • Instruction set Architecture
  • Micro-architecture
  • System Design

Under the Computer architecture, it consists of 6 layers 

  • Electrical and electronic component level
  • Digital logic level
  • Micro programmed level
  • Machine level
  • System software level
  • Application program level

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Forum Time Replies Report

block diagram of compu*architecture ?

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AaratI Kiran Sharma

Is the block diagram of computer architecture and computer system same?

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