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System Description Techniques

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Familiarity with the system:  before going to detailed system design, a study of the existing   system is utmost required which will enable us to determine if there are bottlenecks or weaknesses in the system that need to be corrected, improvement areas can be identified and area of efficiency  due to newer technologies and the identification of software and/or equipment are identified that needs to be replaced. More emphasis has to be given for understanding the details of an existing system and then to analyze whether the existing system needs improvements.

Understanding the proposed  system: after having the clear picture of the existing system, we  have to move on to understanding the new or the proposed system, and  its effectiveness. We must be able to answer some questions like how, when and what? We must look into the user’s requirement,  feasibility of the proposed system, its cost effectiveness and timely  delivery of the finished product.

Types of the techniques: As soon  as we finished with the understanding of the current and the new system, it is now our turn to design the system, develop its prototype by defining data flow and data processing within the system. Several methods may be used to represent a proposed system such as algorithm, flowchart, data flow diagram etc. It is not necessary to follow these techniques if we have better understanding of the system and programming skill. But still it is recommended to use various techniques to design the system. Some of the techniques used are discussed below:


The pictorial-representation of the   programs or the algorithm is known as flow charts. It is nothing but a diagrammatic representation of the various steps involved indesigning a system. Some of the boxes, which are used in flowchart,are.

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Flow Chart Symbols

A flowchart consists of a set of flowchart symbols connected by arrows. Each symbol contains informationabout what must be done at that point and the arrow shows the flowof execution of the algorithm, i.e., they show the order in whichthe instructions must be executed. The purpose of using flowcharts isto graphically present the logical flow of data in the system anddefining major phases of processing along with the various media tobe used.

Flowcharts are of three types:

  • System flowchart
  • Run flowchart
  • Program flowchart

(a) System Flowcharts

System flowchart describes the dataflow for a data processing system. It provides a logical diagram of how the system operates. It represents the flow of documents, theoperations performed in data processing system. It also reflects therelationship between inputs, processing and outputs.

e.g Consider a given algorithm,

1.Prompt the user for the centigrade temperature.

2.Store the value in C

3.Set F to 32 + (9*C/5)

4.Print the value of C, F


Following figure represent the system flow chart for the above algorithm.

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Flow chart example

(b) Run Flowcharts

Run flowcharts are used to representthe logical relationship of computer routines along with inputs,master files, transaction files and outputs. Following figure illustrates a run flow chart.


Flow Chart

(c) Program Flowcharts

A program flowchart represents, indetail, the various steps to be performed within the system fortransforming the input into output. The various steps are logical/arithmetic operations, algorithms, etc. It serves as the basis fordiscussions and communication between the system analyst and theprogrammer. Program flowcharts are quite helpful to programmers inorganizing their programming efforts. These flowcharts constitute animportant component of documentation for an application. Followingfigure represents a program flowchart for finding the sum of firstfive natural numbers, i.e. 1,2,3,4,5


Program flow chart
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