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SYSTEMS ANALYSIS & DESIGN
Systems development is systematic process which includes phases such as planning,
analysis, design, deployment, and maintenance
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System analysis is conducted for the purpose of studying a system or its parts in order to
identify its objectives
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Analysis specifies what the system should do
...
Before planning, you need
to understand the old system thoroughly and determine how computers can best be used
in order to operate efficiently
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System Analysis and Design (SAD) mainly focuses on −


Systems



Processes



Technology

What is a System?
The word System is derived from Greek word Systema, which means an organized
relationship between any set of components to achieve some common cause or objective
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Constraints of a System
A system must have three basic constraints −


A system must have some structure and behavior which is designed to achieve a
predefined objective
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

The objectives of the organization have a higher priority than the objectives of its
subsystems
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Properties of a System
A system has the following properties −
Organization
Organization implies structure and order
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Interaction
It is defined by the manner in which the components operate with each other
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Interdependence
Interdependence means how the components of a system depend on one another
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The output of one subsystem is the required by other subsystem as input
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It means
that the parts of the system work together within the system even if each part performs a
unique function
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It may be real or stated
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The users must know the main objective of a computer application early in the analysis for
a successful design and conversion
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

Inputs are the information that enters into the system for processing
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Processor(s)


The processor is the element of a system that involves the actual transformation of
input into output
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Processors may modify the input either
totally or partially, depending on the output specification
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In some cases, input is
also modified to enable the processor for handling the transformation
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

It is the decision–making subsystem that controls the pattern of activities governing
input, processing, and output
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In order to keep system in balance, what and how much input is needed is
determined by Output Specifications
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

Positive feedback is routine in nature that encourages the performance of the
system
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Environment


The environment is the “supersystem” within which an organization operates
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

It determines how a system must function
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Boundaries and Interfaces


A system should be defined by its boundaries
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

Each system has boundaries that determine its sphere of influence and control
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Types of Systems
The systems can be divided into the following types −
Physical or Abstract Systems


Physical systems are tangible entities
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

Physical System may be static or dynamic in nature
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A programmed computer
is a dynamic system in which programs, data, and applications can change according
to the user's needs
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Open or Closed Systems


An open system must interact with its environment
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For example, an information system
which must adapt to the changing environmental conditions
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It is isolated from
environmental influences
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Adaptive and Non Adaptive System


Adaptive System responds to the change in the environment in a way to improve
their performance and to survive
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

Non Adaptive System is the system which does not respond to the environment
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Permanent or Temporary System


Permanent System persists for long time
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

Temporary System is made for specified time and after that they are demolished
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Natural and Manufactured System


Natural systems are created by the nature
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

Manufactured System is the man-made system
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Deterministic or Probabilistic System


Deterministic system operates in a predictable manner and the interaction between
system components is known with certainty
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

Probabilistic System shows uncertain behavior
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For
example, Weather forecasting, mail delivery
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For example, social clubs, societies
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For example, Computer programming
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All the tasks are
performed by the machine
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Man–Made Information Systems


It is an interconnected set of information resources to manage data for particular
organization, under Direct Management Control (DMC)
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Man-made information systems are divided into three types −



Formal Information System − It is based on the flow of information in the form of
memos, instructions, etc
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

Informal Information System − This is employee based system which solves the
day to day work related problems
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For example, automatic library system, railway
reservation system, banking system, etc
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

Different arrows are used to show information flow, material flow, and information
feedback
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

Program Evaluation and Review Technique (PERT), for example, is used to abstract a
real world system in model form
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

The Gantt chart, for example, gives a static picture of an activity-time relationship
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A dynamic model approximates the
type of organization or application that analysts deal with
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It consists of −
o Inputs that enter the system
o The processor through which transformation takes place
o The program(s) required for processing
o The output(s) that result from processing
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Strategic Information


This information is required by topmost management for long range planning
policies for next few years
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

This type of information is achieved with the aid of Decision Support System (DSS)
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For example, sales
analysis, cash flow projection, and annual financial statements
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Operational information


This type of information is required by low management for daily and short term
planning to enforce day-to-day operational activities
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

It is achieved with the aid of Data Processing Systems (DPS)

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