System analysis and design

Paper II: System Analysis and Design
1. System Concepts and Information Systems Environment: The System Concept:
Definition, Characteristics of Systems, Elements of a System, Open and Closed System,
Formal and Informal Information Systems, Computer based Information Systems,
Management Information System, Decision Support System, General Business
Knowledge and Interpersonal Communicational System.
2. The System Development Life Cycle: Recognition of needs, Impetus for System
Change, Feasibility Study, Analysis, Design, Implementation, Post implementation &
Maintenance.
3. The Role of the Systems Analyst: Historical Perspective, The War Effort,What Dues
it take to do System Analysis, Academic & Personal Qualifications, The Multifaceted role
of the Analyst,The Analyst/User Interface, Behavioral issues.
4. Systems Planning & Initial Investigation: Strategies for Determining Information
Requirement, Problem Definition & Project initiation, Background Analysis, Fact
Analysis, Review of Written Documents, Onsite Observations, Interviews &
Questionnaires, Fact Analysis, Performance Analysis, Efficiency Analysis, Service
Analysis.

5. Information Gathering: What Kind of Information do we need? Information
about the firms, Information gathering tools, The art of Interviewing, Arranging
the Interview, Guides to a Successful Interview, Types of Interviews and
Questionnaires,The Structured and Unstructured Alternatives.
6. The Tools of Structured Analysis: The Dataflow Diagram (DFD), Data
Dictionary, DecisionTrees and Structured English.
7. Feasibility Study: System performance, Economic Feasibility, Technical
Feasibility, Behavioral feasibility, Steps in Feasibility Analysis.
8. Input/Output and Forms Design: Input Design, CRT Screen Design,
Output Design, Requirements of form Design.
9. H/W / S/W Selection and Maintenance: The Computer Industry, S/W
Industry, a Procedure for H/W / S/W Selection, Major Phases in Selection,
Criteria for S/W Selection,The Used Computer,The Computer Contract.
R
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1. Elias M.Awad, “Systems Analysis & Design”, Galgotia Publication.
2. Hoffer,“Modern SystemsAnalysis & Design”,AddisionWesley.
3. Kendall,“Introduction to SystemAnalysis & Design”, McGraw Hill.

Over View of System Analysis and
Design
Systems development can generally be thought of as having
two major components: Systems analysis and Systems design.
System design is the process of planning a new business
system or one to replace or complement an existing system.
But before this planning can be done, we must thoroughly
understand the old system and determine how computers
can best be used to make its operation more effective. System
analysis, then, is the process of gathering and interpreting
facts, diagnosing problems, and using the information to
recommend improvements to the system. This is the job of
the systems analyst.

1. System Concepts and Information
Systems Environment
— The System Concept:
The term system is derived from the Greek word systema, which means
an organized relationship among functioning units or components. A
system exists because it is designed to achieve one or more objectives.
We come into daily contact with the transportation system, the
telephone system, the accounting system, the production system, and,
for over two decades, the computer system. Similarly, we talk of the
business system and of the organization as a system consisting of
interrelated departments (subsystems) such as production, sales,
personnel and an information system. None of these subsystems is of
much use as a single, independent unit. When they are properly
coordinated, however, the firm can function effectively and profitably.
There are more than a hundred definitions of the word system, but most
seem to have a common thread that suggests that a system is an orderly
grouping of interdependent components linked together according to a
plan to achieve a specific objective.

Characteristics of Systems:
The definition of a system suggests some characteristics that
are present in all systems: organization (order), interaction,
interdependence, integration and a central objective.
Organization : Organization implies structure and order. It
is the arrangement of components that helps to achieve
objectives. In the design of a business system, for example,
the hierarchical relationships starting with the president on
top and leading downward to the blue – collar workers
represents the organization structure.

Interaction:
Interaction refers to the manner in which each component
functions with other components of the system. In an
organization, for example, purchasing must interact with
production, advertising with sales and payroll with
personnel.

Interdependence :
Interdependence means that parts of the organization or
computer system depend on one another. They are
coordinated and linked together according to a plan. One
subsystem depends on the input of another subsystem for
proper functioning: that is, the output of one subsystem is
the required input for another subsystem. This
interdependence is crucial in systems work.

Integration:
Integration refers to the holism of systems. Synthesis follows
analysis to achieve the central objective of the organization.
Integration is concerned with how a system is tied together.
It is more than sharing a physical part or location. It means
that parts of the system work together within the system
even though each part performs a unique function. Successful
integration will typically produce a synergistic effect and
greater total impact than if each component works separately

Elements of a System:
In most cases, systems analysts operate in a dynamic
environment where change is a way of life.The environment
may be a business firm, a business application or a computer
system.To reconstruct a system, the following key elements
must be considered:
1. Outputs and inputs.
2. Processor(s).
3. Control.
4. Feedback.
5. Environment.
6. Boundaries and interface.

Outputs and Inputs:
A major objective of a system is to produce an output that
has value to its users. Whatever the nature of the output
(goods, services or information), it must be in line with the
expectations of the intended user. Inputs are the elements
(material, human resources and information) that enter the
system for processing. Output is the outcome of processing.

Processor(s)
The processor is the element of a system that involves the
actual transformation of input into output. It is the
operational component of a system. Processors may modify
the input totally or partially, depending on the specifications
of the output. This means that as the output specifications
change so does the processing. In some cases, input is also
modified to enable the processor to handle the
transformation.

The control element guides the system. It is the decision – making
subsystem that controls the pattern of activities governing input,
processing and output. In an organizational context, management
as a decision – making body controls the inflow, handling and
outflow of activities that affect the welfare of the business. In a
computer system, the operating system and accompanying
software influence the behavior of the system. Output
specifications determine what and how much input is needed to
keep the system in balance. In systems analysis, knowing the
attitudes of the individual who controls the area for which a
computer is being considered can make a difference between the
success and failure of the installation. Management support is
required for securing control and supporting the objective of the
proposed change.
Control:

Feedback:
Control in a dynamic system is achieved by feedback. Feedback
may be positive or negative, routing or informational. Positive
feedback reinforces the performance of the system. It is routine in
nature. Negative feedback generally provides the controller with
information for action. In systems analysis, feedback is important
in different ways. During analysis, the user may be told that the
problems in a given application verify the initial concerns and
justify the need for change. Another form of feedback comes after
the system is implemented. The user informs the analyst about the
performance of the new installation. This feedback often results in
enhancements to meet the user’s requirements.

Environment:
The environment is the “suprasystem” within which an
organization operates. It is the source of external elements
that impinge on the system. In fact, it often determines how
a system must function. For example, the organization’s
environment, consisting of vendors, competitors, and others,
may provide constraints and, consequently, influence the
actual performance of the business.

Boundaries and interface:
A system should be defined by its boundaries – the limits that identify
its components, processes and interrelationship when it interfaces with
another system. For example, a teller system in a commercial bank is
restricted to the deposits, withdrawals and related activities of
customers checking and savings accounts. It may exclude mortgage
foreclosures, trust activities and the like. Each system has boundaries
that determine its sphere of influence and control. For example, in an
integrated banking – wide computer system design, a customer who has
a mortgage and a checking account with the same bank may write a
check through the “teller system” to pay the premium that is later
processed by the “mortgage loan system.” Recently, system design has
been successful in allowing the automatic transfer of funds form a bank
account to pay bills and other obligations to creditors, regardless of
distance or location. This means that in systems analysis, knowledge of
the boundaries of a given system is crucial in determining the nature of
its interface with other systems for successful design.

— Types of systems
The frame of reference within which one views a system is
related to the use of the systems approach for analysis.
Systems have been classified in different ways. Common
classifications are:
(1) Physical or abstract,
(2) Open or closed and
(3) “Man –made” information systems.

— Open or Closed Systems
One classification of systems is based on their degree of
independence. An open system has many interfaces with its
environment. It permits interaction across its boundary; it
receives inputs from and delivers outputs to the outside. An
information system falls into this category, since it must
adapt to the changing demands of the user. In contrast, a
closed system is isolated from environmental influences. In
reality, a completely closed system is rare. In systems
analysis, organizations, applications and computers are
invariably open, dynamic systems influenced by their
environment.

— Formal Information system
A formal information system is based on the organization
represented by the organization chart. The chart is a map of
positions and their authority relationships, indicated by boxes and
connected by straight lines. It is concerned with the pattern of
authority, communication and workflow. Information is formally
disseminated in instructions, memos, or reports from top
management to the intended user in the organization. This
structure also allows feedback up the chain of command for follow
–up. In Figure 1-1 input form the environment provides impetus
for policy decision by top management. Policies are
generalizations that specify what an organization ought to do.
Policies are translated into directives, rules and regulations and
transmitted to lower-level management for implementation. The
output represents employee performance.

— Informal Information Systems
The formal information system is a power structure designed to achieve
company goals. An organization’s emphasis on control to ensure performance
tends to restrict the communication flow among employees. As a result, an
informal information system develops. It is an employee based system designed
to meet personnel and vocational needs and to help solve work – related
problems. It also funnels information upward through indirect channels. In this
respect, it is a useful system because it works within the framework of the
business and it’s stated policies. In doing a systems study, the analyst should have
a knowledge of the chain of command, the power-authority-influence network,
and how decisions are made to get a feel for how much support can be expected
for a prospective installation. Furthermore, knowledge about the inner
workings of the employee- based system is useful during the exploratory phase
of analysis. Employee cooperation and participation are crucial in preventing
sabotage and training users. Since computers cannot provide reliable
information without user staff support, a proper interface with the informal
communication channels could mean the difference between the success and
failure of new systems.

— Computer – Based Information Systems
A third class of information system relies on the computer
for handling business applications. The computer is now a
required source of information. Systems analysis relies
heavily on computers for problem solving. This suggests that
the analyst must be familiar with computer technology and
have experience in handling people in an organizational
context.

— Management Information Systems (MIS)
The computer has had a significant impact on the techniques used
by management to operate a business. The level of the manager in
the organization is also a factor in determining the kind of
information needed to solve a problem. Lower – level
management needs detailed internal information to make day – to
– day, relatively structured control decisions. Higher – level
management, for whom long – range objectives are the primary
concerns, requires summarized information from a variety of
sources to attain goals. In either case, management action is based
on information that is accurate, relevant, complete, concise, and
timely. MIS has been successful in meeting these information
criteria quickly and responsively.

The primary users of MIS are middle and top management,
operational managers and support staff. Middle and top
management use MIS for preparing forecasts, special requests
for analysis, long – range plans and periodic reports.
Operational managers use MIS primarily for short- range
planning, periodic and exception reports. The support staff
finds MIS useful for the special analysis of information and
reports to help management in planning and control.
Providing data for use in MIS is the function of most levels of
personnel in the organization. Once entered into the system,
the information is no longer owned by the initiating user but
becomes available to all authorized users.

— Decision Support Systems (DSS)
One reason cited in the literature of management’s frustration
with MIS is the limited support it provides top management for
decision making. DSS advances the capabilities of MIS. It assists
management in making decisions. It is actually a continually
evolving model that relies heavily on operations research. Gorry
and Morton Coined the term decision support system (DSS). The
origin of the term is simple:
— Decision – emphasizes decision making in problem situations, not
information processing, retrieval, or reporting.
— Support – requires computer-aided decision situations with
enough “structure” to permit computer support.
— System – accentuates the integrated nature of problem solving,
suggesting a combined “man”, machine, and decision environment.

— The intelligence phase of decision making involves the awareness
of a problem at a symptomatic level; it requires a closer look at the
problem and a through evaluation of the variables and their
relationships. The more intelligence management has about the
cause of a problem, the better is the likelihood of designing a good
decision. A DSS can provide intelligence through information
retrieval and statistical packages.
— The design phase of decision making focuses on the evaluation of
decision alternatives. During this phase, computer – based
deterministic or stochastic models may be used for decision
design. DSS plays a major role in decision design under
uncertainty. The output of the model(s) is the basis of the choice
phase of decision-making.

— Questions:
1. Define system. Give examples.
2.What is man made information system.
3. Explain the features of a system.
4. Elaborate the different types of systems.
5.A system leads to a lot of planning and less of
implementation. Do you agree, justify your answer.

— General Business Knowledge and Interpersonal
Communicational System.

The System Development Life Cycle
— The system analyst gives a system development project
meaning & direction. A candidate system is approached after
the analyst has a through understanding of user needs &
problems. A viable solution is worked out and then
communicates the same. Candidate systems often cut across
the boundaries of users in the organization. For example, a
billing system may involve users in the sales order
department, the credit department, the warehouse and the
accounting department. To make sure that all users’ needs are
met, a project from that represents each user works with the
analysis to carry out a system development project.

— Recognition of Needs
One must know what the problem is before it can be solved.The basis of candidate
system is recognition of need for improving the system.The key question is:
— What is the problem?
— This recognition of need leads to a preliminary survey or an initial investigation
of current system to determine whether an alternative system can solve the
problem. If the problem is serious enough, management may have an analyst
look at it.
— The idea for change may originate in the environment or within the firm.
Environment-based ideas originate from customers, vendors, government
sources etc.When investigated each of these ideas may lead to a problem
definition. Idea for change may also come from with in the organization â€“ top
management, the user, the analyst. User-originated ideas also prompt initial
investigation.

— Impetus for system Change
The idea for change originates in the environment or from
within the firm (see Figure 2-1). Environment-based ideas
originate from customers, vendors, government sources, and
the like. For example, new unemployment compensation
regulations may make it necessary to change the restructures.
Customer complaints about the delivery of orders may
prompt an investigation of the delivery schedule, the
experience of truck drivers, or the volume of orders to be
delivered. When investigated, each of these ideas may lead to
a problem definition as a first step in the system life cycle
process.

— Analysis
Analysis is a detailed study of the various operations performed by
a system and their relationships within and outside of the system.
A key question is, what must be done to solve the problem? One
aspect of analysis is defining the boundaries of the system and
determining whether or not a candidate system should consider
other related systems. During analysis, data are collected on the
available files, decision points, and transactions handled by the
present system. Data flow diagrams interviews, on – site
observations, and questionnaires are examples of the analysis
tools. The interviews is a commonly used tool in analysis, it
requires special skills and sensitivity to the subjects being
interviewed. Bias in data collection and interpretation can be a
problem. Training, experience, and common sense are required
for collection of the information needed to do the analysis.

— Once analysis is completed the analyst has a firm understanding of
what is to be done.The next step is to decide how the problem
might be solved.Thus, in systems, design we move from the
logical to the physical aspects of the life cycle.
— Design
— The most creative and challenging phase of the system life cycle is
system design.The term design describes a final system and the
process by which it is developed. It refers to the technical
specifications (analogous to the engineer’s blueprints) that will be
applied in implementing the candidate system. It also includes the
construction of programs and program testing.The key questions
here is: How should the problem be solved?The major steps in
design are shown in Figure 2.2.

— Design, Implementation, Post implementation &
Maintenance.

System Analysis and Design (SAD)
System are created to solve Problems. One can think of the systems approach as an
organized way of dealing with a problem. In this dynamic world, the subject system
analysis and design, mainly deals with the software development activities.
What is System?
— A collection of components that work together to realize some objectives
forms a system. Basically there are three major components in
every system, namely input, processing and output.
— In a system the different components are connected with each other and they are
interdependent. For example, human body represents a complete natural system. We
are also bound by many national systems such as political system, economic system,
educational system and so forth. The objective of the system demands that some
output is produced as a result of processing the suitable inputs. A well-designed
system also includes an additional element referred to as ‘control’ that provides a
feedback to achieve desired objectives of the system.

SYSTEM LIFE CYCLE
System life cycle is an organizational process of developing and maintaining systems. It helps
in establishing a system project plan, because it gives overall list of processes and sub-processes
required for developing a system.
System development life cycle means combination of various activities. In other words we can
say that various activities put together are referred as system development life cycle. In the
System Analysis and Design terminology, the system development life cycle also means
software development life cycle.
Following are the different phases of system development life cycle:
— Preliminary Study
— Feasibility study
— Detailed system study
— System analysis
— System design
— Coding
— Testing
— Implementation
— Maintenance

— The different phases of system development life cycle is shown in this diagram
— Phases of System Development Life Cycle
PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE
Let us now describe the different phases and related activities of system development
life cycle.
(a) Preliminary System Study
Preliminary system study is the first stage of system development life cycle.This is a
brief investigation of the system under consideration and gives a clear picture of
what actually the physical system is? In practice, the initial system study involves the
preparation of a‘System Proposal’ which lists the Problem Definition, Objectives of
the Study,Terms of reference for Study, Constraints, Expected benefits of the new
system, etc. in the light of the user requirements.

— The system proposal is prepared by the System Analyst (who studies the system)
and places it before the user management. The management may accept the
proposal and the cycle proceeds to the next stage. The management may also
reject the proposal or request some modifications in the proposal. In summary,
we would say that system study phase passes through the following steps:
— Problem identification and project initiation
— Background analysis
— Inference or findings (system proposal)
— (b) Feasibility Study
In case the system proposal is acceptable to the management, the next phase is
to examine the feasibility of the system.The feasibility study is basically the test
of the proposed system in the light of its workability, meeting user’s
requirements, effective use of resources and of course, the cost effectiveness.
These are categorized as technical, operational, economic and schedule
feasibility.The main goal of feasibility study is not to solve the problem but to
achieve the scope. In the process of feasibility study, the cost and benefits are
estimated with greater accuracy to find the Return on Investment (ROI).This

(c) Detailed System Study
The detailed investigation of the system is carried out in accordance with the objectives of the
proposed system.This involves detailed study of various operations performed by a system and
their relationships within and outside the system. During this process, data
are collected on the available files, decision points and transactions handled by the present
system. Interviews, on-site observation and questionnaire are the tools used for detailed
system study. Using the following steps it becomes easy to draw the exact boundary of the
new system under consideration:
— Keeping in view the problems and new requirements
— Workout the pros and cons including new areas of the system
— All the data and the findings must be documented in the form of detailed data flow diagrams
(DFDs), data dictionary, logical data structures and miniature specification.The main points to
be discussed in this stage are:
— Specification of what the new system is to accomplish based on the user requirements.
— Functional hierarchy showing the functions to be performed by the new system and their
relationship with each other.
— Functional network, which are similar to function hierarchy but they highlight the functions
which are common to more than one procedure.
— List of attributes of the entities – these are the data items which need to be held about each
entity (record)

(d) System Analysis
Systems analysis is a process of collecting factual data, understand the processes
involved, identifying problems and recommending feasible suggestions for improving
the system functioning.This involves studying the business processes, gathering
operational data, understand the information flow, finding out bottlenecks and
evolving solutions for overcoming the weaknesses of the system so as to achieve the
organizational goals. System Analysis also includes subdividing of complex process
involving the entire system, identification
of data store and manual processes.
The major objectives of systems analysis are to find answers for each business
process:What is being done, How is it being done,Who is doing it,When is he doing
it,Why is it being done and How can it be improved? It is more of a thinking process
and involves the creative skills of the System Analyst. It attempts to give birth to a
new efficient system that satisfies the current needs of the user and has scope for
future growth within the organizational constraints.The
result of this process is a logical system design. Systems analysis is an iterative
process that continues until a preferred and acceptable solution emerges.

— (e) System Design
Based on the user requirements and the detailed analysis of the existing system,
the new system must be designed.This is the phase of system designing. It is the
most crucial phase in the developments of a system.The logical system design
arrived at as a result of systems analysis is converted into physical system
design. Normally, the design proceeds in two stages:
— Preliminary or General Design: In the preliminary or general design, the
features of the new system are specified.The costs of implementing these
features and the benefits to be derived are estimated. If the project is still
considered to be feasible, we move to the detailed design stage.
—

— Structured or Detailed Design: In the detailed design stage, computer oriented
work begins in earnest.At this stage, the design of the system becomes more
structured. Structure design is a blue print of a computer system solution to a given
problem having the same components and inter-relationships among the same
components as the original problem. Input, output, databases, forms, codification
schemes and processing specifications are drawn up in detail.
— In the design stage, the programming language and the hardware and software
platform in which the new system will run are also decided.There are several tools
and techniques used for describing the system design of the system.These tools and
techniques are:
— Flowchart
— Data flow diagram (DFD)
— Data dictionary
— Structured English
— Decision table
— Decision tree
— Each of the above tools for designing will be discussed in detailed in the next lesson.

— The system design involves:
i. Defining precisely the required system output
ii. Determining the data requirement for producing the output
iii. Determining the medium and format of files and databases
iv. Devising processing methods and use of software to produce output
v. Determine the methods of data capture and data input
vi. Designing Input forms
vii. Designing Codification Schemes
viii. Detailed manual procedures
ix. Documenting the Design
—
(f) Coding
The system design needs to be implemented to make it a workable system.This demands the coding of
design into computer understandable language, i.e., programming language.This is also called the
programming phase in which the programmer converts the program specifications into computer
instructions,which we refer to as programs. It is an important stage where the defined procedures are
transformed into control specifications by the help of a computer language.The programs coordinate the
data movements and control the entire process in a system. It is generally felt that the programs must be
modular in nature.This helps in fast development, maintenance and future changes, if required.

(g) Testing
Before actually implementing the new system into operation, a test run of the
system is done for removing the bugs, if any. It is an important phase of a successful
system.After codifying the whole programs of the system, a test plan should be
developed and run on a given set of test data.The output of the test run should
match the expected results. Sometimes, system testing is considered a part of
implementation process.
Using the test data following test run are carried out:
— Program test:When the programs have been coded, compiled and brought to
working conditions, they must be individually tested with the prepared test data.Any
undesirable happening must be noted and debugged (error corrections)

— SystemTest:After carrying out the program test for each of the programs of the
system and errors removed, then system test is done.At this stage the test is
done on actual data.The complete system is executed on the actual data.At
each stage of the execution, the results or output of the system is analysed.
During the result analysis, it may be found that the outputs are not matching the
expected output of the system. In such case, the errors in the particular
programs are identified and are fixed and further tested for the expected
output.When it is ensured that the system is running error-free, the users are
called with their own actual data so that the system could be shown running as
per their requirements.

— During this phase, all the programs of the system are loaded onto the user’s computer.After loading the system,
training of the user starts. Main topics of such type of training are:
— How to execute the package
— How to enter the data
— How to process the data (processing details)
— How to take out the reports
— After the users are trained about the computerized system, working has to shift from manual to computerized
working.The process is called‘Changeover’.The following strategies are followed for changeover of the system.
(i) Direct Changeover:This is the complete replacement of the old system by the new system. It is a risky
approach and requires comprehensive system testing and training.
(ii) Parallel run: In parallel run both the systems, i.e., computerized and manual, are executed simultaneously for
certain defined period.The same data is processed by both the systems.This
strategy is less risky but more expensive because of the following:

(h) Implementation
After having the user acceptance of the new system developed, the implementation phase begins. Implementation is the stage of a project
during which theory is turned into practice.The major steps involved in this phase are:
— Acquisition and Installation of Hardware and Software
— Conversion
— UserTraining
— Documentation
— The hardware and the relevant software required for running the system must be made fully operational before implementation.The
conversion is also one of the most critical and expensive activities in the system development life cycle.The data from the old system needs to
be converted to operate in the new format of the new system.The database needs to be setup with security and recovery procedures fully
defined.
During this phase, all the programs of the system are loaded onto the user’s computer.After loading the system, training of the user starts.
Main topics of such type of training are:
— How to execute the package
— How to enter the data
— How to process the data (processing details)
— How to take out the reports
— After the users are trained about the computerized system,working has to shift from manual to computerized working.The process is called
‘Changeover’.The following strategies are followed for changeover of the system.
(i) Direct Changeover:This is the complete replacement of the old system by the new system. It is a risky approach and requires
comprehensive system testing and training.
(ii) Parallel run: In parallel run both the systems,i.e., computerized and manual, are executed simultaneously for certain defined period.The
same data is processed by both the systems.This
strategy is less risky but more expensive because of the following:

— Manual results can be compared with the results of the computerized system.
— The operational work is doubled.
— Failure of the computerized system at the early stage does not affect the working of the organization, because the manual system continues to
work, as it used to do.
— (iii) Pilot run: In this type of run, the new system is run with the data from one or more of the previous periods for the whole or part of the
system.The results are compared with the old
system results. It is less expensive and risky than parallel run approach.This strategy builds the confidence and the errors are traced easily
without affecting the operations.The documentation of the system is also one of the most important activity in the system development life
cycle.This ensures the continuity of the system.There are generally two types of documentation prepared for any system.These are:
— User or Operator Documentation
— System Documentation
— The user documentation is a complete description of the system from the users point of view detailing how to use or operate the system.It
also includes the major error messages likely to be encountered by the users.The system documentation contains the details of system design,
programs,their coding, system flow, data dictionary, process description, etc.This helps to understand the system and permit changes to be
made in the existing system to satisfy new user needs.
(i) Maintenance
Maintenance is necessary to eliminate errors in the system during its working life and to tune the system to any variations in its working
environments.It has been seen that there are always some errors found in the systems that must be noted and corrected. It also means the
review of the system from time to time.The review of the system is done for:
— knowing the full capabilities of the system
— knowing the required changes or the additional requirements
— studying the performance.
— If a major change to a system is needed, a new project may have to be set up to carry out the change.The new project will then proceed
through all the above life cycle phases.

— System:
— A system is a organized combination of resources working together to convert inputs into useful output. It is derived from a Greek
word ‘system’.A system is an organized grouping of interdependent components working together according a plan to fulfill predetermined
objectives.
— Characteristics of system:
— · Predetermined Objectives
— · It can be further subdivided
— · All components can be interdependent or interrelated
— Types of System:
· Physical System
— · Abstract System
— · Open System
— · Close System
— · Deterministic System
— · Probabilistic System
— · Introduction System
— 1. Physical System :
— A physical system can be tangible or visible which can be touch and also be counted. Physical system can be operated statically or
dynamically.
— 2. Abstract System:
— It can be conceptual or intangible.
— For ex: A model of organization represents the concept.
— 3. Open System:
— An open system is that interacts freely with outside environment and also it can be affected from outside environment.When the
environment changes the open system must also change in order to adopt itself to the environment otherwise it will be fail.
—

— System Analyst:
— A system analyst is a person responsible for the development of software and hardware solution to the efficient working
of the organization.Analysts study the environment and problems of an organization to determine whether a new
information method can provide solution to the problem.
— The main job of system analyst is to provide right type of information, in right quantity at the right time in post effective
manner to the management or the end user.
—
— Roles of System Analyst:
— · Defining IT requirements of organization
— · Gathering Data/Facts
— · Analyzing the problem
— · Setting priority amongst requirements
— · Problem solving
— · Drawing Specification
— · Designing System
— · Evaluating System
—

1. Defining IT requirements of organization:
The most imp and difficult task of an analyst is to understand the organization’s requirement’s information. It includes
interviewing users finding out what information is they are using in the current system.
2. Gathering Data/Facts:
For gathering data or facts, written documents are important because these documents represent the formal information flow
in the system.The analyst studies documents such as input forms, output records, invoices etc to understand how data are
passed and used in the present system.
3. Analyzing the problem:
After gathering data or facts the analyst analyses the working of current system and find out to what extent it meet the user’s
needs.
4. Setting priority amongst requirements:
In the organization there are many types of users, each user has different types of information needs. It may not e possible to
satisfy the requirements of everyone due to limited availability of resources so it is necessary to give priority.The
priorities are set on the basis of urgency and importance of user’s need.
5. Problem solving:
The system analyst helps IT users to solve their information problems. In that role he must understand the problem and
suggest solutions.
6. Drawing specification:
The analyst obtains the input and output specification for optimal functioning of the system to be developed.
7. Designing system:
Once the specifications are accepted by the management the analyst gets on to the design of the system.The analyst must be
aware of the latest design tools for the system design so analyst also knows as architect.
8. Evaluating system:
An analyst must critically test the performance of the designed system with specifications after it has been in use for a
reasonable period of time.

— System Analyst:
— A system analyst is a person responsible for the development of software and hardware solution to the efficient working of the organization. Analysts study the environment and problems of an organization to determine whether a new
information method can provide solution to the problem.
— The main job of system analyst is to provide right type of information, in right quantity at the right time in post effective manner to the management or the end user.
—
— Roles of System Analyst:
— · Defining IT requirements of organization
— · Gathering Data/Facts
— · Analyzing the problem
— · Setting priority amongst requirements
— · Problem solving
— · Drawing Specification
— · Designing System
— · Evaluating System
—
—
— 1. Defining IT requirements of organization:
— The most imp and difficult task of an analyst is to understand the organization’s requirement’s information. It includes interviewing users finding out what information is they are using in the current system.
— 2. Gathering Data/Facts:
— For gathering data or facts, written documents are important because these documents represent the formal information flow in the system. The analyst studies documents such as input forms, output records, invoices etc to understand how
data are passed and used in the present system.
—
— 3. Analyzing the problem:
— After gathering data or facts the analyst analyses the working of current system and find out to what extent it meet the user’s needs.
—
— 4. Setting priority amongst requirements:
— In the organization there are many types of users, each user has different types of information needs. It may not e possible to satisfy the requirements of everyone due to limited availabilityof resources so it is necessary to give priority. The
priorities are set on the basis of urgency and importance of user’s need.
—
— 5. Problem solving:
— The system analyst helps IT users to solve their information problems. In that role he must understand the problem and suggest solutions.
—
— 6. Drawing specification:
— The analyst obtains the input and output specification for optimal functioning of the system to be developed.
—
— 7. Designing system:
— Once the specifications are accepted by the management the analyst gets on to the design of the system. The analyst must be aware of the latest design tools for the system design so analyst also knows as architect.

— SDLC(Software/System Development Life Cycle):
— It is a well defined process by which a system is planned, developed and implemented.The
system development starts with the requirement for improving their business system.
— There are following activities involves in SDLC :-
— · Preliminary Investigation (Problem Identification)
— · Feasibility study
— · System analysis
— · System designing
— · Development of software
— · System testing
— · Implementation & Evaluation
— · Maintenance
—

— System Planning
—
Data & Fact gathering techniques:
— The specific methods that an analyst uses for collecting data about the requirement of a new system are
called fact finding techniques.
—
— 1. Interview:
— In this technique analyst collects information from individuals. It is a formal meeting where the analyst
can obtain information about the operation of the present system and requirements of planned system.
—
— Advantages
— i. It is helpful for gathering information from individuals who do
not communicate effectively by writing.
— ii. It allows discovering areas for unrealistic expectation,
misunderstanding to the proposed system.
— iii. Analyst can observe the interviewee’s non verbal
communication.
— iv. This method gives the analyst the opportunity to motivate the
interview to response freely & openly to questions.
—

Disadvantage
— It is very time consuming.
— Success of interview is dependent on system analyst’s human relation skills.
— Interviewing may be impractical due to location of the interviewees.
Types of interview
Structured Interview:
In structured interview interviewer has specific set of questions to ask.All questions
prepared in advance and answers are already available.
Unstructured Interview:
In this method questions and corresponding responses are open ended.This are
conducted with a general goal or subject.
Planning for interview
1. Purpose of interview should be clear.The purpose of meeting clearly
explained to the all participant so that relevant document can be supplied in advance.
2. Proper time, duration and place for interview must be selected before so this will
allow the participants to scheduled work accordingly.

2. Group Communication/Discussion:
When information is required from face to face communication but there is
not enough time to conduct personal interview, group interviews can be held.
Advantages
There are many persons presents so more types of ideas and views can be discussed in
short time.
The comments of one person may prompt other person to contribute facts which they
thoughts.
Disadvantages
The group may be dominated by a few persons.
The situation could lead to a verbal fight between the persons and may need
moderation.
Internal politics of an organisation may determine what is said and what is left thus
resulting in false picture.
3. Questionnaires:
Questionnaires are special purpose documents that allow the analyst to collect
information and opinions from respondance.This is more structured and formal
method of collecting data.

Advantages
i. When it is used for group of users, it is relatively cheap.
ii. A questionnaire can be administered to larger no of individual simultaneously.
iii. The respondance feels greater confidence.
Disadvantages
i. All the questions given in questionnaire are usually not answered
completely.
ii. It is not possible to observe and analyse the respondance body language.
iii. Good questionnaires are difficult to prepare.
iv. Cost may be high.

Types of questionnaires –
I. Structured – Answer and question are fixed
II. Unstructured – Not fix pattern
4. On site observation:
It allows the analyst to gain information which cannot be obtained by other fact finding methods. It is also
useful when analyst need to actually observe how documents are handled, what processes are carried on
etc.
“On site observation provide close view of working of the real system.The analyst can observe people,
objects,documents and occurrence of events.”
Advantages
i. Data collection by observation highly reliable.
ii. It is relatively inexpensive
Disadvantages
i. People usually feel uncomfortable when being watched.
ii. It is very time consuming.
iii. Some activities may take place odd time causing a scheduling
inconvenience for system analyst.

Elements of system:
A system’s objectives are expressed in terms of output is needs to produce, the inputs are the data which are processed while
the output i.e. information are the outcome of the process.
In addition there are two more components
i. Control
It makes the system to operate within tolerable performance levels. Control of the system is the decision maker that controls
the activities of accepting input, process & producing the output.
ii. Feedback
It is the information on how well a system is performing & it is essential for system modifications.
System may use feedback for control the information generated by comparing results with acceptable level of performance
(standards) and informing the control elements of the difference is termed as feedback.
In feedback control the output is fed back to input. It allows to be majored against some standards and making adjustment in
the processing accordingly.

Feasibility Study:
Feasibility is a process that identifies , describes and evaluates proposed system and selects the
best system for the job. During the study, the problem definition is solved and all aspects of
problem to be included in the system are determined. Size of project, cost and benefits are
also estimated with greater accuracy.The result of feasibility study is simply a report is a
formal document detailing the nature and scope of the proposed solution.
Types-
1. Technical feasibility
2. Economical feasibility
3. Operational feasibility
4. Behavioral feasibility
1. Technical feasibility:
It determines whether the technology needed for the proposed system is available and how it can
be integrated within the organisation.Technical evaluation must also assess whether the staff
have technical expert to understand and use the new technology.
2. Economical feasibility:
The purpose of assessing economical feasibility is to identify the financial benefits and cost
associated with the development of the system. Economic feasibility is often known as the cost
benefit analysis.To carry out an economical feasibility study it is necessary to estimate actual
money value against activities needed for implementing the system.

3. Operational feasibility:
It is concerned with human, organisational and political aspects.
It includes two ways–
i. Technical performance:
It includes issues such as whether the system can provide the right information for
organisation’s personnel at right time and right place.
ii. Acceptance within the organisation:
It determines the general attitudes and job skills of existing personnel and whether any
changes in job work will be acceptable by the current users.
4. Behavioral feasibility:
It includes how strong the reaction of staff will be towards the development of new
system that involves computer’s use in their daily work. So resistant to change is
identified.
After feasibility study feasibility report is prepared and submitted to the management.

— System Design
— 1. System Model:
— A logical or mathematical representation of a system is known as system model.
— Model can be built for the existing system to better understand the proposed system.
— 2. Process Modelling:
— Process modelling is technique which involves graphical representation of functions or processes that capture , manipulates, stores or
distribute data between a system & its environment or among components within a system. DFD(Data Flow Diagram) is one of the common
form of process model.
— 3. Logical & Physical design:
— System design involves two categories-
— a. Logical design:
— It is concerned with the specification of major features of the system that would meet the objectives.The delivered product of logical design
may be called as a blueprint of a new system.
— Logical design of a system includes content requirements and some of following components-
— i. Output(Reports & Displays)
— ii. Input forms
— iii. Procedures(Structured of procedures to collect, transforms & output data)
— iv. Storage(Requirements for data to be stored in the database)
— v. Control(Requirements for data integrity, security & procedure for recovery)

b. Physical design:
It requires logical design or blueprint and produces the program specification, physical files or
database definitions. It also includes user interface design and selects hardware & software
packages.
4. Input Output Design:
a. Input Design:
Part of the system which deals with the design of the interface through which user communicates
with the system and feeds the input data to the system.
b. Output Design:
The part of the system which deals with determining how the output is to be presented, in what
format or shape is known as output design of the system. Computer produces displays and
print reports that are to be read and used by users therefore the output must be clear and easy
to understand.

c. I/O Forms:
It is primary carrier for data or information.They are the user requests for some action.A properly designed form is necessary for efficient
functioning of a system.
Form is used to –
i. To obtain information efficiently
ii. Distributes information easily
iii. Store information effectively and economically
Types of Forms:
1. Action Form:
This type of form requests the user to perform certain actions and they are generally moves from one person to organisation or another person.
2. Memory Form:
It record historical data such as stock ledger, purchase record, bond form.
3. Report Form:
It provides summarised information.These are generally used by managers and such people who are required to make decision making.They guide
supervisors and administrators for decision making.
Form designing:
Steps for form designing-
i. Define the purpose of form
ii. Specify its data contents
iii. Using a guide sheet enter title, form number and indicates position of any specially
located material
iv. Review with the user & revised if necessary
v. Create few test forms.

b. Physical design:
It requires logical design or blueprint and produces the program specification, physical files or database
definitions.It also includes user interface design and selects hardware & software packages.
Input Output Design:
a. Input Design:
Part of the system which deals with the design of the interface through which user communicates with the
system and feeds the input data to the system.
b. Output Design:
The part of the system which deals with determining how the output is to be presented, in what format or
shape is known as output design of the system. Computer produces displays and print reports that are to
be read and used by users therefore the output must be clear and easy to understand.
c. I/O Forms:
It is primary carrier for data or information.They are the user requests for some action.A properly designed
form is necessary for efficient functioning of a system.
Form is used to –

Types of Forms:
1. Action Form:
This type of form requests the user to perform certain actions and they are generally moves from one person to organisation or another person.
2. Memory Form:
3. Report Form:
It provides summarised information.These are generally used by managers and such people who are required to make decision making.They guide
supervisors and administrators for decision making.
Form designing:
iii. Using a guide sheet enter title, form number and indicates position of any specially
located material

System Design
1. System Model:
A logical or mathematical representation of a system is known as system model.
Model can be built for the existing system to better understand the proposed system.
2. Process Modelling:
Process modelling is technique which involves graphical representation of functions or processes that capture , manipulates, stores or distribute
data between a system & its environment or among components within a system. DFD(Data Flow Diagram) is one of the common form of
process model.
3. Logical & Physical design:
System design involves two categories-
a. Logical design:
It is concerned with the specification of major features of the system that would meet the objectives.The delivered product of logical design may
be called as a blueprint of a new system.
Logical design of a system includes content requirements and some of following components-
i. Output(Reports & Displays)
ii. Input forms
iii. Procedures(Structured of procedures to collect, transforms & output data)
iv. Storage(Requirements for data to be stored in the database)
v. Control(Requirements for data integrity, security & procedure for recovery)

b. Physical design:
It requires logical design or blueprint and produces the program specification, physical files or database definitions. It also
includes user interface design and selects hardware & software packages.
4. Input Output Design:
a. Input Design:
Part of the system which deals with the design of the interface through which user communicates with the system and feeds
the input data to the system.
b. Output Design:
The part of the system which deals with determining how the output is to be presented, in what format or shape is known as
output design of the system. Computer produces displays and print reports that are to be read and used by users
therefore the output must be clear and easy to understand.
c. I/O Forms:
It is primary carrier for data or information.They are the user requests for some action.A properly designed form is
necessary for efficient functioning of a system.
Form is used to –

Types of Forms:
1. Action Form:
This type of form requests the user to perform certain actions and they are generally moves from one person to organisation
or another person.
2. Memory Form:
3. Report Form:
It provides summarised information.These are generally used by managers and such people who are required to make
decision making.They guide supervisors and administrators for decision making.
Form designing:
iii. Using a guide sheet enter title, form number and indicates position of
any specially located material

Output Design
1. Designing layout:
The arrangement of information on a monitor screen or printed on a paper is termed as layout.The output
design is specified on layout forms, sheets that describe the location such as length and type of text,
format of column headings, pagination, etc.
2. Category of output:
i. External
ii. Internal
3. Report generation:
Printed reports are formal documents that provide users with the information so that users can perform their
jobs effectively. It must be clear and easy to understand.We have to consider some features while
designing a report such as : titles, subtitles, date, page no and summary.
4. Design of screens:
The reports which are to be shown on a computer screen must be given a clear instruction how a user
proceed to retrieve the information. It also include some facility such as user friendly message or pop ups
for helping the users.

5. User interface design:
A User Interface is a combination of menus, screen design, keyboard commands and language which together create the way a
user interacts with the system. It determines how user interacts with system.The hardware part of user interface consists
of monitor, keyboard and mouse.The software part of interface determines what things look like on the screen and how
user gives commands to get work done.
Features of good user interface:
i. Know the prospective users of the system and their requirements.
ii. The interface should be robust i.e. the interface should not be fail because of
some erroneous actions taken by the user. It requires sufficient checks to prevent the users from taking some false
actions.
iii. If feasible, graphical icons must be used so that key-strokes can be minimised.
iv. Test the user interface on actual users.
v. Practice iterative (repeated) design.

E-R Model
E-R Model:
ER model is a detailed logical representation of entities, association and data elements for an organisation.This technique is
used in database design that helps to describe how entities in an organisation are related to another.
It includes three features for describing data-
(1) Entity:
It can be person, place, events to the organisation & about which data are captured, stored or processed.
(2) Attribute:
Various types of data elements that describe an entity are known as attributes.
For Ex:
An entity employee can have attributes such as name, date of birth, address etc.
(3) Relationship:
An association of several entities in an ER model is called relationship.
Different symbols used in ER model:

Decision Tree:
Decision tree is a graphical representation that presents conditions and actions sequentially. It is a method of showing the relationship of each condition & its permissible
actions. The route of the tree is starting point and it proceeds towards the various possible nodes.
The size of the tree will depend upon the number of conditions & actions. Each condition is expressed in two ways True/False or Yes/No.
Advantages of Decision tree
1. It expresses the logic of if then else in pictorial form.
2. It is useful to express the logic when a value is variable or an action is dependent on nested decision i.e. the outcome of another decision.
3. It helps the analyst to identify the actual decision to be made.
4. It is used to verify logic and problems that involve a few complex decision and limited number of actions.
Disadvantages of Decision tree
1. The lack of decision tree is that there is absence of information in its format to take what other combinations of conditions to test.
2. A large number of branches with many paths will confuse rather than help in analysis.
Ex:
Draw a decision tree for policy followed by a company in giving discount to its customers as follows.
1. If transaction is on credit and customer’s record is good the order will be accepted but do not give any discount.
If customer’s record is not good do not accept any order.
2. If transaction is on cash and sells amount is more than 100 rupees discount will be given 20%.
3. If transaction is on cash and sells amount is between 50 & 100 rupees than discount will be given 10%.
4. If transaction is on cash and sells amount is less than 50 rupees, order is accepted but no discount will be made.

Data Flow Diagram (DFD):
It is a logical model that describes what take place in an existing system, or proposed system; it does not specify how the activities are accomplished.
It shows the flow of data and the flow of logic involved.
Characteristics of DFD:
i. It focuses on the process that transforms incoming data flows (Input) into outgoing data flows (Output).
ii. It shows the passage of data through the system.
iii. This diagram also known as bubble chart.
iv. DFD supports a top down approach for analysis that is an analyst begins with general understanding of system then draws each component’s details.
Symbols used in DFD:
1. External Entity:
It is a source or destination of data; it may be person, organisation or other entity that interact with the system.
For ex: Customer, supplier;
The entity supplying data is known as source & those that consume data or give output are called sinks.
2. Data Flow/Flow line:
It shows how data travels from one point to another point in diagram.
3. Process:
It shows the transformation of input data flows to output data flows.
All processes are numbered in DFD for easy identification. Numbering follows a left to right convention. Name of the process describes what happened to the data as it flows through the process.
4. Data store:
It is warehouse for data
Data

Module Specification
Module is the way to improve the structure design by break down the problem for solving it into independent
task.
Advantages of Module –
I. It breakdown the problem into independent modules so the complexity of the
problem can be minimized.
II. Each independent module can be easily assigned to the various members of the
development team.
III. Module can be easily run and tested independently from another.
Top-Down design approach:-
It is a technique of breakdown a problem into major tasks to be performed. Each task is then further broken
down into separate sub task and so on until each sub task is sufficiently simple to be written as a self
contained module.
InTop-Down design we initially describes the problem at the highest level that descript what must be
done and It does not show how it must be done.Top-Down methods are used throughout the system
analysis and design process.The value of using top-down approach, starting at general level and to
understand and gain the system and moving down to the levels of greater details.

Advantages ofTop-Down Approach –
I. By dividing of the problem into number of sub problems we have made it easier to share problem
development.
II. It is easy to debug a large program as a number of smaller units rather than one big problem.
III. It is good way to delay decision on problems whose solution is not readily prepared.
IV. It allows a programmer to remain on top of a problem and view the developing solutions.The
solution always proceeds from the highest level to the lowest level.
V. It becomes an ideal structure for managing the implementation of a computer program using team
of programmers.
Bottom-Up design approach:-
When we face a large and complex problem , it is difficult to see how the whole thing can be done so it may easier to solve
the part of the problem individual, taking the common and easy aspects first and then more difficult task and finally
gather them all together to form complete solution, this is called bottom-up approach.
The bottom-up approach suffers from disadvantage that the part of the program may not fit together very easily and
there may be a lack of consistency between modules and reprogramming have to be done.
Module Cohesion & Coupling:-
i.) Modules:
Module is represented by a rectangle box with module name.After defining general purpose of each program it is divided
into modules. Each of which performs a single function.
For Ex:-
An accounting system consists of many separate modules that are invoked one at a time as user wish to perform
particular function. Each upper level module leads to using one or more lower level modules until the desired function is
performed.

ii.) Connectors:
Connections between modules are represented using links, modules. It is drown by on arrow line
in downward direction.
iii.) Coupling:
It refers to the strength of relationship between modules in the system. Coupling measures the
degree to which two distinct modules are bound together.
It can be of two types –
a) Data Coupling:
It carries data between two modules and it can have upward or downward direction. Data flows
are shown using named arrow with a small circle at one end. It is shown by an arrow with
blank circle at the tail.
b) Control Coupling:
It carries info about data couple and does not carry any data. It is shown by an arrow with filled
circle at the tail.

iv.) Cohesion:
It is used to denote the intra module strength. It is a relationship among
elements within a module.A system designer should aim at minimizing
coupling and maximizing cohesion to get modular design. Designer insures
that each module performs a specific function and can be developed
independently.A good design has low coupling i.e. low interdependence
between modules and high cohesion i.e. high interrelationship within the
elements of a single module.
UsingTop-Down approach to plan the software for a system is no
guarantee that errors will be avoided totally so properly modularized,
cohesive system, the contents of the module are designed such that they
perform a specific function and easily understood by people.

Data Dictionary
It is store house of data, giving information about data. During system implementation
it serves as common base for programmers who are working on the system, It
compares their data description. It is also an important step in building database.
“Data dictionary contains description & definition consulting the data structure,
data elements, their interrelationship & other characteristics of a system.”
Objectives of Data Dictionary
i. A standard definition of all terms in a system i.e. each data
item is uniquely identified and defined.
ii. Easy cross referencing between subsystem’s program and
modules.
iii. Simple program maintenance.
iv. It contains information about the data of the system and
there is an entry in the data dictionary for every element of DFD.Thus DFD and
Data Dictionary are compliment of each other.

Data Items:
There are three classes of data items –
a. Data Element –
It is the smallest unit of data which cannot be meaningfully
decomposed further.
For Ex:
Employee code, unit of measurement
b. Data Structure –
A group of data elements forms a data structure.
For Ex:
Data Structure of employee consist of a group of data elements such employee
code, name, age, experience, phone no., address etc.
c. Data Flow & Data stores –
Data flows are data structures in motion whereas Data stores are
data structure at rest. Data stores may be files, database etc.

— Format of Data Dictionary:
— A data dictionary is organised into five sections –
— i. Data Elements
— ii. Data Flows
— iii. Data Store
— iv. Process
— v. External Entities
—
—
— Data Dictionary lists all data elements, flows, stores, process of the system and it gives the detail about each item in following format –
— Data types, data name, data description, data characteristics, data control information, composition, physical location of data, etc.
—
—
—
—
— Data dictionary for data element Employee code in dictionary –
—
—
— Data Element - Employee code
— Description - Unique code assigned for each employee
— Type - char
— Length - 4
— Range - 0-9999
— Data Stores - Employee table, Payroll table

Structured English:
It is used to provide step by step specification for any algorithm. It can be used at any desirable level of
description & procedures. It is modified form of English that is used to specify the contents of the process
box in data flow diagram (DFD).It uses English language instead programming language.
It uses there basic types of statements to describe a process –
i. Sequence structure –
It is a single step or action included in a process. It does not depend on the
existence of any condition.
For Ex:
To buy a computer science book we follow the steps –
a. Pick out a desirable book.
b. Take it to the sells counter.
c. Pay cash for the book.
d. Collect cash receipt.
e. Collect the book and leave the store.

It is used when two or more actions can be taken depending on the value of a specific condition.We can describe it by using
following example –
If
Book found on the store
Then
Take the book to sales counter
Pay cash
Take receipt & book
Leave store
Else
Do not take book
Leave store.
ii. Iterative structure –
In various operating condition it is common to find that certain activities are repeatedly
executes while certain conditions exist. It permits analysts to describe these conditions.
Until the category of student is SC
Do give the discount to students on fee 50%
Take next student
End Until

Testing:
It is a process to check the software or system whether it gives the required output or not, on given set of data.
It other terms we can say it is a process to fail particular system because in testing we prepare all possible set of data and apply
to the system to check it gives expected output so system must give expected output or must be properly shutdown in
abnormal cases.
Testing can be categorised into –
1) Black BoxTesting
2) White BoxTesting
1) Black BoxTesting
It emphasizes on input data and expected output of the system. It does not includes the process from which the inputted data
converts into required output such as internal control conditions, loop statements etc.
2) White BoxTesting
In white box testing we emphasizes on each & every step from which data moves and converts into required output such as
control statement, repetitions, constraints, comparisons etc.

System quality control & assurance:
When a system is designed, it must fulfil the goal of the organization so some control must be developed to ensure a quality system.
Quality assurance defines the objectives of the system that is what is expected from the system. Quality assurance activity in the system development involves four types
of sub activities –
I. Verification-
It is a process of confirmation as what is supplied as per system specification to the system. Verification controls are carried out under given environment and test results are
obtained for acceptance of the new system.
II. Validation-
Validation is a process of using system in actual environment in order to find errors and checks whether the validations applied to the system are working properly or not. If the
results obtained from the system are proper, the system is valid otherwise it is not valid.
III. System testing-
It is a review of specification, design and coding. It may be based on feedback obtained from the users.
IV. Certification-
It is a confirmation of the correctness of the program. It provides authenticity of the system design that whether the system is according to its predefined standards and
objectivesor not.

File structure–
A file is a collection of records which are related to each other.The size of file is limited by the size of
memory and storage medium.
Two characteristics determine how the file is organised:
I. File Activity:
It specifies that percent of actual records proceeds in single run. If a small percent of record is accessed at any
given time, the file should be organized on disk for the direct access in contrast.
If a fare percentage of records affected regularly than storing the file on tape would be more efficient & less
costly.
II. FileVolatility:
It addresses the properties of record changes. File records with many changes are highly volatile means the
disk design will be more efficient than tape.
File organisation –
A file is organised to ensure that records are available for processing. It should be designed with the activity
and volatility information and the nature of storage media, Other consideration are cost of file media,
enquiry, requirements of users and file’s privacy, integrity, security and confidentiality.
There are four methods for organising files-
1. Sequential organisation
2. Indexed Sequential organisation
3. Inverted list organisation
4. Direct access organisation
5. Chaining

1. Sequential organization:
Sequential organization means storing and sorting in physical, contiguous blocks within files on tape or disk. Records are also
in sequence within each block.To access a record previous records within the block are scanned. In a sequential
organization, records can be added only at the end of the file. It is not possible to insert a record in the middle of the file
without rewriting the file.
In a sequential file update, transaction records are in the same sequence as in the master file. Records from both the files are
matched, one record at a time, resulting in an updated master file. In a personal computer with two disk drives, the
master file is loaded on a diskette into drive A, while the transaction file is loaded on another diskette into
drive B. Updating the master file transfers data from drive B toA controlled by the software in memory.
Advantages:
i. Simple to design
ii. Easy to program
iii. Variable length and blocked records available
iv. Best use of storage space

Disadvantages
i. Records cannot be added at the middle of the file.
2. Indexed sequential organization:
Like sequential organization, keyed sequential organization stores data in physicallycontiguous blocks.The
difference is in the use of indexes to locate records.There are three areas in disk storage: prime area,
overflow area and index area.
The prime area contains file records stored by key or id numbers.All records are initially stored in the prime
area.
The overflow area contains records added to the file that cannot be placed in logical sequence in the prime
area.
The index area is more like a data dictionary.It contains keys of records and their locations on the disk.A
pointer associated with each key is an address that tells the system where to find a record.
Advantages:
i. Indexed sequential organization reduces the magnitude of the sequential search and provides
quick access for sequential and direct processing.
ii. Records can be inserted in the middle of the file.
Disadvantages:
i. It takes longer to search the index for data access or retrieval.
ii. Unique keys are required.
iii. Periodic reorganization is required.

3. Inverted list organization:
Like the indexed- sequential storage method the inverted list organization maintains an index.The
two methods differ, however, in the index level and record storage.The indexed sequential
method has a multiple index for a given key, where as the inverted list method has a single
index for each key type. In an inverted list, records are not necessarily stored in a particular
sequence.They are placed in the data storage area, but indexes are updated for the record key
and location.The inverted keys are best for applications that request specific data on multiple
keys.They are ideal for static files because additions and deletions cause expensive pointer
updating.
Advantages
i. Used in applications requesting specific data on multiple keys.

Example:
Data for the flight reservation system.
The flight number, description and the departure time are as given as keys. In the data location area, no particular sequence is followed. If a passenger needs information
about the Houston flight, the agent requests the record with Houston flight. The DBMS carries a sequential search to find the required record. The output will then be That
the flight number is 170 departing at 10.10 A.M and flight number 169 departing at 8.15 A.M.
if the passenger searches for information about a Houston flight that departs at 8.15,then the DBMS searches the table and retrievesR3 and R6. Then it checks
the flight departure time and retrieves R6 standing for flight number 169.
4. Direct access organization:
In direct access file organization, records are placed randomly throughout the file. Records need not be in sequence because they are updated directly and
rewritten back in the same location. New records are added at the end of the file or inserted in specific locations based on software commands.
Records are accessed by addresses that specify their disk locations. An address is required for locating a record, for linking records, or for establishing
relationships. Addresses are of two types:
i. Absolute
ii. Relative.
A absolute address represents the physical location of the record. It is usually stated in the format of sector/track/record number. One problem with
absolute address is that they become invalid when the file that contains the records is relocated on the disk.
A relative address gives a record location relative to the beginning of the file. There must be fixed length records for reference. Another way of locating a
record is by the number of bytes it is from the beginning of the file. When the file is moved, pointers need not be updated because the relative location
remains the same.
Advantages:
i. Records can be inserted or updated in the middle of the file.
ii. Better control over record allocation.

Disadvantages:
i. Calculating address required for processing.
ii. Impossible to process variable length records.
5. Chaining:
File organization requires that relationships be established among data items. It must show how characters form fields, fields form files and
files relate to each other. Establishing relationship is done through chaining. It uses pointers
Example:The file below contains auto parts that are an indexed sequential file sequenced by part no.A record can be retrieved by part no.To retrieve the
next record,the whole file has to be searched.This can be avoided by the use of pointers.

— System Security:
— System security is a process to protect the system from damage, error and unauthorized access.The level of protection depends upon the
sensitivity of data, the reliability of the user and the complexity of the system.A well designed system includes control procedures to provide
physical protection, maintenance, data integrity and restrict system access.
— The system security includes for related issues –
— I. System integrity:
— It refers to proper functioning of hardware and programs, safety against external threats such as eavesdropping.
— The data integrity makes sure that data do not differ from its original form and have not been accidently or intentionally disclosed, altered or
destroyed.
— II. System security:
— It refers to the protection of data from loss, disclosure, modification and destruction.
— III. Privacy:
— It defines the rights of the user or organisation to determine what information, we want to show or accept from other and how organisation
can be protected against unfair or excessive dissemination of information.
— IV. Confidentiality:
— It is a special status given to the sensitive information in the database for privacy.
—
— Threats to the system security:
— a. Errors and omissions
— b. Fire
— c. Natural disaster
— d. External attack
— e. Disgruntled and dishonest employees.

Maintenance:
Once a system has been installed and fully operational then the task of system maintenance begins. The maintenance programming term involves keeping the software operational that is undertaking preventive measures
to keep computer program running, monitoring the systems operations, fixing problems if any and modifying programs in response to user requirements.
Types of maintenance:
I. Corrective
II. Adaptive
III. Perfective
I. Corrective maintenance:
It is performed to correct any errors in newly implemented system.
The errors that can occur in the system –
i.) Logical error (Program logic error)
ii.) System error (hardware problem like disk crash, memory overflow etc.)
iii.) Operational error- It occurs due to inappropriate computer schedules.
Ex:
· Improper backup of computer files.
· Failure to change printer ribbon.
iv.) User error - It occurs due to deficiency of user training.
The maintenance programmers repair such errors by redesigning the modules in the implemented software system.
II. Adaptive maintenance:
It performs to cope up with the changing environment of the market and organisation. It is performed with a view to keeping the software up to date. This is because, as internal and external business condition changes
the data processing requirement also changes. It begins with a request for service from users. Then the request is approved by committee. Then maintenance programmer start work for new requirements.
III. Perfective maintenance:
It is performed to further improve the efficiency of working system. Modifying data structure, baking records, eliminating temporary work files etc are some methods of improving overall system performance.
Some ways to improve efficiency are –
i.) Improving loops and calls to external procedures.
ii.) Improving the evolution of algebraic expressions.
iii.) Modifying expensive parts of the system.

System analysis and design

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