System Analysis & Design - I

SYSTEM ANALYSIS & DESIGN - 1
Gagan Deep
Rozy Computech Services
3rd Gate, K.U., Kurukshetra-136119
rozygag@yahoo.com

THE SYSTEM CONCEPT
The term “system” is used in many different ways. Everyone is familiar with
such expressions as “Professor Rajneesh has an impossible grading system”
or “Deepak has a system for betting on the horses.” But for computer users,
a system is a group of parts that are integrated for the purpose of achieving
some objective. The following three characteristics are key:
• A group of parts : A system has more then one element. A steering wheel
is not a system, but it’s a vital part of a familiar system called an
automobile.
• Integrated parts : A logical relationship must exist between the parts of a
system. Mechanical and electronic system, such as washing machines and
video games, have many components that work together.
• A common purpose of achieving some objective : The system is designed
to accomplish one or more goals. All system elements should be tied
together and controlled so that the system goal is achieved.
Since a computer is a group of integrated parts that have the common
purpose of performing the operations called for in the program being
executed, it qualifies as a system.
Gagan Deep, RCS, 3rd Gate, K.U.K.,
rozygag@yahoo.com

• 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. A system is an orderly grouping of
interdependent components linked together
according to a plan to achieve a specific objective.
The word component may refer to physical parts,
managerial steps or a subsystem in a multi-level
structure.
• In our daily life, the word “System” comes across
many a times but rarely the word is understood in its
fullest sense. Almost every one of us have heard
about Systems such as Education System, Economic
System, Office System, Solar System, but what do they
imply in the real sense is a main question.
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• Systems could be man-made such as education
system, office systems etc., or a natural system
such as solar system.
• We would be dealing with man-made systems.
These man-made systems have certain inputs
which are processed and the result is certain
outputs.
• In education system, the main input is new
students where they undergo the process of
education and the output is a educated student.
• We can also define a system where elements
interacts with each other, responding to certain
inputs to produce outputs as shown in figure 1.
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• As the definition goes each system has certain
interacting elements. These elements interact
with each other in a certain way so as to produce
the required output from the given inputs. As we
are dealing with man-made systems, so it is man
who decides about what should be the inputs for
a particular system and in what way different
elements should react with each other to
produce the desired output. This particular man
who analyse (new and existing) and design or
redesign the system is called System Analyst.
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System
Inputs Outputs

• The concept of systems would impose upon the System
Analyst to look at the system as a whole. For example A
Company Managing Director asking the Production
Manager to study the present production system of the
Automobiles Unit and to suggest improvements. The
production system being so large, it can not be analysed
by a single person, so, the system is divided into sub-
systems. These sub-systems could themselves be again
divided into sub-systems and so on till the level where
input and output could be defined as shown in figure 2.
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• In our example where Production Manager could
not analyse the system as a whole so he entrusted
the work to the Assistant Production Managers of
Production Unit who in turn entrust the work to
Supervisors of the Unit. Finally the Production
System was analysed at Supervisors level where all
inputs and process of Production System were
discussed to meet the new objective and the
report submitted back to Production Manager who
in turn reports to Managing Director.
• Similarly system analyst also divides his system into
sub-systems so that it becomes easier for him to go
into the details of the whole system.
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TYPE OF SYSTEMS
DETERMINISTIC AND PROBABILISTIC SYSTEM
• In some of the systems the output or occurrences of all events
are perfectly predictable, but in some of the systems the output
or occurrences of events cannot be always perfectly predictable
Those systems where one can predict the occurrence of events
perfectly are called as deterministic systems and those systems
where the events cannot be perfectly predictable are called
probabilistic systems.
• Example of a deterministic system could be a production system
where the production unit that is a automobile production unit
which produce 3 scooters in one hour, so the output after 8
hours could be perfectly predicted i.e. it would be 24 scooters.
Example of a probabilistic system could be the closing balance of
cash in an airlines reservation office on a given day.
Unfortunately, it is the probabilistic system that the system
analyst deals mostly with.
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CLOSED AND OPEN SYSTEM
• These type of systems is based on their degree of
independence. A closed system is one which is self-
contained, that it does not interact with its
environment. But in reality no system can keep itself
isolated from its environment for a long time. It
controls its input and environmental disturbance is
minimum. Changing environment does not affect on
closed system.
• A open system has many interfaces with its
environment. It does interact with its boundary. If
the educational system in a country is such that it is
directly related to the job requirements of the
country, then we call such an educational system as
an open system..
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There are five important characteristics of open system:
• Inputs from outside : Open systems are self-adjusting and
self-regulating.
• Entropy : All dynamic systems tend to run down over time,
resulting in entropy or loss of energy. Open systems resist
entropy by seeking new inputs or modifying the processes
to return to a steady state.
• Process, Output and Cycles : Open systems produce useful
output and operate in cycles, following a continuous flow
of path
• Differentiation : Open systems can differentiate between
its components and can perform specialised functions.
• Equifinality : Most of the systems like to achieve their
goals no matter what they choose. This form of achieving
goals through different course of actions is another
characteristic of open systems and we call this as
equifinality
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STABLE SYSTEMS
• In stable systems, there are well defined relationship
between the various components but if these
relationships have external disturbances then they are
capable of returning to their desired state. The stability
is measured in terms of certain elements remaining
within previously set limits. For example, in an
Inventory Control System, the Reorder Level of
particular items is based on demand forecasts and past
experiences. We can call a Inventory Control System as
negative feed back mechanism wherein we record the
things when they are deviating from limits. When the
system has several such feed back loops whereby, if
one loop is out of control another is activated to
restore control, it is known as an ultra-stable system.
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CHARACTERISTICS OF SYSTEM
The basic characteristics of system are
• Organization
• Interaction
• Interdependence
• Integration
• Central objective
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Organization : Organization implies structure and order. It is the
arrangement of components that helps to achieve certain
objectives. For example, in a business system the hierarchical
relationships starting with the Managing Director on top and
leading downward to the workers represents the organization
structure. Such an arrangement portrays a system subsystem
relationship. Similarly computer system is designed around an
input device, a central processing unit, an output device, and
one or more storage units: When linked together they work as
a whole system for producing information. The traditional
principles on which organizations have been structured aim to
achieve parity of authority and responsibility.
• Harmony of objectives (all staff working to a common end).
• Unity of command (each person having only one immediate
superior).
• Unit of direction (one manager and one plan for each major
objective or set of objectives).
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Interaction : Interaction refers to the manner in
which each component functions with other
components of the system. In a business system,
for example, purchasing must interact with
production, advertising with sales, and payroll
with personnel.
• In a computer system, the central processing unit
must interact with input devices to solve a
problem. The interrelationship between various
components of computer system enables it to
perform. In an education system a teacher
interacts with a student to disseminate
knowledge or ideas of a particular subject.
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Interdependence : Interdependence means that parts of
the organization or computer system depend upon
each other. They are coordinated and linked together
according to a plan. For example, in an education
system:- a student is dependent on teacher to guide
him/her and a teacher in turn is dependent on student
where teacher expects student to respond him/her
favourably and positively. In addition, the output of
one sub-system may act as an input to another
subsystem. Interdependence is further illustrated by
the activities and support of system analysts,
programmers and the operating staff in a computer
centre. A decision to computerize an application is
initiated by the use, analysed and designed by the
analyst, programmed and tested by the programmer,
and run by the computer operator.
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Integration : Integration refers to the holism of system.
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 system work together within the system even
though each part performs a unique function. Successful
Integration will typically produce a greater, clearer and total
impact than each component works separately.
Central Objective : The last characteristic of a system is its
central objective. Objectives may be real or stated.
Although stated objective may be the real objective, it is
not uncommon for an organization to state one objective
and operate to achieve another. The user should be aware
of the central objectives of a computer application early in
the analysis for a successful design and conversion. The
analyst must work around such obstacles to identify the
real objective of the proposed change.
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CONTROL MECHANISM
• A system is not as simple as definition describes. We
presuppose that output generated by the system is always
according to the specifications. Suppose a computer program
generating a output report might give the output but not
according to desired specifications. A feed back is sought to
check what went wrong in our specification. After we receive
the feed back we correct the program and again run the
program to get the report. Here data was the input, computer
was a process and report was the output. In fact what has
been introduced in the system is a control mechanism. For any
system to be stable, a control mechanism is always necessary.
Whenever the output of a system deviates from the limits
which has been set, a control mechanism is required either to
adjust the process or the inputs. Forces of control mechanism
may not be able to adjust the inputs or processes in a way so
as to bring output within the limits specified. In that case the
output itself has to be adjusted.
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• One can know about the deviation has occurred in the outputs by
seeing the feedback where the generated outputs are compared with
standard outputs. Figure 3 below shows how controls in system would
work
• Every system which gets out of control, there must be a way of
restoring controls. Therefore, there should be a control mechanism for
each possible state of the system. The primary task of the system
analyst is to analyse and design a system which is absolutely new or
make a existing system more effective by modifications or by
substantial redesign. The system involved could be economic, political,
social institution such as business houses, government agencies,
colleges and universities and usually a computer could be considered as
an aid for improving the systems operation. System analyst may be
responsible for system analysis, detail design of the computer system
and outlining system specification.
rozygag@yahoo.com

SYSTEM ANALYST
The system analyst has two primary objectives
• Assessment objective
• Assistance objective
Assessment objective : A system analyst has to observe,
understand and evaluate the interactions which routinely occurs
as a part of the Job under investigation.
Herein the analyst has to know.
• What is being done ?
• Who is doing it ?
• Why is it being done ?
• How is it being done ?
• What are major problems in doing it ?
After the completion of assessment objective, the system analyst
offers specific suggestions for improving the efficiency of Job
under consideration. He does so by providing assistance.
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Assistance Objective : A system analyst is to provide
alternative solutions to make the existing system more
efficient. For this job, he seeks the help of the computer.
At such times he acts like a communication-link between
technology and user. Analyst now finds out other ways to
deal with the existing problem and also checks the
benefits and liabilities associated with these alternative
approaches.
• Better assessment of problems will provide better
assistance, and probably the presence of other kinds of
assistance gives the analyst a broader perspective for the
assessment.
• A system analyst must have good communication with all
the people affected. Communication skill of system analyst
should be sharp as he depends on others for both
information and co-operation. System analyst in facts as
an agent of change.
rozygag@yahoo.com

Thanks!
Dear Users
I am writing and preparing these slides for you but not
hearing anything from your side. If you want more slides
please give me comments, they will work like a control
mechanism and I will try to do the work as per your
requirements.
Regards
Gagan Deep
Rozy Computech Services
3rd Gate, K.U., Kurukshetra -136119
rozygag@yahoo.com
rozygag@yahoo.com

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