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Analysis and Design
System Components and Characteristics
A big system may be seen as a set of interacting smaller systems known as subsystems
or functional units each of which has its defined tasks. All these work in coordination
to achieve the overall objective of the system. System engineering requires development
of a strong foundation in understanding how to characterize a system, product,
or service in terms of its attributes, properties, and performance.
As discussed above, a system is a set of components working together to achieve
some goal. The basic elements of the system may be listed as:
Every system requires certain resources for the system to exist. Resources
can be hardware, software or liveware. Hardware resources may include the computer,
its peripherals, stationery etc. Software resources would include the programs
running on these computers and the liveware would include the human beings required
to operate the system and make it functional.
Thus these resources make an important component of any system. For instance,
a Banking system cannot function without the required stationery like cheque books,
pass books etc. such systems also need computers to maintain their data and trained
staff to operate these computers and cater to the customer requirements.
Every system functions under a set of rules that govern the system to accomplish
the defined goal of the system. This set of rules defines the procedures for the
system to Chapter 1 - Introduction to Systems operate.
For instance, the Banking systems have their predefined rules for providing interest
at different rates for different types of accounts.
Every system has some predefined goal. For achieving the goal the system requires
certain inputs, which are converted into the required output. The main objective
of the System is to produce some useful output. Output is the outcome of processing.
Output can be of any nature e.g. goods, services or information.
However, the Output must conform to the customer's expectations. Inputs are
the elements that enter the system and produce Output. Input can be of various
kinds, like material, information, etc.
Various processes process system's Inputs. Before it is transformed into Output,
it goes through many intermediary transformations. Therefore, it is very important
to identify the Intermediate Data. For example, in a college when students register
for a new semester, the initial form submitted by student goes through many departments.
Each department adds their validity checks on it.
Finally the form gets transformed and the student gets a slip that states whether
the student has been registered for the requested subjects or not. It helps in
building the System in a better way. Intermediate forms of data occur when there
is a lot of processing on the input data. So, intermediate data should be handled
as carefully as other data since the output depends upon it.
The systems have some processes that make use of the resources to achieve the
set goal under the defined procedures. These processes are the operational element
of the system.
For instance in a Banking system there are several processes that are carried
out. Consider for example the processing of a cheque as a process. A cheque passes
through several stages before it actually gets processed and converted. These
are some of the processes of the Banking system. All these components together
make a complete functional system.
Systems also exhibit certain features and characteristics, some of which are:
Every system has a predefined goal or objective towards which it works. A system
cannot exist without a defined objective. For example an organization would have
an objective of earning maximum possible revenues, for which each department and
each individual has to work in coordination.
It is the acceptable level of performance for any system. Systems should be
designed to meet standards. Standards can be business specific or organization
For example take a sorting problem. There are various sorting algorithms. But
each has its own complexity. So such algorithm should be used that gives most
optimum efficiency. So there should be a standard or rule to use a particular
algorithm. It should be seen whether that algorithm is implemented in the system.
Every system whether it is natural or man made co-exists with an environment.
It is very important for a system to adapt itself to its environment. Also, for
a system to exist it should change according to the changing environment. For
example, we humans live in a particular environment. As we move to other places,
there are changes in the surroundings but our body gradually adapts to the new
environment. If it were not the case, then it would have been very difficult for
human to survive for so many thousand years.
Another example can be Y2K problem for computer systems. Those systems, which
are not Y2K compliant, will not be able to work properly after year 2000. For
computer systems to survive it is important these systems are made Y2K compliant
or Y2K ready.
Feedback is an important element of systems. The output of a system needs to
be observed and feedback from the output taken so as to improve the system and
make it achieve the laid standards. In fig 1.1, it is shown that a system takes
input. It then transforms it into output. Also some feedback can come from customer
(regarding quality) or it can be some intermediate data (the output of one process
and input for the other) that is required to produce final output.
Boundaries and Interfaces
Every system has defined boundaries within which it operates. Beyond these
limits the system has to interact with the other systems. For instance, Personnel
system in an organization has its work domain
with defined procedures. If the financial details of an employee are required,
the system has to interact with the Accounting
system to get the required details.
Interfaces are another important element through which the system interacts
with the outside world. System interacts with other systems through its interfaces.
Users of the systems also interact with it through interfaces. Therefore, these
should be customized to the user needs. These should be as user friendly as possible.
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