Information Technology Reference
In-Depth Information
SUMMARY
Principle
Designing new systems or modifying existing ones
should always help an organization achieve its goals.
tight systems controls to maintain data security. Systems
controls can help prevent computer misuse, crime, and fraud
by employees and others. Systems controls include input,
output, processing, database, telecommunications, and per-
sonnel controls.
Environmental design, also called green design, involves
systems development efforts that slash power consumption,
require less physical space, and result in systems that can be
disposed in a way that doesn't negatively affect the environ-
ment. A number of companies are developing products and
services to help save energy. Environmental design also deals
with how companies are developing systems to dispose of old
equipment. The U.S. government is also involved in environ-
mental design. It has a plan to require federal agencies to
purchase energy-efficient computer systems and equipment.
The plan would require federal agencies to use the Electronic
Product Environmental Assessment Tool (EPEAT) to analyze
the energy usage of new systems. The U.S. Department of
Energy rates products with the Energy Star designation to
help people select products that save energy and are friendly
to the environment.
Whether an individual is purchasing a personal computer
or an experienced company is acquiring an expensive main-
frame computer, the system could be obtained from one or
more vendors. Some of the factors to consider in selecting
a vendor are the vendor's reliability and financial stability,
the type of service offered after the sale, the goods and ser-
vices the vendor offers and keeps in stock, the vendor's will-
ingness to demonstrate its products, the vendor's ability to
repair hardware, the vendor's ability to modify its software,
the availability of vendor-offered training of IS personnel and
system users, and evaluations of the vendor by independent
organizations.
If new hardware or software will be purchased from a
vendor, a formal request for proposal (RFP) is needed. The
RFP outlines the company's needs; in response, the vendor
provides a written reply. In addition to responding to the com-
pany's stated needs, the vendor provides data on its opera-
tions. This data might include the vendor's reliability and
stability, the type of postsale service offered, the vendor's
ability to perform repairs and fix problems, the available ven-
dor training, and the vendor's reputation. Financial options to
consider include purchase, lease, and rent.
RFPs from various vendors are reviewed and narrowed
down to the few most likely candidates. In the final evaluation,
a variety of techniques—including group consensus, cost/
benefit analysis, point evaluation, and benchmark tests—can
be used. In group consensus, a decision-making group is
appointed and given responsibility for making the final eval-
uation and selection. With cost/benefit analysis, all costs
and benefits of the alternatives are expressed in monetary
terms. Benchmarking involves comparing computer systems
The purpose of systems design is to prepare the detailed
design needs for a new system or modifications to the existing
system. Logical systems design refers to the way that the
various components of an information system will work
together. The logical design includes data requirements for
output and input, processing, files and databases, telecom-
munications, procedures, personnel and job design, and con-
trols and security design. Physical systems design refers to
the specification of the actual physical components. The phys-
ical design must specify characteristics for hardware and
software design, database and telecommunications, and per-
sonnel and procedures design.
Logical and physical design can be accomplished using
the traditional systems development life cycle or the object-
oriented approach. Using the OO approach, analysts design
key objects and classes of objects in the new or updated sys-
tem. The sequence of events that a new or modified system
requires is often called a scenario, which can be diagrammed
in a sequence diagram.
A number of special design considerations should be
taken into account during both logical and physical system
design. Interface design and control relates to how users
access and interact with the system. A sign-on procedure
consists of identification numbers, passwords, and other
safeguards needed for individuals to gain access to computer
resources. If the system under development is interactive, the
design must consider menus, help facilities, table lookup
facilities, and restart procedures. A good interactive dialogue
will ask for information in a clear manner, respond rapidly, be
consistent among applications, and use an attractive format.
Also, it will avoid use of computer jargon and treat the user
with respect.
System security and control involves many aspects. Error
prevention, detection, and correction should be part of the
system design process. Causes of errors include human
activities, natural phenomena, and technical problems.
Designers should be alert to prevention of fraud and invasion
of privacy.
Disaster recovery is an important aspect of systems
design. Disaster planning is the process of anticipating and
providing for disasters. A disaster can be an act of nature (a
flood, fire, or earthquake) or a human act (terrorism, error,
labor unrest, or erasure of an important file). The primary
tools used in disaster planning and recovery are hardware,
software, database, telecommunications, and personnel
backup.
Security, fraud, and the invasion of privacy are also impor-
tant design considerations. Most IS departments establish
