Chapter 20
Systems Design,
Implementation, and
Operation
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Overview
• The last four phases (2-5) in SDLC:
– 1.
– 2.
– 3.
– 4.
– 5.
Systems Analysis (Chapter 18)
Conceptual Design
Physical Design
Implementation and Conversion
Operation and Maintenance
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Overview
• Questions to be addressed in this chapter include:
– What are the activities that take place in the conceptual
design phase of the systems development life cycle
(SDLC)?
– What activities take place in the physical systems design
phase?
– What happens during the systems implementation and
conversion process?
– What activities occur in the systems operation and
maintenance process?
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Introduction
• Accountants must understand the entire systems
development process, because they are involved in
several ways:
– Helping to specify their needs.
– As members of the development team.
– As auditors after the fact.
• Accountants also help keep the project on track by:
– Evaluating and measuring benefits.
– Measuring costs.
– Ensuring the project stays on schedule.
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CONCEPTUAL SYSTEMS DESIGN
• In the conceptual systems design phase, a
general framework is created for
implementing user requirements and solving
the problems identified in the analysis phase.
• The three main steps are:
– Evaluate design alternatives.
– Prepare design specifications.
– Prepare the conceptual systems design report.
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CONCEPTUAL SYSTEMS DESIGN
• Evaluating design alternatives
– There are many design decisions that must be
made. For example:
• Should a document be hard-copy or sent by EDI?
• Should the company use a large centralized mainframe
or some form of distributed processing?
• What form should data entry take, e.g., keyboard,
optical character recognition, POS devices?
• Data storage medium, structure, file access?
• Frequency of updates?
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CONCEPTUAL SYSTEMS DESIGN
• Also, there are many ways to approach the systems
development process:
–
–
–
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Packaged software
In-house development
End-user development
Outsourcing
• The company also chooses between:
– Modifying or enhancing existing software
– Replacing existing software
– Reengineering its business processes
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CONCEPTUAL SYSTEMS DESIGN
• Prepare design specifications
– Once a design has been selected, the
project team develops the more detailed
conceptual design specifications for the
following elements:
• Output (prepared first to meet user’s needs)
• Data storage (what data, type of file)
• Input (where, when, & how to collect data)
• Processing procedures and operations (steps)
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CONCEPTUAL SYSTEMS DESIGN
• Prepare the conceptual systems design report
– A conceptual systems design report is prepared at
the end of the conceptual design phase to:
• Guide physical system design activities.
• Communicate how management and user information
needs will be met.
• Help the steering committee assess system feasibility.
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Physical Systems Design
• During the physical systems design phase, the
company determines how the conceptual AIS design
is to be implemented.
– The broad, user-oriented requirements of conceptual
design are translated into detailed specifications used to
code and test computer programs.
– Phases include:
•
•
•
•
•
•
Designing output
Creating files and databases
Designing input
Writing computer programs
Developing procedures
Building in controls
Let’s look at each of these phases, next
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Physical Systems Design
Output Design:
• Output usually fits into one of the following four categories:
• Scheduled reports have a prespecified content and format and are
prepared on a regular basis.
• Special-purpose analysis reports have no prespecified content or
format and are not prepared on a regular schedule.
• Triggered exception reports have a prespecified content and format
but are prepared only in response to abnormal conditions.
• Demand reports have a prespecified content and format but are
prepared only on request.
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Physical Systems Design
File and Database Design:
• Data needs to be stored in compatible formats to help
avoid the problem of having incompatible systems that
makes it impossible to share information and prepare
reports.
•
•
•
•
•
What is the medium (tape, disc)?
Is processing batch, manual or real-time?
What is the size of the database?
How is the database maintained?
When will information be added, deleted and
updated?
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Physical Systems Design
Input Design:
• How does data get in the system? Is it
through printed forms? Or is it through online
entry?
• Forms design: more and more companies are
moving away from paper documents, but it is
still important.
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Physical Systems Design
Computer screen design: it is more efficient to enter data
directly into the computer than on paper for
subsequent entry.
Design considerations:
+ data should be entered quickly, accurately and
completely.
+ enter data in the same order as displayed on paper.
+ enter left to right & top to bottom, group related data.
+ easy movement across the screen.
+ avoid clutter (e.g., limit number of menu options).
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Physical Systems Design
Program development: is one of the most time-consuming
activities in the SDLC.
Programs subdivided into small, well-defined modules are a
process called structured programming.
To improve software quality, organizations should develop
programming standards.
Although accountants need not be computer programmers,
they should understand how software is created.
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Physical Systems Design--Program Design
Eight steps for developing software: (Program Design)
Step 1 Determine user needs. Systems analysts consult with users and agree
on software requirements. Step 1 is performed as a part of the systems
analysis phase of the SDLC.
Step 2 Develop a plan. A development plan is produced and documented.
Step 2 is done during conceptual systems design and may carry over to the
beginning of physical design.
Step 3 Write program instructions (code). This is when the computer code (or
program instructions) is written.
Step 4 Test the program. Debugging is discovering and eliminating program
errors. After a program is coded, a visual and mental review, referred to as
desk checking, is conducted to discover programming errors. Cost a lot
more to debug later rather than sooner.
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Physical Systems Design--Program Design
continued
Step 5 Documents the program. Documentation explains how programs work
and is used to help correct and resolve errors.
Step 6 Train program users. Program documentation is often used to train
users. Steps 5 and 6 are begun in systems design, but most of the work is
done during systems implementation.
Step 7 Install the system. All system components, including the programs, are
combined and the company begins to use the system. Step 7 is completed
during systems implementation and conversion.
Step 8 Use and modify the system. Factors that require existing programs to
be revised, referred to as program maintenance, include requests for new
or revised reports; changes in input, file content, or values such as tax
rates; error detection; and conversion to new hardware. Step 8 is part of
the operation and maintenance phase.
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Physical Systems Design
--Procedures Design
• Procedures design
– Individuals who interact with a newly-designed
AIS need procedures to cover:
•
•
•
•
•
•
•
•
Input preparation
Transaction processing
Error detection and correction
Controls
Reconciliation of balances
Database access
Output preparation and distribution
Computer operator instructions
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Physical Systems Design
--Procedures Design
• The procedures may be written by:
– Development teams;
– Users; or
– Teams representing both groups.
• Procedures may take the form of:
– System manuals
– User instruction classes
– Training materials
– Online help screens
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Physical Systems Design
--Controls Design
• Controls design
– Improperly controlled input, processing, and
database functions produce information of
questionable value. (garbage in, garbage out)
– Controls must be built into an AIS to ensure its
effectiveness, efficiency, and accuracy. These
controls should:
• Minimize errors.
• Detect and correct errors when they do occur.
– Accountants play a vital role in this area.
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Physical Systems Design
--Controls Design
Important control concerns that must be addressed
include: (more detail in chapters 6-9)
–
–
–
–
–
–
–
–
–
Validity
Authorization
Accuracy
Security
Numerical control
Availability
Maintainability
Integrity
Audit trail (can you trace transaction from source to final output and back)
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Physical Systems Design
--Design report
• Physical systems design report
– At the end of the physical design phase, a physical
systems design report is prepared, summarizing
what was accomplished.
– This report serves as the basis for management’s
decision whether to proceed to implementation.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
• Systems implementation
– Systems implementation is the process of
installing hardware and software and getting the
AIS up and running.
– Phases include:
•
•
•
•
•
•
Developing a plan
Preparing the site
Installing and testing hardware and software
Selecting and training personnel
Completing documentation
Testing the system
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SYSTEMS IMPLEMENTATION AND
CONVERSION
• Implementation planning
– An implementation plan consists of:
•
•
•
•
Implementation tasks
Expected completion dates
Cost estimates
Specification of the person(s) responsible for each task
• AIS changes may require adjustments to the
company’s organizational structure, including:
– Creation of new departments.
– Elimination or downsizing of existing departments.
– Changes even in the data processing department.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
• Site preparation: A large computer may require changes such as:
•
•
•
•
•
•
New electrical outlets
Data communications facilities
Humidity controls
Special lighting
Air-conditioning
Security measures, such as:
– Fire protection
– Emergency power supply
• Space for equipment, storage, and offices, etc.
• Site preparation is a lengthy process and should begin
well ahead of the installation date.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Select and train personnel:
• When training is insufficient, the company will not
achieve the expected return on investment.
• The hidden cost is that users will turn to their
coworkers who have mastered the system for help.
Results in:
– Less productive coworkers
– Increased costs
• Effective training includes:
– Hardware and software skills
– Orientation to new policies and operations
• The training should be scheduled just before systems
testing and conversion.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
• Types of staff training include:
– Technical training from vendors
– Self-study manuals
– Computer-aided instruction
– Videotape presentations
– Role-playing
– Case studies
– Experimenting with the AIS under the guidance of
experienced users
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Complete Documentation:
Three types of documentation must be prepared
for new systems:
– Development documentation (describes new AIS)
– Operations documentation (operating schedules, security,
file-retention requirements)
– User documentation (how to use system, users manual)
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Test the system:
– Inadequate system testing has contributed to the failure of
systems.
– All of the following should be given a trial run in realistic
circumstances.
•
•
•
•
•
Documents and reports
User input
Operating and control procedures
Processing procedures
Computer programs
– Should also test:
• Capacity limits
• Backup and recovery procedures
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SYSTEMS IMPLEMENTATION AND
CONVERSION
• Three common forms of testing include:
– Walk-throughs (step-by-step reviews of procedures or program
logic.)
– Processing test transactions (valid and erroneous data are
processed to determine if transactions are processed appropriately.)
– Acceptance tests (use copies of real transactions and files
rather than hypothetical ones. Users develop the acceptance
criteria and make a decision whether to accept the AIS.)
• Even software purchased from an outside vendor
must be tested thoroughly before installation.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Systems conversion
– Conversion is the process of changing from the old AIS to
the new.
– Many elements must be converted, including:
•
•
•
•
Hardware
Software
Data files
Procedures
– The process is complete when the new AIS has become a
routine, ongoing part of the system.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Systems Conversion
a. Direct conversion -- immediately terminate the
old AIS when the new one is introduced (risky,
but may be cost effective).
b. Parallel conversion -- operates the old and new
system simultaneously for a period of time.
c. Phase-in conversion -- gradually replaces
elements (modules) of the old AIS with a new
one.
d. Pilot conversion -- implements a system just in
one part (e.g., location) of the organization.
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SYSTEMS IMPLEMENTATION AND
CONVERSION
Data Conversion:
– Data conversion can be time-consuming, tedious,
and expense.
– The difficulty and magnitude is easy to
underestimate.
– Data files may need to be modified in three ways:
• Files may be moved to a different storage medium (e.g.,
tape to disk).
• Data content may be changed (e.g., fields added or
deleted).
• A file or database format may be changed.
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OPERATIONS AND MAINTENANCE
• The last step in the SDLC is to operate and
maintain the new system.
• A post-implementation review should be
conducted to ensure the new AIS meets its
planned objectives. This completes the
process.
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Post-implementation review
Addresses the following:
--does the system meet objectives?
--are the users satisfied?
--what were the actual costs?
--is it reliable, accurate, timely?
--are the users trained?
--is documentation complete and accurate?
--recommendations for improving the new system
--recommendations for improving the systems development
process
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• Studies show that over the life of a system,
only 30% of the work takes place during
development. The remaining 70% is spent on
maintaining the system (mostly software
modifications & updates).
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QUIZ
Multiple Choice 1 (pg. 747)
In the conceptual design phase of the systems development life cycle, _______
specifications must be prepared first.
A. Input
B. Output
C. Data storage
D. Data processing
Multiple Choice 2 (pg. 762)
Assumptions and unresolved problems are included in the following report(s):
A. Conceptual systems design report
B. Physical systems design report
C. Post-implementation review report
D. All of the above
E. A and B
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QUIZ
Multiple Choice 3 (pg. 750)
The following consideration(s) are involved in the file and database design.
A. Use
B. Operations
C. Medium
D. A and C
Multiple Choice 4 (751)
“Is additional training necessary?” is a concern to be answered during _______
design.
A. Input
B. Output
C. Files and database
D. Program
E. Controls
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QUIZ
Multiple Choice 5 (pg. 752)
_________ development is one of the most time consuming activities in the SDLC.
A.
B.
C.
D.
E.
Input
Output
Files and database
Program
Controls
Multiple Choice 6 (pg. 752-3)
____________ is done during systems design and is completed during systems
implementation.
A. Develop a plan
B. Desk checking
C. Write program instructions
D. All of the above
E. B and C
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QUIZ
Multiple Choice 7 (pg. 758)
Walk-throughs are conducted by:
A. Development team
B. System users
C. Programmers
D. All of the above
E. A and B
Multiple Choice 8 (pg. 759)
The first step in the data conversion process is:
A. Check data for completeness, and any data inaccuracies and remove any
inconsistencies.
B. Decide which data files need to be converted.
C. Conduct data conversion
D. Validate new files
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Case 1
Gouge, Cheatum & Holdup, a legal firm, has a problem:
most of the general partners are having a difficult time
recording all the time spent on client matters for billing
purposes. It is estimated that only 70% of the actual
time is billed. Several discussions among the partners
revealed that a lot of time is spent on the telephone
with clients, but the information is not recorded into
the system for billing the client.
REQUIRED: Discuss some alternatives to fix the
problem.
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Case 2
The Daily Express Newspaper Company serves a small
community and derives a considerable amount of revenue
from advertising. All advertising orders are taken by
salespeople at the customers’ places of business. At the
end of three days, all advertising orders are processed in a
batch. It normally takes four days between the time the
order is taken and the time the ad appears in the
newspaper. Recently, a competitive newspaper has offered
faster service to its customers.
REQUIRED: Discuss some alternatives to solve the problem.
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