SYSTEMS DESIGN, IMPLEMENTATION AND OPERATION

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SYSTEMS DESIGN, IMPLEMENTATION ANDOPERATION

• Chapter 20

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Conceptual Systems Design
Systems Analysis
Prepare Design Specifications
Prepare Conceptual Systems Design report
Evaluate Design Alternatives
Physical Design
Implementation And Conversion
Operation And Maintenance
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CONCEPTUAL SYSTEMS DESIGN

• Evaluating Design Alternatives
• Hard copy v. soft copy
• Centralized v. distributed processing
• Data entry approach
• Packaged software
• In-house development
• End-user development
• Outsourcing
• Modifying or enhancing existing software
• Replacing existing software
• Reengineering its business processes

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CONCEPTUAL SYSTEMS DESIGN

• Prepare design specifications
• Develop the conceptual design specifications for
  the following elements
• Output
• Data storage
• Input
• Processing procedures and operations

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CONCEPTUAL SYSTEMS DESIGN

• Prepare the Conceptual Systems Design Report
• Guides physical system design activities.
• Communicates how management and user information
  needs will be met.
• Helps the steering committee assess system
  feasibility.

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Systems Analysis
Physical Systems Design
Conceptual Systems Design
Output Design
File DB Design
Input Design
Program Design
Proce- dures Design
Controls Design
Implementation And Conversion
Operation And Maintenance
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PHYSICAL SYSTEMS DESIGN

• Output Design
• The objective is to determine the nature, format,
  content, and timing of printed reports,
  documents, and screen displays
• Requires cooperation between users and designers

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PHYSICAL SYSTEMS DESIGN

• Important design considerations include
• Use of the output
• Output medium
• Output format
• Pre-printed
• Location
• Access
• Detail
• Timeliness

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PHYSICAL SYSTEMS DESIGN

• Outputs usually fit into one of the following
  four categories
• Scheduled reports
• Special-purpose analysis reports
• Triggered exception reports
• Demand reports

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PHYSICAL SYSTEMS DESIGN

• File and Database Design
• Various company segments need to store data in
  compatible formats so that data can be shared
  across units.
• Important file and database design considerations
  include
• Storage medium
• Processing mode
• Maintenance
• Size
• Activity level

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PHYSICAL SYSTEMS DESIGN

• Input Design
• There are two principal types of data input
• Forms
• Computer screens

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PHYSICAL SYSTEMS DESIGN

• Considerations in input design include
• Input medium
• Input source
• Input format
• Input type
• Volume
• Personnel
• Frequency
• Cost
• Error detection and correction

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PHYSICAL SYSTEMS DESIGN

• Program Design
• Program development is one of the most
  time-consuming activities in the SDLC.
• A structured programming process should be
  followed
• With structured programming, programs should be
  subdivided into small, well-defined modules to
  reduce complexity and enhance reliability and
  modifiability.
• Modules should interact with a control module
  rather than with each other.
• To facilitate testing and modification, each
  module should have only one entry and exit point.

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PHYSICAL SYSTEMS DESIGN

• 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
• Improperly controlled input, processing, and
  database functions produce information of
  questionable value.
• 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

• Control design issues
• Validity
• Authorization
• Accuracy
• Security
• Numerical control
• Availability
• Maintainability
• Integrity
• Audit trail

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Systems Analysis
Conceptual Systems Design
System Implementation And Conversion
Physical Systems Design
Prepare site Install test hardware
Complete documentation
Conversion
Implementation Planning
Select Train Personnel
Test system
Operation And Maintenance
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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

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Site Preparation
• A large computer may require changes such as
• New electrical outlets
• Data communications facilities
• Raised floors
• Humidity controls
• Special lighting
• Air-conditioning
• Security measures, such as
• Fire protection
• Emergency power supply
• Space for equipment, storage, and offices

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Select and Train Personnel
• Employees can be hired from outside or
  transferred internally.
• Companies take shortcuts because
• Effective training is time-consuming and
  expensive.
• Those who understand the system are maintaining
  and upgrading it.

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Three types of documentation must be prepared for
  new systems
• Development documentation
• Operations documentation
• User documentation

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Test the System
• Documents and reports
• User input
• Operating and control procedures
• Processing procedures
• Computer programs
• Capacity limits
• Backup and recovery procedures

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Three common forms of testing include
• Walk-throughs
• Processing test transactions
• Acceptance tests

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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

• Conversion Approaches
• Direct conversion
• Parallel conversion
• Phase-in conversion
• Pilot conversion

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SYSTEMS IMPLEMENTATION AND CONVERSION

• Data Conversion
• Data conversion can be time-consuming, tedious,
  and expensive.
• 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.

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OPERATIONS AND MAINTENANCE

• Factors and questions include
• Goals and objectives
• Satisfaction
• Benefits
• Costs
• Reliability
• Accuracy
• Timeliness

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OPERATIONS AND MAINTENANCE

• Factors and questions include
• Compatibility
• Controls and security
• Errors
• Training
• Communications
• Organization changes
• Documentation

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SUMMARY

• We have
• Discussed the activities that take place in the
  conceptual design phase of the systems
  development life cycle (SDLC).
• Identified activities that take place in the
  physical systems design phase.
• Explored what happens during the systems
  implementation and conversion process.
• Examined the activities in the systems operation
  and maintenance process.