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Chapter 24 Systems Design, Implementation, and Operation, Evaluate Design…
Chapter 24
Systems Design, Implementation, and Operation
Conceptual Systems Design Activities
System Analysis
Conceptual System Design
Prepare Design Specifications
Prepare Conceptual Systems Design Report
Physical Design
Implementation and Conversion
Operation and Maintenance
Phase 3: Physical Systems Design
File and Database Design
Output Design
4 Categories:
1) Scheduled reports
Prepared on a regular basis, with a pre-specified content and format.
2) Special purpose analysis reports
No pre-specified content, format or schedule, usually prepared in response to a management request.
3) Triggered exception reports
Pre-specified content and format, prepared only in response to abnormal conditions.
4) Demand reports
Pre-specified content and format, prepared only on request.
Input Design
Form design
Computer Screen Design
Procedures:
a) Organize the screen so data can be entered quickly, accurately and completely. Minimize data input by retrieving as much data from the system
b) Enter data in the same order as displayed on paper forms that capture the data
c) Group logically related data together
d) Design the screen so users can jump from one data entry location to another or use a single key to go directly to screen locations
e) Make it easy to correct mistakes. Clear and explicit error messages consistent across all screens are essential
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Program Design
1) Determine user needs
2) Create and document a development plan
3) Write program instructions (computer code)
4) Test the program
5) Document the program
6) Train program users
7) Install the system
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Program documentation is often used to train users
Documentation explains how programs work and is used to correct errors. Program documentation includes flowcharts, data flow diagrams. These items are stores in a documentation manual
Debugging is the process of discovering and eliminating program errors. A program is tested for logic errors using test data that simulate as many real processing situations and input data combinations as possible
Computer programs should be subdivided into small, well-defined modules to reduce complexity and enhance reliability and modifiability, a process called structured programming. Modules should interact with a control module rather than with each others
Systems analysts consult with users and reach an agreement on user needs and software requirements
Procedures Design
Control Design
Phase 4: Systems Implementation
Implementation plan
Select and train personnel
Complete documentation
1) Development documentation
2) Operations documentation
3) User documentation
Testing the system
Walk-throughs
Step by step review
Processing test data
Test all valid transactions and error conditions
Acceptance tests
Use copies of real data
Phase 5: Operations and Maintenance
Postimplementation review
Review made after a new system has been operating for a brief period to ensure that the new system is meeting its planned objectives, identify the adequacy of system standards, and review system controls
Postimplementation review report.
A report that analyzes a newly delivered system to determine if the system achieved its intended purpose and was completed within budget.
Phase 4: Systems Conversion
Direct conversion
Parallel conversion
Phase-in conversion
Pilot conversion
Changing from an old system to a new one by implementing a system in one location, using it until all problems are resolved and then implementing it in the rest of the organization
Changing from an old system to a new one by gradually replacing elements of the old with the new until the old system has been entirely replaced
Changing from an old system to a new one by operating both system simultaneously until the organization is confident the new system is functioning correctly
Changing from an old system to a new one by terminating the old IS when the new one is introduced
Evaluate Design Alternatives