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SYSTEMS DESIGN, IMPLEMENTATION AND OPERATION: In chapter 20 we focused on the first phase of the Systems Development Life Cycle – Systems Analysis. Chapter 22 deals with the remaining four phases: - conceptual systems design - physical systems design - systems implementation and conversion - operation and maintenance 70-358

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CONCEPTUAL SYSTEMS DESIGN: In the conceptual systems design phase, the developer creates a general framework for implementing user requirements and solving problems identified in the analysis phase. 70-358

1. evaluating design alternatives, As shown in Figure 22-1 on page 684 there are three main steps in conceptual design: 1. evaluating design alternatives, 2. preparing design specifications, and 3. preparing the conceptual systems design report. 70-358

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Evaluate Design Alternatives: As we have seen already in chapter 21, there are many ways to design an AIS, so accountants and others involved in systems design must continually make design decisions. 70-358

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The steering committee evaluates the alternatives. The design team should identify a variety of design alternatives and evaluate each with respect to the following standards: how well it meets organizational and system objectives, how well it meets user needs, whether it is economically feasible, and what its advantages and disadvantages are.  The steering committee evaluates the alternatives. 70-358

Table 22-1 on page 684 presents examples of conceptual and physical design considerations and their corresponding design alternatives. The answers to these questions significantly designs the system in selecting from the alternatives. 70-358

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Prepare Design Specifications: Once a design alternative has been selected, the project team develops the conceptual design specifications for the following elements: 1. Output. Because the system is designed to meet users’ information needs, output specifications are usually prepared first. 70-358

2. Data storage. In the example in the text, decisions included: which data needs to be stored for the required reports, whether the data should be stored in sequential or random order, what type of file or database to use, and which field size is appropriate for the data items? 70-358

3. Input. Design considerations for the 3. Input. Design considerations for the example include which sales data to enter, sale location and amount, and where, when, and how to collect data. 70-358

4. Processing procedures and operations 4. Processing procedures and operations. Design considerations for the example include how to process the input and stored data to produce the sales report and also the sequence in which the processes must the performed. 70-358

Prepare the Conceptual Systems Design Report: At the end of the conceptual design phase, a conceptual systems design report is prepared to: 1. guide physical systems design activities, 2. communicate how management and user information needs will be met, and 3. help the steering committee assess system feasibility. 70-358

The table of contents of the example report is shown in Table 22-8 on page 695. 70-358

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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. As shown in Figure 22-2 on page 685, physical system design phases include: Designing output Files and databases design Designing input Computer programs design Procedures design Controls design 70-358

Physical Systems Design Systems Analysis Conceptual Systems Design Output Design File and DB Design Input Design Program Design Proce- dures Design Controls Design Implementation and Conversion Operation and Maintenance

Output Design: The objective of output design is to determine the nature, format, content, and timing of printed reports, documents, and screen displays. Completing this requires cooperation between users and designers. Some important output design considerations are summarized in Table 22-2 on page 686. 70-358

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Output usually fits into one of the following four categories: 1. Scheduled reports have a prespecified content and format and are prepared on a regular basis. Examples: weekly sales analysis, monthly financial statements 2. Special-purpose analysis reports have no prespecified content or format and are not prepared on a regular schedule. Typically prepared in response to a management request. Example: analysis of impact of a new government requirement on profitability 70-358

3. Triggered exception reports have a prespecified content and format but are prepared only in response to abnormal conditions. Example: cost overruns reports 4. Demand reports have a prespecified content and format but are prepared only on request. 70-358

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File and Database Design: Various company segments need to store data in compatible formats so that data can be shared across units. Table 22-3 on page 687 summarizes some of the more important file and database design considerations: 70-358

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1)storage medium 2) processing mode 3) maintenance 4) size 5) activity level 70-358

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