Objectives: Introduction Over View of System Analysis and Design
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- 8.5.2.1 Purpose
| 8.5.1.4 Using Structured Flowcharts Structured flowcharts use no arrows or continuations on separate pages. Each structured flowchart is shown on a single sheet of paper (or single display screen, if developed online. When designing a structured flowchart the systems analyst specifies the logic in atop down fashion. The first consideration in a processor decision is the top element. The second in sequence is the next one shown, and so forth. Similarly, there is a single exit from the process. The analyst beings with a major process and introduces other symbols to subdivide the process. Each process is named, but, if the name is not underlined, it is a reference to some other diagram or description. This simple convention makes it possible to link together easily different procedures that are performed to complete an entire activity. The structure chart reads from top to bottom and left to right. Each activity is nested within the iteration and alternative processes of which it is part. In addition, each condition is clearly shown. Individual parts of processes are often further described in lower-level diagrams. Individual modules are referenced to handle the processing for each type of transaction. An important use of structured flowcharts for the designer concerned about verifying systems specifications against planned software logic is to identify conditions and procedures followed when the conditions exist. The fact that the structure chart is easy to read will enable the analyst to determine whether the debit adjustment transaction, for example, has been added by the programmer or is apart of the original systems specifications. 8.5.2 HIPO HIPO is another commonly used method for developing systems software. IBM developed this method of Hierarchical Input Process Output (HIPO), for large, complex operating systems. 8.5.2.1 Purpose The assumption on which HIPO is based is that is easy to lose track of the intended function of a system or component in a large system. This is one reason why it is difficult to compare existing systems against their original specifications (and therefore why failures can occur even in systems that are technically well formulated. From the user’s view, single functions can often extend across several modules. The concern of the analyst then is understanding, describing, and documenting the modules and their interaction in away that provides sufficient detail but that does not lose sight of the larger picture. HIPO diagrams are graphic, rather than prose or narrative, descriptions of the system. They assist the analyst in answering three guiding questions 1. What does the system or module do (Asked when designing the system. 2. How does it do it (Asked when reviewing the code for testing or maintenance. 3. What are the inputs and outputs (Asked when reviewing the code for testing or maintenance) A HIPO description fora system consists of the visual table of contents and the functional diagrams. Download 0.94 Mb. Share with your friends:
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