【正文】 y expense. On the other hand, a poor selection discourages shoppers. Ideally, a balance can be achieved: enough, but not too much. Complicating matters is the fact that inventory is constantly changing, with customer purchases depleting stock, and returns and reorders adding to it. [1] The owner would like to track inventory levels and reorder and given item just before the store runs out. For a single item, the task is easyjust count the stockonhand. Unfortunately, the store has hundreds of different items, and keeping track of each one is impractical. Perhaps a puter might help. 21 Problem Definition The first step in the systems analysis and design process is problem definition. The analyst39。 because the program is but one ponent in a system. A system is a group of ponents that work together to acplish an objective. For example, consider a payroll system. Its objective is paying employees. What ponents are involved? Each day， employees record their hours worked on time cards. At the end of each week, the time cards are collected and delivered to the puter center, where they are read into a payroll program. As it runs, the progra m accesses data files. Finally, the paychecks are printed and distributed. For the system to work, people, procedures, input and output media, files, hardware, and software must be carefully coordinated. Note that the program is but one ponent in a system. Computerbased systems are developed because people need information. Those people, called users, generally know what is required, but may lack the expertise to obtain it. Technical professionals, such as programmers, have the expertise, but may lack training in the user39。I 附錄 1 外文翻譯 (原文 ) Systems Analysis and Design Working under control of a stored program, a puter processes data into information. Think about that definition for a minute. Any given puter application involves at least three ponents: hardware, software, and data. Merely writing a program isn39。t enough。s field. To plicate matters, users and programmers often seem to speak different languages, leading to munication problems. A systems analyst is a professional who translates user needs into technical terms, thus serving as a bridge between users and technical professionals. Like an engineer or an architect, a systems analyst solves problems by bining solid technical skills with insight, imagination, and a touch of art. Generally, the analyst follows a welldefined, methodical process that includes at least the following steps。s objective is determining what the user (in this case, the store39。s understanding of the problem is essential. The user should review and correct this written statement. The time to catch misunderstandings and oversights is now, before time, money and effort are wasted. Often, following a preliminary problem definition, the analyst performs a feasibility study. The study a brief capsule version of the entire systems analysis and design process, attempts to answer three questions: the problem be solved? it be salved in the user39。 this knowledge is extracted and formally documented. Most users think in terms of the functions to be performed and the data elements to be manipulated. The objective is to identify and link these key functions and data elements, yielding a logical system design. Start with the system39。s owner wants to selectively look at the inventory level for any product in short supply and, if appropriate, order replacement stock, so the system must be able to municate with management. Finally, following management authorization, the system should generate a reorder ready to send to a supplier. Fig 1 Given the system39。s next task is gaining a sense of their logical relationship. A good way to start is by describing how data flow between the functions. As the name implies, data flow diagrams are particularly useful for graphically describing these data flows. Four symbols are used (Fig. 1). Data sources and destinations are represented by squares。s memory. 4 Finally, data flow between sources, destinations, proc