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Computer Studies

Computer Studies. Systems Development. Systems Development. Systems investigation Systems analysis Systems design Systems implementation Systems testing Systems evaluation. System Analysis and Design. System Analysts ($$$$$$$$$$) EXAMINING business situation

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Computer Studies

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  1. Computer Studies Systems Development

  2. Systems Development • Systems investigation • Systems analysis • Systems design • Systems implementation • Systems testing • Systems evaluation

  3. System Analysis and Design • System Analysts ($$$$$$$$$$) • EXAMINING business situation • BETTER procedures and methods

  4. Case Study • 97-AL-Comp Stud II-14 • A wholesale company recently decided to computerize its existing manual system. The company had previously not used computers at all.

  5. Case Study (cont’) • Peter, with three years’ experience as a programmer, was recruited to carry out the computerization of the system. Besides programming, Peter is also knowledgeable about the latest microcomputers on the market and commonly-used software packages, such as word processors and spreadsheets. He recommended that the company should buy a number of microcomputers and some applications software packages. He did a good job in helping the staff to use these packages.

  6. Case Study (cont’) • Later, Peter started to develop a billing system for processing sates orders, recording the sales, updating the customer accounts and printing monthly bills. After several months of work on his own. Peter finished the whole program for the system.

  7. Case Study (cont’) • The clerks of the company slopped using the old manual system and started using Peter's system but encountered immediate difficulties. They complained that the system's operating procedure was too different from the original working procedure and even complicated the tasks. Peter helped the clerks and finally the billing statements were printed. A week later, the company received complaints from some customers saying that their statements were wrong. The company had to redo the erroneous statements manually.

  8. Question (a) ~ 2 marks • What is the advantage of creating a system over purchasing one from the market?

  9. Question (b) ~ 4 marks • The fact that Peter's system has caused difficulties for the staff and created errors in the billing statements is probably due to Peter's negligence in the system development process. Suggest two ways by which Peter can improve his work in the system development process.

  10. Question (c) ~ 2 marks • Suppose everything had gone well with Peter's system. Give one reason for using Peter's approach to system conversion.

  11. Question (d) ~ 6 marks • Describe how Peter should carry out the system conversion in each of the following cases and support your answers with reasons: • Case 1: The manager of the company will not allow any increase in the error rate of the system during system conversion. • Case 2: The company has many branches and the system is to be used in each branch.

  12. Techniques, Tools and System documentation • System flowchart • Data flow analysis (Data flow diagram) • Critical path analysis (PERT charts) • Data dictionary • Decision table • Decision tree

  13. System flowchart (Symbols) Directional flow Processing Display Output Document

  14. System flowchart (Symbol 2) Manual Input File storage

  15. 2000-AL-COMP STUD 2-8 • The purchasing department of the Gold Light Company is responsible for supplier selection and the issuing of purchase orders.

  16. 2000-AL-COMP STUD 2-8 (Cont’) • In the supplier selection process. • Requirements for items to be ordered and quotations from the suppliers are obtained from two files; • Tentative orders will be generated after suppliers are selected; • An orders summary report will also be printed

  17. 2000-AL-COMP STUD 2-8 (Cont’) • In the purchase order issuing process, • The tentative orders will be checked by the purchasing supervisor via a visual display unit; • Purchase orders will be printed for confirmed orders; • Unconfirmed orders will undergo the supplier selection process again to select another supplier

  18. Supplier Quotations Orders Summary Report Tentative Orders Order Confirmation 2000-AL-COMP STUD 2-8 (Cont’) Supplier Selection Issue Order Keyboard

  19. Unconfirmed Orders Orders requirement Supplier Quotations Orders Summary Report Purchase Orders Tentative Orders Order Confirmation 2000-AL-COMP STUD 2-8 (Cont’) Supplier Selection Issue Order Keyboard

  20. Data flow diagram • Data drive business activities • For example, new sales order data • Simple notations can be easily understood by user and business persons

  21. Notations Yourdon Gane and Sarson Data Flow Process Entity (People, organization) Data Store

  22. Library system(Context diagram) D2 Borrowing Records 0 Personal Information Library system Borrowing information Borrower Book Details D1 Book Information

  23. Errors Data flow should not split into two or more different data flows Processes need to have at least one input data. All data flows must either originate or terminate at a process

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