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IB Computer Science

IB Computer Science. Section 1: Systems life cycle and software development. The systems life cycle. Analysis: Data Collection. Interviews with users and domain experts Questionnaires and Surveys Observation of existing system Reading documentation.

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IB Computer Science

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  1. IB Computer Science Section 1: Systems life cycle and software development

  2. The systems life cycle

  3. Analysis: Data Collection • Interviewswith users and domain experts • Questionnaires and Surveys • Observation of existing system • Reading documentation

  4. Analysis: Requirements Specification • Requirements specification • Inputs: what data/information will the system require • Outputs: what information is expected from the system • Human resources requirements • Schedule • Critical success factors. Key objectives.

  5. Analysis: IPO Three stages of programming: Input Processing Output What data or information will the system need? What will the system do to the data? How will information be stored and represented? What information should the system give its users?

  6. Analysis: Feasibility Report • Brief description of the proposed system • Estimated costs • Financial, technical, legal responsibility • Estimated completion date

  7. Analysis: Systems Flowcharting Tape Storage Documents Document Input/ Output Disk Storage Manual Input Process

  8. Analysis: Pay System Example Transaction File Master File Hours worked Calculate Pay Updated Master File Payslips

  9. Analysis: Systems FlowchartPast Paper Question

  10. Analysis: Systems FlowchartPast Paper Answer Customer orders are collected on paper, keyed in, and stored in a customer orders file. A stock master file is searched to determine whether sufficient stock is available, and a report produced. The mark scheme awarded one mark for each of the boxes, up to a maximum of five boxes. In my opinion you could have left out the keyboard input, or you could have specified the master file as tape drive (sequential access storage), and you would still get full marks.

  11. Analysis: Review • Why is software development considered to be cyclic? • Why is data collection important? What are the methods of data collection? • What is a requirements specification? What does it contain and what purpose does it serve? • Outline the features of a feasibility report. • Annotate the systems flowchart you created in the past paper exercise. Try to think of another computerised process you could model with a systems flowchart. Discuss with a colleague and prepare the flowchart. Resources: Computer Science Java Enabled, IB Computing website, Richard Jones’ site (Int. Sch. Toulouse).

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