Introduction to Structure Design

1. Introduction to Structure Design Anh Nguyen February 10, 1998

2. Structured Design • Motivation • traditional flowcharts are not sufficient • convoluted and vague verbiage documents • bridge between problem specifications and implementation • Goal • to produce maintainable, reliable, and adaptable systems

3. Structured Design • To reduce the cost of the system in terms of time, money, person-power. • Steps to structured design • understanding the problem and requirements that need to be satisfied • break up the system into smaller, manageable units • apply modeling tool to capture your requirements into a systems design that involves hw and sw

4. Structured Design • Provide a set of criteria for evaluating the quality of your design

5. Structured Design Methods • Structure charts, process specifications, data flow diagrams, etc. • Example of data (control) flow diagram (DFD) • DFD elements • process bubble • data flows and controls • data stores • source/sink

6. Structured Design Methods

7. Structured Design Example • Specifications • Serial task that receives data, transmits data, has flow control • Receive process can receive one character or a block of characters • Transmit process can receive one character or block of characters • Flow control that flows off when receive buffer reaches 70 bytes of its 75 byte buffer by sending a FLOW OFF character (0x13)

8. Structured Design Example • Flow control that flows on when there is at least room for 25 bytes in its receive buffer by sending a FLOW ON character (0x11) • Frequency task that measures the frequency of an input square wave signal and outputs serially the frequency measurement.

9. Structured Design Example

10. Structured Design Example

11. Reference • “The Practical Guide to Structured Systems Design”, Meilir Page-Jones, 2nd Edition, 1988.