Introduction to Structure Design Anh Nguyen February 10, 1998

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

Structured Design Steps to 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

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

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

Structured Design Methods

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)

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.

Structured Design Example

Structured Design Example

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