Category: Design notations

Used in both ISDD and SDD

Higher – Design Notations (Revision)

Make sure you read the N5 post on design notations for examples of Structure Diagrams, Flow Charts and Pseudocode.

Wire-Framing: A wireframe can show how a website will look and how its navigations structure works; can be as simple as a rough sketch or can be a detailed design showing colour combinations and images

Entity Relationship Diagrams

Relationships can be represented graphically using an Entity-Relationship (ER) diagram.

There are many different notations for ER diagrams, we will use crow’s foot notation.
• The names of entities are written in boxes joined by straight lines.
• At the “many” end the line forks.
• At the “one” end the line it judt joins the box.

ERD

Data dictionaries

A data dictionary is a design notation used to show the fields required in each table of a relational database, including field types, validation required, etc.

dd

Thank you to C O’Toole & A Madill from Braidhurst High School for allowing me to edit and publish this here.

National 5 – Design Notations (Revision)

N4

  • graphical to illustrate selection and iteration
  • other contemporary design notations

N5

  • pseudocode to exemplify programming constructs other contemporary design notations

 

Flow Chart
Flow Chart

You read a flow chart from the START block and follow the arrows (normally downward). In the example above you can see selection taking place in the first diamond, while the second diamond allows for iteration (repetition) to take place.

Structure Diagram
Structure Diagram

A structure diagram shows how the program is structured and in some cases how data can be passed from one part to the other.

Pseudocode

Pseudocode is an informal text description of the working of a program it is written using English words but not in a sentence structure. There are no syntax rules due to its informal nature, sometime they are numbered and sometimes they are not.

The SQA can sometimes refer to pseudocode in the exam when describing a program. However, they are often referring to Standard Reference Language. Rule of thumb, if they are asking you to read pseudocode it will be SRL, if they are asking you to write psuedocode then they mean psuedocode. Hopefully they will start using the correct terms in future papers.

Example 1

  1. set total = 0
  2. set count =0
  3. while count less than 10
  4.     get nextInput from user
  5.     add nextInput to total
  6.     add one to count
  7. end while
  8. display total/10

Example 2

get age from user
while age < 0 or age >130
    display error
    get age from user

display age

Scratch revision task

You have to create a program that generates a random number between 1 and 15. The user has to make as many guesses as they need to get the correct number. To make it easier on the user, the computer will tell them if each guess is higher or lower.

  • Task 1 – Design the program (Completed below)
  • Task 2 – Implement the program in scratch
  • Task 3 – Test the program

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