Topic 2.2: USER INTERFACES

INTRODUCTION

• User interface is also called as a 'human computer interface (H.C.I.)' or 'man machine interface'. It is used to describe the interaction between a user and a computer, in other words, the method by which the user tells the computer what to do and the responses which the computer makes.

THE IMPORTANCE OF GOOD INTERFACE DESIGN

A good interface design can help to ensure that users carry out their tasks:

• safely
• effectively
• efficiently
• enjoyably

Well designed systems can improve the output of employees, improve the quality of life and make the world safer and more enjoyable place to live in.

DESIGNING USABLE SYSTEMS

In order to design a usable interface, the designer has to take into considerations the following factors:

• WHO will use the system. For example, will the users be the computer professionals or members of the general public who may be wary of computers? For an educational program, will the users be young, for example primary school children, or teenagers on an A Level course? Will the system have to cater for both beginners and experienced users?
• WHAT TASKS the computer is performing. Is the task very repetitive? Does the task require skill and knowledge? Do tasks vary greatly from one occasion to the next? A travel agent who spends most of the day making holiday bookings will require a different interface from an office worker who needs to be able to switch between word processing, accounts and accessing the company database.
• THE ENVIRONMENT in which the computer is used. Will the environment be hazardous, noisy, or calm and quiet?
• WHAT IS TECHNOLOGICALLY FEASIBLE. Is it possible to simply dictate a letter to a word processor instead of typing it in?

MENU INTERFACE

There are several different types of menu interface as the following:

1) Full Screen Menu. This type of menu is often used as the 'front end' of an application. It stays on screen until the user makes a choice. Try on your own!!

2) Pull-Down Menu. This type of menu is displayed along the top of the screen, and when the user clicks on an item, a sub-menu appears. The menu is always present whatever screen the user is looking at in the application.

3) Pop-up Menu. The menu pops up in response to, say, a click of the right mouse button on a particular area of the screen.

WIMP INTERFACE

• WIMP stands for Windows, Icons, Mouse and Pull-down menus.
• A window is an area on the screen through which a particular piece of software of a data file may be viewed. The window may occupy the whole screen, or the user can choose to have several windows on the screen with a different application running in each one. Windows can be moved, sized, stacked one top of the other, opened and closed.
• An icon is a small picture representing an item such as a piece of software, a file, storage medium (such as disk) or command. By pointing with a mouse at particular icon and clicking the mouse button the user can select it.

FORMS

When a user is required to enter data such as sales invoices or customer names and addresses, it is common to have a 'form' displayed on the screen for the user to fill in.

The following should be noted when designing forms of this type:

• The display should be given a title to identify it.
• The form should not be too cluttered. Spaces and blanks in a display are important.
• It should give some indication of how many character can be entered in each field of data.
• The user should be given a chance to go back and correct any field before the data is accepted.
• Items should appear in a logical sequence to assist the user.
• Default values should wherever possible be pre-written onto the form so that a minimum of data entry is required.
• Full exit and help facilities should be provided. For example, the user could enter '?' in a field if he requires more information.
• Lower case in a display is neater and easier to read than upper case.
• 'Attention-getting' devices such as blinking cursors, underlining etc should not be over-used.

DIALOGUE BOXES

• Dialogue boxes are a special type of form associated with the Windows environment: an example: open MS WORD, <FILE>, <PRINT>. Try on your own (DIY). Or open MS FrontPage, <INSERT>, <FORM>, <CHECKBOX> OR <OPTION BUTTON>.

COMMAND-DRIVEN INTERFACES

• With this type of interface very little help is given to the user who has to type a command such as, for example using MSDOS PROMPT: <DELETE FILE1> to delete a file. DIY!
• Commands enable a user to quickly and concisely instruct the computer what to do but they do require the user to have a knowledge of the commands available and the syntax for using them.

Resource: P M Heatcote, [A level Computing, 3rd. Edition], Ashford Colour Press Ltd, 1996.