Human Computer Interface
A term used to describe the interaction
between the user and a computer. The
method by which the user tells the computer
what to do and the responses which the
computer makes
Importance of good interface
design
A good interface design ensures that users carry out
their tasks
• Safely – think of a pilot flying a jumbo jet
• Effectively – operating a video recorder successfully
to record the correct program
• Efficiently – users can obtain money from a cash
machine, inserting card and pin, obtaining cash and
removing their card
•Enjoyably – can use a computer program to learn
tables, for example
Interface Styles
There are a number of interface
styles including:
•Command line interface
•Menus
•Natural Language
•Forms and dialogue boxes
•WIMP
Command Line Interface
• Provides a means of expressing instructions to the computer directly
using single characters, whole word commands or abbreviations.
• Very little help is given.
• Commands enable a user to quickly and concisely instruct the
computer what to do
• User requires the knowledge of the commands available and the
syntax for using them
• Operates via DOS
Menu interface
• Full screen menu – front end application use. Stays on screen until
the user makes a choice. Eg A switchboard on a database
• Pull down menu – displayed along the top of a screen. When the
user clicks on an item, a submenu appears. Always present at the
top of the screen whatever screen the user is looking at in the
application.
• Pop-up menu – menu pops up due to a response, say, a click of the
right mouse button on a particular area of the screen.
Natural Language – “plain English”
Advantages
• No need for training in a specialised command language
• Extremely flexible and powerful
• User is free to construct her own commands, frame her own
questions, etc.
Disadvantages
• People find it difficult to stick to grammatical correct English
• A well designed artificial language can say the same thing more
concisely than natural language
• A natural language can mislead a user into believing the computer is
more intelligent than it actually is
Forms & Dialogue Boxes
• A form is used to enter data, such as customers names.
• A dialogue box is a special type of form, usually in the Windows
environment, for example, a form appears when a print job is set up
to the printer.
Points to consider when designing a form:• Should have a title to identify it
• Not be too cluttered – space and blanks are important
• Corrections should be allowed before the data is accepted
• Items should appear in a logical sequence to assist the user
• Default values should be set up whenever possible so a minimum of
data entry is required
• Full help and exit facilities should be provided
WIMP Interface
Windows, Icons, Mouse and pull down menus.
• Window – area on screen through which a particular piece of
software or data file may be viewed.
• The window can be the whole screen or several windows can be set
up, each one being moved or resized, as necessary.
• An icon is a small picture representing an item such as a piece of
software. Selected by using the mouse.
• Mouse moves a cursor, positioning it were required and then
selecting the item.