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.