Types of user interfaces

1. There are field names, names next to a place where information must be entered. The places where information should be entered in by the operator are known as 'response fields'.
2. Other types of response fields include radio buttons and drop-down selectors.
3. The cursor 'tabs' automatically from one response field to the next. This guides the user logically through the form, ensuring that all the information needed is gathered.
4. As data is entered, it is 'validated'. Validation attempts to ensure that only sensible data is entered into the system and data that is not sensible is rejected. Validation helps ensure that data entered into any system maintains its 'consistency'. This means that any data stored is only of the format expected in a particular field. Data can be validated using a range of methods. (These are discussed in more detail later in this chapter). The methods include: A range check. 
   
   
   • A character length check.
   • A data input mask.
   • A presence check.
   • Getting the user to select from a list using combo boxes or look-up tables.
   • Using check digits.
   
   
5. Input can be changed/cancelled if necessary.
6. Data is finally entered into the system only when an 'OK' button, ENTER or something similar is pressed.
7. There is some kind of HELP facility.
8. Some options are not displayed on the main screen, to avoid cluttering up the form. Access to less commonly needed facilities is via a selection button that links to a separate screen.

Examples include

• Someone taking telephone orders for a product such as a CD.
• Someone recording responses to questions in a telephone questionnaire.
• Someone entering in details of people who want to apply for a credit card.
• Someone applying to join a club or open a free email account on the Internet.
• Someone who is buying something online.

Menu-based systems are ideal for situations where the user's IT skills cannot be guaranteed or in situations which require selections to be made from a very wide range of options or in situations which require very fast selection. The user of a system that uses a menu-based interface will be presented with a limited number of options on the screen. Once a selection has been made, the user is presented with a sub-menu. This gives them further options. They make another selection and may be presented with a further sub-menu. This continues until the user is able to select exactly what they want from the choices finally displayed on the screen.

Users interact with this interface by typing a set of code for the computer to follow, the code that is written must be in a language which the computer understands, this means that only specific words can be used in order to carry out the response desired by the user. This was used to navigate the interface before the windows interface was created. The codes were mostly typed up by a keyboard  and was used in order to modify files or copying them.

This kind of interface requires the user to enter responses to questions asked by the computer. The questions are displayed on the VDU and the answers are entered via the keyboard. This kind of interface is called a 'natural language' interface because the computer and the user appear to be holding a conversation. For example, imagine the user has initiated a 'save file' request. The 'conversation' might go like this:

• A 'window' for each open application. Many windows can be open at the same time but only one window can be active at any one time. There may be some way of indicating which one is active (perhaps by making the bar at the top of the active window bright blue).
• Menus and icons. Available functions can be selected in one of two ways, either by using pop-up menus or drop-down menus, or by clicking on 'icons'. An icon is simply a small picture that represents a specific function - clicking on it selects that function.
• A pointing device, to make selections. It is typically a mouse or a graphics tablet and pen. The use of a keyboard to navigate through the application is minimised because it is a relatively time-consuming way of working.