User Interfaces_1_1_1

User Interfaces_1_1_1

1. Menu Driven

   • Menu driven interfaces present the user with a list of options from which to select.
   • Categories
     • Full Menu Screen
       • These menus usually present the options to the user as a sequential list which occupies the entire screen. This is usually followed by a message prompting the user to select one of the options. In order to facilitate quick selection, the options may be numbered or a letter may be used to uniquely identify each option. In either case, the user selects an option by simply entering the corresponding number or letter.
     • Bar and Pull-down Menu
       • The main options available to the user are presented as pads on a horizontal bar across the screen. When the user selects one of the pads on this menu, the second-level options are displayed in a pull-down menu. This type of menu system is primarily used in conjunction with a pointing device. However, options may also be selected using 'short-cut' key combinations and arrow keys.
     • Pop Up Menu
       • These menus usually appear as a box with one of the options already selected. When the user points to the box with a mouse and presses the mouse button, the other options are displayed in a list. The user can then select the required option with the mouse. The menu options remain visible only while the mouse button is depressed. These menus are usually used in the task area of the application. If all the options cannot be displayed on the menu, the menu may scroll automatically or on command from the user.
   • Advantages
     • The user is presented with a choice and so does not need to remember any commands. This interface is suitable for beginners and knowledgeable intermittent users.
     • The opportunities for making serious errors are reduced since the user does not have to type in any commands.
     • Menus can utilise special pointing devices such as mice, trackballs and light pens. Thus the typing effort required can be kept to a minimum.
   • Disadvantages
     • They are not as concise as command-driven interfaces. Accomplishing a task in a menu driven interface generally involves more steps than is required for doing the same task in a command-driven interface.

2. Special Purpose

3. GUI

4. Command Driven

   • Teletypewriters (TTYs)
   • Video Display terminals (VDTs)
   • Advantages
     • They may be implemented using cheap, alphanumeric displays.
     • More experienced users prefer to have direct control over the operations of the computer.
     • Commands of almost arbitrary complexity can be created by combining individual commands. This allows command macros and command language programs to be written.
     • It is faster to issue a command sequence directly rather than searching through a menu.
   • Disadvantages
     • Users have to learn a command language which is sometimes complex. In some cases few users ever learn the complete language. The learning time for this type of interface is also greater than that for menu systems and GUIs. New users spend more time learning the interface than getting work done on the computer.
     • Users always make mistakes in typing. This requires error handling and message generation facilities to be included in the command language processor. Systems interaction is through a keyboard. The interface cannot make use of pointing devices.
     • For a novice it can be quite daunting and difficult to get even the simplest of operations performed.