HCI

HCI

1. Command-line interface

   • The user types in a command at a prompt character
     • The operating system then executes this command
       • This way of telling a computer what to do was used in the early days of computing
   • A switch, \W, specifies that the filenames are to be printed across the screen instead of down
     • The instruction that needs to be entered at the command prompt is: DIR C:\DOCS /W
   • Some of the commands may have “switches”
     • To provide options for the command
   • Microsoft operating systems
     • The command for listing the files in a folder
       • Called “DOCS” on drive C, is: DIR C:\DOCS
   • Some instructions may have a number of switches
     • The commands can become quite complex
   • Advantages
     • Instructions execute quickly
     • Instructions are versatile
       • Meaning the user can select a large number of options for each instruction
     • The operating system s smaller when loaded into memory
   • Disadvantages
     • You need to learn the special instructions used
     • If you mistype an instruction or spell it wrong, then it cannot be executed
     • Some commands and their options can be very complex
       • So high-level ICT skills are needed

2. Menu driven interface

   • A list of options available to the user is displayed and the user then selects one of them
     • Usually by clicking the mouse button with the mouse pointer on the option required
     • By pressing a key on the keyboard
   • Advantages
     • Navigation to find the option required is simple
     • User input is validated as only the options shown can be used
     • You do not need to learn what instructions are available
       • As they are displayed in the menu
   • Disadvantages
     • Some options in a menu may not mean anything to the user
     • It can be difficult to find options if there are many menus and sub-menus
   • Several menus may be available to the user
     • They are usually organised into groups of similar options
     • Selecting one option may open another menu
     • Some sub-menus can then also have further sub-menus too

3. Graphical user interface

   • Most modern computer operating systems use a graphical user interface (GUI)
   • Small meaningful pictures called icons
     • Represent instructions that are available to the user
     • Each one is selected by using the mouse pointer
   • Modern operating systems use WIMP environments
     • Window
     • Icon
     • Menu
     • Pointer
   • Advantages
     • Only a low level of ICT skills is needed for the easy-to-use, intuitive interface
     • There is no need to learn any instructions
     • Pictures are more meaningful than words
       • So small children or people with reading problems can use this sort of interface
     • You can alter the way in which a GUI displays data to suit your own circumstances
   • Disadvantages
     • It is large and complex
     • It can take up a lot of a computer’s resources and may run slowly
   • Most GUIs provide help if users have difficulty
     • The purpose of a command button is often displayed
       • If the mouse pointer hovers over it and a help menu provided a searchable database
         • That explains how to perform various tasks
           • Sometimes the help provided is a link to a website

4. Sound and speech interfaces

   • A microphone is used as an input device
     • The user speaks spoken commands and the sound is analysed and the command then carried out
   • Advantages
     • It can be used without hands
   • Disadvantages
     • People speak differently
     • The computer may have difficulty understanding different people
     • People speak different languages
     • The interface may only be able to understand one of them
   • This type of user interface is useful if the user has a disability
     • Or has no hands free to operate other input devices
       • Such as keyboards or mice

5. Touch-sensitive interface

   • Some devices work by a user touching them
     • Touch screens are often used in places where devices may get stolen or damaged
       • Such as a mouse or keyboard
   • Touch screens are often situated in places where members of the public can use them
     • e.g. doctors’ surgeries, banks etc
   • Advantages
     • Only a low level of ICT skills is needed to use it
     • There is little possibility of damage or theft
     • They can be used in environments where gloves are necessary
       • So a keyboard cannot easily be used
   • Disadvantages
     • It may become dirty or scratched and difficult to read