Revision on Interfaces

Revision on Interfaces

1. HCI ( Human computer interface ) is the boundary where the computer and the user meet

2. It is mostly referred to as user interface

   • It shows the way the user interacts and gives instructions on what is wanted
     • Command-line interface
       • Users type a command, then the operating system then does what you have commanded. This way of telling a computer what to do was used in the early days of computing.
       • Some commands include "Switches" to give options for command. For example, in Microsoft operating systems, the command for listing the files in a folder called “DOCS” on drive C, is: DIR C:\DOCS
         • A switch, \W, specifies that the filenames are to be printed across the screen instead of down and the instruction that needs to be entered at the command prompt is: DIR C:\DOCS /W
       • Advantages
         • instructions are performed quickly
           • users can select a large number of options for each instruction, showing instructions are versatile
             • Disadvantages
               • You must 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.
                 • Computer software
                   • This is a program set of instructions that tells a computer what to do
                     • Software is defined as the programs that run on a computer system
                       • Systems software: programs that help a computer system to work (e.g. operating system, disk defragmenter and compilers)
                         • Applications software: programs that perform a specific task (e.g. stock control program or computer game) and generic programs that can be used for general-purpose tasks (e.g. a word-processing program).
         • when loaded into memory the operating systems are smaller

3. Types of Interface

   • Command- line interface
     • This is used by symbols and a set of words, users instructions. This is the interface used in the early days of computing and is really only suitable for skilled ICT users
   • Menu – driven interface
     • Options in a menu are displayed and users select only one of them. An advantage is that this is more user-friendly than a command-line interface as the options do not have to be remembered.
   • Graphical user interface (GUI):
     • Small pictures are used to represent options that the user can select. An example of this is the new windows on laptops where each tile leads to a certain app
   • Voice interface
     • This is where the user speaks through a microphone to give commands, Sophisticated software analyses the voice pattern and executes the instruction given.
   • Special devices
     • Braille keyboards, “Concept keyboards” with overlays places on the keyboards, touch-sensitive screens, puff-suck switched and foot switches allow input for people with no arm movement these can all help people who still want to be able to communicate with the computer.

4. Menu driven interface

   • Options are available to the user and is displayed, the user can then select one of them, usually by clicking the mouse button with the mouse pointer on the option required or by pressing a key on the keyboard.
     • Advantages
       • Navigation to find the option required is simple.
         • instructions are available in the menu, therefore you do not need to learn the instructions
           • User input is validated as only the options shown can be used
           • Biometric systems
             • Biometric systems use physical characteristics e.g. fingerprints, voice, facial features and eye scans to identify people.
               • Theses systems although offer high levels of security but are expensive to buy and install.
                 • The latest passports in the UK are known as biometric passports because they contain an electronic chip storing digitally coded measurements of passport holders’ features, such as the distance between eyes, nose, mouth and ears.
                   • The latest passports in the UK are known as biometric passports because they contain an electronic chip storing digitally coded measurements of passport holders’ features, such as the distance between eyes, nose, mouth and ears.
       • 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 are available for the user and 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.