Topic 20- Human- Computer Interface

Operating Sytems and Processing

What is an Operating System?

• An operating system is software which controls the general operation of a computer
• A computer cannot work without an operating system installed

Types of operating systems:

• There are a number of types of operating system available for computer
• These include:
• Windows
• Mac OS
• Linux
• Unix
• MS DOS
• Android (a mobile phone operating system)

Functions of an OS:

• An OS plays a number of important functions that help you use a computer properly
• These functions include:
• Organising the use of the computers memory and allocating it to different areas
• Loading and running programs like work processing software, browsing software
• Controlling how the computer communicated with printers and scanners etc known as peripherals
• Managing the security of the system i.e. usernames and passwords
• Dealing with errors that arise

Operating systems:

• Operating systems can be further broken down into typed depending upon the actual job they are doing
• There are three distinct types:
• Single program
• Multi programming
• Multi tasking

Types of Software:

• An operating systems as you have seen is one type of software essential for operating a computer
• Another type of software, whilst not essential, is very popular when using computer systems
• This type is software is known as Applications software

Applications Software:

• Software applications work through the operating system to gain access to the hardware
• A software application carries out taks that the user is interested in doing such as writing a letter, creating graphs, sending an email or downloading a webpage
• Applications software can be classifies under three main categories:
• General purpose software
  • Spreadsheet
  • Database

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  • Gaming
• Specialist software
• Tailor made or bespoke software

Human Computer interfaces/ User Interfaces:

User interfaces:

• People need a way of interacting with machines if they are to be useful 
• Think os a vending machine- you want a drink, hut how do you get the machine to give it to you?
• Well, you will have to read the display and follow the instructions, put your money in the slot, press the right buttons and eventually your drink will pop out
• You got the machine to give you a drink by interacting with it via its "user interface"
• Think aboout all of the other machines that you interact with on a daily basis. You have to do a certain thing and make choices to get them to work

Types of User Interface:

• There are 3 main types of user interface that are commonly used in ICT systems today
• Command Line
• Menu Driven 
• Graphical User Interface (GUI)

Command Line (CLI)

• A Command Line Interface allows the user to interact directly with the computer system by typing in commands (instructions) into a screen which looks similar to the one at the side
• You cannot just type in any kind of instructions of course, because the computer will only react to a definite set of words

Advantages and Disadvantages of CLI

Advantages:

• This type of interface needs much less memory (RAM) in order to use it than other user interfaces
• If the user knows the correct commands then this type of interface can be much faster than any other type of interface

Disadvantages:

• For somon who has never used a command line interface it can be very confusing
• Commands have to be types in precisely, if there is a spelling error the command will fail
• There are a large number of commands which need to be learned- in the case of Unix, it can be hundreds
• You can't just guess what the instructions might be and you can't just "have a go"

Menu Driven Interface (MDI):

• This type of interface lets you interact witha computer or device by working your way through a series of screens or menus
• Think about you iPod or mobole phone, they both use a menu driven interface.

• You are presented with a menu, you make a choice and then the next menu appears on the screen. You make another choice and so on 
• Menu driven interfaces can also be verbal rather than visual

Advantages and disadvantages of MDI:

Advantages:

• They are extremely easy to use, someone who has never seen the interface before can work out what to do
• There are no commands to learn or remember
• Step-by-step options are given so that the user doesn't have to remember anything
• Even if you don't know what to do, you can usually guess your way around the options

Disadvantages:

• A poorly designes menu interface may be slow to use
• It can be irritating if there are too many menu screens to work through- users get annoyed or bored if it takes too long

• You often can't go to the exact place you want right at the start. You have to work you way through the menu screens even if you know where you want to get to

Graphical User Interface (GUI)

• A graphical user interface is the most common type of user interface seen today. It is a very "friendly" way for people to interact with the computer because it makes use of pictures, graphics and icons- hence why it is called "graphical"

Features of GUI:

• A GUI (pronounces gooey) is also known as a WIMP interface because it makes use of:
• Windows- a rectangular area on the screen where the commonly used applications run
• Icons- a picture or symbol whihc is used to represent a software application or hardware device
• Menus- a list of options from which the user can choose what they require
• Pointers- a symbol such as an arrow which moves arounf the screen as you move your mouse. Helps you to select objects

Other features of GUI:

• Colourful
• Intuitive- easy to use
• Help menus
• Tutorials 
• Wizard guides

Advantages and Disadvantages of GUI:

Advantages:

• This type of user interface is extremely easy to use, espically for a beginner
• It is easy to explore and find your ways around the system using a GUI
• You do not have to learn complicated commands
• There are usually good help facilities provided with GUIs

Disadvantages: 

• GUI take up a much larger amount of hard disk space than other interfaces
• GUI need significantly more memory (RAM) to run than other interface types
• GUI use more processing power than other types of interface
• GUI can be slow for experienced programmers to use, they find CLI interfaces much faster to use 

Other types of interface:

• Natural language- this interface uses commn words and expressions to help users interact with a system. A search engine is an example of a natural language interface as you use search terms to find out information about certain things
• Voice driven applications-also knows as voice recognition can be used to:
  • Issue commands to the software
  • Enter data into software
• Touch sensitive applications-interaction with the interface is through touching certain parts of the screen with your fingers
• Biometrics- makes use of features of the human body that are unique to a particualr person. Examples include face recognition, finger print scanning, retina scanning etc:

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  • Rather then go through a lengthy lof in process a user can just scan their finger to gain immediate access