Computer Science: Chapter 5

Computer Science: Chapter 5

1. Managing Resources

   • Managing Peripherals
     • Communicates with and sends data output to a printer/monitor/another valid output device
     • Communicates with and receives data input to a keyboard/mouse/other valid input device
   • Managing printing using spooling
     • Data is stored on hard disc/in memory/stored in a queue
     • Document is printed when printer is free/in correct order
     • The benefit of spooling – user can carry on working/log off when waiting for the job to print
   • Managing backing store
     • Ensures that data is stored and can be retrieved correctly from any disk drive
     • Creates and maintains Filing system such as FAT or NTFS (accepted but not expected)
     • Organize files in a hierarchical directory structure.
   • Managing RAM
     • Ensures that programs/data do not corrupt each other
     • Ensures that all programs and data including itself is stored in correct memory locations
   • Managing Processes
     • Ensures that different processes can utilise the CPU and do not interfere with each other or crash
     • On a multi-tasking O/S ensure that all tasks appear to run simultaneously
   • Managing Security
     • Allows creation and deletion of user accounts
     • Allows users to logon and change passwords

2. Function Of Operating Systems

   • An operating system is a software that manages a computer system. The operating system is loaded by the bootstrap loader.
   • Another function of the operating system is to provide a user interface.
   • One of its primary functions is to manage resources

3. User Interface

   • allows copying/deleting/moving/sorting/searching of file or folders
   • allows access to system settings such as hardware
   • provides a command line interface
   • allows users to have more than one window open
   • provides a graphical user interface (Windows, Icons, Menus, Pointers)
   • provides the user with errors/help messages
   • allows customization of interface, e.g. change desktop background/layout
   • allows user to switch between tasks (programs/windows)

4. Graphical User Interface

   • A GUI is a type of interface that allows users to interact with a computer system through graphical icons. GUIs were introduced to help users, especially beginners, to use computer systems as Command Line Interfaces (CLI) was found to be difficult.
   • Features of a GUI
     • Windows
     • Icons
     • Menus
     • Pointers
     • assistants/help files/tutorials
     • shortcuts/hot keys
     • task bar/ribbon bar/tabs/customised toolbar
   • Benefits
     • Intuitive
     • Easy to navigate
     • Uses Windows, Icons, Menus, and Pointers
     • No complicated commands
     • Data between different software applications is easily exchanged
   • Drawbacks
     • Computing experts may find a GUI slower than a command line interface
     • Is relatively processor intensive
     • Requires a large amount of memory
     • GUIs take up a much larger amount of hard disk space than other interfaces

5. Menu Driven Interface

   • This type of interface allows people to interact with a computer system by presenting the user and allowing them to work through a series of menus. The iPod Classic is a perfect example of a device that uses a menu-driven interface as users are presented with a menu that contains a list of artists. Having chosen an artist, another menu appears with a list of albums belonging to that artist. Following this, another menu is presented with a list of songs belonging to the chosen album.
   • Benefits
     • No need to learn a lot of commands
     • Intuitive/easy to understand
     • Easy to navigate
     • Ideal for beginners – everything is in a logical place/order
     • No need of expert language to learn
     • Little processing power needed
   • Drawbacks
     • Irritating if there are too many menu screens to work through – users get annoyed or bored if it takes too long
     • Navigating can be a long process

6. Voice-Driven Interface

   • Voice-driven interfaces, also called voice recognition, can be used to issue commands to a computer system and enter data into it. Voice-driven interface is a popular interface as it is natural for people to communicate in this way.
   • Benefits
     • Speech input is much faster than keyboard input
     • No need to learn to type
     • Less danger of RSI
     • Reduces typing mistakes such as spelling/hitting wrong key
     • The keyboard takes up room on the desk
     • Hands-free advantages – can multitask
     • Users find talking more natural than typing.
   • Drawbacks
     • Background noise interferes with speech recognition
     • User, when they have a speech impediment, sore throat, cold or a strong accent, will not be understood
     • Users with a disability that prevents speech would need to find a different method for input
     • Difficult to keep data input private as people can hear what you are saying
     • Words that sound the same, such as ‘too’ and ‘two’ may not be recognised

7. Command Line Interface

   • A Command Line Interface is an entirely text-based interface that allows a user to communicate with a computer system by typing in commands. However, computer systems will only execute specific commands that are predefined. Before GUIs were developed, command line interfaces were the most widely used interface.
   • Benefits
     • Quicker to type commands
     • Quicker to input commands as shortcut keys can be used
     • Little memory and processing power needed compared with other interfaces
     • Little storage space is required (no graphical images to store)
     • Experts who have memorised the commands find it very fast to use
   • Drawbacks
     • Very confusing for someone who has never used a command line interface
     • Commands have to be typed precisely. If there is a spelling error the command will fail
     • A large number of commands need to be learned
     • Instructions cannot be guessed
     • Not suitable for a novice

8. Touch Sensitive Interface

   • Touch sensitive interfaces are becoming more popular and are extensively used in mobile computing devices. Commands are issued or data is input by touching the screen with your finger or a stylus pen. As well as tapping the touch-sensitive screen, the screen can interpret other actions made by the user, such as pinching and swiping.
   • Benefits
     • Very intuitive
     • Easier to use as the user simply touches what is seen on the display
     • No keyboard or mouse is required
     • Touching a visual display of choices requires little thinking and is a form of direct manipulation that is easy to learn
     • Easier hand-eye coordination than mice or keyboards
   • Drawbacks
     • Screen can be easily damaged/scratched
     • Dirty screens are difficult to read
     • Users must be within arm’s reach of the display
     • It is difficult to select small items
     • User's hand may obscure the screen