SOFTWARE

SOFTWARE

1. Explain the need for the functions of an Operating System

   • User Interface
     • Created to allow easy control of the operating system by the user of the system
       • Forms
         • suitable for any application that involves entering predictable pieces of information into the computer
       • Menu
         • Ideal for situation where the users it skills cannot be garneted or where selections need to be made from a wide range of options
       • GUI (graphical user interface)
         • User faces that graphical in nature- expect to be availavle in multi-tasking environments
       • CLI (command line interface)
         • Requires the user to type in commands from a list of allowable commmades
       • Natural Language
         • Requires the user to enter responses to questions asked by the computer. Computer and user appear to be having a conversation.
   • Memory Management
     • The operating system loads the necessary parts of the application into memory (extra modules will be loaded into memory when required). If some of the features of the application aren't used for a while, the OS will remove them from memory to free up space.
       • When the application is closed, the OS will remove it from memory
   • Peripheral Management
     • Manages the way software and hardware interact in order to receive data from input devices and to send its result to output devices
   • Multi-tasking
     • Schedules all processes that that are waiting to have instructions executed by the CPU (a single CPU can only executer 1 instruction at a time)
       • Works on the first program for short time, stops and saves, and the then starts working on the second program for a short time and stops and saves, and repeats. Gives each application aa little bit of CPU time before moving on to the next application. Does this so quickly, appears simultaneous.
   • Security
     • Allows the OS to distinguish which request should be allowed to be processed e.g., user names and passwords

2. Describe the purpose and use of common utility programs

   • Security
     • Antivirus
     • Spyware protection
     • Firwalls
   • Disk Organism
     • Formatting
     • File transfer
     • Defragmentation
   • System Maintenance
     • System information and diagnosis
     • automatic updating
     • System clean up tools

3. Discuss the relative merits of different types of software

   • Off the shelf
     • Software that you can go out and buy, take home, install, and then use immediately
       • ADVANTAGES : Don't have to wait for someone to write and test the software, lots of forums online to get help, can be used for many different jobs, been tested by lots of people using it (bugs already reported and corrected)
       • DISADVANTAGES: isn't suited specifically for you needs (can be less efficient), can cost more money if you need to adapt it further to your needs
   • Custom written
     • Hire a company to write software for your personal specification
       • ADVANTAGES: provides exactly what functions a company needs, can be designed to integrate with existing software, can be used in situations where off the shelf software doesn't exist for this particular task
       • DISADVANTAGES: company that wrote it may charge a lot of money for support, more expensive, takes a long time to write
   • Open source
     • Where a piece of software display its code for the user to modify or distribute
       • ADVANTAGES: great way to learn programming skills, input of different users can result in a improvements,, can be adapted for the users specific needs, can be distributed
       • DISADVANTAGE: less safe; bugs can be written into it, difficult for writer to enforce payment for the software
   • Proprietary software
     • Someone owns legal write to the program, and the owner gives permission for others to use it (BUT NOT OWN IT!)
       • DISADVANTAGES: can't modify the code, can't make copies and distribute
       • ADVANTAGE: safer