Computer Software

Computer Software

1. Refers to the programs we run on our computer - the programs are the stored sets of instructions given to the processor to carry out. It also refers to the data that is used by the proograms

2. Types

   • Utility Software
     • Has limited functionality and is used to maintain computer systems
   • Application Software
     • Handles real-world jobs that users want to do
   • System Software
     • Operating System
       • Functions
         • Memory Management
           • The OS manages the transfer of data between the CPU, RAM and main storage
         • User Interface
           • The OS provides the user with a way of controlling the functions of the computer without resorting to machine code
             • Command line interface (CLI) e.g. MSDOS. Commands can be grouped into shell scripts to carry out maintenance jobs
             • Graphical (GUI) e.g. Windows. Uses icons to represent actions. No commands have to be learned.
           • Acts as a boundary between human and machine
           • The interface lets users give commands, ask questions and display a response
         • Peripheral Management
           • The OS manages the input and output devices connected to the computer, like a keyboard, mouse and printer
         • Multi-tasking
           • The OS allows more than one program to be run at once so users can switch between applications easily
         • Security
           • The OS provides security features to restrict access to the system or particular files
     • Controls hardware and acts an an intermediary between application and hardware (hides complexities and allows user to operate computer without writing programs

3. Utility Programs

   • Security
     • Anti-virus
       • Detects and protects the computer against virus threats and quarantines infected files
     • Firewall
       • Restrict communication in and out of the computer from the applications that are running
     • Spyware protection
       • Detects and removes spyware (small programs that quietly monitor what you are doing)
   • Disk Operations
     • Formatting
       • Sets up a hard drive, memory stick or card into a format that the computer can use to store/retrieve data. the process of formatting erases any data that was previously on the storage medium
     • File transfer
       • Allows movement of files from one location to another, either locally or via memory stick
     • Defragmentation
       • Re-organises the data on the hard drive to improve read/write access time
   • System Maintenance
     • System info and diagnosis
       • Provides information about the system in order to help with diagnosis of problem
     • System cleanup tools
       • Removes temporary files and compresses/archives unused files to increase free storage
     • Automatic updating
       • Uses the Internet to check the OS is up-to-date and applies software patches/fixes as necessary

4. Software Procurement

   • Proprietary
     • Written by developers and allowed to be used by others but with restrictions e.g. can't adapt software (source code is hidden)
       • Extensively tested, updates are scheduled regularly, reliable, someone to go to if problem
         • Source code cannot be inspected so may contain spyware within the software, expensive, inflexible, deliberate incompatibilities to lock users in
   • Off the shelf
     • Developed by a software company to be sold to the general public
       • Cheaper than developing it yourself, tech support available, extensively tested, ready, forums online
         • Inflexible so customisation (not exact needs), search for traning
   • Open Source
     • Written by general public for everyone to use. Source code provided so software can be tweaked
       • Allows anyone to use/adopt the software to meet their needs and a collaborative approach to development can lead to better quality software, and cheap
         • By making source code available to all, provides opportunity for people to take advantage of software installed on users' computers compromising security, no or irregular updates,
   • Custom Written
     • Developed specifically for a particular organisation. Specially commissioned for a particular customer.
       • Meets exact purposes, doesn't require adaptations, the developer can train, be contacted, and maintain
         • Expensive, needs technical expertise to develop, not extensively tested, time-consuming