Operating systems

Operating systems

1. Operating System

   • The core software that controls and manages the hardware and software
     • Classed as system software
     • Acts as a "go-between" so that application software is able to interact with the hardware
     • 4 main components
       • Kernel
       • Device drivers
       • User interface
       • System utilities

2. Kernel

   • Responsible for many of the essential background processes such as memory management and data security
   • Manages computer memory effectively
     • The memory manager is a piece of software in the kernel
       • Loads any software application you want to run into Main memory (RAM)
         • Multiple applications can be run
           • it is essential programs do not interfere with each other
             • The memory manger gives each application a private space to run
         • Kernel is responsible for moving programs between RAM and virtual memory
   • Schedules important tasks first then least important
     • This allows them to run efficiently on the CPU
   • Responsible or data security
   • Also responsible for user permissions and user access rights

3. device drivers

   • The interface between hardware peripherals and the computers software
   • A piece of software that tells the operating system how to communicate with a specific piece of hardware
     • Each piece of hardware has its own device driver that are specific to that piece of hardware
       • Each device driver has its own operating system
       • A new computer will already have a preloaded operating system with many different device drivers
         • However if not then you will need to install that driver your self
           • this can be done from a CD or download from the manufacturers website

4. user interface

   • Provides a way for the user to interact with the operating system and applications
     • Graphical user interface (GUI)
       • The most commonly used
       • Uses pictures graphics and icons to allow the the user to interact with the computer system
         • Reacts to key presses, mouse clicks and touch on a touch sensitive screen
     • Menu
     • Command line
       • Allows th user to interact directly with the computer system by typing in commands into a screen
     • Three different types of user interface

5. System utilities

   • A collection of useful specialist software applications that perform specific tasks
   • System restore utilities
   • Defragmentation utilities
     • Files are stored in memory in chunks called sectors
       • when a file is save the operating system looks for free on the disk but these sectors are rarely next to one another
         • This means that files are fragmented across separate memory sectors
           • This makes it hard for the HDD to aces all the pieces of a file causing the computer to run slow
             • The defragmentation toll juggles the contents of memory sectors around to keep files together as much as possible
   • Backup
     • the simplest way is to makes a copy of the file that can be stores on a removable hard drive, cd, e.t.c
       • Backup allows to
         • Set up a schedule to backup automatically
         • SPecific exactly what to and not to back up
         • CHoose the type of backup you require
         • Tell it where to back up
   • Compression utilities
     • A compression utility makes file sizes smaller
       • This is good because less storage space is needed, faster to download and upload files and better performance is achieved when streaming audio or video files
         • Lossy compression
           • Removes unecessary data from the files e.g some data is lost
             • better for MP3 and MP4 files and Image files
         • Lossless compression
           • Does not remove anything from the file instead it looks for patterns within the data to allow to be stored more efficiently
             • Used for text documents
             • Popular format is in ZIP fies