Section 1 Extension Topic - Software

Section 1 Extension Topic - Software

1. The OS

   • OS's manage hardware and run software
     • It communicates with internal and external hardware via device drivers
     • Provide a user interface
     • Provide a platform for different applications
     • Allows the computer to multi-task by controlling memory resources and the CPU
     • Deals with file and disk management
   • Essentially the bridge between the computer and the user
   • Device Drivers let the OS and hardware talk to each other
     • Every piece hardware connected to the computer system requires a device driver
       • Device drivers essentially act as a 'translator' for the signals between OS and hardware
     • When a computer is booted up...
       • The OS will choose the correct device drivers for the hardware it detects
         • If new hardware is connected to the computer, the system will install the new, matching driver
     • Device manufacturers may release updates to devices drivers
       • This is in order to fix bugs, add features or improve the hardware's performance
         • Updates may be installed automatically by the OS or manually by the user
   • Operating Systems provide a user interface
     • A user interface allows the user to interact with a computer system
     • A GUI is the most common type of user interface
       • Designed to be easy for everyday users by making them visual, interactive and intuitive
       • GUIs are optimised for specific input methods.
         • In the past they were WIMP based (windows, icons, menus and pointers
           • Android an iOS were made for touchscreen devices
     • A command line interface is text-based
       • The user must enter specific commands to complete tasks
         • Less resource heavy than GUIs
         • They are not suitable for everyday tasks as they're for much more advanced users
           • Can be far more efficient and powerful than a GUI as they can automate processes
   • OS allows multitasking by managing resources
     • Can run multiple applications at the same time
     • The OS helps the CPU carry out more efficient multitasking
       • It will manage memory and CPU processing time
   • Handles file and disk management
     • The OS is responsible for file management
       • The organisation of data into a usable hierarchical structure.
         • It also deals with the movement, editing and deletion of data
       • OS also organises and maintains the hard disk with utility software
     • OS manages the hard disk and it splits the physical disk into storage sectors
       • And it decides which sectors to write data to and keeps track of free space
         • Ideally data for the same file would be put in adjacent sectors.. can't always happen
   • OSs deal with user accounts
     • OSs can be single or multi user
       • Single user
         • Windows 10 and OS X allow one user to use the computer at once
       • Multi user
         • UNIX server is an example and they allow several users to use the computer at the same time
         • Multi user OSs tend to be used on mainframes and give many users simultaneous access
     • OS is responsible for user account control
     • On most desktop OSs users have access to their own personal data and desktop but cannot access others personal data
     • OSs have anti-theft measures to prevent users from accessing locked devices/accounts
       • User accounts usually are protected by password/pin
         • Some devices require a pattern, fingerprint or retina scanners

2. Utilities

   • Defragmentation utilities put broken files back together
     • Some files move, change size and are deleted in which causes many small gaps to appear on the disk
       • The OS splits files into smaller blocks to fill the gaps
     • Over time the disk becomes more and more fragmented
       • This makes read/write speeds slower across the disk
     • Defrag software reorganises data on the HD putting fragmented files back together
     • Also moves files to put free space together
   • Compression and Encryption Software
     • Compresssion
       • Reduces a file's size so it doesn't take up as much disk space
       • Used a lot on the Internet to make file downloads quicker
         • Standard formats are .zip and .rar
       • Must be extracted before they can be used
     • Encryption
       • This scrambles (encrypts) data to stop and third-parties from accessing it
       • To decrypt data you must have a special key

3. Open Source and Proprietary Software

   • Open Source
     • Given away with its source code
       • This source code is made freely available for users to legally modify and create their own spin off software
         • This software can then be shared under the same licence terms as the original software
     • Popular open source software is always supported by a strong online community
       • Users help improve the software as anyone can play with the source code and suggest potential bug fixes and improvements to the original developers
   • Proprietary Software
     • This is closed source software
     • This is when only the compiled code is released and the source code is usually a closely-guarded secret
     • Proprietary software licenses restrict the modification, copyiing and redistribution of the software
       • Usually paid for

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