Software

Software

1. Hardware - the physical electronic components of a computer.

   • Platform - A combination of hardware and operating system that supports the running of particular applications.

2. Software - the instructions/algorithms that tell the hardware what to do.

   • The three main types of software are: Systems software, Applications and Utilities.
     • Utilities - single purpose programs that are normally used in the maintenance of computer systems.
       • Antivirus - minimises danger from malware by scanning incoming files or the hardware to identify and remove threats.
       • Auto update - ensures that the latest versions of utilities are downloaded.
       • Defragmenter - software that brings together fragments of files on a disk and collects the free space in one area.
       • Disk checking and repairing - utilities that locate and solve issues with the hard disk and takes note of them so they can be avoided.
       • System cleanup - software that identifies temporary and copies of files that can be removed so there is more space.
       • Encryption software - encrypts data using algorithms.
       • Compression software - enables data to be made into a smaller file by removing redundant data also used to move large files onto CDs etc.
     • Applications - Software designed to carry out useful real world tasks.
       • Snapchat
     • Systems software - software which makes the computer hardware easily available to users and applications.
       • Mac OS X

3. Where to get software.

   • Custom software
     • Designed exactly to the needs of the client.
     • More expensive
     • Takes time to develop
     • More likely to have bugs as not tested by many people.
   • Off the shelf software
     • Ready to buy
     • Cheaper
     • Well tested
     • Reliable
     • Big user base so lots of resources and help online.
     • May have unwanted features.
   • Repository - a storage location from where software packages may be retrieved and stored on a computer.
   • Package management software - often used to download all necessary files for an application from reliable sources and keep everything updated.

4. Operating system - collections of programs that control the hardware and provide a platform that acts as a user-friendly platform and takes control of the low level computer functions.

   • Operating systems are organised using layers.
     • The kernel is the layer that directly interacts with the hardware. Applications are not allowed to interact with the hardware in order to protect the system.
   • What does it do?
     • Multitasking - the operating system switches very fast from one process to another. The OS manages allocation of RAM for all processes so the data is either waiting, running or runable.
     • User management - the OS can create profiles for different users storing login details etc. and keep data separated from each other.
     • Memory management - the RAM is used to store data currently in use by different applications and the OS manages this and makes sure that it can only be accessed by the correct programs.
     • Peripheral management - Peripherals communicate with the OS through device drivers, which are programs written by the manufacturer. When a peripheral requires the attention of the OS it will generate an interrupt.
   • User interfaces
     • CLI - Command line interface
       • Preferred by programmers
       • More powerful
       • More flexible
       • More efficient
       • Multiple instructions can be grouped in shell scripts
     • GUI - Graphic user interface
       • Easier to use as has icons menus and tools
       • Perfect for touchscreen
       • Simplicity but as a result less options for the user
     • WIMP interfaces use windows icons menus and pointers
   • Developers are able to use DLL - Dynamic Linked Library files when programming. Static libraries are parts of the program which are added by the developer and not in an operating system.
     • Linux is an open source operating system and can be changed by programmers. It is small, fast, secure and thoroughly tested. Mac OS is proprietry
   • Firmware - system software that is permanently stored in ROM.

5. Backing up data - a copy of the programs on a drive used to restore them if they are lost.

   • Differential - takes a copy of all the changed data since the last full backup.
     • Much quicker than a full backup
     • Backup copy takes less storage than a full copy that is created each day.
     • The time taken for the backup grows each day and can become very slow and large in size.
   • Incremental - takes copies of changed data since last incremental backup.
     • Faster than other backups
     • Require very little storage
     • Restore process takes a long time.
   • Full - everything is backed up.