Software

Software

1. Utility Systems

   • Applications
     • Data Compression
       • There are two types of compression - Lossy and Lossless
         • E.g. A lossless song may have a file size of around 30MB while the same song with lossy compression may be 5MB
         • Lossless compression makes the file smaller by temporarily removing data to store the file and then restores it to its original state when it's opened
           • File Types - FLAC (audio) TIFF (image) PNG (image)
           • Cons
             • Only a slight reduction in file size so they still take up quite a bit of space on your device
           • Pros
             • Can be used on text and software files
             • Can be decompressed
             • Data is only removed temporarily so there is no reduction in quality - should look and or sound like the original
         • Lossy compression works by permantley removing data from the file - this limits the number of bits the file needs and so reduces its size
           • File Types - MP3 (audio) AAC (audio) JPEG (image)
           • Cons
             • Are a worse quality than the original - the loss in quality is normally unnoticeable
             • Can't be used on text or software files as these files need to retain all information of the original
             • It loses data - the file can't be turned back into the original
           • Pros
             • Commonly used - lots of software can read lossy files
             • Can take up less bandwidth so can be downloaded and streamed more quickly
             • Greatly reduced file size, meaning more files can be stored
       • Has many uses: Smaller files take up less storage space on a device, Straming and downloading files from the internet is a lot quicker as they take up less bandwidth, Allows web pages to load more quickly, Email services have restrictions on the size of the attachment you can send - compressing the file allows you to send the same content with a much smaller file size
       • Make files smaller - while trying to make the compressed files true to the original as possible
     • Defragmentation
       • As SSD's use flash storage with no moving parts, fragmentation doesn't cause them any problems - they can access data just as quickly however it's arranged. As SSD's have a limited number of read/writes, defragmenting them can actually shorten their lifespan
       • The software reorganises data on the hard drive to put fragmented files back together. It also moves files to collect all the free space together - helps prevent further fragmentation
       • Files are stored on hard disk in available space. Ideally entire files would be stored together.
         • As files are moved, deleted and change size, lots of small gaps begin to appear on the disk. When writing files to the disk, the OS splits files into smaller blocks to fill up the gaps
           • Over time, the disk becomes more and more fragmented. This makes reading and writing files slower as the read/write heads to move back and forth across the disk
     • Encryption Software
       • It scrambles (encrypts) data to stop their parties from accessing it. Encrypted data can be decrypted using a special 'key'. Unauthorised users cannot read it. It is essential for sending data over a network securely
     • The role and method of backups
       • Is a copy of a computer system's files and settings stored externally. Data can be recovered in the event of data loss
       • A backup utility is software with facilities such as scheduling of regular backups, creating rescue disks, disk images adoptions for full or incremental backups
         • A full backup is where a copy is taken of every file on the system. They often take up lots of storage space. A full back up can take a long time to create, but is faster to restore from
         • An incremental backup is when only the files created or edited since the last backup are copied. They use less storage space and are much quicker to create. A full system restore is slow - the last full backup must be restored, followed by every incremental backup since that point
   • Help maintain and configure computer

2. The purpose and functionality of systems software

   • Systems software is designed to run and maintain a computer system.
     • Operating Systems
       • Applications
         • User Interface
           • Allows the user to interact with a computer system
           • Graphical User Interfaces(GUI's) are the most common type - they're designed to be easy for everyday users by making them visual, interactive and intuitive
             • They're optimised for specific input methods. In the past, GUI's have been WIMP-based (windows, icons, menus and pointers). Android and iOS were created for touchscreen devices using finger gestures like pinching and swiping in place of a mouse
           • A command-line interface is text based. The user enters specific commands to complete tasks. Command- line interfaces are less resource-heavy than GUI's
             • Command-line interfaces interfaces aren't suitable for everyday users but for advanced users.
               • They can be far more efficient and powerful than a GUI. They can be used to automate processes using scripts (simple programs).
         • Peripheral Management and Drivers
           • Operating systems use device driver software to communicate with internal hardware or peripherals connected to the computer system
           • Every piece of hardware connected to the computer system requires a device driver
             • 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 device drivers in order to fix bugs, add features or improve the performance of their hardware. Updates may be installed automatically by the OS or manually by the user
         • Memory Management / Multitasking
           • OS provide a platform to run applications (by configuring hardware so they can use it, and giving access to the CPU and memory).
           • OS that can run multiple applications at the same time are called multi-tasking OS's
           • The OS helps the CPU carry out multi-tasking by efficiently managing memory and CPU processing time
             • When an app is opened the OS moves the necessary parts of the application to memory, followed by additional parts when they're not required. It will decide if app's or features have been used recently - if not, the may be removed from memory
             • To run multiple app's, the OS meeds to make sure that the app's don't overwrite or interfere with each other. A memory manager allocates certain app's certain memory addresses, to make sure their processes are placed into separate locations
             • Only one app is processed by the CPU at a time so the other processes must wait. The OS divides CPU time between open app's and may prioritise certain processes in order for instructions to be executed in the most efficient order
         • File and Disk Management
           • Computers store data as files. Images, music, videos, and spreadsheets are all collections of data. File extensions (e.g. .jpg, .mp3, .mpeg tell the computer which software should be used to open the file
           • 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.
           • The OS manages the hard disk. it splits the physical disk into storage sectors, decides which sectors to write data to and keeps track of free space on the disk. Ideally, the data for a single file would be placed in adjacent sectors, but this isn't always possible
         • User Management
           • OS can be single-user or multi-user
             • Single-user OS's (such as Windows 10 and OS X) allow one user to use the computer at once
             • Multi-user OS's (such as UNIX server) allow several users to use the computer at the same time. They're often used on mainframes (huge supercomputers) and give many users simultaneous access. E.g. ATMs allow thousands of people access to a large bank's mainframe at the same time
           • It s also responsible for user account control. User accounts allow different users to be granted access to specific data or resources on a computer system
           • On most desktop operating systems each user has access to their own personal data and desktop but cannot access other users personal data
           • They may have anti-theft measures to prevent other users from accessing locked devices or accounts to steal information. user accounts may be password, or pin protected. Some devices also require a user to draw a specific pattern on the screen or have fingerprint or retina scanners
       • Manage Hardware and Run Software