Systems Software

Systems Software

1. Utility Software

   • A 'utility' application has a specific job to do regarding the computer's operation and performance.
     • Utility software interacts with the computers hardware E.g. the Disk Drive. Utility programs can be stand alone but are also inbuilt in to the Operating System
   • Types of utility software: File Compression, Disk Defragmentation, File Repair, Disk Copying, Disk Formatting, Disk Backup / Restore and Anti-Virus.
     • File compression
       • Reducing the size of the file by performing an algorithm on the original data. Lossless: The original file can be re-created as no data is lost. Lossy: Some of the original data is lost and the original file can not be re-created
     • Disk Defragmentation
       • When a hard disk drive is new – files get added onto the disk in order – very much like starting with a blank piece of paper and adding to it. As files are deleted – this leaves gaps. When new files are saved – the files fill the gaps and become fragmented. Defragmentation software groups fragmented files back together
     • Encryption
       • Encryption means to scramble data in a way that it is unreadable to anybody who doesn’t have a key to be able to unscramble this. Data is encrypted using a key and then decrypted using a key. Data is encrypted so that it is unreadable if anyone is to intercept it.
     • Back-ups
       • Completed to ensure there is a way of restoring files/data/programs in case of computer failure. Copies of data and/or software are taken regularly and usually stored in a different location. Ensures that if computers are stolen or damaged in for e.g. a fire or a natural disaster that data can be restored and a company do not lose much money.
         • A full back-up
           • A copy of all data and software on the hard disk drive / server is copied to a backup medium (e.g. an external hard disk drive / DVD-R) and the medium is kept at a different location. Take a long time to complete (usually overnight). Recovery takes a long time as it restores all data and programs
         • A Incremental back-up
           • A full backup is made initially. Each night only the files which have been changed since the last incremental back-up are copied. Much faster to complete that full back-ups. Takes much longer at restoring than a Full Back up as the full back up would need restoring first and then every incremental back-up since the last full back up.

2. Operating system

   • An operating system, sometimes called a platform, is a collection of programs that control the hardware in a computer or device.
     • CPU
     • MEMORY
       • KERNEL
         • CPU
         • DEVICES
         • APPLICATIONS
     • DEVICES
   • Examples of operating systems
     • Windows
     • UNIX
       • LINUX is designed to behave like UNIX but was developed separately and is the basis for many other operating systems
     • MacOS
   • Interface
     • The user interface is how the user interacts with the system. This can be provided as part of the operating system or can be a separate program running on top of the operating system.
     • A GUI uses icons (small pictures) to represent the resources and actions, reducing the need to learn commands. GUIs use mouse pointers or touch screens to select objects.
   • Memory Management
     • When a program is running it must be in the computer’s main memory and the operating system must manage where in memory each program and the data it needs must go.
       • When the program finishes or data is no longer needed the memory management system frees up that space for reuse.
   • Multi tasking
     • Multi-tasking allows the computer to make best use of the CPU.
     • The CPU works much faster than RAM and the other components of the computer. While the CPU waits for other actions to complete, e.g. loading data to RAM, it works on other tasks.
     • A multi-tasking operating system allows several processes to be in RAM at the same time
       • Running: The CPU is currently dealing with this process and others must wait
       • Runnable: These are ready to go and just need the running program to finish or be interrupted to get the CPU’s attention so they can run
       • Waiting: these processes are waiting to get into the queue and become runnable.
   • Peripheral Management
     • When a peripheral is required, a signal, called an interrupt, is generated to signal to the operating system that it needs to deal with something. This tells the CPU to stop the running process as soon as it can and to deal with another process linked to the peripheral device. These programs are called device drivers. When the job is finished, the CPU returns to the point where it was interrupted and carries on.