8. Operating System

Files that can only be open and read, no changes can be made.

Files that are not regularly used are archived, in case they are needed in the future.

Files that are only used by the OS and not the user.

Files that are not visible to the user, often being important system files.

• compression • defrag • backup • file conversion • file indexing • task management • anti virus • disk scan and repair

Reduces file sizes so that they take up less space

Physically rearranges data on a hard drive so that parts of files are all stored together

Scans for viruses and deals with them appropriately if found

Allows users to keep a copy of their data in case the original data is somehow lost

Converts one type of file to another, for example a sound file can be converted from WAV to MP3

Assigns an index to files to allow easy random access to any record given its file key

Fixes problems on the disk

Allows user to view how much % of memory is being used and allows user to shut down any programs

• processes are carried out with no user interaction • avoids peak times • errors are stored in a file for later use and not dealt with as they occur example: generating utility bills

• inputs are processed very quickly • processing needs to be quick enough to deliver output on time • outputs need to be adjusted accordingly so accidents can be avoided example: reactor temperature control in a nuclear power station

• a user submits an input and the record is updated very quickly • the record is locked during the update example: booking seats at a theatre

• intuitive • easy to navigate for non-specialised users • uses windows, icons and menus • no need to learn text commands • no need to be a proficient typist

• requires a lot of memory • is processor intensive • take up a large amount of disk space • could be inefficient for experienced users

• efficient for experienced users as it is quicker to type commands • shortcut keys can be used to input commands • little memory and processing power required

• confusing for inexperienced users • commands have to be typed precisely • a large number of commands need to be learned

• more convenient to find and access files • stores related files in a logical way in the same order • can use the same file name in different directories • shows the path to a file

It allocates a small amount of time to each process and cycles between them. As this happens so quickly, it appears as though they are happening simultaneously.

• communicates with and sends data to output devices • communicates with and receives data from input devices • manages network communication • manages backing store by ensuring that data is stored and can be retrieved correctly from any disk drive • creates and maintains a filing system • organises files in a hierarchical structure • manages RAM by ensuring there is enough memory for all programs and that each program has enough memory allocated • offers compression whish saves space

• provides a user interface with meaningful icons, dropdown menus and avoids text input • can provide CLI • allows customisation of the interface • allows access to system settings • allows copying, deleting and moving of files • allows creation of shortcuts • controls security using passwords and access permissions • provides users with warning and help messages • allows user to have more than one window open