operating systems Flashcards
operating system
software that manages a computer system
Managing memory
Ensures that programs/data do not corrupt each other.
Ensures that all programs and data including itself is stored in correct memory locations.
Managing processes
Ensures that different processes can utilise the CPU and do not interfere with each other or crash.
On a multi-tasking operating system, the operating system ensures that all tasks appear to run simultaneously.
Managing backing store
Ensures that data is stored and can be retrieved correctly from any disk drive.
Creates and maintains a filing system, such as a File Allocation Table (FAT) or New Technology File Systems (NTFS).
Organises files in a hierarchical directory structure.
Managing peripherals (including input and output devices).
Communicates with and sends data output to a printer/monitor/other valid output device.
Communicates with and receives data input to a keyboard/mouse/other valid input device.
Spooling
Data is stored on hard disc/in memory/stored in a queue
Document is printed when printer is free/in correct order.
Benefit of spooling – user can carry on working/log off when waiting for job to print.
Managing security
Allows creation and deletion of user accounts.
Allows users to log on and change passwords.
File compression
reducing the size of a file. This may be advantageous as it allows more data to be stored on the disk and files may also be transferred more quickly.
Software based disk compression is often included as a facility of an operating system and so it is readily available on most computer systems. The disadvantage of this is that it slows down the process of reading and writing to disk.
Hardware disk compression requires specialist hardware, which can be expensive. However, it does not affect the speed of access as much as software-based disk compression.
Disk based compression is always lossless.
Disk defragmentation
Files are stored on computer systems that can, over time, become fragmented.
Defragmentation is the process where files are physically re-arranged on disk so that they are no longer fragmented and the parts of each file are stored together. This improves the speed of accessing data from disk.
Providing user interface
Allows copying/deleting/moving/sorting/searching of file or folders.
Allows access to system settings such as hardware.
Provides a command line interface.
Allows users to have more than one window open.
Provides a graphical user interface (Windows, Icons, Menus, Pointers).
Provides user with error/help messages.
Human Computer Interfaces (HCIs)
way in which people and computer systems interact. To allow a person and a computer system to communicate, an interface is required.
Command Line Interface (CLI)
entirely text-based interface that allows a user to communicate with a computer system by typing in commands.
