Operating Systems

Operating Systems

1. Manages 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

2. Manages printing using spooling

   • 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

3. Manages backing store

   • Ensures that data is stored and can be retrieved correctly from any disk drive
   • Creates and maintains Filing system such as FAT or NTFS (accepted but not expected)
   • Organize files in a hierarchical directory structure.

4. File compression

   • The amount of data is reduced and the file is made smaller
   • Compression is used to save disk space

5. Disk de-fragmentation

   • Data is stored on hard disc/in memory/stored in a queue
   • Fragmented files are split up and stored on different parts of the disk

6. Manages memory (RAM)

   • Ensures that programs/data do not corrupt each other
   • Ensures that all programs and data including itself is stored in correct memory locations

7. Manages processes

   • Ensures that different processes can utilize the CPU and do not interfere with each other or crash
   • On a multi-tasking O/S ensure that all tasks appear to run simultaneously

8. Manages security

   • Allows creation and deletion of user accounts
   • Allows users to logon and change passwords

9. Libary

   • related private functions and subprograms are stored in the same location
   • time is saved as the programmer can simply use the private functions and programs stored in a library
   • subroutines contained in a library have already been tested, so they should work reliably and not need further testing
   • programs will contain less code and will therefore be easier to maintain