Topic 3.1 Operating systems

Topic 3.1 Operating systems

1. Managing resources and providing user interface

   • An operating system is software that manages a computer system. The operating system is loaded by the bootstrap loader. One of its primary functions is to manage resources. Here are some examples of how the operating system manages the computer systems resources:

2. Manages peripherals such as 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

3. Manages printing using 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

4. 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) • Organise files in a hierarchical directory structure.

5. File compression

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

6. Disk de-fragmentation

   • • Fragmented files are split up and stored on different parts of the disk • Disk fragmentation will slow down disk access speed • Disk de-fragmentation is when file parts are physically re-arranged (re-organised, moved, re-ordered on disk into the order required for access)

7. 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

8. Manages processes

   • • Ensures that different processes can utilise 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

9. Manages security

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