Functions of the Operating System

1. Functions of the Operating System

2. Functions of an Operating System: • File management • Memory management • Security • Device management • Input/output management • User interface • Process management

3. File Management • This is a part of the operating system that is responsible for managing the data that is held in secondary storage, usually magnetic disk. • It performs four main functions: • It keeps track of all files in the system • It controls sharing and enforces protection of files • It manages disk space and its allocation and de-allocation • It maps logical file addresses to physical addresses

4. File Organisation and Referencing • The file manager allows users to organise their work into logical units of storage called files, for example, a document file consisting of word processed text. • The term referencing refers to the naming of a file.eg. technology.doc. • Some examples of file extensions you may be familiar with are: • doc – Microsoft Word • xls – Microsoft Excel • ppt – Power Point • wma – Windows Media Audio

5. Directories This is a logical grouping of files and is known in modern versions of Windows as folders. C: Program Files My Documents Windows Finance.xls Memory.ppt Technology.doc

6. Memory Management • This is the act of managing computer memory. In its simpler forms, this involves providing ways to allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. The management of main memory is critical to the computer system. • The memory management subsystem provides: • Large Address Spaces • Protection • Memory Mapping • Fair Physical Memory Allocation • Shared Virtual Memory

7. Security File systems often contain information that is highly valuable to their users. Protecting this information against unauthorised usage is therefore a major concern in all file systems. Device Management The path between the operating system and virtually all hardware not on the computer's motherboard goes through a special program called a driver.

8. Input/Output Management This is the part of the operating system that deals with the control of all the computer’s input/output devices. Due to the diversity of different devices, it became necessary for the operating system to be able to handle this. What happens is that the operating system can allow a new device to be used via an intermediate special-purpose program called a device driver.

9. User Interface • This refers to the means by which people (users) can interact with the system, a particular machine, device, application software, etc. The user interface provides means of: • Input – allowing the users to manipulate a system • Output – allowing the system to produce the effects of the users' manipulation. • There are many different types of user interfaces, but for this course you would be required to familiarise yourself with the two most popular types: • Command Line Interface (CLI) • Graphical User Interface (GUI)