Description and exemplification of the main functions of a single user operating system :
- interpreting users commands
- file management
- memory management
- input/output management
- resource allocation
- managing processes
Interpreting user’s commands
- takes the instructions from the user and passes them on to the rest of the operating system.
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This is the part of the OS that the user interacts with to give instructions to the computer.It can be command-driven, menu-driven or a GUI which may use a WIMP system.
File Management
- Controls the organisation of backing storage
- It uses part of the disc as a file catalog, which holds details of where data is stored on disc.
- Files are organised into a hierarchical filing system storing files in separate directories and subdirectories.
Memory Management
- controls where programs and data are placed in main memory
- Many OS’s allow more than one program to be in memory at the same time.
- Memory management tries to make sure that any program does not overwrite any other program (including the OS itself!).
Input/Output Management
- communicates between the computer system and the input and output devices
- handles the transfer of data between peripherals and the CPU.
Managing Processes
- controls processes and handles interrupts
- Kernel manages processes (when a program runs it starts a process and this may start further processes) and handles interrupts.
Resource Allocation
- The OS allocates resources to other programs such as applications. For example:
- Scheduler to share processor – batch, foreground/background, timesharing
- Memory management – e.g. Virtual memory paging, swapping memory contents to hard disc
- Ensures drivers are given access to hardware devices
- Mechanisms for accounting; limit enforcement – e.g. no. of pages printed, file space per user etc
