Contents
Functions of an Operating System
An OS usually provides all or more of the following features. Before reading the functions I recommend reading about Introduction about Operating System.
1. I/ O management
Input/ Output management is essential to the operation of any computer. It allows the computer to interact and control access with peripheral devices such as a keyboard, mouse, terminals (like the modem and NEC card), disks, monitor, and printer.
In computing, input/ output management refers to the transformation of data between input and output devices of the computer system. So, an OS must respond to user keystrokes and mouse clicks, interpret I/ O requests and provide the required services of a device at the same time. A request for I/ O requests and provide the required services of a device at the same time. A request for I/ O from a user process is signaled to the operating system using a system call (sometimes called a software interrupt). When a process makes a system call, it effectively controls the processor back to the operating system to enable it to service the request through the appropriate device driver.
2. Command interpreter
Every OS must provide a command interpreter for its operation. Command interpreters can have direct access to the functions of the operating system. The command interpreter reads and executes the commands that a user types at a terminal or keyboard, interprets them, and translated them into a detailed set of instructions, which the computer hardware can understand.
Advanced users may prefer the command line interface because of its concise and powerful access. In most Windows operating systems, the primary command-line interpreter is Command Prompt.
3. Data management
The data management functions of an OS govern the input and output of data and their location, storage, and retrieval. It also is responsible for storing and retrieving information on disk drives and for the organization of that information on the drive.
4. Memory management
The operating system manages the main memory. Main memory is made up of a large collection of words or bytes where each word or byte is assigned a certain its own memory address. Main memory can be accessed directly by the CPU. For a program execution, it should be the first loaded in the main memory. When the user requests a CPU for reading/ write operation, OS determines the amount of required memory to load the program and data into RAM or main memory. An OS checks how much memory is to be allocated to processes and decides which process will get memory at what time. It also tracks whenever some memory gets freed or unallocated and correspondingly it updates the status. When the program terminates, its memory space will be free and the same memory area or address can be allocated to other new programs.
5. Process management
In a multi-programming environment, the OS decides the order in which processes have access to the processor, and how much processing time each process has. This function of OS is called process-scheduling.
The process management allocates a processor to execute a chosen process. It finds the status of processors and processes, is called Traffic-controller, chooses a job using Job-Scheduler, chooses the process in the job using process-scheduler, allocates the processor to the process, is called dispatcher, and frees the processor when the process is executed.
In short, an Operating system performs the following activities for processor management:
- It keeps track of the status processes. The program which performs this task is known as a traffic controller.
- It allocates the CPU that is the processor to a process. Reallocated processor when a process is no more required.
