- Operating System Tutorial
- OS - Home
- OS - Overview
- OS - Components
- OS - Types
- OS - Services
- OS - Properties
- OS - Processes
- OS - Process Scheduling
- OS - Scheduling algorithms
- OS - Multi-threading
- OS - Memory Management
- OS - Virtual Memory
- OS - I/O Hardware
- OS - I/O Software
- OS - File System
- OS - Security
- OS - Linux
- OS - Exams Questions with Answers
- OS - Exams Questions with Answers
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Components of Operating System
There are various components of an Operating System to perform well defined tasks. Though most of the Operating Systems differ in structure but logically they have similar components. Each component must be a well-defined portion of a system that appropriately describes the functions, inputs, and outputs.
There are following 8-components of an Operating System:
- Process Management
- I/O Device Management
- File Management
- Network Management
- Main Memory Management
- Secondary Storage Management
- Security Management
- Command Interpreter System
Following section explains all the above components in more detail:
A process is program or a fraction of a program that is loaded in main memory. A process needs certain resources including CPU time, Memory, Files, and I/O devices to accomplish its task. The process management component manages the multiple processes running simultaneously on the Operating System.
A program in running state is called a process.
The operating system is responsible for the following activities in connection with process management:
- Create, load, execute, suspend, resume, and terminate processes.
- Switch system among multiple processes in main memory.
- Provides communication mechanisms so that processes can communicate with each others
- Provides synchronization mechanisms to control concurrent access to shared data to keep shared data consistent.
- Allocate/de-allocate resources properly to prevent or avoid deadlock situation.
I/O Device Management
One of the purposes of an operating system is to hide the peculiarities of specific hardware devices from the user. I/O Device Management provides an abstract level of H/W devices and keep the details from applications to ensure proper use of devices, to prevent errors, and to provide users with convenient and efficient programming environment.
Following are the tasks of I/O Device Management component:
- Hide the details of H/W devices
- Manage main memory for the devices using cache, buffer, and spooling
- Maintain and provide custom drivers for each device.
File management is one of the most visible services of an operating system. Computers can store information in several different physical forms; magnetic tape, disk, and drum are the most common forms.
A file is defined as a set of correlated information and it is defined by the creator of the file. Mostly files represent data, source and object forms, and programs. Data files can be of any type like alphabetic, numeric, and alphanumeric.
A files is a sequence of bits, bytes, lines or records whose meaning is defined by its creator and user.
The operating system implements the abstract concept of the file by managing mass storage device, such as types and disks. Also files are normally organized into directories to ease their use. These directories may contain files and other directories and so on.
The operating system is responsible for the following activities in connection with file management:
- File creation and deletion
- Directory creation and deletion
- The support of primitives for manipulating files and directories
- Mapping files onto secondary storage
- File backup on stable (nonvolatile) storage media
The definition of network management is often broad, as network management involves several different components. Network management is the process of managing and administering a computer network. A computer network is a collection of various types of computers connected with each other.
Network management comprises fault analysis, maintaining the quality of service, provisioning of networks, and performance management.
Network management is the process of keeping your network healthy for an efficient communication between different computers.
Following are the features of network management:
- Network administration
- Network maintenance
- Network operation
- Network provisioning
- Network security
Main Memory Management
Memory is a large array of words or bytes, each with its own address. It is a repository of quickly accessible data shared by the CPU and I/O devices.
Main memory is a volatile storage device which means it loses its contents in the case of system failure or as soon as system power goes down.
The main motivation behind Memory Management is to maximize memory utilization on the computer system.
The operating system is responsible for the following activities in connections with memory management:
- Keep track of which parts of memory are currently being used and by whom.
- Decide which processes to load when memory space becomes available.
- Allocate and deallocate memory space as needed.
Secondary Storage Management
The main purpose of a computer system is to execute programs. These programs, together with the data they access, must be in main memory during execution. Since the main memory is too small to permanently accommodate all data and program, the computer system must provide secondary storage to backup main memory.
Most modern computer systems use disks as the principle on-line storage medium, for both programs and data. Most programs, like compilers, assemblers, sort routines, editors, formatters, and so on, are stored on the disk until loaded into memory, and then use the disk as both the source and destination of their processing.
The operating system is responsible for the following activities in connection with disk management:
- Free space management
- Storage allocation Disk scheduling
The operating system is primarily responsible for all task and activities happen in the computer system. The various processes in an operating system must be protected from each other’s activities. For that purpose, various mechanisms which can be used to ensure that the files, memory segment, cpu and other resources can be operated on only by those processes that have gained proper authorization from the operating system.
Security Management refers to a mechanism for controlling the access of programs, processes, or users to the resources defined by a computer controls to be imposed, together with some means of enforcement.
For example, memory addressing hardware ensure that a process can only execute within its own address space. The timer ensure that no process can gain control of the CPU without relinquishing it. Finally, no process is allowed to do it’s own I/O, to protect the integrity of the various peripheral devices.
Command Interpreter System
One of the most important component of an operating system is its command interpreter. The command interpreter is the primary interface between the user and the rest of the system.
Command Interpreter System executes a user command by calling one or more number of underlying system programs or system calls.
Command Interpreter System allows human users to interact with the Operating System and provides convenient programming environment to the users.
Many commands are given to the operating system by control statements. A program which reads and interprets control statements is automatically executed. This program is called the shell and few examples are Windows DOS command window, Bash of Unix/Linux or C-Shell of Unix/Linux.
Other Important Activities
An Operating System is a complex Software System. Apart from the above mentioned components and responsibilities, there are many other activities performed by the Operating System. Few of them are listed below:
Security − By means of password and similar other techniques, it prevents unauthorized access to programs and data.
Control over system performance − Recording delays between request for a service and response from the system.
Job accounting − Keeping track of time and resources used by various jobs and users.
Error detecting aids − Production of dumps, traces, error messages, and other debugging and error detecting aids.
Coordination between other softwares and users − Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.