Definition of operating system

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Definition of operating system

The “Operating System (OS)” is a “Computer Software” which controls “Computer Hardware Resources” and gives “Common Services” for the “Computer Programs”. After pressing the “Power Button” from the “CPU Casing Box”, the Computer Runs with the help of the “Operating System (OS)” in a Compute. All “Application Programs” usually need an “Operating System (OS)” to do function properly in a Computer. A Computer can not Run without a “Operating System (OS)” in a Computer. A Computer control depends on the “Operating System (OS)” in a Computer. So, you should know about the “Operating System (OS)” for getting performance from a Computer.


List of operating systems


Microsoft Windows

Definition of operating system

The “Microsoft Windows” is an “Operating System (OS)” which designed by “Microsoft Corporation”. It was primarily targeted to “Intel Architecture” based Computers which share on Web connected Computers. The newest version is “Windows 8.1” for workstations and “Windows Server 2012 R2” for “Server Computer”. “Windows 7” recently overtook “Windows XP” as most used “Operating System (OS)”.


Definition of operating system

The “Linux” is like as “Unix Operating System (OS)” that was developed without any actual “Unix Code”, unlike BSD and its variants. “Linux” can be used different devices from “Super Computers” to “Wrist Watches”. The “Linux Kernel” is released under an “Open Source License”. That’s why, anyone can “Read” and “Modify” the “Linux Kernel Code”. “Linux” has been widely adopted for use in “Computer Servers”.


For example- The “Linux Kernel” is used in different “Operating System (OS)” such as “Red Hat, Debian, Ubuntu, Linux Mint and Google’s Android etc.”



Definition of operating system

The “Unix” was firstly written in “Assembly Language”. “Ken Thompson” wrote “B”, mainly based on “BCPL” from his experience in the “MULTICS Project”. “B” was replaced by “C” and “Unix” rewritten in “C”.

BSD and its descendants

“Berkeley Software Distribution” is the subgroup of the “Unix” family which includes FreeBSD, NetBSD and OpenBSD. Most of the time, these “Operating Systems (OS)” are used on “Webservers”. They can also used as a “Personal Computer Operating System (OS)”.

Mac OS X

Definition of operating system

“Mac OS X” is an “Operating System (OS)” which is developed, marketed, and sold by “Apple Inc.”. “Mac OS X” is the successor to the original “Mac OS”. “Mac OS” was “Apple’s Primary Operating System” since “1984”.

Google Chromium OS

Definition of operating system

“Google Chromium OS” is an “Operating System (OS)” based on the “Linux Kernel” and designed by “Google”. “Google Chromium OS” is usually by “Computer Users” who spend most of their time on the “Internet”.


Types of operating systems


Real time

The “Real Time Operating System (OS)” is a multitasking “Operating System (OS)” that perform “Real Time Applications”. “Real Time Operating System (OS)” often applies specialized “Scheduling Algorithms”. That’s why; they can get a deterministic nature of performance. The main objective of “Real Time Operating System (OS)” is their quick and predictable response to events.


For example- “Real Time Operating System (OS)” can do the “Transaction Processing Facility” for a Company.



The “Distributed Operating System” controls a group of independent Computers and creates them show to be a single Computer. “Distributed Computations” are carried out on more than one machine. “Distributed System” is used when Computers in a group work in cooperation.

Multi user

The “Multi User Operating System (OS)” permits “Multiple Users” to enter a “Computer System” at the similar time. “Time Sharing Systems” and “Internet Servers” can be classified as “Multi User Operating System (OS)”. Then, they enable “Multiple Users” enter to a Computer through the sharing of time.

Multi tasking vs single tasking

The “Multi Tasking Operating System (OS)” permits more than one “Computer Program” to be running at the similar time. The “Single Tasking System” has only one running “Computer Program”.


“Embedded Operating System (OS)” are designed to be used in “Embedded Computer Systems”. “Embedded Operating System (OS)” are designed to run on small machines like “PDAs” with less independence.


For example- “Embedded Operating System (OS)” such as “Windows CE, Minix 3 etc.”



The “Templated Operating System (OS)” can be used both in virtualization and cloud computing management and is common in large server warehouses.


Features of operating system


Vital component of system software

The “Operating System (OS)” is a vital component of the “System Software” in a “Computer System”.

Hardware functions

“Operating System (OS)” does some “Hardware Functions” such as input and output of instructions, memory allocation, intermediary between “Computer Program” and the “Computer Hardware”.

Operating system supported devices

“Operating System (OS)” can be set up on any device that includes a Computer from “Cellular Phones” and “Video Game Consoles” to “Super Computers” and “Web Servers”.


For example- “Operating System (OS)” supported Devices such as “Microsoft Windows, Windows Phone, Android, Linux, OS X, IBM z/OS, UNIX etc.”



Definition of operating system

A “Kernel” connects the “Application Software” to the “Computer Hardware” of a Computer. The “Kernel” provides the majority basic level of run over all of the “Computer’s Hardware Devices”. “Kernel” controls “Memory Access” for “Computer Programs” in the Random Access Memory (RAM) to settle on which “Computer Programs” get access to which “Computer Hardware Resources”. The long term “Non Volatile storage” arranges the data by using the “Kernel” with file systems on such media as Flash Memory, Tapes, Disks, etc.

Interact with computer hardware

The “Operating System (OS)” give an interface between an “Application Program” and the “Computer Hardware”. Then, an “Application Program” can interact with the “Computer Hardware” only by obeying rules and procedures programmed into the “Operating System (OS)”.

Program execution

The “Operating System (OS)” helps to do execution of “Application Programs”.


For example- “Operating System (OS)” establishes a priority for the process in Multi Tasking Systems; loads “Computer Program Binary Code” into memory and start execution of the “Application Program” which then interacts with the “Computer User” and with “Computer Hardware Devices”.



The “Interrupts” are vital to “Operating Systems (OS)” which provide an efficient way for the “Operating Systems (OS)” to connect with and respond to its environment. The “Operating Systems (OS)” watch the various sources of input for events that need action.


Modern “CPUs” supports multiple modes of operation. “CPUs” with this capability use at least two modes such as “Protected Mode” and “Supervisor Mode”. The “Operating System’s Kernel” is for low level tasks that need unrestricted access to “Computer Hardware” in the “Supervisor Mode”. The “Protected Mode” is used for almost everything else. The “Computer Application Software” run within “Protected Mode” and can only use “Computer Hardware” by communicating with the “Kernel” which operates everything in “Supervisor Mode”.


For example- “Operating System Modes” such as “32 Bit Operating System” and “64 Bit Operating System”


Access hardware and memory

The “Computer Program” may have access to a more limited set of the “CPU’s Instructions” in the “Operating System (OS)”. “Operating System (OS)” can maintain exclusive control over things like access to “Computer Hardware” and “Memory” by triggering an interrupt causing control to be passed back to the “Kernel”.

Protected mode resource

The “Protected Mode Resource” normally refers to one or more “CPU Registers” which hold information that the running “Computer Program” isn’t allowed to alter. Attempts to alter these resources normally cause of a switch to “Supervisor Mode” where the “Operating System (OS)” can control with the unlawful operation the “Computer Program” was attempting.


For example- “Stop” a specific “Computer Program”.


Memory management

The “Multi Programming Operating System Kernel” must be dependable for managing all “System Memory” which is at present in use by “Computer Program” in the “Operating System (OS)”. It ensures that, a “Computer Program” does not interfere with “Memory” already in use by “Another Computer Program”.

Memory protection

The “Memory Protection” allow the “Kernel” to limit a “Process Access” to the “Computer’s Memory” in the “Operating System (OS)”.


For example- Different methods of “Memory Protection” exist such as “Memory Segmentation” and “Paging”.


Access running program

Certain “Protected Mode” registers specify to the “CPU” what “Memory Address” it should allow a running “Computer Program” to access in both “Memory Segmentation” and “Paging” in the “Operating System (OS)”. Attempts to use other addresses will trigger an interrupt which will reason the “CPU” to re-enter “Supervisor Mode” to put the “Kernel” in charge.

Virtual memory

Using “Memory” scattered around the “Hard Disk Drive (HDD)” and “Random Access Memory (RAM)” as if it is one continuous chunk of “Memory” in the “Operating System (OS)” which is called “Virtual Memory”. The utilize of “Virtual Memory Addressing (Paging or Segmentation)” means that the “Kernel” can choose what “Memory” each “Computer Program” may use at any given time. It also allows the “Operating System (OS)” to use the same “Memory Locations” for “Multiple Tasks”. If a “Computer Program” attempt to use “Memory” that is not in its current range of accessible “Memory”, but nonetheless has been allocated to it, the “Kernel” will be interrupted in the similar way as it would if the “Computer Program” were to exceed its allocated “Memory”.


The “Multitasking” refers to the running of multiple independent “Computer Programs” on the same Computer which giving the look that it is performing the tasks at the similar time. Since most Computers can do at most one or two things at one time. But, this is normally done via “Time Sharing” where every “Computer Program” uses a share of the Computer’s time to execute. “Windows NT” was the primary version of “Microsoft Windows” which enforced preemptive “Multitasking” which did not reach the “Home User Market” until “Windows XP”.

Disk access and file systems

The “File Systems” allow “Computer Users” and “Computer Programs” to arrange and sort “Computer Files” on a Computer through the use of “Directories” or “Folders”. Access to “Computer Data” stored on Disks is a vital feature of all “Operating Systems (OS)”. Computers store “Computer Data” on disks using “Compute Files” which are structured in specific ways in arrange to use for faster access, and to make better use out of the “Drive’s Available Space”. The specific way in which “Computer Files” are stored on a Disk is called a “File System” and enables “Computer Files” to have specific “Names” and “Attributes”. This allows them to be stored in a Hierarchy of “Folders” or “Directories”. It is very difficult for an “Operating System (OS)” to support more than one “File System”. When the “Kernel” has a suitable “Device Driver” in place, that time, it can then access the contents of the “Disk Drive” in “Raw Format” which may contain one or more “File Systems”. The “File System Driver” is used to “Translate” the commands used to access each specific “File System” into a standard set of commands that the “Operating System (OS)” can use to talk to all “File Systems”. The “Computer Programs” can then deal with these “File Systems” on the basis of “File Names” and “Directories” or “Folders” contained within a hierarchical structure. They can Create, Delete, Open and Close the “Computer Files”. They can also gather various kinds of information about them including Access Permissions, Size, Free Space and Creation and Modification Dates.

Device drivers

The “Computer Device Driver” is a particular type of “Computer Software” developed to use interaction with “Hardware Devices” in a Computer. Normally, this represent an interface for communicating with the “Computer Device” through the specific “Computer Bus” or “Communications Subsystem” that the “Computer Hardware” is connected to, providing instructions to and/or receiving data from the “Computer Device” and on the other end, the necessary interfaces to the “Operating System (OS)”. Every model of “Computer Hardware” is not similar. Newer models of “Computer Hardware” are also released by “Manufacturers” that provide more reliable or better performance and these newer models are often controlled in a different way. Computers and their “Operating System (OS)” cannot be expected to know how to run every “Computer Device”, both now and in the future. To solve this problem, “Operating System (OS)” essentially dictate how each type of “Computer Device” should be controlled. The function of the “Computer Device Driver” is then to translate these “Operating System (OS)” mandated function calls into “Computer Device” specific calls. In theory a latest “Computer Device” which is controlled in a new manner to function correctly if an appropriate “Computer Driver” is presented.


Usually, “Operating Systems (OS)” maintain a variety of networking protocols, hardware and applications for using them. Computers running different “Operating Systems (OS)” can join in a “Common Network” for sharing “Computer Resources” such as Computing, Files, Printers and Scanners using both “Wired” or “Wireless Connections”. “Networks” can essentially permit a Computer’s “Operating Systems (OS)” to use the “Computer Resources” of a “Remote Computer” to maintain the similar functions as it could if those “Computer Resources” were connected directly to the “Local Computer” in the “Operating Systems (OS)”.


For example- Simple Communication, Using Networked File Systems, Sharing another Computer’s Graphics or Sound Hardware.



A “Computer’s Security” is very important for a Computer. The “Security” of “Operating System (OS)” has gotten priority because of highly sensitive “Computer Data” held on Computers. The “Operating System (OS)” must be able of distinguishing between requests which should be allowed to be processed with the “Operating System’s User Name” and others which should not be processed. Each “Operating System’s User Name” may have a “Password” to enter the Computer. The “Internal Security” or “Security” from an already “Running Computer Program” is only possible if all possibly “Harmful Requests” must be approved out through interrupts to the “Operating System Kernel”. Because, direct access of hardware and resources by using “Computer Programs”, they cannot be secured. The “Internal Security” is related for “Multi User Systems” which allows each “Computer User” of the system to have “Private Files” that “Other Computer Users” cannot tamper with or read. The “Network Services” include offerings such as File Sharing, Print Services, File Transfer Protocols (FTP), Email, and Websites. Most of the “Operating Systems (OS)” include a “Software Firewall Protection” which is enabled by “Default”. Security of “Compute Software” is known as “Software Firewall Prevention Systems”. A “Software Firewall” can be configured to allow or deny “Network Traffic” to or from a “Application” running on the “Operating System (OS)”.

User interface

“User Interface” is generally referred to as a shell and is necessary if human communication is to be maintained in the “Operating System (OS)”. The “User Interface” shows the “Directory Structure” and “Requests Services” from the “Operating System (OS)” that will obtain data from “Input Hardware Devices” such as a “Mouse” or “Keyboard”. Then, “Requests Operating System (OS) Services” to display timely the status messages to the “Output Hardware Devices” such as a “Video Monitor”.

          a) Command-line interface

The “Command Line Interface” is a “User Interface” where every “Computer Commands” are typed out “Line-by-Line”.

          b) Graphical user interface (GUI)

The “Graphical User Interface (GUI)” is a “User Interface” where all “Visual Environment” is present. Most of the modern “Computer Systems” support “Graphical User Interface (GUI)” and often include them. The “Graphical User Interface (GUI)” is integrated into the “Kernel” in “Mac OS”.




1. Need “Computer User”.

2. Need “Computer”.

3. Need “Computer Monitor” to “Display” to the “Operating System (OS)”.

4. Need to choose “32 Bit Operating System (OS)” or “64 Bit Operating System (OS)” which you want for your Computer.

5. Need to “Buy” a “Licensed Operating System (OS) Disk” such as “Windows XP, Windows 7, Windows8, Linux, Unix, Mac OS X, Google Chromium OS etc.” for your Computer.

6. Need to give the “Partition” to your “New Computer Hard Disk Drive (HDD)” before “Installing” the “Operating System (OS)” in your Computer.

7. Next Time, need to give the “Format” to the “C: Drive” from your “Computer Hard Disk Drive (HDD)” only before “Installing” the “Operating System (OS)” in your Computer.

8. Need to “Install” any “Licensed Operating System (OS)” such as “Windows XP, Windows 7, Windows8, Linux, Unix, Mac OS X, Google Chromium OS etc.” in your Computer.

9. Need to “Install” the “Operating System (OS)” supported “Application Program Software”. That means, if your “Operating System (OS)” is “32 Bit”, that time, you have to “Install” the “32 Bit Operating System (OS)” supported “Application Program Software” in your Computer. If your “Operating System (OS)” is “64 Bit”, that time, you have to “Install” the “64 Bit Operating System (OS)” supported “Application Program Software” in your Computer. Otherwise, it will not work in your Computer.




1. You should choose “32 Bit Operating System (OS)” to do the “Normal Computer Work” in your Computer.

2. You should “Buy” a “Licensed Operating System (OS) Disk” such as “Windows XP, Windows 7, Windows8, Linux, Unix, Mac OS X, Google Chromium OS etc.” for your Computer.

3. You should give the “Partition” to your “New Computer Hard Disk Drive (HDD)” perfectly before “Installing” the “Operating System (OS)” in your Computer.

4. You should give the “Format” to the “C: Drive” from your “Computer Hard Disk Drive (HDD)” only before “Installing” the “Operating System (OS)” in your Computer. In this way; your “Computer Hard Disk Drive (HDD) Other Drives” all “Computer File” and “Computer Folder” will not be “Deleted” from your “Computer Hard Disk Drive (HDD)”.

5. You should “Install” the “Licensed Operating System (OS) Disk” for preventing to enter the “Computer Virus” in your Computer.

6. You should “Install” the “Operating System (OS)” to the “C: Drive” from the “Hard Disk Drive (HDD)” in your Computer.

7. You should keep the important “Computer Files” and “Computer Folders” to the “Other Drive” except the “C: Drive” from the “Hard Disk Drive (HDD)” in your Computer. Because, if you “Install” the “Operating System (OS)” to the “C: Drive” from the “Hard Disk Drive (HDD)” in your Computer, that time, those “Computer Files” and “Computer Folders” will be “Deleted” from your “Computer Hard Disk Drive (HDD)” in your Computer.

8. You should “Install” the “32 Bit Operating System (OS)” supported “Application Program Software” in your Computer. Otherwise, it will not work properly in your Computer.

9. You should keep “Turn On” the “Windows Firewall Protection” from the “Operating System (OS)” in your Computer.

10. You should not “Install” the unnecessary “Application Program Software” in your Computer. Otherwise, your Computer will be very slow.




1. You should not “Buy” the “Pirate Operating System (OS)” for your Computer.

2. You should not use the “Pirate Operating System (OS)” for preventing the “Computer Virus” in your Computer.

3. You should not use the “Pirate Application Program Software” for preventing the “Computer Virus” in your Computer.

4. The “Windows Operating System’s Firewall Protection” should not be “Turn Off” in your Computer.


Operating System


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In this way, you can understand about Definition of operating system, List of operating systems, Types of operating systems, Features of operating system, Requirements, Tips and Warnings of “Operating System (OS)” in your Computer.

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{ 1 comment… read it below or add one }

Maria James August 13, 2014 at 3:25 pm

I like to use the Windows operating System. Usually, I use the Windows XP Operating System. It is a great Operating System I have ever used.


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