The operating system is one of the most important parts of a computer, usually pre-installed in computers. Almost every type of computer-like; including mobile telephones, video game systems, DVR, embedded systems need an operating system in order to operate properly. We use OS in all day task on our various devices.

### What is Operating Sysytem
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<center><a href="https://pixabay.com/en/monitor-binary-binary-system-1307227/">Monitor with Binaries from Pixabay under CC0 license</a></center> </div> 
Operating system (OS) is a software that act as an intermediary between the software and hardware components, it manages and controls the resources between the hardware and software. 
Without software hardware is useless but all things work for each other, without hardware, there won't be software. 
The operating system tells the computer what to do according to the instruction given by the end user through GUI or CLI without having prior knowledge of how hardware works. 
This tells us many things happen behind the scene of hardware and software which are calculated and carried out in nanoseconds.

> Other applications such as system applications or user applications make use of the operating system by making requests for services through a defined application program interface (API). [source](https://whatis.techtarget.com/definition/operating-system-OS)

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### Tasks Operating System Performs

  - It handles both the hardware and software resources, an operating system communicates with the hardware through kernel to perform a specified task.
  
  - In computers that support parallel processing, an operating system can manage how the processor should be shared between multiple programs at a time.
  
  - Operating system handles both input and output devices such as hard-drive, flash-drive, printers. 
  
  - Operating system allocates usable internal memory between multiple programs.
  
  - Operating can cancel already sent request/batch jobs such as printing, shutdown request so that the initiating application is freed from this work.
  
  - Operating system can tell the status of operation and any errors that may have occurred if requested by a program or by the end user.
  
  - Operating system controls and manages how the User interface or display of programs are rendered, how given information instructed to the program is display on the monitor. 

  - Operating system handles network communication, it acts as the core to presides network communication enabling of the connected network devices to interact with the computer and with any programs that require them Examples is Network cards, such as Ethernet ports and wireless local area network (LAN) cards, enable connection to networks but they also require an operating system to interface them for the end users.

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### Types of Operating System

<div class="pull-right"><img src="https://cdn.pixabay.com/photo/2013/07/13/11/23/apple-158063_1280.png
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<center><a href="https://pixabay.com/en/apple-linux-mac-penguin-windows-158063/">Apple linux mac logo from Pixabay under CC0 license</a></center> </div>

Most simple, single-function computers i.e devices designed to do one task (such as in microwave ovens with digital keypads) do not require an operating system to work. But for mobile phones, personal computers, servers do require an operating system for them to work properly. 

#### Single User
**single user, single-task operating systems:** This is a system designed to allow only one user to perform one task at a time. This operating system is found in [personal computers](https://en.m.wikipedia.org/wiki/Personal_computer).

**single user, multi-tasking operating systems:** This is a system designed to allow one user to perform multiple tasks, run multiple applications simultaneously at a time. Examples of this operating system are Linux, Mac OS, and Windows operating system.

#### Multiple User
This is an operating system designed to allow multiple users to take advantage of single computer's resources.  
Example of this operating system is Unix.

#### Real-time Operating system (RTOS)
This is an operating system designed to handle events, used to control machinery, scientific instruments, and industrial systems. The user does not have much control over RTOS functions like other operating systems (multi-user operating system). 

#### Embedded System
This is the type of operating system designed with software and hardware to perform a specific task. [Embedded System](https://en.m.wikipedia.org/wiki/Embedded_system).  Examples include Mobile Phones, Laptops, Surveillance Cameras, Washing Machines, Radio Reviewers etc.

![steemit-border](https://img.esteem.ws/av4tt0mlsg.png) 
### Popular PC Operating Systems

#### Windows
Windows operating system is graphical operating system families, developed by Microsoft, founded by Paul Allen and Bill Gates on April 4, 1975, released its first version as version 1.0 on November 20, 1985.
Windows operating system is not free and also not an open source (closed source). [read more](https://en.m.wikipedia.org/wiki/Microsoft_Windows)

#### Mac OSX
Mac OS X also known as  Macintosh, is a series of graphical operating systems for Apple's Mac family computers developed and marketed by Apple Inc. since 2001. Founded by Steve Jobs In 1984, the Macintosh it is the second most widely used desktop OS, after Microsoft Windows. [read more](https://en.m.wikipedia.org/wiki/MacOS)

#### Unix
Unix is a family of multitasking, multiuser computer operating systems developed by well known Dennis Ritchie (founder of C language), Ken Thompson with other colleagues at original AT&T Bell Labs in the 1970s. [read more](https://en.m.wikipedia.org/wiki/Unix)

#### Linux
Linux is a kernel released on September 17, 1991 by Linus Torvalds as an open source, today Linux has over 18 million lines of code with the contribution of other developers written in C and Assembly Language. Linux is now dominants in many sectors due to the support it has from superfluous developers, the combination of [GNU](https://en.m.wikipedia.org/wiki/GNU) softwares and Linux kernel makes up the Linux operating system. [read more](https://en.m.wikipedia.org/wiki/Linux)

#### GNU/Linux Controversial
<div class="pull-right"><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Richard_Stallman_-_F%C3%AAte_de_l%27Humanit%C3%A9_2014_-_010.jpg/320px-Richard_Stallman_-_F%C3%AAte_de_l%27Humanit%C3%A9_2014_-_010.jpg
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<center><a href="https://commons.m.wikimedia.org/wiki/File:Richard_Stallman_-_F%C3%AAte_de_l%27Humanit%C3%A9_2014_-_010.jpg#mw-jump-to-license">Richard Stallman from Wikimedia under CC0 license</a></center> </div>

There is controversy in Linux naming which is "Linux" or "GNU/Linux";
*Let me tell you short story that happened [how Linux became famous and why the controversial name] * [Richard Stallman](https://en.m.wikipedia.org/wiki/Richard_Stallman), the founder of Free Source Software (FOSS) and GNU. After he had problem with one of his printers and which he had no authority to modify the software in other to fix the issues unless it's taken back to the company, He campaigns for software to be distributed in a manner such that its users receive the freedoms to use, study, distribute and modify that software. This led him in creation of GNU OS with the aim to make the operating system free to use and modify. GNU has all of it operating system components completed but struggled to complete the core part which is the **kernel** namely [GNU Hurd](https://en.m.wikipedia.org/wiki/GNU_Hurd).

<div class="pull-left"><img src="https://upload.wikimedia.org/wikipedia/commons/5/5c/Linus_Torvalds_%28cropped%29.jpg
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<center><a href="https://commons.m.wikimedia.org/wiki/File:Linus_Torvalds_(cropped).jpg">Linus Torvald from Wikimedia under CC0 license</a></center> </div> 

[Linus Torvard](https://en.m.wikipedia.org/wiki/Linus_Torvalds) a software engineer developed Linux kernel in 1991 and released it as an open source at which time Hurd was still in early development, Linux can be used with GNU software; Since a GPL kernel already exists (Linux), there’s no longer a huge incentive to develop Hurd, and most people just used Linux. 
**The Combination of GNU and Linux Kernel makes up the Unix-like operating systems.**

![steemit-border](https://img.esteem.ws/av4tt0mlsg.png) 
### Kernel
<div class="pull-left"><img src="https://upload.wikimedia.org/wikipedia/commons/6/6b/Kernel_basic.jpg
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<center><a href="https://commons.m.wikimedia.org/wiki/File:Kernel_basic.jpg">Kernel basic from Wikimedia under CC0 license</a></center> </div>
Kernel is the smallest core program of an operating system, manages input/output requests from software, and translates them into data processing instructions for the central processing unit and other electronic components of a computer. It has two types namely; micro kernel and monolythic kernel. 

> A microkernel, which only contains basic functionality; [source](https://simple.m.wikipedia.org/wiki/Kernel_(computer_science))

> A monolithic kernel, which contains many device drivers. [source](https://simple.m.wikipedia.org/wiki/Kernel_(computer_science))

![steemit-border](https://img.esteem.ws/av4tt0mlsg.png) 
### Conclusion
Operating system is the important part of a machine for users to interact and render it properly, the operating system handles the resources such as memory, processing unit, input and output devices. 
The kernel is the core program of an operating system. A computer user never interacts directly with the kernel, It runs behind the scenes and cannot be seen unless its log is printed from a printer. Every operating system has its own kernel and some OS uses different types of kernel, without kernel the operating system can't interact with the hardware.

`Thanks for visiting my blog, expect more on computer science related articles.`

### REFERENCES
***
- [operating system - wikipedia](https://en.m.wikipedia.org/wiki/Operating_system)
- [operating system types - techtarget](https://whatis.techtarget.com/definition/operating-system-OS)
- [operating system functions - kenaplex](https://www.kenyaplex.com/resources/13801-types-and-functions-of-computer-operating-systems.aspx)
- [OS software - encyclopedia](https://www.encyclopedia.com/science-and-technology/chemistry/compounds-and-elements/operating-systems-software)
- [kernel - Wikipedia](http://www.greenrhinoenergy.com/solar/radiation/extraterrestrial.php)
- [GNU/Linux naming controversy - Wikipedia](https://en.m.wikipedia.org/wiki/GNU/Linux_naming_controversy)
- [kernel types - Wikipedia](https://simple.m.wikipedia.org/wiki/Kernel_(computer_science))

***
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