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Operating System



An operating system (OS) is a set of programs that manage computer hardware resources and provide common services for application software.

The operating system is the most important type of system software in a computer system. A user cannot run an application program on the computer without an operating system, unless the application program is self booting.

Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting for cost allocation of processor time, mass storage, printing, and other resources.

For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between application programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently call the OS or be interrupted by it.

Operating systems are found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Examples of popular modern operating systems include Android, iOS, Linux, Mac OS X, all of which have their roots in Unix, and Microsoft Windows.

Types of Operating System

Real-time
Real-time operating systems are designed to allow computers to process and respond to input instantly. Usually, general-purpose operating systems, such as disk operating system (DOS), are not considered real time, as they may require seconds or minutes to respond to input.

Real-time operating systems are typically used when computers must react to the consistent input of information without delay. For example, real-time operating systems may be used in navigation.



Multi-user vs. Single-user
A multi-user operating system allows multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time.

Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system.



Multi-tasking vs. Single-tasking

When only a single program is allowed to run at a time, the system is grouped under a single-tasking system. However, when the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system.

Multi-tasking can be of two types:

In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking.

Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. MS Windows prior to Windows 2000 used to support cooperative multitasking.



Distributed
A distributed operating system manages a group of independent computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing.

Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.



Embedded
Embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy.

They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems.

Other Operating System Functions

The operating system provides for several other functions including:
  • System tools (programs) used to monitor computer performance, debug problems, or maintain parts of the system. 
  • A set of libraries or functions which programs may use to perform specific tasks especially relating to interfacing with computer system components.
The operating system makes these interfacing functions along with its other functions operate smoothly and these functions are mostly transparent to the user.

Operating System Concerns

An operating system is a computer program. Operating systems are written by human programmers who make mistakes. Therefore there can be errors in the code even though there may be some testing before the product is released.

Some companies have better software quality control and testing than others so you may notice varying levels of quality from operating system to operating system. Errors in operating systems cause three main types of problems:
  • System crashes and instabilities - These can happen due to a software bug typically in the operating system, although computer programs being run on the operating system can make the system more unstable or may even crash the system by themselves. This varies depending on the type of operating system. A system crash is the act of a system freezing and becoming unresponsive which would cause the user to need to reboot. 
    • Security flaws - Some software errors leave a door open for the system to be broken into by unauthorized intruders. As these flaws are discovered, unauthorized intruders may try to use these to gain illegal access to your system. Patching these flaws often will help keep your computer system secure. How this is done will be explained later. 
      • Sometimes errors in the operating system will cause the computer not to work correctly with some peripheral devices such as printers. 



      There are three major OS that you should consider using for your first desktop/notebook PC.
      • Windows: The most recent edition of Windows is Windows 7, previous versions are Windows Vista, Windows XP, and so on.
      • Mac: The second most common OS in desktop systems, Mac OS X is comparatively compared to Windows, although it's market share is increasing. Macs have been designed to be very easy for people to use, and are thus a good choice for a first system, as long as you don't mind not having as many software and games options as Windows users. Many Mac users are extremely loyal to the OS, due to the popularity of the iPod MP3 device, and various other Apple iDevices.
      • Linux: While it is also rare compared to Windows, Linux does have it's advantages. Linux is open source, which means that anyone can change the code around and redistribute it as they want, resulting in many different versions. Though it can be daunting, a Google search can help the average person decide which version of the OS would be best for them


      Last updated on: 02/10/2019

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