WORKING WITH OPERATING SYSTEM

We all know what a “computer” is, it’s one of those very useful electronic devices that perform a variety of operations in accordance with a set of instructions called program. By now all mid-aged teenagers might know that a computer, in fact all electronic devices work on a simple cycle called I-P-O cycle. Also it’s crystal clear that I/O would obviously stand for Input and Output. Now what is P? P stands for “processing”. Processing actually is what the computer does and displays the output in response of the input. Being a computer science engineer we must know that, whatever this system does is actually what generally we humans do. So then how does it make a difference? The difference is that the computer works on a set of rules and these rules are called protocols. It has some syntax i.e. conventions which it is bound to follow. Since the processor is responsible for processing, it must be faster than what our human brain is capable of doing and, it’s always faster.

Thus if computer processes just in the same way we humans solve a problem then, it should practically use the same formulas we work on, then what is going to make this system run on the same formulas? Well if we can control the flow of signal as per our wish and compel the system to do what we instruct then we can get the desired output, isn’t it? But that too doesn’t seem pleasing as it’s not as easy as it seems to appear. To compel it to do something we must have certain rules which it should follow. These rules are nothing but “software”.

Software, another very complex but important term in computing that is to be understood in depth. Software represents the set of programs that governs the operation of a computer system and make the hardware run. Technically software is a man-made program that can control the flow of information depending on what we have coded it for. It’s just like an object designed for particular work (Pencil’s work is to write where Eraser’s work is to erase).

Software can be subdivided into two basic types:

• System Software.

• Application Software.

As we observe the word “system” appears here so it obviously has got something to do with the controlling of system. System software primarily focuses on managing the hardware run properly, flow of information in and out and governs the working of Application software.

It can be further divided into two types, viz. Operating System and Language Processors.

Ex. of Operating system: Windows, Macintosh, UNIX, Linux, etc.

Ex. of Language processors: Assembler, Interpreter, Compiler.

Set of programs necessary to carry out operations of specific application. These are the programs that are written as well as used by the humans. These programs are written to fulfill the personal requirements of human like an application for playing games. Does neither good nor any bad to humankind or machines, just for our entertainment we have made the software. Similarly there are several applications.

Ex. of the Applications: AutoCAD, MS-Word, etc.

An operating system can be defined as a program which acts as an interface between a user and the hardware (i.e. all computer resources).

A simple way to understand the operating system is:

The above shown sketch depicts the interaction starting from User till the Hardware/C.P.U.

To understand the Operating system (here onwards OS), we compare it with real world. Our duty is to study and excel. For that we go to different institutions. Now we are nothing but the ‘End User’. Teachers act as application software, each expert in their field, conveying us the knowledge. Here the Principal has no work practically i.e. they don’t consult us directly but, they still control the institution and its proper functioning. Here hardware is the classrooms, benches and other tools we use in school. The Principal who they act as OS over here has to maintain proper conditioning of the hardware, functioning of application software and also control the interaction between the three.

In the same way OS acts as a guide, one that has been designed such that it maintains a correct balance between user and applications used by them, and the proper flow of data between the applications and hardware.

Now as I have mentioned that an OS looks on both the hardware and the user, the OS must have to separate units to do so. Thus OS has two parts: Kernel and the Shell.

A real-time operating system is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main objective of real-time operating systems is their quick and predictable response to events. They have an event-driven or time-sharing design and often aspects of both. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.

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.

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: pre-emptive or co-operative. 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, as does AmigaOS. 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 and Mac OS prior to OS X used to support cooperative multitasking.

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 operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDA’s 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.

With the aid of the firmware and device drivers, the kernelprovides the most basic level of control over all of the computer's hardware devices. It manages memory access for programs in the RAM, it determines which programs get access to which hardware resources, it sets up or resets the CPU's operating states for optimal operation at all times, and it organizes the data for long-term non-volatile storage with file systems on such media as disks, tapes, flash memory, etc.

Every computer that is to be operated by an individual requires a user interface. The user interface is not actually a part of the operating system—it generally runs in a separate program usually referred to as a shell, but is essential if human interaction is to be supported. The user interface requests services from the operating system that will acquire data from input hardware devices, such as a keyboard, mouse or credit card reader, and requests operating system services to display prompts, status messages and such on output hardware devices, such as a video monitor or printer. The two most common forms of a user interface have historically been the command-line interface, where computer commands are typed out line-by-line, and the graphical user interface, where a visual environment is present.

Most of the OS today run in Graphical User Interface or commonly called GUI.