by Dinesh Thakur

To overcome the problem of underutilization of CPU and main memory, the multiprogramming was introduced. The multiprogramming is interleaved execution of multiple jobs by the same computer.



 
by Dinesh Thakur

To avoid the problems of early systems the batch processing systems were introduced. The problem of early systems was more setup time. So the problem of more set up time was reduced by processing the jobs in batches, known as batch processing system. In this approach similar jobs were submitted to the CPU for processing and were run together.



 
by Dinesh Thakur

Following are the services provided by an operating system for the convenience of users:

 

  1. Program Execution

 

The purpose of computer system is to allow the users to execute programs in an efficient manner. The operating system provides an environment where the user can conveniently run these programs. The user does not have to worry about the memory allocation or de-allocation or any other thing because these things are taken care of by the operating system.



 
by Dinesh Thakur

A computer system can be divided into five components; the hardware, the operating system, the utilities, the application programs and the end users. Following diagram shows the actual position of an operating system among these components.



 
by Dinesh Thakur

Spooling - simultaneous peripheral operations on-line, spooling refers to as a process that putting jobs in a buffer or say spool, or temporary storage area, a special area in memory or on a disk where a device can access them when it is ready. Spooling is useful because devices access data at different rates.



 
by Dinesh Thakur

Operating System is the System Software that makes the Computer work. We can say that an Operating System (OS) is Software that acts as an interface between you and the hardware. It not only contains drivers used to speak the hardware's language, but also offers you a very specific graphical user interface (GUI) to control the computer.



 
by Dinesh Thakur

Real Time System : There is also a Operating System which is known as Real Time Processing System. In this Response Time is already fixed. Means time to Display the Results after Possessing has fixed by the Processor or CPU.



 
by Dinesh Thakur

Marshalling is the process of gathering data and transforming it into a standard format before it is transmitted over a network so that the data can transcend network boundaries.

 
by Dinesh Thakur

Memory partitioning is the way to distribute the Kernel and User Space Area in Memory.

 

Paging is actually a minimum memory, which can be swap in and swap out from Memory. In modern Server operating systems, we can use Multiple Page Size Support. That actually helps to tune OS performance, depending on type of applications.



 
by Dinesh Thakur

The Demand Paging is also same with the Simple Paging. But the Main Difference is that in the Demand Paging Swapping is used. Means all the Pages will be in and out from the Memory when they are required. When we specify a Process for the Execution then the Processes is stored firstly on the Secondary Memory which is also known as the Hard Disk.

 
by Dinesh Thakur

Virtual Memory:   As we know that a Computer is designed for Performing the Multiple Tasks at a Time and for this Some Memory is also used by the Computer for executing the instructions those are given by the user. But when there is a Situation when the Memory (RAM) which is required by the user is high from the Available Memory. So at that situation we will use the Concept of Virtual Memory.



 
by Dinesh Thakur

As we know that operating system is that which executes the system and the operating system is the software which is responsible for running all the user programs so that generally memory is divided in to the two parts, first part is used by the operating system and the second part is used by the user programs and there may be some situations that the memory size of the operating system may be higher from the user memory and also vice versa.



 
by Dinesh Thakur

As we know that there are many problems arise in the continues memory allocation so that we uses the concept of the dynamic memory allocation. In the dynamic memory allocation memory is divided into the various partitions at the run time.



 
by Dinesh Thakur

For improving the performance of the system we use the concept of swapping. In the swapping the processes those are on waiting state and those are on suspend or temporary suspend will be stored from out side the memory locations so that the speed of process will be high.



 
by Dinesh Thakur

As we know that memory is that which stores the programs and these programs are used by the CPU for processing.  And there are two types of memories first is the logical memory and second is the physical memory. the memory which is temporary such as ram is also known as the temporary memory and the memory which is permanent such as hard disk is also known as the physical memory of system.



 
by Dinesh Thakur

Process Control block is used for storing the collection of information about the Processes and this is also called as the Data Structure which Stores the information about the process. The information of the Process is used by the CPU at the Run time. The various information which is Stored into the PCB as followings:



 
by Dinesh Thakur

Files are used for storing the Information of the user. Generally for arranging all the Files directories or Folders are used. A Folder or Directory is also called as the Container of the Files in which many Sub directors and Files are Stored. So that Files System Specifies the Arrangement of the Files in the System. There are following Directory Structures Available for organizing all the Files.

 
by Dinesh Thakur

File System: Files are used for storing the Information of the user; But Files are organized into the System by using a Specific Manner. Generally for arranging all the Files, directories or Folders are used.

 
by Dinesh Thakur

The Concept of File Sharing and Locking is used in the Multi-users Environment, or in which there are many users those are Requesting for a Single File, to Perform Some Operations.

 
by Dinesh Thakur

Files: As we know that Computers are used for storing the information for a Permanent Time or the Files are used for storing the Data of the users for a Long time Period. And the files can contains any type of information means they can Store the text, any Images or Pictures or any data in any Format. So that there must be Some Mechanism those are used for Storing the information, Accessing the information and also Performing Some Operations on the files.



 
by Dinesh Thakur

Disk Scheduling: As we know that on a single Computer we can Perform Many Operations at a Time so that Management is also necessary on all the Running Processes those are running on the System at a Time. With the help or Advent of the Multi-programming we can Execute Many Programs at a Time. So fir Controlling and providing the Memory to all the Processes Operating System uses the Concept of Disk Scheduling.



 
by Dinesh Thakur

Booting: When we start our Computer then there is an operation which is performed automatically by the Computer which is also called as Booting. In the Booting, System will check all the hardware’s and Software’s those are installed or Attached with the System and this will also load all the Files those are needed for running a system.



 
by Dinesh Thakur

Cache Memory : The Cache Memory is the Memory which is very nearest to the CPU , all the Recent Instructions are Stored into the Cache Memory. The Cache Memory is attached for storing the input which is given by the user and which is necessary for the CPU to Perform a Task. But the Capacity of the Cache Memory is too low in compare to Memory and Hard Disk.



 
by Dinesh Thakur

Operating System is software that works as an interface between a user and the computer hardware. The primary objective of an operating system is to make computer system convenient to use and to utilize computer hardware in an efficient manner. The operating system performs the basic tasks such as receiving input from the keyboard, processing instructions and sending output to the screen.



 
by Dinesh Thakur

Inter-Process Communication : Cooperating processes can communicate in a shared-memory environment. Cooperating processes communicate with each other via an Inter-Process-Communication (IPC) facility.

 
by Dinesh Thakur

Both the Shell and the Kernel are the Parts of this Operating System. These Both Parts are used for performing any Operation on the System. When a user gives his Command for Performing Any Operation, then the Request Will goes to the Shell Parts, The Shell Parts is also called as the Interpreter which translate the Human Program into the Machine Language and then the Request will be transferred to the Kernel. So that Shell is just called as the interpreter of the Commands which Converts the Request of the User into the Machine Language. 



 
by Dinesh Thakur

As we know that for performing any Operation as user must have to specify the Operation which he wants to Operate on the Computer. We can say that For Performing any Operation a user must have to Request for a Service from the System. For Making any Request a user will prepare a Special call which is also known as the System Call.



 
by Dinesh Thakur

Multi programming: Multiprogramming is the technique of running several programs at a time using timesharing. It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism. The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously.



 
by Dinesh Thakur

There are Many Functions those are Performed by the Operating System But the Main Goal of Operating System is to Provide the Interface between the user and the hardware Means Provides the Interface for Working on the System by the user. The various Functions those are Performed by the Operating System are as Explained below:-



 
by Dinesh Thakur

There are Many Operating Systems those have be Developed for Performing the Operations those are requested by the user. There are Many Operating Systems which have the Capability to Perform the Requests those are received from the System. The Operating system can perform a Single Operation and also Multiple Operations at a Time. So there are many types of Operating systems those are organized by using their Working Techniques.



 
by Dinesh Thakur

In this Jobs or Processes are Executed in the Manner in which they are entered into the Computer. In this Operating System Creates a Queue which contains the Sequence Order in which they are to be Executed and the Sequence in which the CPU will Execute the Process.



 
by Dinesh Thakur

In this Technique The Operating System will Search for the Shortest time means this will search which job will takes a Less Time of CPU for Running. And After Examining all the jobs, all the Jobs are arranged in the Sequence wise or they are Organized into the Priority Order.



 
by Dinesh Thakur

In the Round Robin Scheduling the Time of CPU is divided into the Equal Numbers which is also called as Quantum Time. Each Process which is Request for Execution will Consumes the Equal Number of Times of the CPU and after the Quantum Time of First Process, the CPU will automatically goes to the Next Process.



 
by Dinesh Thakur

In the C-Scan all the Processes are Arranged by using Some Circular List. Circular List is that in which there is no start and end point of the list means the End of the List is the Starting Point of the list. In the C-Scan Scheduling the CPU will search for the Process from Start to end and if an End has Found then this again start from the Starting Process.



 
by Dinesh Thakur

Mutex is a program object that allows multiple program threads to share the same resource, such as file access, but not simultaneously. When a program is started a mutex is created with a unique name. After this stage, any thread that needs the resource must lock the mutex from other threads while it is using the resource. The mutex is set to unlock when the data is no longer needed or the routine is finished.

 
by Dinesh Thakur

Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.



 
by Dinesh Thakur

Semaphores are often used to restrict the number of threads than can access some (physical or logical) resource.

 
by Dinesh Thakur

A Single Process may also contain sub Processes those are also known as the Child Process. So that we can say that a Process which is given to the System is also known as the Parent Process and all the other Parts of the Single Process are known as the Child Process. So that Every Process may also Contains Some Child process.

 
by Dinesh Thakur

A process which is Executed by the Process have various States, the State of the Process is also called as the Status of the process, The Status includes whether the Process has Executed or Whether the process is Waiting for Some input and output from the user and whether the Process is Waiting for the CPU to Run the Program after the Completion of the Process.



 
by Dinesh Thakur

Process: Process is the job which is the under Execution. Process is also known as the Running Job. For Execution there must be a System call which call the Processor or CPU for Performing any Operation. Process includes reading data from a File, Writing a Data from a File, Printing a document means to Say any Type of Operation is known as the Process. Every Process has some Attributes Like



 
by Dinesh Thakur

After Detecting the Deadlock, we must have to Apply Some Conditions for Removing a Deadlock. After Examining the Four Conditions which Occurs deadlock. Means Detect how and why a deadlock has occurred. Avoidance and Prevention means handle the Deadlock or Remove the Deadlock. Or Make a Program to handle the Deadlock. Various Ways for handing a deadlock.

 
by Dinesh Thakur

Dead-Lock is occurred in multiple users Computing Environment. As we know that there is Many Number of users those are going to perform their Transactions. Dead-Lock has occurred when two or More Users are requesting for data item or for a Resource of System for example two or more users Request for the Printers at a Same Time and When Dead-Lock has occurred.

 
by Dinesh Thakur

A process is a collection of virtual memory space, code, data, and system resources. A thread is code that is to be serially executed within a process. A processor executes threads, not processes, so each application has at least one process, and a process always has at least one thread of execution, known as the primary thread.



 
by Dinesh Thakur

DOS commands are small programs, which are made to perform a particular job. Every DOS command performs different task. It is not possible to work on the computer without these commands. There are two types of DOS command.



 
by Dinesh Thakur

Languages are used for Communication with the System. As we know that there are also Some Human Languages  like English, Punjabi and Hindi those are used for Communicating with the Other Humans. As we know that different Humans Understands different Languages.