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

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

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

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

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 which is required by the user is high from the Available Memory.



 
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.

 
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

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

 
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

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

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

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

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

Multitasking is a logical extension of multiprogramming system that supports multiple programs to run concurrently. In multitasking more than one task are executed at the same time. In this technique the multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with single CPU, only one job can be processed at a time. Multitasking solves the problem by scheduling and deciding which task should be the running task and when a waiting task should get turn. This attempt is done with the help of interrupt (a signal) which is attended by CPU by keeping the current activity aside, saves its present status in buffer and returns to another important job whatever task it was doing earlier. The act of re-assigning a CPU from one task to another one is known as context switch.



 
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

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

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

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

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

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

Real time Operating Systems are very fast and quick respondent systems. These systems are used in an environment where a large number of events (generally external) must be accepted and processed in a short time. Real time processing requires quick transaction and characterized by supplying immediate response. For example, a measurement from a petroleum refinery indicating that temperature is getting too high and might demand for immediate attention to avoid an explosion.



 
by Dinesh Thakur

Network Operating System is an operating system that includes special functions for connecting computers and devices into a local-area network (LAN) or Inter-network. Some popular network operating systems are Novell Netware, Windows NT/2000, Linux, Sun Solaris, UNIX, and IBM OS/2.



 
by Dinesh Thakur

Parallel Processing Systems are designed to speed up the execution of programs by dividing the program into multiple fragments and processing these fragments simultaneously. Such systems are multiprocessor systems also known as tightly coupled systems. Parallel systems deal with the simultaneous use of multiple computer resources that can include a single computer with multiple processors, a number of computers connected by a network to form a parallel processing cluster or a combination of both.



 
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

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

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

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

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

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 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

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

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

Batch processing: The grouping together of several processing jobs to be executed one after another by a computer, without any user interaction. This is achieved by placing a list of the commands to start the required jobs into a BATCH FILE that can be executed as if it were a single program: hence batch processing is most often used in operating systems that have a COMMAND LINE user interface. Indeed, batch processing was the normal mode of working in the early days of mainframe computers, but modern personal computer applications typically require frequent user interaction, making them unsuitable for batch execution.



 
by Dinesh Thakur

MS-DOS (pronounced "em ess doss") stands for Microsoft disk operating system, the most widely-used operating system for IBM PC and compatible computers (an operating system is the master control software program that runs the computer itself). This means that MS-DOS is the most widely used computer operating system, period, since there are something like 80 to 100 million PCs in the world, and most of them use MS-DOS. There are at least two other versions of DOS that are compatible with MS-DOS (meaning they work the same way and run the same programs). So please see the definition for DOS for the whole story.



 
by Dinesh Thakur

If you have a PC you probably have a file named CONFIG.SYS on the disk you use to start, or boot, the computerA file that is automatically read at start up by the MS-DOS operating system used to load the DEVICE DRIVERS required by the various peripherals connected to the computer, and to set the correct configuration parameters for them. This file contains a variety of instructions used to customize the way your system works. Each time you start or restart the machine, the CONFIG.SYS file is read by the operating system (DOS or OS/2), which configures itself according to the instructions in the file. In DOS the typical CONFIG.SYS file starts with commands that tell the operating system how many files can be in use at anyone time, and how many buffers to create, like this:



 
by Dinesh Thakur

Computers are asked to store massive amounts of information on storage media such as floppy disks and hard disks. Long ago, the computer just saved all the files on the disk, and if you weren't careful, you could end up with a list of files so long you could strain your wrist just trying to scroll through them all! It was kind of like putting all the papers into your filing cabinet without folders.



 
by Dinesh Thakur

Cipher textis information that has been changed into secret code for security reasons. A scheme for encoding messages to prevent them being read by unauthorized persons. It may have been enciphered,encrypted,or encoded, but it all means the same thing: it doesn't look like English so no one can use the information unless they have thepasswordto decode it.

 
by Dinesh Thakur

In operating systems like DOS and Unix, and in many text-based or character mode programs, you control what's happening by typing commands on a command line. The command line is simply the line on the screen where you type your commands. The only way to control an operating system or a program that uses a command line interface like this is by typing commands-you don't get menus, dialog boxes, or buttons.



 
by Dinesh Thakur

A command interpreter, or command processor, is that crucial part of the operating system software that interprets, or processes, the commands you give, and then carries them out for you. In DOS, the command processor is usually COMMAND. COM, although DOS lets you substitute another command processor if you want. This sounds pretty technical and scary, but it really isn't difficult.



 
by Dinesh Thakur

BSD UNIX (Berkeley System Distribution) A family of versions of the UNIX operating system developed at the University of California at Berkeley in the early 1980s. BSD Unix version 4.0 was released in 1980 for DEC's VAX and PDP-ll computers. BSD Unix introduced many technical enhancements that have now been universally adopted, such as paged VIRTUAL MEMORY and built-in TCP/IP networking. It formed the basis for several commercial UNIX versions, including Sun's (prior to Solaris 2) and Hewlett Packard's ULTRIX.



 
by Dinesh Thakur

OS/2 stands for operating system/2, an operating system that was developed by Microsoft C01poration and IBM, and now being improved and marketed exclusively by IBM. OS/2 runs on 286-, 386-, and 486-based IBM PCs and compatibles. OS/2 has many of the same commands as DOS, can read DOS disks, but it is more sophisticated than DOS. In particular, OS/2 is a multi-tasking, multi-threaded operating system. Multi-tasking means it can run more than one application at a time; multi-threaded means that a single program can perform multiple separate tasks at the same time.



 
by Dinesh Thakur

Cooperative multitasking A MULTITASKING scheme under which each concurrently running program must at intervals voluntarily relinquish control of the CPU to the next program. Such programs must be specially written to suspend themselves in some non critical section and so, conversely, programs that are not so written cannot be multitasked. This contrasts with PRE-EMPTIVE MULTITASKING in which the OPERATING SYSTEM itself periodically suspends each task, so that any program may be multitasked. Apple's MACOS is a cooperative multitasking system, whereas UNIX and WINDOWS are preemptive.



 




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Dinesh ThakurDinesh Thakur is a Columinist and designer with strong passion and founder of Computer Notes. if you have any ideas or any request Find Dinesh Thakur on
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