by Dinesh Thakur Category: Operating System

An operating system basically performs three independent tasks: it allows load after each other programs, it emulates a virtual machine and manages resources. Specify each task.



 
by Dinesh Thakur Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

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.

 
by Dinesh Thakur Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

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 Category: Operating System

Multiprocessor Operating System refers to the use of two or more central processing units (CPU) within a single computer system. These multiple CPUs are in a close communication sharing the computer bus, memory and other peripheral devices. These systems are referred as tightly coupled systems.



 
by Dinesh Thakur Category: Operating System

The real-time operating system used for a real-time application means for those applications where data processing should be done in the fixed and small quantum of time. It is different from general purpose computer where time concept is not considered as much crucial as in Real-Time Operating System. RTOS is a time-sharing system based on clock interrupts. Interrupt Service Routine (ISR) serve the interrupt, raised by the system. RTOS used Priority to execute the process. When a high priority process enters in system low priority process preempted to serve higher priority process. Real-time operating system synchronized the process. So that they can communicate with each other. Resources can be used efficiently without wastage of time.



 
by Dinesh Thakur Category: Operating System

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. Short form of Network Operating system is NOS. Some popular network operating systems are Novell Netware, Windows NT/2000, Linux, Sun Solaris, UNIX, and IBM OS/2. The network operating system which was first developed is Novell Netware. It was developed in 1983.



 
by Dinesh Thakur Category: Operating System

Distributed Operating System is a model where distributed applications are running on multiple computers linked by communications. A distributed operating system is an extension of the network operating system that supports higher levels of communication and integration of the machines on the network.



 
by Dinesh Thakur Category: Operating System

In earlier days, Computers was programmed to solve the problem. More prior day’s computer could perform only one job at a time. This computation resulted least CPU utilization. Most of time CPU was idle. To use CPU more efficiently, computer crossed many stages of evaluation.

In 1950 first operating system known as the batch operating system was introduced. Batch Operating System could execute a group of jobs in the form of a single deck of punched card.



 
by Dinesh Thakur Category: Operating System

A time sharing system allows many users to share the computer resources simultaneously. In other words, time sharing refers to the allocation of computer resources in time slots to several programs simultaneously. For example a mainframe computer that has many users logged on to it. Each user uses the resources of the mainframe -i.e. memory, CPU etc. The users feel that they are exclusive user of the CPU, even though this is not possible with one CPU i.e. shared among different users.



 
by Dinesh Thakur Category: Operating System

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 Category: Operating System

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.

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.